Datasets:

gabrielaltay

/

wiki-test

like 0

[ { "plaintext": "In physics, the term dielectric strength has the following meanings:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22939 ], "anchor_spans": [ [ 3, 10 ] ] }, { "plaintext": "for a pure electrically insulating material, the maximum electric field that the material can withstand under ideal conditions without undergoing electrical breakdown and becoming electrically conductive (i.e. without failure of its insulating properties).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 15066, 41092, 853826 ], "anchor_spans": [ [ 11, 34 ], [ 57, 71 ], [ 146, 166 ] ] }, { "plaintext": "For a specific piece of dielectric material and location of electrodes, the minimum applied electric field (i.e. the applied voltage divided by electrode separation distance) that results in breakdown. This is the concept of breakdown voltage.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 10008, 1224250 ], "anchor_spans": [ [ 60, 69 ], [ 225, 242 ] ] }, { "plaintext": "The theoretical dielectric strength of a material is an intrinsic property of the bulk material, and is independent of the configuration of the material or the electrodes with which the field is applied. This \"intrinsic dielectric strength\" corresponds to what would be measured using pure materials under ideal laboratory conditions. At breakdown, the electric field frees bound electrons. If the applied electric field is sufficiently high, free electrons from background radiation may be accelerated to velocities that can liberate additional electrons by collisions with neutral atoms or molecules, in a process known as avalanche breakdown. Breakdown occurs quite abruptly (typically in nanoseconds), resulting in the formation of an electrically conductive path and a disruptive discharge through the material. In a solid material, a breakdown event severely degrades, or even destroys, its insulating capability.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41026, 4882, 3134232, 36104, 853826 ], "anchor_spans": [ [ 16, 26 ], [ 463, 483 ], [ 625, 644 ], [ 692, 703 ], [ 774, 794 ] ] }, { "plaintext": "Electric current is a flow of electrically charged particles in a material caused by an electric field. The mobile charged particles responsible for electric current are called charge carriers. In different substances different particles serve as charge carriers: in metals and other solids some of the outer electrons of each atom (conduction electrons) are able to move about the material; in electrolytes and plasma it is ions, electrically charged atoms or molecules, and electrons. A substance that has a high concentration of charge carriers available for conduction will conduct a large current with the given electric field created by a given voltage applied across it, and thus has a low electrical resistivity; this is called an electrical conductor. A material that has few charge carriers will conduct very little current with a given electric field and has a high resistivity; this is called an electrical insulator.", "section_idx": 1, "section_name": "Electrical breakdown", "target_page_ids": [ 6207, 352541, 41092, 488140, 9476, 46870556, 48336, 25916521, 18963787, 902, 19555, 32549, 61580, 198984, 15066 ], "anchor_spans": [ [ 0, 16 ], [ 43, 59 ], [ 88, 102 ], [ 178, 192 ], [ 311, 319 ], [ 335, 354 ], [ 397, 408 ], [ 414, 420 ], [ 427, 430 ], [ 454, 458 ], [ 463, 471 ], [ 655, 662 ], [ 701, 723 ], [ 743, 763 ], [ 913, 933 ] ] }, { "plaintext": "However when a large enough electric field is applied to any insulating substance, at a certain field strength the concentration of charge carriers in the material suddenly increases by many orders of magnitude, so its resistance drops and it becomes a conductor. This is called electrical breakdown. The physical mechanism causing breakdown differs in different substances. In a solid, it usually occurs when the electric field becomes strong enough to pull outer valence electrons away from their atoms, so they become mobile. The field strength at which break down occurs is an intrinsic property of the material called its dielectric strength. ", "section_idx": 1, "section_name": "Electrical breakdown", "target_page_ids": [ 568674 ], "anchor_spans": [ [ 468, 484 ] ] }, { "plaintext": "In practical electric circuits electrical breakdown is often an unwanted occurrence, a failure of insulating material causing a short circuit, resulting in a catastrophic failure of the equipment. The sudden drop in resistance causes a high current to flow through the material, and the sudden extreme Joule heating may cause the material or other parts of the circuit to melt or vaporize explosively. However, breakdown itself is reversible. If the current supplied by the external circuit is sufficiently limited, no damage is done to the material, and reducing the applied voltage causes a transition back to the material's insulating state.", "section_idx": 1, "section_name": "Electrical breakdown", "target_page_ids": [ 9559, 235898, 604798 ], "anchor_spans": [ [ 13, 29 ], [ 128, 141 ], [ 304, 317 ] ] }, { "plaintext": "It may vary with sample thickness. (see \"defects\" below)", "section_idx": 2, "section_name": "Factors affecting apparent dielectric strength", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "It may vary with operating temperature.", "section_idx": 2, "section_name": "Factors affecting apparent dielectric strength", "target_page_ids": [ 25950683 ], "anchor_spans": [ [ 17, 38 ] ] }, { "plaintext": "It may vary with frequency.", "section_idx": 2, "section_name": "Factors affecting apparent dielectric strength", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For gases (e.g. nitrogen, sulfur hexafluoride) it normally decreases with increased humidity as ions in water can provide conductive channels.", "section_idx": 2, "section_name": "Factors affecting apparent dielectric strength", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For gases it increases with pressure according to Paschen's law", "section_idx": 2, "section_name": "Factors affecting apparent dielectric strength", "target_page_ids": [ 614192 ], "anchor_spans": [ [ 50, 63 ] ] }, { "plaintext": "For air, dielectric strength increases slightly as the absolute humidity increases but decreases with an increase in relative humidity", "section_idx": 2, "section_name": "Factors affecting apparent dielectric strength", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The field strength at which break down occurs depends on the respective geometries of the dielectric (insulator) and the electrodes with which the electric field is applied, as well as the rate of increase of the applied electric field. Because dielectric materials usually contain minute defects, the practical dielectric strength will be a significantly less than the intrinsic dielectric strength of an ideal, defect-free, material. Dielectric films tend to exhibit greater dielectric strength than thicker samples of the same material. For instance, the dielectric strength of silicon dioxide films of thickness around 1 μm is about 0.5GV/m. However very thin layers (below, say, ) become partially conductive because of electron tunneling. Multiple layers of thin dielectric films are used where maximum practical dielectric strength is required, such as high voltage capacitors and pulse transformers. Since the dielectric strength of gases varies depending on the shape and configuration of the electrodes, it is usually measured as a fraction of the dielectric strength of nitrogen gas.", "section_idx": 3, "section_name": "Break down field strength", "target_page_ids": [ 41092, 20627, 643769, 4932111, 30906, 21175 ], "anchor_spans": [ [ 147, 161 ], [ 625, 627 ], [ 725, 743 ], [ 873, 882 ], [ 894, 905 ], [ 1081, 1093 ] ] }, { "plaintext": "Dielectric strength (in MV/m, or 10volt/meter) of various common materials:", "section_idx": 3, "section_name": "Break down field strength", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In SI, the unit of dielectric strength is volts per meter (V/m). It is also common to see related units such as volts per centimeter (V/cm), megavolts per meter (MV/m), and so on.", "section_idx": 4, "section_name": "Units", "target_page_ids": [ 26764, 32567, 18947, 7669 ], "anchor_spans": [ [ 3, 5 ], [ 42, 46 ], [ 52, 57 ], [ 122, 132 ] ] }, { "plaintext": "In United States customary units, dielectric strength is often specified in volts per mil (a mil is 1/1000 inch). The conversion is:", "section_idx": 4, "section_name": "Units", "target_page_ids": [ 32308, 5978127, 14775 ], "anchor_spans": [ [ 3, 32 ], [ 86, 89 ], [ 107, 111 ] ] }, { "plaintext": " Breakdown voltage", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 1224250 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Relative permittivity", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 53781 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Rotational Brownian motion", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 20793410 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Paschen's law - variation of dielectric strength of gas related to pressure", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 614192 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Electrical treeing", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 4592652 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Lichtenberg figure", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 476416 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Article \"The maximum dielectric strength of thin silicon oxide films\" from IEEE Transactions on Electron Devices", "section_idx": 7, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Electricity" ]

[]

[ { "plaintext": "Differential Manchester encoding (DM) is a line code in digital frequency modulation in which data and clock signals are combined to form a single two-level self-synchronizing data stream. In various specific applications, this method is also called by various other names, including biphase mark code (CC), F2F (frequency/double frequency), Aiken biphase, and conditioned diphase.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41317, 18985040, 182693, 28738, 47868 ], "anchor_spans": [ [ 44, 53 ], [ 95, 99 ], [ 104, 116 ], [ 163, 176 ], [ 177, 188 ] ] }, { "plaintext": "Differential Manchester encoding is a differential encoding technology, using the presence or absence of transitions to indicate logical value. An improvement to Manchester coding which is a special case of binary phase-shift keying, it is not necessary to know the initial polarity of the transmitted message signal, because the information is not represented by the absolute voltage levels but by their transitions.", "section_idx": 1, "section_name": "Definition", "target_page_ids": [ 4934468, 161711, 41350, 41551 ], "anchor_spans": [ [ 38, 59 ], [ 129, 142 ], [ 162, 179 ], [ 207, 232 ] ] }, { "plaintext": "Differential Manchester encoding has the following advantages over some other line codes:", "section_idx": 1, "section_name": "Definition", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A transition is guaranteed at least once every bit, for robust clock recovery.", "section_idx": 1, "section_name": "Definition", "target_page_ids": [ 6076335 ], "anchor_spans": [ [ 64, 78 ] ] }, { "plaintext": " In a noisy environment, detecting transitions is less error-prone than comparing signal levels against a threshold.", "section_idx": 1, "section_name": "Definition", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Unlike with Manchester encoding, only the presence of a transition is important, not the polarity. Differential coding schemes will work exactly the same if the signal is inverted (e.g. wires swapped). Other line codes with this property include NRZI, bipolar encoding, coded mark inversion, and MLT-3 encoding.", "section_idx": 1, "section_name": "Definition", "target_page_ids": [ 4934468, 41425, 1431410, 8532309, 1357879 ], "anchor_spans": [ [ 100, 119 ], [ 247, 251 ], [ 253, 269 ], [ 271, 291 ], [ 297, 311 ] ] }, { "plaintext": " If the high and low signal levels have the same magnitude with opposite polarity, the average voltage around each unconditional transition is zero. Zero DC bias reduces the necessary transmitting power, minimizes the amount of electromagnetic noise produced by the transmission line, and eases the use of isolating transformers.", "section_idx": 1, "section_name": "Definition", "target_page_ids": [ 2047311 ], "anchor_spans": [ [ 154, 161 ] ] }, { "plaintext": "These positive features are achieved at the expense of doubling the clock frequencythere are two clock ticks per bit period (marked with full and dotted lines in the figure). At every second clock tick, marked with a dotted line, there is a potential level transition conditional on the data. At the other ticks, the line state changes unconditionally to ease clock recovery. One version of the code makes a transition for 0 and no transition for 1; the other makes a transition for 1 and no transition for 0.", "section_idx": 1, "section_name": "Definition", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Differential Manchester encoding is specified in the IEEE 802.5 standard for Token Ring local area networks, and is used for many other applications, including magnetic and optical storage. As Biphase Mark Code (BMC), it is used in AES3, S/PDIF, SMPTE time code, USB PD, xDSL and DALI. Many magnetic stripe cards also use BMC encoding, often called F2F (frequency/double frequency) or Aiken Biphase, according to the ISO/IEC 7811 standard. Differential Manchester encoding is also the original modulation method used for single-density floppy disks, followed by double-density modified frequency modulation (MFM), or Differential Manchester encoding.", "section_idx": 1, "section_name": "Definition", "target_page_ids": [ 7016168, 175426, 150049, 164385, 32073, 41038, 5743345, 45532780, 82382, 10891, 383902 ], "anchor_spans": [ [ 53, 63 ], [ 232, 236 ], [ 238, 244 ], [ 246, 261 ], [ 263, 269 ], [ 271, 275 ], [ 280, 284 ], [ 291, 306 ], [ 417, 429 ], [ 537, 548 ], [ 578, 607 ] ] }, { "plaintext": " Manchester code", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 41350 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " McASP", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 8382758 ], "anchor_spans": [ [ 1, 6 ] ] }, { "plaintext": " FM", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 449077 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " Watkinson, John (1994) The Art of Digital Audio, 2nd edition. Oxford: Focal Press. ", "section_idx": 4, "section_name": "Further reading", "target_page_ids": [ 13631649 ], "anchor_spans": [ [ 71, 82 ] ] }, { "plaintext": " Introduction to magnetic stripe technology", "section_idx": 4, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " (https://www.sqa.org.uk/e-learning/NetTechDC01ECD/page_09.htm) Introduction to rudimentary biphase encoding", "section_idx": 4, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] } ]

[ "Line_codes" ]

[ "BMC" ]

[ { "plaintext": "In optics, a diffraction grating is an optical component with a periodic structure that diffracts light into several beams travelling in different directions (i.e., different diffraction angles). The emerging coloration is a form of structural coloration. The directions or diffraction angles of these beams depend on the wave (light) incident angle to the diffraction grating, the spacing or distance between adjacent diffracting elements (e.g., parallel slits for a transmission grating) on the grating, and the wavelength of the incident light. The grating acts as a dispersive element. Because of this, diffraction gratings are commonly used in monochromators and spectrometers, but other applications are also possible such as optical encoders for high precision motion control and wavefront measurement.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22483, 8603, 32747596, 172333, 516414, 45311025 ], "anchor_spans": [ [ 3, 9 ], [ 88, 97 ], [ 233, 254 ], [ 570, 580 ], [ 649, 662 ], [ 668, 680 ] ] }, { "plaintext": "For typical applications, a reflective grating has ridges or rulings on its surface while a transmissive grating has transmissive or hollow slits on its surface. Such a grating modulates the amplitude of an incident wave on it to create a diffraction pattern. There are also gratings that modulate the phases of incident waves rather than the amplitude, and these type of gratings can be produced frequently by using holography.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 521267, 66338 ], "anchor_spans": [ [ 28, 38 ], [ 417, 427 ] ] }, { "plaintext": "James Gregory (1638–1675) observed the diffraction patterns caused by a bird feather, which was effectively the first diffraction grating (in a natural form) to be discovered, about a year after Isaac Newton's prism experiments. The first man-made diffraction grating was made around 1785 by Philadelphia inventor David Rittenhouse, who strung hairs between two finely threaded screws. This was similar to notable German physicist Joseph von Fraunhofer's wire diffraction grating in 1821. The principles of diffraction were discovered by Thomas Young and Augustin-Jean Fresnel. Using these principles, Fraunhofer was the first who used a diffraction grating to obtain line spectra and the first who measured the wavelengths of spectral lines with a diffraction grating.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 220425, 14627, 445597, 50585, 461524, 64659, 423781, 51624, 1141 ], "anchor_spans": [ [ 0, 13 ], [ 195, 207 ], [ 284, 288 ], [ 292, 304 ], [ 314, 331 ], [ 431, 452 ], [ 483, 487 ], [ 538, 550 ], [ 555, 576 ] ] }, { "plaintext": "Gratings with the lowest line-distance (d) were created, in the 1860s, by Friedrich Adolph Nobert (1806–1881) in Greifswald; then the two Americans Lewis Morris Rutherfurd (1816–1892) and William B. Rogers (1804–1882) took over the lead; and, by the end of the 19th century, the concave gratings of Henry Augustus Rowland (1848–1901) were the best available.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 70419031, 747120 ], "anchor_spans": [ [ 74, 97 ], [ 299, 321 ] ] }, { "plaintext": "A diffraction grating can create \"rainbow\" colors when it is illuminated by a wide-spectrum (e.g., continuous) light source. Rainbow-like colors from closely spaced narrow tracks on optical data storage disks such as CDs or DVDs are an example of light diffraction caused by diffraction gratings. A usual diffraction grating has parallel lines (It is true for 1-dimensional gratings, but 2 or 3-dimensional gratings are also possible and they have their own applications such as wavefront measurement), while a CD has a spiral of finely spaced data tracks. Diffraction colors also appear when one looks at a bright point source through a translucent fine-pitch umbrella-fabric covering. Decorative patterned plastic films based on reflective grating patches are inexpensive and commonplace. A similar color separation seen from thin layers of oil (or gasoline, etc.) on water, known as iridescence, are not caused by diffraction from a grating but rather by thin film interference from the closely stacked transmissive layers.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 29329, 6429, 11014498, 8603, 371786, 27301235 ], "anchor_spans": [ [ 83, 91 ], [ 217, 219 ], [ 224, 227 ], [ 253, 264 ], [ 886, 897 ], [ 958, 980 ] ] }, { "plaintext": "For a diffraction grating, the relationship between the grating spacing (i.e., the distance between adjacent grating grooves or slits), the angle of the wave (light) incidence to the grating, and the diffracted wave from the grating, is known as the grating equation. Like many other optical formulas, the grating equation can be derived by using the Huygens–Fresnel principle, stating that each point on a wavefront of a propagating wave can be considered to act as a point wave source, and a wavefront at any subsequent point can be found by adding together the contributions from each of these individual point wave sources on the previous wavefront.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [ 14359 ], "anchor_spans": [ [ 351, 376 ] ] }, { "plaintext": "Gratings may be of the 'reflective' or 'transmissive' type, analogous to a mirror or lens, respectively. A grating has a 'zero-order mode' (where the integer order of diffraction m is set to zero), in which a ray of light behaves according to the laws of reflection (like a mirror) and refraction (like a lens), respectively.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An idealized diffraction grating is made up of a set of slits of spacing , that must be wider than the wavelength of interest to cause diffraction. Assuming a plane wave of monochromatic light of wavelength at normal incidence on a grating (I.e., wavefronts of the incident wave are parallel to the grating main plane), each slit in the grating acts as a quasi point wave source from which light propagates in all directions (although this is typically limited to the forward hemisphere from the point source). Of course, every point on every slit to which the incident wave reaches plays as a point wave source for the diffraction wave and all these contributions to the diffraction wave determine the detailed diffraction wave light property distribution, but diffraction angles (at the grating) at which the diffraction wave intensity is highest are determined only by these quasi point sources corresponding the slits in the grating. After the incident light (wave) interacts with the grating, the resulting diffracted light from the grating is composed of the sum of interfering wave components emanating from each slit in the grating; At any given point in space through which the diffracted light may pass, typically called observation point, the path length from each slit in the grating to the given point varies, so the phase of the wave emanating from each of the slits at that point also varies. As a result, the sum of the diffracted waves from the grating slits at the given observation point creates a peak, valley, or some degree between them in light intensity through additive and destructive interference. When the difference between the light paths from adjacent slits to the observation point is equal to an odd integer-multiple of the half of the wavelength, l with an odd integer , the waves are out of phase at that point, and thus cancel each other to create the (locally) minimum light intensity. Similarly, when the path difference is a multiple of , the waves are in phase and the (locally) maximum intensity occurs. For light at the normal incidence to the grating, the intensity maxima occur at diffraction angles , which satisfy the relationship , where is the angle between the diffracted ray and the grating's normal vector, is the distance from the center of one slit to the center of the adjacent slit, and is an integer representing the propagation-mode of interest called the diffraction order.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [ 173224, 15112, 15112, 173224, 14563 ], "anchor_spans": [ [ 211, 217 ], [ 1073, 1084 ], [ 1600, 1624 ], [ 2245, 2251 ], [ 2352, 2359 ] ] }, { "plaintext": "When a plane light wave is normally incident on the grating, the diffracted light has maxima at diffraction angles given by the diffraction equation as", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "It can be shown that if the plane wave is incident at any arbitrary angle to the grating normal, the grating equation becomes", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "or Either choice is fine as long as the choice is kept through diffraction-related calculations. The resulting difference between two choices is the signs of diffraction orders, e.g., in the first choice becomes in the second choice. When solved for diffracted angle at which the diffracted wave intensity are maximized, the equation becomes", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The diffracted light that corresponds to direct transmission for a transmissive diffraction grating or specular reflection for a reflective grating is called the zero order, and is denoted . The other diffracted light intensity maxima occur at angles represented by non-zero integer diffraction orders . Note that can be positive or negative, corresponding to diffracted orders on the both sides of the zero order diffracted beam.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [ 679297 ], "anchor_spans": [ [ 103, 122 ] ] }, { "plaintext": "Even if the grating equation is derived from a specific grating such as the grating in the right diagram (This grating is called a blazed grating.), the equation can apply to any regular structure of the same spacing, because the phase relationship between light scattered from adjacent diffracting elements of the grating remains the same. The detailed diffracted light property distribution (e.g., intensity) depends on the detailed structure of the grating elements as well as on the number of elements in the grating, but it always gives maxima in the directions given by the grating equation.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Depending on how a grating modulates incident light on it to cause the diffracted light, there are the following grating types.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Transmission amplitude diffraction grating, that spatially and periodically modulates the intensity of an incident wave that transmits though the grating (and the diffracted wave is the consequence from this modulation). ", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Reflection amplitude diffraction gratings, that spatially and periodically modulates the intensity of an incident wave that is reflected from the grating.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Transmission phase diffraction grating, that spatially and periodically modulates the phase of an incident wave passing though the grating.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Reflection phase diffraction grating, that spatially and periodically modulates the phase of an incident wave reflected from the grating.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An optical axis diffraction grating, in which the optical axis is spatially and periodically modulated, is also considered a either reflection or transmission phase diffraction grating.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [ 5179603 ], "anchor_spans": [ [ 3, 35 ] ] }, { "plaintext": "The grating equation applies to all these gratings due to the same phase relationship between the diffracted waves from adjacent diffracting elements of the gratings, even if the detailed distribution of the diffracted wave property depends on the detailed structure of each grating.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Quantum electrodynamics (QED) offers another derivation of the properties of a diffraction grating in terms of photons as particles (at some level). QED can be described intuitively with the path integral formulation of quantum mechanics. As such it can model photons as potentially following all paths from a source to a final point, each path with a certain probability amplitude. These probability amplitudes can be represented as a complex number or equivalent vector—or, as Richard Feynman simply calls them in his book on QED, \"arrows\".", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [ 25268, 23535, 438476, 429425, 25523 ], "anchor_spans": [ [ 0, 23 ], [ 111, 117 ], [ 191, 216 ], [ 360, 381 ], [ 479, 494 ] ] }, { "plaintext": "For the probability that a certain event will happen, one sums the probability amplitudes for all of the possible ways in which the event can occur, and then takes the square of the length of the result. The probability amplitude for a photon from a monochromatic source to arrive at a certain final point at a given time, in this case, can be modeled as an arrow that spins rapidly until it is evaluated when the photon reaches its final point. For example, for the probability that a photon will reflect off of a mirror and be observed at a given point a given amount of time later, one sets the photon's probability amplitude spinning as it leaves the source, follows it to the mirror, and then to its final point, even for paths that do not involve bouncing off of the mirror at equal angles. One can then evaluate the probability amplitude at the photon's final point; next, one can integrate over all of these arrows (see vector sum), and square the length of the result to obtain the probability that this photon will reflect off of the mirror in the pertinent fashion. The times these paths take are what determine the angle of the probability amplitude arrow, as they can be said to \"spin\" at a constant rate (which is related to the frequency of the photon).", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [ 32533 ], "anchor_spans": [ [ 928, 938 ] ] }, { "plaintext": "The times of the paths near the classical reflection site of the mirror are nearly the same, so the probability amplitudes point in nearly the same direction—thus, they have a sizable sum. Examining the paths towards the edges of the mirror reveals that the times of nearby paths are quite different from each other, and thus we wind up summing vectors that cancel out quickly. So, there is a higher probability that light will follow a near-classical reflection path than a path further out. However, a diffraction grating can be made out of this mirror, by scraping away areas near the edge of the mirror that usually cancel nearby amplitudes out—but now, since the photons don't reflect from the scraped-off portions, the probability amplitudes that would all point, for instance, at forty-five degrees, can have a sizable sum. Thus, this lets light of the right frequency sum to a larger probability amplitude, and as such possess a larger probability of reaching the appropriate final point.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This particular description involves many simplifications: a point source, a \"surface\" that light can reflect off of (thus neglecting the interactions with electrons) and so forth. The biggest simplification is perhaps in the fact that the \"spinning\" of the probability amplitude arrows is actually more accurately explained as a \"spinning\" of the source, as the probability amplitudes of photons do not \"spin\" while they are in transit. We obtain the same variation in probability amplitudes by letting the time at which the photon left the source be indeterminate—and the time of the path now tells us when the photon would have left the source, and thus what the angle of its \"arrow\" would be. However, this model and approximation is a reasonable one to illustrate a diffraction grating conceptually. Light of a different frequency may also reflect off of the same diffraction grating, but with a different final point.", "section_idx": 1, "section_name": "Theory of operation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The wavelength dependence in the grating equation shows that the grating separates an incident polychromatic beam into its constituent wavelength components at different angles, i.e., it is angular dispersive. Each wavelength of input beam spectrum is sent into a different direction, producing a rainbow of colors under white light illumination. This is visually similar to the operation of a prism, although the mechanism is very different. A prism refracts waves of different wavelengths at different angles due to their different refractive indices, while a grating diffracts different wavelengths at different angles due to interference at each wavelength.", "section_idx": 2, "section_name": "Gratings as dispersive elements", "target_page_ids": [ 969793, 172333, 10134, 3871014, 8178295 ], "anchor_spans": [ [ 95, 108 ], [ 198, 208 ], [ 241, 249 ], [ 298, 305 ], [ 396, 401 ] ] }, { "plaintext": "The diffracted beams corresponding to consecutive orders may overlap, depending on the spectral content of the incident beam and the grating density. The higher the spectral order, the greater the overlap into the next order.", "section_idx": 2, "section_name": "Gratings as dispersive elements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The grating equation shows that the angles of the diffracted orders only depend on the grooves' period, and not on their shape. By controlling the cross-sectional profile of the grooves, it is possible to concentrate most of the diffracted optical energy in a particular order for a given wavelength. A triangular profile is commonly used. This technique is called blazing. The incident angle and wavelength for which the diffraction is most efficient (the ratio of the diffracted optical energy to the incident energy is the highest) are often called blazing angle and blazing wavelength. The efficiency of a grating may also depend on the polarization of the incident light. Gratings are usually designated by their groove density, the number of grooves per unit length, usually expressed in grooves per millimeter (g/mm), also equal to the inverse of the groove period. The groove period must be on the order of the wavelength of interest; the spectral range covered by a grating is dependent on groove spacing and is the same for ruled and holographic gratings with the same grating constant (meaning groove density or the groove period). The maximum wavelength that a grating can diffract is equal to twice the grating period, in which case the incident and diffracted light are at ninety degrees (90°) to the grating normal. To obtain frequency dispersion over a wider frequency one must use a prism. The optical regime, in which the use of gratings is most common, corresponds to wavelengths between 100 nm and 10 µm. In that case, the groove density can vary from a few tens of grooves per millimeter, as in echelle gratings, to a few thousands of grooves per millimeter.", "section_idx": 2, "section_name": "Gratings as dispersive elements", "target_page_ids": [ 17975799, 37510191, 41564, 33125, 282998, 21837, 20627, 9019008 ], "anchor_spans": [ [ 365, 372 ], [ 594, 604 ], [ 641, 653 ], [ 919, 929 ], [ 1400, 1405 ], [ 1511, 1513 ], [ 1521, 1523 ], [ 1616, 1632 ] ] }, { "plaintext": "When groove spacing is less than half the wavelength of light, the only present order is the m = 0 order. Gratings with such small periodicity (with respect to the incident light wavelength) are called subwavelength gratings and exhibit special optical properties. Made on an isotropic material the subwavelength gratings give rise to form birefringence, in which the material behaves as if it were birefringent.", "section_idx": 2, "section_name": "Gratings as dispersive elements", "target_page_ids": [ 14865, 174412, 174412 ], "anchor_spans": [ [ 276, 285 ], [ 340, 353 ], [ 399, 411 ] ] }, { "plaintext": "SR gratings are named due to its surface structure of depressions (low relief) and elevations (high relief). Originally, high-resolution gratings were ruled by high-quality ruling engines whose construction was a large undertaking. Henry Joseph Grayson designed a machine to make diffraction gratings, succeeding with one of 120,000 lines to the inch (approx. 4,724 lines per mm) in 1899. Later, photolithographic techniques created gratings via holographic interference patterns. A holographic grating has sinusoidal grooves as the result of an optical sinusoidal interference pattern on the grating material during its fabrication, and may not be as efficient as ruled gratings, but are often preferred in monochromators because they produce less stray light. A copying technique can make high quality replicas from master gratings of either type, thereby lowering fabrication costs.", "section_idx": 3, "section_name": "Fabrication", "target_page_ids": [ 13288679, 9652225, 18426, 66338, 11459267, 516414, 21416745 ], "anchor_spans": [ [ 173, 187 ], [ 232, 252 ], [ 396, 413 ], [ 446, 457 ], [ 483, 502 ], [ 708, 721 ], [ 749, 760 ] ] }, { "plaintext": "Semiconductor technology today is also utilized to etch holographically patterned gratings into robust materials such as fused silica. In this way, low stray-light holography is combined with the high efficiency of deep, etched transmission gratings, and can be incorporated into high volume, low cost semiconductor manufacturing technology.", "section_idx": 3, "section_name": "Fabrication", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Another method for manufacturing diffraction gratings uses a photosensitive gel sandwiched between two substrates. A holographic interference pattern exposes the gel, which is later developed. These gratings, called volume phase holography diffraction gratings (or VPH diffraction gratings) have no physical grooves, but instead a periodic modulation of the refractive index within the gel. This removes much of the surface scattering effects typically seen in other types of gratings. These gratings also tend to have higher efficiencies, and allow for the inclusion of complicated patterns into a single grating. A VPH diffraction grating is typically a transmission grating, through which incident light passes and is diffracted, but a VPH reflection grating can also be made by tilting the direction of a refractive index modulation with respect to the grating surface. In older versions of such gratings, environmental susceptibility was a trade-off, as the gel had to be contained at low temperature and humidity. Typically, the photosensitive substances are sealed between two substrates that make them resistant to humidity, and thermal and mechanical stresses. VPH diffraction gratings are not destroyed by accidental touches and are more scratch resistant than typical relief gratings.", "section_idx": 3, "section_name": "Fabrication", "target_page_ids": [ 1595922, 25880, 164483 ], "anchor_spans": [ [ 61, 75 ], [ 358, 374 ], [ 424, 434 ] ] }, { "plaintext": "A new technology for grating insertion into integrated photonic lightwave circuits is digital planar holography (DPH). DPH gratings are generated in computer and fabricated on one or several interfaces of an optical waveguide planar by using standard micro-lithography or nano-imprinting methods, compatible with mass-production. Light propagates inside the DPH gratings, confined by the refractive index gradient, which provides longer interaction path and greater flexibility in light steering.", "section_idx": 3, "section_name": "Fabrication", "target_page_ids": [ 6424117, 18785756 ], "anchor_spans": [ [ 44, 82 ], [ 86, 111 ] ] }, { "plaintext": "Diffraction gratings are often used in monochromators, spectrometers, lasers, wavelength division multiplexing devices, optical pulse compressing devices, and many other optical instruments.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [ 516414, 45311025, 17556, 80464, 8433728 ], "anchor_spans": [ [ 39, 52 ], [ 55, 67 ], [ 70, 75 ], [ 78, 110 ], [ 128, 145 ] ] }, { "plaintext": "Ordinary pressed CD and DVD media are every-day examples of diffraction gratings and can be used to demonstrate the effect by reflecting sunlight off them onto a white wall. This is a side effect of their manufacture, as one surface of a CD has many small pits in the plastic, arranged in a spiral; that surface has a thin layer of metal applied to make the pits more visible. The structure of a DVD is optically similar, although it may have more than one pitted surface, and all pitted surfaces are inside the disc.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [ 6429, 11014498 ], "anchor_spans": [ [ 17, 19 ], [ 24, 27 ] ] }, { "plaintext": "Due to the sensitivity to the refractive index of the media, diffraction grating can be used as sensor of fluid properties.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In a standard pressed vinyl record when viewed from a low angle perpendicular to the grooves, a similar but less defined effect to that in a CD/DVD is seen. This is due to viewing angle (less than the critical angle of reflection of the black vinyl) and the path of the light being reflected due to this being changed by the grooves, leaving a rainbow relief pattern behind.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [ 172121, 30426 ], "anchor_spans": [ [ 22, 34 ], [ 201, 215 ] ] }, { "plaintext": "Diffraction gratings are also used to distribute evenly the frontlight of e-readers such as the Nook Simple Touch with GlowLight.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [ 1180830, 8712750, 32061122 ], "anchor_spans": [ [ 60, 70 ], [ 74, 82 ], [ 96, 128 ] ] }, { "plaintext": "Some everyday electronic components contain fine and regular", "section_idx": 4, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "patterns, and as a result readily serve as diffraction", "section_idx": 4, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "gratings. For example, CCD sensors from discarded mobile phones and", "section_idx": 4, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "cameras can be removed from the device. With a laser pointer,", "section_idx": 4, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "diffraction can reveal the spatial structure of the CCD", "section_idx": 4, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "sensors.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This can be done for LCD or LED displays of smart phones as well.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Because such displays are usually protected just by transparent", "section_idx": 4, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "casing, experiments can be done without damaging the phones.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "If accurate measurements are not intended, a spotlight can reveal", "section_idx": 4, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "the diffraction patterns.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Striated muscle is the most commonly found natural diffraction grating and, this has helped physiologists in determining the structure of such muscle. Aside from this, the chemical structure of crystals can be thought of as diffraction gratings for types of electromagnetic radiation other than visible light, this is the basis for techniques such as X-ray crystallography.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [ 605851, 34151 ], "anchor_spans": [ [ 0, 15 ], [ 351, 372 ] ] }, { "plaintext": "Most commonly confused with diffraction gratings are the iridescent colors of peacock feathers, mother-of-pearl, and butterfly wings. Iridescence in birds, fish and insects is often caused by thin-film interference rather than a diffraction grating. Diffraction produces the entire spectrum of colors as the viewing angle changes, whereas thin-film interference usually produces a much narrower range. The surfaces of flowers can also create a diffraction, but the cell structures in plants are usually too irregular to produce the fine slit geometry necessary for a diffraction grating. The iridescence signal of flowers is thus only appreciable very locally and hence not visible to man and flower visiting insects. However, natural gratings do occur in some invertebrate animals, like the peacock spiders, the antennae of seed shrimp, and have even been discovered in Burgess Shale fossils.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [ 371786, 63610, 395569, 48338, 27301235, 5826377, 509042, 18225748 ], "anchor_spans": [ [ 57, 67 ], [ 78, 85 ], [ 96, 111 ], [ 117, 126 ], [ 192, 214 ], [ 792, 807 ], [ 825, 836 ], [ 871, 892 ] ] }, { "plaintext": "Diffraction grating effects are sometimes seen in meteorology. Diffraction coronas are colorful rings surrounding a source of light, such as the sun. These are usually observed much closer to the light source than halos, and are caused by very fine particles, like water droplets, ice crystals, or smoke particles in a hazy sky. When the particles are all nearly the same size they diffract the incoming light at very specific angles. The exact angle depends on the size of the particles. Diffraction coronas are commonly observed around light sources, like candle flames or street lights, in the fog. Cloud iridescence is caused by diffraction, occurring along coronal rings when the particles in the clouds are all uniform in size.", "section_idx": 4, "section_name": "Examples", "target_page_ids": [ 19904, 2051536, 345035, 14424426 ], "anchor_spans": [ [ 50, 61 ], [ 63, 82 ], [ 214, 219 ], [ 602, 619 ] ] }, { "plaintext": "Angle-sensitive pixel", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 35566863 ], "anchor_spans": [ [ 0, 21 ] ] }, { "plaintext": "Blazed grating", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 17975799 ], "anchor_spans": [ [ 0, 14 ] ] }, { "plaintext": "Diffraction efficiency", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 37510191 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "Diffraction from slits", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 9825116 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "Diffraction spike", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 3562876 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Echelle grating", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 9019008 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "Fraunhofer diffraction", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 799986 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "Fraunhofer diffraction (mathematics)", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 32267080 ], "anchor_spans": [ [ 0, 36 ] ] }, { "plaintext": "Fresnel diffraction", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 2649192 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": "Grism", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 1575913 ], "anchor_spans": [ [ 0, 5 ] ] }, { "plaintext": "Henry Augustus Rowland", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 747120 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "Kapitza-Dirac effect", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 18303445 ], "anchor_spans": [ [ 0, 20 ] ] }, { "plaintext": "Kirchhoff's diffraction formula", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 31559837 ], "anchor_spans": [ [ 0, 31 ] ] }, { "plaintext": "N-slit interferometric equation", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 25474577 ], "anchor_spans": [ [ 0, 31 ] ] }, { "plaintext": "Ultrasonic grating", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 18741874 ], "anchor_spans": [ [ 0, 18 ] ] }, { "plaintext": "Virtually imaged phased array", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 60667578 ], "anchor_spans": [ [ 0, 29 ] ] }, { "plaintext": "Zone plate", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 901172 ], "anchor_spans": [ [ 0, 10 ] ] }, { "plaintext": " Diffraction Gratings Lecture 9, Youtube", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Diffraction Gratings — The Crucial Dispersive Element", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Optics Tutorial — Diffraction Gratings Ruled & Holographic", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Ray-Tracing program handling general reflective concave gratings for Windows XP and above", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Interference in Diffraction Grating Beams -Wolfram demonstration", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Diffraction", "Diffraction_gratings", "Optical_components", "Photonics" ]

[ "grating" ]

[ { "plaintext": "In signal processing, a digital filter is a system that performs mathematical operations on a sampled, discrete-time signal to reduce or enhance certain aspects of that signal. This is in contrast to the other major type of electronic filter, the analog filter, which is typically an electronic circuit operating on continuous-time analog signals.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 29324, 201605, 40240263, 275871, 1866533, 23431648, 8707643, 40240263, 993 ], "anchor_spans": [ [ 3, 20 ], [ 94, 101 ], [ 103, 116 ], [ 117, 123 ], [ 225, 242 ], [ 248, 261 ], [ 285, 303 ], [ 317, 332 ], [ 333, 346 ] ] }, { "plaintext": "A digital filter system usually consists of an analog-to-digital converter (ADC) to sample the input signal, followed by a microprocessor and some peripheral components such as memory to store data and filter coefficients etc. Program Instructions (software) running on the microprocessor implement the digital filter by performing the necessary mathematical operations on the numbers received from the ADC. In some high performance applications, an FPGA or ASIC is used instead of a general purpose microprocessor, or a specialized digital signal processor (DSP) with specific paralleled architecture for expediting operations such as filtering.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40367, 10969, 147845, 154505 ], "anchor_spans": [ [ 47, 74 ], [ 451, 455 ], [ 459, 463 ], [ 534, 558 ] ] }, { "plaintext": "Digital filters may be more expensive than an equivalent analog filter due to their increased complexity, but they make practical many designs that are impractical or impossible as analog filters. Digital filters can often be made very high order, and are often finite impulse response filters, which allows for linear phase response. When used in the context of real-time analog systems, digital filters sometimes have problematic latency (the difference in time between the input and the response) due to the associated analog-to-digital and digital-to-analog conversions and anti-aliasing filters, or due to other delays in their implementation.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1291180, 40367, 92943, 1291949 ], "anchor_spans": [ [ 312, 324 ], [ 522, 539 ], [ 544, 561 ], [ 578, 598 ] ] }, { "plaintext": "Digital filters are commonplace and an essential element of everyday electronics such as radios, cellphones, and AV receivers.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 15368428, 19644137, 5235850 ], "anchor_spans": [ [ 89, 94 ], [ 97, 106 ], [ 113, 125 ] ] }, { "plaintext": "A digital filter is characterized by its transfer function, or equivalently, its difference equation. Mathematical analysis of the transfer function can describe how it will respond to any input. As such, designing a filter consists of developing specifications appropriate to the problem (for example, a second-order low pass filter with a specific cut-off frequency), and then producing a transfer function which meets the specifications.", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [ 31146, 146806 ], "anchor_spans": [ [ 41, 58 ], [ 81, 100 ] ] }, { "plaintext": "The transfer function for a linear, time-invariant, digital filter can be expressed as a transfer function in the Z-domain; if it is causal, then it has the form:", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [ 31146, 171589 ], "anchor_spans": [ [ 4, 21 ], [ 114, 122 ] ] }, { "plaintext": "where the order of the filter is the greater of N or M.", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "See Z-transform's LCCD equation for further discussion of this transfer function.", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [ 171589, 31146 ], "anchor_spans": [ [ 4, 31 ], [ 63, 80 ] ] }, { "plaintext": "This is the form for a recursive filter, which typically leads to an infinite impulse response (IIR) behaviour, but if the denominator is made equal to unity, i.e. no feedback, then this becomes a finite impulse response (FIR) filter.", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [ 1735759, 570140, 1704824, 22770, 443101 ], "anchor_spans": [ [ 23, 39 ], [ 69, 94 ], [ 123, 134 ], [ 152, 157 ], [ 197, 220 ] ] }, { "plaintext": "A variety of mathematical techniques may be employed to analyze the behavior of a given digital filter. Many of these analysis techniques may also be employed in designs, and often form the basis of a filter specification.", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Typically, one characterizes filters by calculating how they will respond to a simple input such as an impulse. One can then extend this information to compute the filter's response to more complex signals.", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The impulse response, often denoted or , is a measurement of how a filter will respond to the Kronecker delta function. For example, given a difference equation, one would set and for and evaluate. The impulse response is a characterization of the filter's behaviour. Digital filters are typically considered in two categories: infinite impulse response (IIR) and finite impulse response (FIR).", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [ 545825, 182890, 570140, 443101 ], "anchor_spans": [ [ 4, 20 ], [ 95, 110 ], [ 333, 358 ], [ 369, 392 ] ] }, { "plaintext": "In the case of linear time-invariant FIR filters, the impulse response is exactly equal to the sequence of filter coefficients, and thus:", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "IIR filters on the other hand are recursive, with the output depending on both current and previous inputs as well as previous outputs. The general form of an IIR filter is thus:", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Plotting the impulse response reveals how a filter responds to a sudden, momentary disturbance.", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An IIR filter is always recursive. While it is possible for a recursive filter to have a finite impulse response, a non-recursive filter always has a finite impulse response. An example is the moving average (MA) filter, which can be implemented both recursively and non recursively.", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In discrete-time systems, the digital filter is often implemented by converting the transfer function to a linear constant-coefficient difference equation (LCCD) via the Z-transform. The discrete frequency-domain transfer function is written as the ratio of two polynomials. For example:", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [ 40240263, 31146, 171589, 171589, 370346 ], "anchor_spans": [ [ 3, 16 ], [ 84, 101 ], [ 107, 154 ], [ 170, 181 ], [ 197, 213 ] ] }, { "plaintext": "This is expanded:", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "and to make the corresponding filter causal, the numerator and denominator are divided by the highest order of :", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [ 3304717 ], "anchor_spans": [ [ 37, 43 ] ] }, { "plaintext": "The coefficients of the denominator, , are the 'feed-backward' coefficients and the coefficients of the numerator are the 'feed-forward' coefficients, . The resultant linear difference equation is:", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [ 146806 ], "anchor_spans": [ [ 168, 194 ] ] }, { "plaintext": "or, for the example above:", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "rearranging terms:", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "then by taking the inverse z-transform:", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "and finally, by solving for :", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This equation shows how to compute the next output sample, , in terms of the past outputs, , the present input, , and the past inputs, . Applying the filter to an input in this form is equivalent to a Direct Form I or II (see below) realization, depending on the exact order of evaluation.", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In plain terms, for example, as used by a computer programmer implementing the above equation in code, it can be described as follows:", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " = the output, or filtered value", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " = the input, or incoming raw value", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " = the sample number, iteration number, or time period number", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "and therefore:", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " = the current filtered (output) value", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " = the last filtered (output) value", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " = the 2nd-to-last filtered (output) value", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " = the current raw input value", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " = the last raw input value", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " = the 2nd-to-last raw input value", "section_idx": 1, "section_name": "Characterization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Although filters are easily understood and calculated, the practical challenges of their design and implementation are significant and are the subject of much advanced research.", "section_idx": 2, "section_name": "Filter design", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "There are two categories of digital filter: the recursive filter and the nonrecursive filter. These are often referred to as infinite impulse response (IIR) filters and finite impulse response (FIR) filters, respectively.", "section_idx": 2, "section_name": "Filter design", "target_page_ids": [ 1735759, 46558807, 570140, 443101 ], "anchor_spans": [ [ 48, 64 ], [ 73, 92 ], [ 126, 151 ], [ 170, 193 ] ] }, { "plaintext": "After a filter is designed, it must be realized by developing a signal flow diagram that describes the filter in terms of operations on sample sequences.", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A given transfer function may be realized in many ways. Consider how a simple expression such as could be evaluated one could also compute the equivalent . In the same way, all realizations may be seen as \"factorizations\" of the same transfer function, but different realizations will have different numerical properties. Specifically, some realizations are more efficient in terms of the number of operations or storage elements required for their implementation, and others provide advantages such as improved numerical stability and reduced round-off error. Some structures are better for fixed-point arithmetic and others may be better for floating-point arithmetic.", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [ 449736, 11376 ], "anchor_spans": [ [ 598, 620 ], [ 650, 675 ] ] }, { "plaintext": "A straightforward approach for IIR filter realization is direct form I, where the difference equation is evaluated directly. This form is practical for small filters, but may be inefficient and impractical (numerically unstable) for complex designs. In general, this form requires 2N delay elements (for both input and output signals) for a filter of order N.", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [ 10280692 ], "anchor_spans": [ [ 57, 70 ] ] }, { "plaintext": "The alternate direct form II only needs N delay units, where N is the order of the filter – potentially half as much as direct form I. This structure is obtained by reversing the order of the numerator and denominator sections of Direct Form I, since they are in fact two linear systems, and the commutativity property applies. Then, one will notice that there are two columns of delays () that tap off the center net, and these can be combined since they are redundant, yielding the implementation as shown below.", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [ 10280692 ], "anchor_spans": [ [ 14, 28 ] ] }, { "plaintext": "The disadvantage is that direct form II increases the possibility of arithmetic overflow for filters of high Q or resonance. It has been shown that as Q increases, the round-off noise of both direct form topologies increases without bounds. This is because, conceptually, the signal is first passed through an all-pole filter (which normally boosts gain at the resonant frequencies) before the result of that is saturated, then passed through an all-zero filter (which often attenuates much of what the all-pole half amplifies).", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A common strategy is to realize a higher-order (greater than 2) digital filter as a cascaded series of second-order \"biquadratric\" (or \"biquad\") sections (see digital biquad filter). The advantage of this strategy is that the coefficient range is limited. Cascading direct form II sections results in N delay elements for filters of order N. Cascading direct form I sections results in N + 2 delay elements, since the delay elements of the input of any section (except the first section) are redundant with the delay elements of the output of the preceding section.", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [ 10280692 ], "anchor_spans": [ [ 159, 180 ] ] }, { "plaintext": "Other forms include:", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Direct form I and II transpose", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Series/cascade lower (typical second) order subsections", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Parallel lower (typical second) order subsections", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Continued fraction expansion", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Lattice and ladder", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " One, two and three-multiply lattice forms", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Three and four-multiply normalized ladder forms", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ARMA structures", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " State-space structures:", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " optimal (in the minimum noise sense): parameters", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " block-optimal and section-optimal: parameters", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " input balanced with Givens rotation: parameters", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Coupled forms: Gold Rader (normal), State Variable (Chamberlin), Kingsbury, Modified State Variable, Zölzer, Modified Zölzer", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Wave Digital Filters (WDF)", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Agarwal–Burrus (1AB and 2AB)", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Harris–Brooking", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ND-TDL", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Multifeedback", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Analog-inspired forms such as Sallen-key and state variable filters", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Systolic arrays", "section_idx": 3, "section_name": "Filter realization", "target_page_ids": [ 351517 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": "Digital filters are not subject to the component non-linearities that greatly complicate the design of analog filters. Analog filters consist of imperfect electronic components, whose values are specified to a limit tolerance (e.g. resistor values often have a tolerance of ±5%) and which may also change with temperature and drift with time. As the order of an analog filter increases, and thus its component count, the effect of variable component errors is greatly magnified. In digital filters, the coefficient values are stored in computer memory, making them far more stable and predictable.", "section_idx": 4, "section_name": "Comparison of analog and digital filters", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Because the coefficients of digital filters are definite, they can be used to achieve much more complex and selective designs specifically with digital filters, one can achieve a lower passband ripple, faster transition, and higher stopband attenuation than is practical with analog filters. Even if the design could be achieved using analog filters, the engineering cost of designing an equivalent digital filter would likely be much lower. Furthermore, one can readily modify the coefficients of a digital filter to make an adaptive filter or a user-controllable parametric filter. While these techniques are possible in an analog filter, they are again considerably more difficult.", "section_idx": 4, "section_name": "Comparison of analog and digital filters", "target_page_ids": [ 172071 ], "anchor_spans": [ [ 529, 544 ] ] }, { "plaintext": "Digital filters can be used in the design of finite impulse response filters. Equivalent analog filters are often more complicated, as these require delay elements.", "section_idx": 4, "section_name": "Comparison of analog and digital filters", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Digital filters rely less on analog circuitry, potentially allowing for a better signal-to-noise ratio. A digital filter will introduce noise to a signal during analog low pass filtering, analog to digital conversion, digital to analog conversion and may introduce digital noise due to quantization. With analog filters, every component is a source of thermal noise (such as Johnson noise), so as the filter complexity grows, so does the noise.", "section_idx": 4, "section_name": "Comparison of analog and digital filters", "target_page_ids": [ 41706, 182745 ], "anchor_spans": [ [ 81, 102 ], [ 376, 389 ] ] }, { "plaintext": "However, digital filters do introduce a higher fundamental latency to the system. In an analog filter, latency is often negligible; strictly speaking it is the time for an electrical signal to propagate through the filter circuit. In digital systems, latency is introduced by delay elements in the digital signal path, and by analog-to-digital and digital-to-analog converters that enable the system to process analog signals.", "section_idx": 4, "section_name": "Comparison of analog and digital filters", "target_page_ids": [ 40367, 92943 ], "anchor_spans": [ [ 327, 344 ], [ 349, 376 ] ] }, { "plaintext": "In very simple cases, it is more cost effective to use an analog filter. Introducing a digital filter requires considerable overhead circuitry, as previously discussed, including two low pass analog filters.", "section_idx": 4, "section_name": "Comparison of analog and digital filters", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Another argument for analog filters is low power consumption. Analog filters require substantially less power and are therefore the only solution when power requirements are tight.", "section_idx": 4, "section_name": "Comparison of analog and digital filters", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "When making an electrical circuit on a PCB it is generally easier to use a digital solution, because the processing units are highly optimized over the years. Making the same circuit with analog components would take up a lot more space when using discrete components. Two alternatives are FPAAs and ASICs, but they are expensive for low quantities.", "section_idx": 4, "section_name": "Comparison of analog and digital filters", "target_page_ids": [ 65910, 8707643, 6680502, 147845 ], "anchor_spans": [ [ 39, 42 ], [ 248, 267 ], [ 290, 295 ], [ 300, 305 ] ] }, { "plaintext": "There are various ways to characterize filters; for example:", "section_idx": 5, "section_name": "Types of digital filters", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A linear filter is a linear transformation of input samples; other filters are nonlinear. Linear filters satisfy the superposition principle, i.e. if an input is a weighted linear combination of different signals, the output is a similarly weighted linear combination of the corresponding output signals.", "section_idx": 5, "section_name": "Types of digital filters", "target_page_ids": [ 18102, 146103, 1201321 ], "anchor_spans": [ [ 22, 43 ], [ 80, 89 ], [ 118, 141 ] ] }, { "plaintext": " A causal filter uses only previous samples of the input or output signals; while a non-causal filter uses future input samples. A non-causal filter can usually be changed into a causal filter by adding a delay to it.", "section_idx": 5, "section_name": "Types of digital filters", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A time-invariant filter has constant properties over time; other filters such as adaptive filters change in time.", "section_idx": 5, "section_name": "Types of digital filters", "target_page_ids": [ 172071 ], "anchor_spans": [ [ 82, 97 ] ] }, { "plaintext": " A stable filter produces an output that converges to a constant value with time, or remains bounded within a finite interval. An unstable filter can produce an output that grows without bounds, with bounded or even zero input.", "section_idx": 5, "section_name": "Types of digital filters", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A finite impulse response (FIR) filter uses only the input signals, while an infinite impulse response (IIR) filter uses both the input signal and previous samples of the output signal. FIR filters are always stable, while IIR filters may be unstable.", "section_idx": 5, "section_name": "Types of digital filters", "target_page_ids": [ 443101, 570140 ], "anchor_spans": [ [ 3, 26 ], [ 78, 103 ] ] }, { "plaintext": "A filter can be represented by a block diagram, which can then be used to derive a sample processing algorithm to implement the filter with hardware instructions. A filter may also be described as a difference equation, a collection of zeros and poles or an impulse response or step response.", "section_idx": 5, "section_name": "Types of digital filters", "target_page_ids": [ 1176981, 775, 146806, 81560, 545825, 545863 ], "anchor_spans": [ [ 33, 46 ], [ 101, 110 ], [ 199, 218 ], [ 236, 251 ], [ 258, 274 ], [ 278, 291 ] ] }, { "plaintext": "Some digital filters are based on the fast Fourier transform, a mathematical algorithm that quickly extracts the frequency spectrum of a signal, allowing the spectrum to be manipulated (such as to create very high order band-pass filters) before converting the modified spectrum back into a time-series signal with an inverse FFT operation. These filters give O(n log n) computational costs whereas conventional digital filters tend to be O(n2).", "section_idx": 5, "section_name": "Types of digital filters", "target_page_ids": [ 11512, 202672 ], "anchor_spans": [ [ 38, 60 ], [ 113, 131 ] ] }, { "plaintext": "Another form of a digital filter is that of a state-space model. A well used state-space filter is the Kalman filter published by Rudolf Kálmán in 1960.", "section_idx": 5, "section_name": "Types of digital filters", "target_page_ids": [ 548156, 180855, 396498 ], "anchor_spans": [ [ 46, 57 ], [ 103, 116 ], [ 130, 143 ] ] }, { "plaintext": "Traditional linear filters are usually based on attenuation. Alternatively nonlinear filters can be designed, including energy transfer filters, which allow the user to move energy in a designed way so that unwanted noise or effects can be moved to new frequency bands either lower or higher in frequency, spread over a range of frequencies, split, or focused. Energy transfer filters complement traditional filter designs and introduce many more degrees of freedom in filter design. Digital energy transfer filters are relatively easy to design and to implement and exploit nonlinear dynamics.", "section_idx": 5, "section_name": "Types of digital filters", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Bessel filter", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 2071179 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Bilinear transform", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 4628 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Butterworth filter", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 562353 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Chebyshev filter", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 327003 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Electronic filter", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 1866533 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Elliptical filter (Cauer filter)", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 1875715 ], "anchor_spans": [ [ 1, 33 ] ] }, { "plaintext": " Filter design", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 173371 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " High-pass filter, Low-pass filter", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 56486, 56484 ], "anchor_spans": [ [ 1, 17 ], [ 19, 34 ] ] }, { "plaintext": " Infinite impulse response, Finite impulse response", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 570140, 443101 ], "anchor_spans": [ [ 1, 26 ], [ 28, 51 ] ] }, { "plaintext": " Linkwitz–Riley filter", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 5036132 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Matched filter", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 1135311 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Sample (signal)", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 201605 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Savitzky–Golay filter", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 1988157 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Two-dimensional filter", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 41074252 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": "J. O. Smith III, Introduction to Digital Filters with Audio Applications, Center for Computer Research in Music and Acoustics (CCRMA), Stanford University, September 2007 Edition.", "section_idx": 8, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] } ]

[ "Digital_signal_processing", "Synthesiser_modules", "Signal_processing_filter" ]

[]

[ { "plaintext": "In digital telephony, the digital milliwatt is a standard test signal that serves as a reference for analog signal levels in the telecommunications network. When decoding the digital milliwatt, a PCM decoder produces a sinusoidal signal with a frequency of with one milliwatt in power ().", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41831, 41737, 25513330, 10779, 21347693, 24236 ], "anchor_spans": [ [ 3, 20 ], [ 49, 69 ], [ 196, 199 ], [ 244, 253 ], [ 267, 276 ], [ 280, 285 ] ] }, { "plaintext": "The digital milliwatt signal is encoded by eight 8-bit words corresponding to one pulse-code modulated cycle of the signal, sampled 8000 times per second. It is typically stored in read-only memory (ROM) in the telecommunication equipment.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3364, 18934934 ], "anchor_spans": [ [ 51, 54 ], [ 181, 197 ] ] }, { "plaintext": "The digital milliwatt signal is often generated in instruments in place of separate test equipment. It has the advantage of being tied in frequency and amplitude to the relatively stable digital clock signal and power (voltage) supply, respectively, that are used by the digital channel bank.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 182693, 18334778 ], "anchor_spans": [ [ 195, 207 ], [ 279, 291 ] ] } ]

[ "Telephony_signals" ]

[]

[ { "plaintext": "In telecommunications, a digital multiplex hierarchy is a hierarchy consisting of an ordered repetition of tandem digital multiplexers that produce signals of successively higher data rates at each level of the hierarchy.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 677931, 38542, 18985040 ], "anchor_spans": [ [ 3, 20 ], [ 107, 113 ], [ 114, 133 ], [ 179, 183 ] ] }, { "plaintext": "Digital multiplexing hierarchies may be implemented in many different configurations depending on; (a) the number of channels desired, (b) the signaling system to be used, and (c) the bit rate allowed by the communications media.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41389, 41703, 8286675, 272290, 33094374 ], "anchor_spans": [ [ 8, 20 ], [ 143, 152 ], [ 153, 159 ], [ 184, 192 ], [ 208, 222 ] ] }, { "plaintext": "Some currently available digital multiplexers have been designated as Dl-, DS-, or M-series, all of which operate at T-carrier rates. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1371669, 41779 ], "anchor_spans": [ [ 70, 91 ], [ 117, 126 ] ] }, { "plaintext": "In the design of digital multiplex hierarchies, care must be exercised to ensure interoperability of the multiplexers used in the hierarchy.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41285 ], "anchor_spans": [ [ 81, 97 ] ] }, { "plaintext": "Digroup is an abbreviation for digital group. In telephony, a basic group in the digital multiplex hierarchy. ", "section_idx": 1, "section_name": "Digroup", "target_page_ids": [ 8276, 41831 ], "anchor_spans": [ [ 31, 38 ], [ 49, 58 ] ] }, { "plaintext": "In the North American and Japanese T-carrier digital hierarchies, each digroup supports 12 PCM voice channels or their equivalent in other services. The DS1 line rate (2 digroups plus overhead bits) is 1.544 Mbit/s, supporting 24 voice channels or their equivalent in other services. ", "section_idx": 1, "section_name": "Digroup", "target_page_ids": [ 41779, 9559 ], "anchor_spans": [ [ 35, 44 ], [ 157, 161 ] ] }, { "plaintext": "In the E-carrier European hierarchy, each digroup supports 15 PCM channels or their equivalent in other services. The DS1 line rate (2 digroups plus overhead bits) is 2.048 Mbit/s, supporting 30 voice channels or their equivalent in other services.", "section_idx": 1, "section_name": "Digroup", "target_page_ids": [ 46728 ], "anchor_spans": [ [ 7, 16 ] ] }, { "plaintext": "Plesiochronous digital hierarchy", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 38512 ], "anchor_spans": [ [ 0, 32 ] ] }, { "plaintext": "Synchronous digital hierarchy", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 38536 ], "anchor_spans": [ [ 0, 29 ] ] } ]

[ "Multiplexing" ]

[]

[ { "plaintext": "Digital Signal 0 (DS0) is a basic digital signaling rate of 64 kilobits per second (kbit/s), corresponding to the capacity of one analog voice-frequency-equivalent communication channel. The DS0 rate, and its equivalents E0 in the E-carrier system and T0 in the T-carrier system, form the basis for the digital multiplex transmission hierarchy in telecommunications systems used in North America, Europe, Japan, and the rest of the world, for both the early plesiochronous systems such as T-carrier and for modern synchronous systems such as SDH/SONET.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 14832328, 41855, 156700, 46728, 41779, 609152, 162999, 41779, 38536, 38536 ], "anchor_spans": [ [ 84, 90 ], [ 137, 152 ], [ 164, 185 ], [ 231, 240 ], [ 262, 271 ], [ 321, 333 ], [ 458, 472 ], [ 489, 498 ], [ 542, 545 ], [ 546, 551 ] ] }, { "plaintext": "The DS0 rate was introduced to carry a single digitized voice call. For a typical phone call, the audio sound is digitized at an 8 kHz sample rate, or 8000 samples per second, using 8-bit pulse-code modulation for each of the samples. This results in a data rate of 64 kbit/s.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 14121, 25513330, 14832328 ], "anchor_spans": [ [ 132, 135 ], [ 189, 210 ], [ 271, 277 ] ] }, { "plaintext": "Because of its fundamental role in carrying a single phone call, the DS0 rate forms the basis for the digital multiplex transmission hierarchy in telecommunications systems used in North America. To limit the number of wires required between two involved in exchanging voice calls, a system was built in which multiple DS0s are multiplexed together on higher capacity circuits. In this system, twenty-four (24) DS0s are multiplexed into a DS1 signal. Twenty-eight (28) DS1s are multiplexed into a DS3. When carried over copper wire, this is the well-known T-carrier system, with T1 and T3 corresponding to DS1 and DS3, respectively. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 609152, 41389, 907542, 1219567, 41779, 907542, 1219567 ], "anchor_spans": [ [ 120, 132 ], [ 329, 340 ], [ 442, 445 ], [ 501, 504 ], [ 561, 570 ], [ 584, 586 ], [ 591, 593 ] ] }, { "plaintext": "Besides its use for voice communications, the DS0 rate may support twenty 2.4 kbit/s channels, ten 4.8 kbit/s channels, five 9.67 kbit/s channels, one 56 kbit/s channel, or one 64 kbit/s clear channel.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "E0 (standardized as ITU G.703) is the European equivalent of the North American DS0 for carrying a single voice call. However, there are some subtle differences in implementation. Voice signals are encoded for carriage over E0 according to ITU G.711. Note that when a T-carrier system is used as in North America, robbed bit signaling can mean that a DS0 channel carried over that system is not an error-free bit-stream. The out-of-band signaling used in the European E-carrier system avoids this.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2107946, 104113, 962020, 41703 ], "anchor_spans": [ [ 20, 29 ], [ 243, 252 ], [ 318, 338 ], [ 429, 450 ] ] }, { "plaintext": "DS0A", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 33394057 ], "anchor_spans": [ [ 0, 4 ] ] }, { "plaintext": "Digital Signal 1", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 907542 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Digital Signal 3", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 1219567 ], "anchor_spans": [ [ 0, 16 ] ] } ]

[ "Telecommunications_standards" ]

[ "DS0" ]

[ { "plaintext": "Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly installed DSL technology, for Internet access.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8276, 946963, 18934536, 300602 ], "anchor_spans": [ [ 120, 132 ], [ 138, 152 ], [ 230, 264 ], [ 321, 336 ] ] }, { "plaintext": "DSL service can be delivered simultaneously with wired telephone service on the same telephone line since DSL uses higher frequency bands for data. On the customer premises, a DSL filter on each non-DSL outlet blocks any high-frequency interference to enable simultaneous use of the voice and DSL services.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 160834, 5167862, 3207081 ], "anchor_spans": [ [ 49, 72 ], [ 122, 136 ], [ 176, 186 ] ] }, { "plaintext": "The bit rate of consumer DSL services typically ranges from 256kbit/s to over 100Mbit/s in the direction to the customer (downstream), depending on DSL technology, line conditions, and service-level implementation. Bit rates of 1Gbit/s have been reached.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 272290, 298551, 14832328 ], "anchor_spans": [ [ 4, 12 ], [ 122, 132 ], [ 229, 235 ] ] }, { "plaintext": "In ADSL, the data throughput in the upstream direction (the direction to the service provider) is lower, hence the designation of asymmetric service. In symmetric digital subscriber line (SDSL) services, the downstream and upstream data rates are equal. Researchers at Bell Labs have reached speeds over 1Gbit/s for symmetrical broadband access services using traditional copper telephone lines, though such speeds have not yet been deployed elsewhere.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 20804372, 100110, 3712 ], "anchor_spans": [ [ 36, 44 ], [ 153, 186 ], [ 269, 278 ] ] }, { "plaintext": "It was originally thought that it was not possible to operate a conventional phone line beyond low-speed limits (typically under 9600 bit/s). In the 1950s, ordinary twisted-pair telephone cable often carried four megahertz (MHz) television signals between studios, suggesting that such lines would allow transmitting many megabits per second. One such circuit in the United Kingdom ran some between the BBC studios in Newcastle-upon-Tyne and the Pontop Pike transmitting station. However, these cables had other impairments besides Gaussian noise, preventing such rates from becoming practical in the field. The 1980s saw the development of techniques for broadband communications that allowed the limit to be greatly extended. A patent was filed in 1979 for the use of existing telephone wires for both telephones and data terminals that were connected to a remote computer via a digital data carrier system.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 19344654, 70348, 1840753, 1387827, 147184 ], "anchor_spans": [ [ 404, 407 ], [ 419, 438 ], [ 447, 479 ], [ 533, 547 ], [ 657, 666 ] ] }, { "plaintext": "The motivation for digital subscriber line technology was the Integrated Services Digital Network (ISDN) specification proposed in 1984 by the CCITT (now ITU-T) as part of Recommendation I.120, later reused as ISDN digital subscriber line (IDSL). Employees at Bellcore (now Telcordia Technologies) developed asymmetric digital subscriber line (ADSL) by placing wide-band digital signals at frequencies above the existing baseband analog voice signal carried on conventional twisted pair cabling between telephone exchanges and customers. A patent was filed by AT&T Bell Labs on the basic DSL concept in 1988.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 15231, 14744, 299727, 1141972, 18934536, 40773, 80506, 26668156 ], "anchor_spans": [ [ 62, 97 ], [ 154, 159 ], [ 210, 238 ], [ 274, 296 ], [ 308, 342 ], [ 421, 429 ], [ 474, 486 ], [ 503, 521 ] ] }, { "plaintext": "Joseph W. Lechleider's contribution to DSL was his insight that an asymmetric arrangement offered more than double the bandwidth capacity of symmetric DSL. This allowed Internet service providers to offer efficient service to consumers, who benefited greatly from the ability to download large amounts of data but rarely needed to upload comparable amounts. ADSL supports two modes of transport: fast channel and interleaved channel. Fast channel is preferred for streaming multimedia, where an occasional dropped bit is acceptable, but lags are less so. Interleaved channel works better for file transfers, where the delivered data must be error-free but latency (time delay) incurred by the retransmission of error-containing packets is acceptable.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 46702545, 4237207, 28682, 3364 ], "anchor_spans": [ [ 0, 20 ], [ 413, 432 ], [ 464, 484 ], [ 514, 517 ] ] }, { "plaintext": "Consumer-oriented ADSL was designed to operate on existing lines already conditioned for Basic Rate Interface ISDN services. Engineers developed high speed DSL facilities such as high bit rate digital subscriber line (HDSL) and symmetric digital subscriber line (SDSL) to provision traditional Digital Signal 1 (DS1) services over standard copper pair facilities.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 64519, 5649030, 100110, 907542 ], "anchor_spans": [ [ 89, 109 ], [ 179, 216 ], [ 228, 261 ], [ 294, 310 ] ] }, { "plaintext": "Older ADSL standards delivered 8Mbit/s to the customer over about of unshielded twisted-pair copper wire. Newer variants improved these rates. Distances greater than significantly reduce the bandwidth usable on the wires, thus reducing the data rate. But ADSL loop extenders increase these distances by repeating the signal, allowing the LEC to deliver DSL speeds to any distance.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 14832328, 80506, 15612827, 12628378 ], "anchor_spans": [ [ 32, 38 ], [ 70, 93 ], [ 193, 202 ], [ 257, 275 ] ] }, { "plaintext": "Until the late 1990s, the cost of digital signal processors for DSL was prohibitive. All types of DSL employ highly complex digital signal processing algorithms to overcome the inherent limitations of the existing twisted pair wires. Due to the advancements of very-large-scale integration (VLSI) technology, the cost of the equipment associated with a DSL deployment lowered significantly. The two main pieces of equipment are a digital subscriber line access multiplexer (DSLAM) at one end and a DSL modem at the other end.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 154505, 8525, 80506, 32823, 245584, 2895884 ], "anchor_spans": [ [ 34, 58 ], [ 124, 149 ], [ 214, 226 ], [ 261, 289 ], [ 430, 472 ], [ 498, 507 ] ] }, { "plaintext": "A DSL connection can be deployed over existing cable. Such deployment, even including equipment, is much cheaper than installing a new, high-bandwidth fiber-optic cable over the same route and distance. This is true both for ADSL and SDSL variations. The commercial success of DSL and similar technologies largely reflects the advances made in electronics over the decades that have increased performance and reduced costs even while digging trenches in the ground for new cables (copper or fiber optic) remains expensive.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 3372377 ], "anchor_spans": [ [ 151, 162 ] ] }, { "plaintext": "These advantages made ADSL a better proposition for customers requiring Internet access than metered dial up, while also allowing voice calls to be received at the same time as a data connection. Telephone companies were also under pressure to move to ADSL owing to competition from cable companies, which use DOCSIS cable modem technology to achieve similar speeds. Demand for high bandwidth applications, such as video and file sharing, also contributed to the popularity of ADSL technology.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 300602, 295981 ], "anchor_spans": [ [ 72, 87 ], [ 310, 328 ] ] }, { "plaintext": "Early DSL service required a dedicated dry loop, but when the U.S. Federal Communications Commission (FCC) required incumbent local exchange carriers (ILECs) to lease their lines to competing DSL service providers, shared-line DSL became available. Also known as DSL over unbundled network element, this unbundling of services allows a single subscriber to receive two separate services from two separate providers on one cable pair. The DSL service provider's equipment is co-located in the same telephone exchange as that of the ILEC supplying the customer's pre-existing voice service. The subscriber's circuit is rewired to interface with hardware supplied by the ILEC which combines a DSL frequency and POTS signals on a single copper pair.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 4237345, 55974, 620244, 5432673, 26668156 ], "anchor_spans": [ [ 39, 47 ], [ 67, 100 ], [ 116, 148 ], [ 272, 297 ], [ 497, 515 ] ] }, { "plaintext": "By 2012, some carriers in the United States reported that DSL remote terminals with fiber backhaul were replacing older ADSL systems.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 4624565 ], "anchor_spans": [ [ 90, 98 ] ] }, { "plaintext": "Telephones are connected to the telephone exchange via a local loop, which is a physical pair of wires. The local loop was originally intended mostly for the transmission of speech, encompassing an audio frequency range of 300 to 3400 hertz (commercial bandwidth). However, as long-distance trunks were gradually converted from analog to digital operation, the idea of being able to pass data through the local loop (by utilizing frequencies above the voiceband) took hold, ultimately leading to DSL.", "section_idx": 2, "section_name": "Operation", "target_page_ids": [ 26668156, 59602, 14121, 2000194, 593233 ], "anchor_spans": [ [ 32, 50 ], [ 57, 67 ], [ 235, 240 ], [ 242, 262 ], [ 291, 296 ] ] }, { "plaintext": "The local loop connecting the telephone exchange to most subscribers has the capability of carrying frequencies well beyond the 3400Hz upper limit of POTS. Depending on the length and quality of the loop, the upper limit can be tens of megahertz. DSL takes advantage of this unused bandwidth of the local loop by creating 4312.5Hz wide channels starting between 10 and 100kHz, depending on how the system is configured. Allocation of channels continues to higher frequencies (up to 1.1MHz for ADSL) until new channels are deemed unusable. Each channel is evaluated for usability in much the same way an analog modem would on a POTS connection. More usable channels equate to more available bandwidth, which is why distance and line quality are a factor (the higher frequencies used by DSL travel only short distances).", "section_idx": 2, "section_name": "Operation", "target_page_ids": [ 59602, 160834, 3967, 20647197 ], "anchor_spans": [ [ 4, 14 ], [ 150, 154 ], [ 282, 291 ], [ 603, 615 ] ] }, { "plaintext": "The pool of usable channels is then split into two different frequency bands for upstream and downstream traffic, based on a preconfigured ratio. This segregation reduces interference. Once the channel groups have been established, the individual channels are bonded into a pair of virtual circuits, one in each direction. Like analog modems, DSL transceivers constantly monitor the quality of each channel and will add or remove them from service depending on whether they are usable. Once upstream and downstream circuits are established, a subscriber can connect to a service such as an Internet service provider or other network services, like a corporate MPLS network.", "section_idx": 2, "section_name": "Operation", "target_page_ids": [ 20804372, 298551, 156700, 1952952, 41805, 259338, 100245, 20623 ], "anchor_spans": [ [ 81, 89 ], [ 94, 104 ], [ 247, 254 ], [ 260, 266 ], [ 347, 358 ], [ 543, 553 ], [ 590, 615 ], [ 660, 664 ] ] }, { "plaintext": "The underlying technology of transport across DSL facilities uses modulation of high-frequency carrier waves, an analog signal transmission. A DSL circuit terminates at each end in a modem which modulates patterns of bits into certain high-frequency impulses for transmission to the opposing modem. Signals received from the far-end modem are demodulated to yield a corresponding bit pattern that the modem passes on, in digital form, to its interfaced equipment, such as a computer, router, switch, etc.", "section_idx": 2, "section_name": "Operation", "target_page_ids": [ 20637, 153217, 20647197, 3364 ], "anchor_spans": [ [ 66, 76 ], [ 95, 107 ], [ 183, 188 ], [ 217, 221 ] ] }, { "plaintext": "Unlike traditional dial-up modems, which modulate bits into signals in the 300–3400Hz audio baseband, DSL modems modulate frequencies from 4000Hz to as high as 4MHz. This frequency band separation enables DSL service and plain old telephone service (POTS) to coexist on the same cables. On the subscriber's end of the circuit, inline DSL filters are installed on each telephone to pass voice frequencies but filter the high-frequency signals that would otherwise be heard as hiss. Also, nonlinear elements in the phone could otherwise generate audible intermodulation and may impair the operation of the data modem in the absence of these low-pass filters. DSL and RADSL modulations do not use the voice-frequency band so high-pass filters are incorporated in the circuitry of DSL modems filter out voice frequencies.", "section_idx": 2, "section_name": "Operation", "target_page_ids": [ 160834, 3207081, 590995, 56484, 56486 ], "anchor_spans": [ [ 221, 248 ], [ 334, 344 ], [ 552, 567 ], [ 639, 654 ], [ 723, 739 ] ] }, { "plaintext": "Because DSL operates above the 3.4kHz voice limit, it cannot pass through a loading coil, which is an inductive coil that is designed to counteract loss caused by shunt capacitance (capacitance between the two wires of the twisted pair). Loading coils are commonly set at regular intervals in POTS lines. Voice service cannot be maintained past a certain distance without such coils. Therefore, some areas that are within range for DSL service are disqualified from eligibility because of loading coil placement. Because of this, phone companies endeavor to remove loading coils on copper loops that can operate without them. Longer lines that require them can be replaced with fiber to the neighborhood or node (FTTN).", "section_idx": 2, "section_name": "Operation", "target_page_ids": [ 41326, 3492955 ], "anchor_spans": [ [ 76, 88 ], [ 713, 717 ] ] }, { "plaintext": "Most residential and small-office DSL implementations reserve low frequencies for POTS, so that (with suitable filters and/or splitters) the existing voice service continues to operate independently of the DSL service. Thus POTS-based communications, including fax machines and dial-up modems, can share the wires with DSL. Only one DSL modem can use the subscriber line at a time. The standard way to let multiple computers share a DSL connection uses a router that establishes a connection between the DSL modem and a local Ethernet, powerline, or Wi-Fi network on the customer's premises.", "section_idx": 2, "section_name": "Operation", "target_page_ids": [ 10826, 20647197, 59602, 25748, 9499, 238420, 63973 ], "anchor_spans": [ [ 261, 273 ], [ 278, 291 ], [ 355, 370 ], [ 455, 461 ], [ 526, 534 ], [ 536, 545 ], [ 550, 555 ] ] }, { "plaintext": "The theoretical foundations of DSL, like much of communication technology, can be traced back to Claude Shannon's seminal 1948 paper: A Mathematical Theory of Communication. Generally, higher bit rate transmissions require a wider frequency band, though the ratio of bit rate to symbol rate and thus to bandwidth are not linear due to significant innovations in digital signal processing and digital modulation methods.", "section_idx": 2, "section_name": "Operation", "target_page_ids": [ 5177, 5693, 828061, 272290, 2518170, 8525, 20637 ], "anchor_spans": [ [ 49, 62 ], [ 97, 111 ], [ 134, 172 ], [ 267, 275 ], [ 279, 290 ], [ 362, 387 ], [ 392, 418 ] ] }, { "plaintext": "Naked DSL is a way of providing only DSL services over a local loop. It is useful when the customer does not need the traditional telephony voice service because voice service is received either on top of the DSL services (usually VoIP) or through another network (E.g., mobile telephony). It is also commonly called an unbundled network element (UNE) in the United States; in Australia it is known as a unconditioned local loop (ULL); in Belgium it is known as \"raw copper\" and in the UK it is known as Single Order GEA (SoGEA).", "section_idx": 2, "section_name": "Operation", "target_page_ids": [ 1484114, 59602, 41831, 75028, 1145887, 5432673 ], "anchor_spans": [ [ 0, 9 ], [ 57, 67 ], [ 130, 139 ], [ 231, 235 ], [ 271, 287 ], [ 320, 345 ] ] }, { "plaintext": "It started making a comeback in the United States in 2004 when Qwest started offering it, closely followed by Speakeasy. As a result of AT&T's merger with SBC, and Verizon's merger with MCI, those telephone companies have an obligation to offer naked DSL to consumers.", "section_idx": 2, "section_name": "Operation", "target_page_ids": [ 19196565, 4250612, 24536639, 37608860, 18619278, 59695 ], "anchor_spans": [ [ 63, 68 ], [ 110, 119 ], [ 136, 140 ], [ 155, 158 ], [ 164, 171 ], [ 186, 189 ] ] }, { "plaintext": "On the customer side, a DSL modem is hooked up to a phone line. The telephone company connects the other end of the line to a DSLAM, which concentrates a large number of individual DSL connections into a single box. The DSLAM cannot be located too far from the customer because of attenuation between the DSLAM and the user's DSL modem. It is common for a few residential blocks to be connected to one DSLAM.", "section_idx": 3, "section_name": "Typical setup", "target_page_ids": [ 245584, 40735 ], "anchor_spans": [ [ 126, 131 ], [ 281, 292 ] ] }, { "plaintext": "The above figure is a schematic of a simple DSL connection (in blue). The right side shows a DSLAM residing in the telephone company's telephone exchange. The left side shows the customer premises equipment with an optional router. The router manages a local area network which connects PCs and other local devices. The customer may opt for a modem that contains both a router and wireless access. This option (within the dashed bubble) often simplifies the connection.", "section_idx": 3, "section_name": "Typical setup", "target_page_ids": [ 17739 ], "anchor_spans": [ [ 253, 271 ] ] }, { "plaintext": "At the exchange, a digital subscriber line access multiplexer (DSLAM) terminates the DSL circuits and aggregates them, where they are handed off to other networking transports. The DSLAM terminates all connections and recovers the original digital information. In the case of ADSL, the voice component is also separated at this step, either by a filter integrated in the DSLAM or by specialized filtering equipment installed before it.", "section_idx": 3, "section_name": "Typical setup", "target_page_ids": [ 245584, 344136, 27313582 ], "anchor_spans": [ [ 19, 61 ], [ 70, 79 ], [ 134, 144 ] ] }, { "plaintext": "The customer end of the connection consists of a DSL modem. This converts data between the digital signals used by computers and the analog voltage signal of a suitable frequency range which is then applied to the phone line.", "section_idx": 3, "section_name": "Typical setup", "target_page_ids": [ 2895884, 32549 ], "anchor_spans": [ [ 49, 58 ], [ 140, 147 ] ] }, { "plaintext": "In some DSL variations (for example, HDSL), the modem connects directly to the computer via a serial interface, using protocols such as Ethernet or V.35. In other cases (particularly ADSL), it is common for the customer equipment to be integrated with higher-level functionality, such as routing, firewalling, or other application-specific hardware and software. In this case, the equipment is referred to as a gateway.", "section_idx": 3, "section_name": "Typical setup", "target_page_ids": [ 5649030, 9499, 5419226 ], "anchor_spans": [ [ 37, 41 ], [ 136, 144 ], [ 148, 152 ] ] }, { "plaintext": "Most DSL technologies require the installation of appropriate DSL filters to separate the DSL signal from the low-frequency voice signal. The separation can take place either at the demarcation point, or with filters installed at the telephone outlets inside the customer premises.", "section_idx": 3, "section_name": "Typical setup", "target_page_ids": [ 3207081, 250347, 775245 ], "anchor_spans": [ [ 62, 72 ], [ 182, 199 ], [ 234, 251 ] ] }, { "plaintext": "Modern DSL gateways often integrate routing and other functionality. The system boots, synchronizes the DSL connection and finally establishes the internet IP services and connection between the local network and the service provider, using protocols such as DHCP or PPPoE.", "section_idx": 3, "section_name": "Typical setup", "target_page_ids": [ 1338556, 8622, 299686 ], "anchor_spans": [ [ 11, 19 ], [ 259, 263 ], [ 267, 272 ] ] }, { "plaintext": "Many DSL technologies implement an asynchronous transfer mode (ATM) layer over the low-level bitstream layer to enable the adaptation of a number of different technologies over the same link.", "section_idx": 4, "section_name": "Protocols and configurations", "target_page_ids": [ 2499, 574775, 50082 ], "anchor_spans": [ [ 35, 61 ], [ 68, 73 ], [ 93, 102 ] ] }, { "plaintext": "DSL implementations may create bridged or routed networks. In a bridged configuration, the group of subscriber computers effectively connect into a single subnetwork. The earliest implementations used DHCP to provide the IP address to the subscriber equipment, with authentication via MAC address or an assigned hostname. Later implementations often use Point-to-Point Protocol (PPP) to authenticate with a user ID and password.", "section_idx": 4, "section_name": "Protocols and configurations", "target_page_ids": [ 2702169, 25750, 149426, 8622, 14921, 47967, 20668, 611421, 23511 ], "anchor_spans": [ [ 31, 37 ], [ 42, 48 ], [ 155, 165 ], [ 201, 205 ], [ 221, 231 ], [ 266, 280 ], [ 285, 296 ], [ 312, 320 ], [ 354, 377 ] ] }, { "plaintext": "Transmission methods vary by market, region, carrier, and equipment.", "section_idx": 5, "section_name": "Transmission modulation methods", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Discrete multitone modulation (DMT), the most common kind, also known as Orthogonal frequency-division multiplexing (OFDM)", "section_idx": 5, "section_name": "Transmission modulation methods", "target_page_ids": [ 22691, 22691 ], "anchor_spans": [ [ 1, 30 ], [ 74, 116 ] ] }, { "plaintext": " Trellis-coded pulse-amplitude modulation (TC-PAM), used for HDSL2 and SHDSL", "section_idx": 5, "section_name": "Transmission modulation methods", "target_page_ids": [ 5447449, 5533133, 487923 ], "anchor_spans": [ [ 1, 41 ], [ 61, 66 ], [ 71, 76 ] ] }, { "plaintext": " Carrierless amplitude phase modulation (CAP), deprecated in 1996 for ADSL, used for HDSL", "section_idx": 5, "section_name": "Transmission modulation methods", "target_page_ids": [ 1920923 ], "anchor_spans": [ [ 1, 39 ] ] }, { "plaintext": " Two-binary, one-quaternary (2B1Q), used for IDSL and HDSL", "section_idx": 5, "section_name": "Transmission modulation methods", "target_page_ids": [ 64524 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": "DSL technologies (sometimes collectively summarized as xDSL) include:", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Symmetric digital subscriber line (SDSL), umbrella term for xDSL where the bitrate is equal in both directions.", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 100110 ], "anchor_spans": [ [ 0, 33 ] ] }, { "plaintext": "ISDN digital subscriber line (IDSL), ISDN-based technology that provides a bitrate equivalent to two ISDN bearer and one data channel, 144kbit/s symmetric over one pair", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 299727 ], "anchor_spans": [ [ 0, 28 ] ] }, { "plaintext": "High-bit-rate digital subscriber line (HDSL), ITU-T G.991.1, the first DSL technology that used a higher frequency spectrum than ISDN, 1,544kbit/s and 2,048kbit/s symmetric services, either on 2 or 3 pairs at 784kbit/s each, 2 pairs at 1,168kbit/s each, or one pair at 2,320kbit/s", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 5649030 ], "anchor_spans": [ [ 0, 37 ] ] }, { "plaintext": "High-bit-rate digital subscriber line 2/4 (HDSL2, HDSL4), ANSI, 1,544kbit/s symmetric over one pair (HDSL2) or two pairs (HDSL4)", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 5533133 ], "anchor_spans": [ [ 0, 41 ] ] }, { "plaintext": "Symmetric digital subscriber line (SDSL), specific proprietary technology, up to 1,544kbit/s symmetric over one pair", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 100110 ], "anchor_spans": [ [ 0, 33 ] ] }, { "plaintext": "Single-pair high-speed digital subscriber line (G.SHDSL), ITU-T G.991.2, standardized successor of HDSL and proprietary SDSL, up to 5,696kbit/s per pair, up to four pairs", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 487923 ], "anchor_spans": [ [ 0, 46 ] ] }, { "plaintext": "Asymmetric digital subscriber line (ADSL), umbrella term for xDSL where the bitrate is greater in one direction than the other.", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 18934536 ], "anchor_spans": [ [ 0, 34 ] ] }, { "plaintext": "ANSI T1.413 Issue 2, up to 8Mbit/s and 1Mbit/s", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 1344512 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": "G.dmt, ITU-T G.992.1, up to 10Mbit/s and 1Mbit/s", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 296348 ], "anchor_spans": [ [ 0, 5 ] ] }, { "plaintext": "G.lite, ITU-T G.992.2, more noise and attenuation resistant than G.dmt, up to 1,536kbit/s and 512kbit/s", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 2270505 ], "anchor_spans": [ [ 0, 6 ] ] }, { "plaintext": "Asymmetric digital subscriber line 2 (ADSL2), ITU-T G.992.3, up to 12Mbit/s and 3.5Mbit/s", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 2768686 ], "anchor_spans": [ [ 0, 36 ] ] }, { "plaintext": "Asymmetric digital subscriber line 2 plus (ADSL2+), ITU-T G.992.5, up to 24Mbit/s and 3.5Mbit/s", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 1773908 ], "anchor_spans": [ [ 0, 41 ] ] }, { "plaintext": "Very-high-bit-rate digital subscriber line (VDSL), ITU-T G.993.1, up to 52Mbit/s and 16Mbit/s", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 179265 ], "anchor_spans": [ [ 0, 42 ] ] }, { "plaintext": "Very-high-bit-rate digital subscriber line 2 (VDSL2), ITU-T G.993.2, an improved version of VDSL, compatible with ADSL2+, sum of both directions up to 200Mbit/s. G.vector crosstalk cancelling feature (ITU-T G.993.5) can be used to increase range at a given bitrate, e.g. 100Mbit/s at up to 500 meters.", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 179265, 179265 ], "anchor_spans": [ [ 0, 44 ], [ 162, 170 ] ] }, { "plaintext": "G.fast, ITU-T G.9700 and G.9701, up to approximately 1Gbit/s aggregate uplink and downlink at 100m. Approved in December 2014, deployments planned for 2016.", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 41933979 ], "anchor_spans": [ [ 0, 6 ] ] }, { "plaintext": "Bonded DSL Rings (DSL Rings), a shared ring topology at 400Mbit/s", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 16236528 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Cable/DSL gateway", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 29979890 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Etherloop Ethernet local loop", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 8444724 ], "anchor_spans": [ [ 0, 9 ] ] }, { "plaintext": "High-speed voice and data link", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 13412252 ], "anchor_spans": [ [ 0, 30 ] ] }, { "plaintext": "Rate-adaptive digital subscriber line (RADSL), designed to increase range and noise tolerance by sacrificing upstream speed", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 840579 ], "anchor_spans": [ [ 0, 37 ] ] }, { "plaintext": "Uni-DSL (Uni digital subscriber line or UDSL), technology developed by Texas Instruments, backwards compatible with all DMT standards", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 3919363 ], "anchor_spans": [ [ 0, 7 ] ] }, { "plaintext": " Hybrid Access Networks combine existing xDSL deployments with a wireless network such as LTE to increase bandwidth and quality of experience by balancing the traffic over the two access networks.", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 57836368, 19752979 ], "anchor_spans": [ [ 1, 23 ], [ 90, 93 ] ] }, { "plaintext": "The line-length limitations from telephone exchange to subscriber impose severe limits on data transmission rates. Technologies such as VDSL provide very high-speed but short-range links. VDSL is used as a method of delivering triple play services (typically implemented in fiber to the curb network architectures).", "section_idx": 6, "section_name": "DSL technologies", "target_page_ids": [ 179265, 2065003, 3492955 ], "anchor_spans": [ [ 136, 140 ], [ 227, 238 ], [ 274, 291 ] ] }, { "plaintext": " Dynamic spectrum management (DSM)", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 7391821 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " John Cioffi – Known as \"the father of DSL\"", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 27560341 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " List of countries by number of Internet subscriptions", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 13230505 ], "anchor_spans": [ [ 1, 54 ] ] }, { "plaintext": " List of device bandwidths", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 399520 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " pp 53–86", "section_idx": 9, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ADSL Theory—Information about the background & workings of ADSL, and the factors involved in achieving a good sync between your modem and the DSLAM.", "section_idx": 10, "section_name": "External links", "target_page_ids": [ 245584 ], "anchor_spans": [ [ 143, 148 ] ] } ]

[ "Digital_subscriber_line", "American_inventions", "Modems", "Internet_access" ]

[ "DSL" ]

[ { "plaintext": "In telecommunication, a digital transmission group is a group of digitized voice or data channels or both with bit streams that are combined into a single digital bit stream for transmission over communications media. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 18985040, 8276, 50082, 609152, 47867 ], "anchor_spans": [ [ 3, 20 ], [ 84, 88 ], [ 155, 162 ], [ 163, 173 ], [ 178, 190 ], [ 196, 210 ] ] }, { "plaintext": "Digital transmission groups usually are categorized by their maximum capacity, not by a specific number of channels. However, the maximum digital transmission group capacity must be equal to or greater than the sum of the individual multiplexer input channel capacities.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 38542 ], "anchor_spans": [ [ 233, 244 ] ] }, { "plaintext": "Digital Signal 1", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 907542 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "E-carrier", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 46728 ], "anchor_spans": [ [ 0, 9 ] ] }, { "plaintext": "Plesiochronous Digital Hierarchy", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 38512 ], "anchor_spans": [ [ 0, 32 ] ] } ]

[ "Multiplexing" ]

[]

[ { "plaintext": "Direct access may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "DirectAccess, a network technology in Windows 7 and Windows Server 2008 R2, and Windows 8 and Windows Server 2012", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22996169 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": "Direct access (computing), a concept in computer science", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 25612 ], "anchor_spans": [ [ 0, 25 ] ] }, { "plaintext": "Direct Access Archive, a proprietary file format", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5431445 ], "anchor_spans": [ [ 0, 21 ] ] }, { "plaintext": "Direct access storage device, a secondary computer storage device", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 54691 ], "anchor_spans": [ [ 0, 28 ] ] }, { "plaintext": "Direct Access Test Unit, special numbers used to test telephone exchanges", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3759730 ], "anchor_spans": [ [ 0, 23 ] ] }, { "plaintext": "Direct access trading, a technology for stock trading", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 21010744 ], "anchor_spans": [ [ 0, 21 ] ] } ]

[]

[]

[ { "plaintext": "Direct connect may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Direct Connect (protocol), a file sharing client and protocol", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 70342 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " A protocol used by the program AOL Instant Messenger", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2923 ], "anchor_spans": [ [ 32, 53 ] ] }, { "plaintext": " Sprint Direct Connect, a brand name used by Sprint Corporation for its digital push-to-talk service, similar to a walkie-talkie", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2380393 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Direct Connect is an Australian company related to Lumo Energy", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 28488434 ], "anchor_spans": [ [ 52, 63 ] ] } ]

[]

[ "Direct Connect" ]

[ { "plaintext": "Direct distance dialing (DDD) is a telecommunication service feature in North America by which a caller may, without operator assistance, call any other user outside the local calling area. Direct dialing by subscribers typically requires extra digits to be dialed as prefixes to the directory telephone number of the destination. International Direct Distance Dialing (IDDD) extends the system beyond the geographic boundaries of the North American Numbering Plan (NANP).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 406712, 406687, 2052479, 214971 ], "anchor_spans": [ [ 35, 52 ], [ 97, 103 ], [ 117, 136 ], [ 153, 157 ], [ 435, 464 ] ] }, { "plaintext": "The first direct-dialed long-distance telephone calls were possible in the New Jersey communities of Englewood and Teaneck. Customers of the ENglewood 3, ENglewood 4 and TEaneck 7 exchanges, who could already dial telephone numbers in the New York City area, could place calls to eleven major cities across the United States by dialing the three-digit area code and the seven-digit directory number. Local telephone numbers still consisted of the first two letters of the central office name and five digits. On November 10, 1951, Englewood Mayor M. Leslie Denning made the first customer-dialed long-distance call, to Mayor Frank Osborne of Alameda, California.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 21648, 124980, 125011, 627405, 2201331, 33459878, 1394709, 10480587, 3052 ], "anchor_spans": [ [ 75, 85 ], [ 101, 110 ], [ 115, 122 ], [ 352, 361 ], [ 472, 491 ], [ 547, 564 ], [ 596, 614 ], [ 625, 638 ], [ 642, 661 ] ] }, { "plaintext": "The destinations, and their area codes, equipped with a long-distance toll-switch at that time were:", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " 617: Boston, Massachusetts", "section_idx": 1, "section_name": "History", "target_page_ids": [ 3901420, 24437894 ], "anchor_spans": [ [ 1, 4 ], [ 6, 12 ] ] }, { "plaintext": " 312: Chicago, Illinois", "section_idx": 1, "section_name": "History", "target_page_ids": [ 1627561, 6886 ], "anchor_spans": [ [ 1, 4 ], [ 6, 13 ] ] }, { "plaintext": " 216: Cleveland, Ohio", "section_idx": 1, "section_name": "History", "target_page_ids": [ 5852747, 5951 ], "anchor_spans": [ [ 1, 4 ], [ 6, 15 ] ] }, { "plaintext": " 313: Detroit, Michigan", "section_idx": 1, "section_name": "History", "target_page_ids": [ 1649238, 8687 ], "anchor_spans": [ [ 1, 4 ], [ 6, 13 ] ] }, { "plaintext": " 414: Milwaukee, Wisconsin", "section_idx": 1, "section_name": "History", "target_page_ids": [ 1832288, 53117 ], "anchor_spans": [ [ 1, 4 ], [ 6, 15 ] ] }, { "plaintext": " 415: Oakland, California", "section_idx": 1, "section_name": "History", "target_page_ids": [ 932914, 50548 ], "anchor_spans": [ [ 1, 4 ], [ 6, 13 ] ] }, { "plaintext": " 215: Philadelphia, Pennsylvania", "section_idx": 1, "section_name": "History", "target_page_ids": [ 4268269, 50585 ], "anchor_spans": [ [ 1, 4 ], [ 6, 18 ] ] }, { "plaintext": " 412: Pittsburgh, Pennsylvania", "section_idx": 1, "section_name": "History", "target_page_ids": [ 4440394, 25101 ], "anchor_spans": [ [ 1, 4 ], [ 6, 16 ] ] }, { "plaintext": " 401: Providence, Rhode Island", "section_idx": 1, "section_name": "History", "target_page_ids": [ 5836716, 19356538 ], "anchor_spans": [ [ 1, 4 ], [ 6, 30 ] ] }, { "plaintext": " 916: Sacramento, California", "section_idx": 1, "section_name": "History", "target_page_ids": [ 932904, 29631 ], "anchor_spans": [ [ 1, 4 ], [ 6, 16 ] ] }, { "plaintext": " 318: San Francisco, California", "section_idx": 1, "section_name": "History", "target_page_ids": [ 4567920, 49728 ], "anchor_spans": [ [ 1, 4 ], [ 6, 19 ] ] }, { "plaintext": "Other areas could not yet be included in DDD as they did not have the necessary toll switching equipment, or because they still did not use a seven-digit local numbering plan. Montreal, Quebec, and Toronto, Ontario, in Canada, for example, had a mix of six- and seven-digit telephone numbers from 1951 to 1957, and did not have DDD until 1958. Whitehorse, Yukon, had seven-digit numbers starting in 1965, but the necessary switching equipment was not in place until 1972.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 7954681, 7954867, 64646, 22218, 33056, 34230 ], "anchor_spans": [ [ 176, 184 ], [ 186, 192 ], [ 198, 205 ], [ 207, 214 ], [ 344, 354 ], [ 356, 361 ] ] }, { "plaintext": "San Francisco required the special area code 318 due to temporary routing requirements. San Francisco and Oakland each had their own separate toll-switches, so calls had to be routed accordingly depending on the final destination. As the telephone equipment used at the time could only handle three-digit translation, the temporary use of area code 318 was required to distinguish between the two areas. Area code 318 was temporarily used to specify San Francisco and areas north of the Golden Gate, while calls with destinations in Oakland and the East Bay continued to use area code 415. When the electromechanical card-translator box became available sometime during 1952–53, six-digit translation became possible and the use of area code 318 was no longer required. Area code 318 was reclaimed for future use (now used as an area code for northern Louisiana), and the entire San Francisco Bay Area returned to using area code 415.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 141983, 50548, 1307148, 18130, 19283806 ], "anchor_spans": [ [ 487, 498 ], [ 533, 540 ], [ 549, 557 ], [ 852, 861 ], [ 879, 901 ] ] }, { "plaintext": "The No. 4 Crossbar switching system had been introduced in the early 1940s to switch four-wire circuits and replace the incoming operator. With semiautomatic operation analogous to the early days of the panel switch, the operator in the originating city used a multifrequency keypad to dial an access code to connect to the correct city and to send the seven-digit number to incoming equipment at the terminating city. This design was further refined to serve DDD.", "section_idx": 2, "section_name": "Hardware", "target_page_ids": [ 41170, 50350318, 502892 ], "anchor_spans": [ [ 85, 102 ], [ 203, 215 ], [ 261, 275 ] ] }, { "plaintext": "The card sorter of the 4A/CTS (Number 4A Crossbar / Card Translator System) allowed six-digit translation of the central office code number dialed by the customer. This determined the proper trunk circuits to use, where separate circuit groups were used for different cities in the same area code, as in the case of Oakland and San Francisco. The new device used metal cards similar in principle to computer punched cards, and they were rapidly scanned as they fell past a light beam. CTS machines were called 4A (Advanced) if the translator was included in the original installation, and 4M (Modified) if it was added later. A 1970s version of 4XB, the 4A/ETS, used a computer to translate. For international dialing, Traffic Service Position System (TSPS) provided the extra computer power.", "section_idx": 2, "section_name": "Hardware", "target_page_ids": [ 26668156, 593233, 24420, 1308433 ], "anchor_spans": [ [ 113, 127 ], [ 191, 205 ], [ 408, 421 ], [ 719, 750 ] ] }, { "plaintext": "The reach of DDD was limited due to the inefficiency and expense of switching equipment, and the limited ability to process records of completed calls. An early obstacle was that the majority of switching systems did not provide Automatic Number Identification (ANI). Common control switches, such as the 1XB switch, were fairly quickly retrofitted to provide ANI, and most 5XB switches were initially installed with ANI services. Panel switch were eventually retrofitted, as were some step-by-step systems that were not scheduled for immediate replacement. Even if a switch had ANI, it could not identify callers on party lines. This was only partly overcome by tip-party identification for two-party lines. As the cost of subscriber line carrier declined, party lines were gradually phased out.", "section_idx": 2, "section_name": "Hardware", "target_page_ids": [ 250906, 40911, 8319248, 8222445, 50350318, 179918, 5892970, 2788463 ], "anchor_spans": [ [ 229, 260 ], [ 268, 282 ], [ 305, 315 ], [ 374, 384 ], [ 431, 443 ], [ 486, 506 ], [ 617, 628 ], [ 724, 747 ] ] }, { "plaintext": "As this and other improved technologies became available, as well as Automatic Message Accounting (AMA) computers to process the long-distance records into customer bills, the reach of DDD was slow in the 1950s, but quickened in the early 1960s. Electronic switching systems allowed electronic processing of the dialed digits, referring to electronic memories to determine call routing, and this has reached the state of the art, with digital telephone exchanges which are basically specialized computers that route voice traffic from one \"peripheral\" to another as digital data. Call routing can now be done based on the area code, central office code and even the first two digits of the line number, although routing based on digits past the central office code is usually limited to cases of competitive local exchange carriers, number pooling and number portability.", "section_idx": 2, "section_name": "Hardware", "target_page_ids": [ 7813346, 41101, 26668156, 307830, 1624952, 645581 ], "anchor_spans": [ [ 69, 97 ], [ 246, 273 ], [ 443, 461 ], [ 796, 830 ], [ 833, 847 ], [ 852, 870 ] ] }, { "plaintext": "In the 1960s, with the domestic conversion still underway, plans were laid to extend Direct Distance Dialing beyond North America (including a number of the Caribbean Islands). Some subscribers could already directly dial transatlantic telephone calls to certain destinations as early as in 1957 over the recently completed Atlantic cable to England. A new systematic extension of Direct Distance Dialing was developed and was introduced as International Direct Distance Dialing (IDDD) in March 1970.", "section_idx": 3, "section_name": "IDDD", "target_page_ids": [ 5093327 ], "anchor_spans": [ [ 157, 174 ] ] }, { "plaintext": "With so much new equipment already working that could not handle more than the requisite ten-digit telephone numbers of DDD, the new system was based on designs by which most toll offices did not have to store and forward the whole international telephone number. Gateway offices were set up in New York, London and Paris, connected to the ordinary automatic toll network. The New York gateway was at 32 Avenue of the Americas. The new LT1 5XB switch on the tenth floor of 435 West 50th Street received new originating registers and outgoing senders able to handle fifteen-digit telephone numbers, with appropriate modifications to completing markers and other equipment. Other 5XB in the next few years were installed with IDDD as original equipment, and in the 1970s ESS offices also provided the service.", "section_idx": 3, "section_name": "IDDD", "target_page_ids": [ 28744944, 8222445, 3857668 ], "anchor_spans": [ [ 401, 426 ], [ 440, 450 ], [ 643, 650 ] ] }, { "plaintext": "The key to the new system was two-stage multi-frequency pulsing. The outgoing sender sent its Class 4 toll center an off-hook signal as usual, received a wink as usual as a \"proceed to send\" signal, and outpulsed only a special three-digit (later six-digit) access code. The toll center picked a trunk through the long-distance network to the gateway office, which sent a second wink to the originating office, which then sent the whole dialed number. Thus the toll switching system needed no modification except at the gateway. The international trunks used Signaling System No. 5, a \"North Atlantic\" version of the North American multi-frequency signaling system, with minor modifications including slightly higher digit rate. European MF systems of the time used compelled signaling, which would slow down too much on a long transoceanic connection.", "section_idx": 3, "section_name": "IDDD", "target_page_ids": [ 502892, 41438, 7148381, 9140755 ], "anchor_spans": [ [ 40, 55 ], [ 117, 125 ], [ 559, 581 ], [ 766, 785 ] ] }, { "plaintext": "In the 1970s, toll centers were modified by adding the Traffic Service Position System (TSPS). With these new computers in place, digit storage in the toll system was no longer a problem. End offices were less extensively modified, and sent all their digits in a single stream. TSPS handled the gateway codes and other complexities of toll connections to the gateway office.", "section_idx": 3, "section_name": "IDDD", "target_page_ids": [ 1308433 ], "anchor_spans": [ [ 55, 86 ] ] }, { "plaintext": "In the United Kingdom and other parts of the Commonwealth of Nations, an equivalent service to direct distance dialing is subscriber trunk dialing (STD), and ISD for international subscriber trunk dialing. Queen Elizabeth II inaugurated STD on 5 December 1958, when she dialed a call from Bristol to Edinburgh and spoke to the Lord Provost.", "section_idx": 4, "section_name": "Equivalent service in the United Kingdom", "target_page_ids": [ 21175158, 409120, 12153654, 720209 ], "anchor_spans": [ [ 45, 68 ], [ 122, 146 ], [ 212, 224 ], [ 327, 339 ] ] }, { "plaintext": "1958 in the United Kingdom", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 8142505 ], "anchor_spans": [ [ 0, 26 ] ] }, { "plaintext": "4XB switch", "section_idx": 7, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Teleselezione", "section_idx": 7, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Telecommunication_services", "Telecommunications-related_introductions_in_1951" ]

[]

[ { "plaintext": "In telecommunications, direct-sequence spread spectrum (DSSS) is a spread-spectrum modulation technique primarily used to reduce overall signal interference. The direct-sequence modulation makes the transmitted signal wider in bandwidth than the information bandwidth. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 41734, 20637, 2889864 ], "anchor_spans": [ [ 3, 20 ], [ 67, 82 ], [ 83, 93 ], [ 144, 156 ] ] }, { "plaintext": "After the despreading or removal of the direct-sequence modulation in the receiver, the information bandwidth is restored, while the unintentional and intentional interference is substantially reduced.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The first known scheme for this technique was introduced by a Swiss inventor, Gustav Guanella. With DSSS, the message bits are modulated by a pseudorandom bit sequence known as a spreading sequence. Each spreading-sequence bit, which is known as a chip, has a much shorter duration (larger bandwidth) than the original message bits. The modulation of the message bits scrambles and spreads the pieces of data, and thereby results in a bandwidth size nearly identical to that of the spreading sequence. The smaller the chip duration, the larger the bandwidth of the resulting DSSS signal; more bandwidth multiplexed to the message signal results in better resistance against interference.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 7351032, 37021521, 2006896 ], "anchor_spans": [ [ 62, 67 ], [ 78, 93 ], [ 142, 167 ] ] }, { "plaintext": "Some practical and effective uses of DSSS include the code-division multiple access (CDMA) method, the IEEE 802.11b specification used in Wi-Fi networks, and the Global Positioning System.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 7143, 14739, 63973, 11866 ], "anchor_spans": [ [ 54, 83 ], [ 103, 115 ], [ 138, 143 ], [ 162, 187 ] ] }, { "plaintext": " DSSS phase-shifts a sine wave pseudorandomly with a continuous string of chips, each of which has a much shorter duration than an information bit. That is, each information bit is modulated by a sequence of much faster chips. Therefore, the chip rate is much higher than the information bit rate.", "section_idx": 1, "section_name": "Features", "target_page_ids": [ 41551, 324749, 23210, 27701, 3364, 8883303, 18985062, 40688 ], "anchor_spans": [ [ 6, 18 ], [ 21, 30 ], [ 31, 43 ], [ 64, 70 ], [ 143, 146 ], [ 242, 251 ], [ 276, 287 ], [ 288, 296 ] ] }, { "plaintext": " DSSS uses a signal structure in which the spreading sequence produced by the transmitter is already known by the receiver. The receiver can then use the same spreading sequence to counteract its effect on the received signal in order to reconstruct the information signal.", "section_idx": 1, "section_name": "Features", "target_page_ids": [ 41703 ], "anchor_spans": [ [ 13, 19 ] ] }, { "plaintext": "Direct-sequence spread-spectrum transmissions multiply the data being transmitted by a pseudorandom spreading sequence that has a much higher bit rate than the original data rate. The resulting transmitted signal resembles bandlimited white noise, like an audio recording of \"static\". However, this noise-like signal is used to exactly reconstruct the original data at the receiving end, by multiplying it by the same spreading sequence (because , and ). This process, known as despreading, is mathematically a correlation of the transmitted spreading sequence with the spreading sequence that the receiver already knows the transmitter is using. After the despreading, the signal-to-noise ratio is approximately increased by the spreading factor, which is the ratio of the spreading-sequence rate to the data rate. ", "section_idx": 2, "section_name": "Transmission method", "target_page_ids": [ 46182, 157057, 41706 ], "anchor_spans": [ [ 235, 246 ], [ 512, 523 ], [ 675, 696 ] ] }, { "plaintext": "While a transmitted DSSS signal occupies a much wider bandwidth than a simple modulation of the original signal would require, its frequency spectrum can be somewhat restricted for spectrum economy by a conventional analog bandpass filter to give a roughly bell-shaped envelope centered on the carrier frequency. In contrast, frequency-hopping spread spectrum pseudorandomly retunes the carrier and requires a uniform frequency response since any bandwidth shaping would cause amplitude modulation of the signal by the hopping code.", "section_idx": 2, "section_name": "Transmission method", "target_page_ids": [ 153217, 46890 ], "anchor_spans": [ [ 294, 311 ], [ 326, 359 ] ] }, { "plaintext": "If an undesired transmitter transmits on the same channel but with a different spreading sequence (or no sequence at all), the despreading process reduces the power of that signal. This effect is the basis for the code-division multiple access (CDMA) property of DSSS, which allows multiple transmitters to share the same channel within the limits of the cross-correlation properties of their spreading sequences.", "section_idx": 2, "section_name": "Transmission method", "target_page_ids": [ 7143, 714163 ], "anchor_spans": [ [ 214, 243 ], [ 355, 372 ] ] }, { "plaintext": " Resistance to unintended or intended jamming", "section_idx": 3, "section_name": "Benefits", "target_page_ids": [ 1838227 ], "anchor_spans": [ [ 38, 45 ] ] }, { "plaintext": " Sharing of a single channel among multiple users", "section_idx": 3, "section_name": "Benefits", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Reduced signal/background-noise level hampers interception", "section_idx": 3, "section_name": "Benefits", "target_page_ids": [ 29122 ], "anchor_spans": [ [ 47, 59 ] ] }, { "plaintext": " Determination of relative timing between transmitter and receiver", "section_idx": 3, "section_name": "Benefits", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The United States GPS, European Galileo and Russian GLONASS satellite navigation systems; earlier GLONASS used DSSS with a single spreading sequence in conjunction with FDMA, while later GLONASS used DSSS to achieve CDMA with multiple spreading sequences.", "section_idx": 4, "section_name": "Uses", "target_page_ids": [ 11866, 13009, 46149, 1515653, 201958, 7143 ], "anchor_spans": [ [ 19, 22 ], [ 33, 40 ], [ 53, 60 ], [ 61, 81 ], [ 170, 174 ], [ 217, 221 ] ] }, { "plaintext": " DS-CDMA (Direct-Sequence Code Division Multiple Access) is a multiple access scheme based on DSSS, by spreading the signals from/to different users with different codes. It is the most widely used type of CDMA.", "section_idx": 4, "section_name": "Uses", "target_page_ids": [ 86392, 7143 ], "anchor_spans": [ [ 62, 77 ], [ 207, 211 ] ] }, { "plaintext": " Cordless phones operating in the 900MHz, 2.4GHz and 5.8GHz bands", "section_idx": 4, "section_name": "Uses", "target_page_ids": [ 785028, 634183 ], "anchor_spans": [ [ 1, 16 ], [ 60, 65 ] ] }, { "plaintext": " IEEE 802.11b 2.4GHz Wi-Fi, and its predecessor 802.11-1999. (Their successor 802.11g uses both OFDM and DSSS)", "section_idx": 4, "section_name": "Uses", "target_page_ids": [ 13420417, 63973, 13359674, 13420705, 22691 ], "anchor_spans": [ [ 1, 13 ], [ 21, 26 ], [ 48, 59 ], [ 78, 85 ], [ 96, 100 ] ] }, { "plaintext": " Automatic meter reading", "section_idx": 4, "section_name": "Uses", "target_page_ids": [ 435397 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " IEEE 802.15.4 (used, e.g., as PHY and MAC layer for ZigBee, or, as the physical layer for WirelessHART)", "section_idx": 4, "section_name": "Uses", "target_page_ids": [ 455777, 195337, 21398953 ], "anchor_spans": [ [ 1, 14 ], [ 53, 59 ], [ 91, 103 ] ] }, { "plaintext": " Radio-controlled model Automotive, Aeronautical and Marine vehicles", "section_idx": 4, "section_name": "Uses", "target_page_ids": [ 100482 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Complementary code keying", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 2266648 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Frequency-hopping spread spectrum", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 46890 ], "anchor_spans": [ [ 1, 34 ] ] }, { "plaintext": " Linear-feedback shift register", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 58992 ], "anchor_spans": [ [ 1, 31 ] ] }, { "plaintext": " Orthogonal frequency-division multiplexing", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 22691 ], "anchor_spans": [ [ 1, 43 ] ] }, { "plaintext": " The Origins of Spread-Spectrum Communications", "section_idx": 6, "section_name": "References", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " NTIA Manual of Regulations and Procedures for Federal Radio Frequency Management", "section_idx": 6, "section_name": "References", "target_page_ids": [ 218360 ], "anchor_spans": [ [ 1, 81 ] ] }, { "plaintext": " Civil Spread Spectrum History", "section_idx": 7, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "スペクトラム拡散", "section_idx": 7, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Quantized_radio_modulation_modes", "Wireless_networking", "IEEE_802.11" ]

[]

[ { "plaintext": "In telecommunication, a disengagement originator is the user or execution unit that initiates a disengagement attempt. The disengagement originator may be the originating user, the destination user, or the communications system. The communications system may deliberately originate the disengagement because of preemption, or inadvertently due to system malfunction.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 2052479, 9828, 40925, 1172827 ], "anchor_spans": [ [ 3, 20 ], [ 56, 60 ], [ 64, 78 ], [ 206, 227 ], [ 311, 321 ] ] }, { "plaintext": " Call setup", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 65790632 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Clearing (telecommunications) (a.k.a. teardown)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 3322453 ], "anchor_spans": [ [ 1, 30 ] ] }, { "plaintext": " Signaling System 7", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 100098 ], "anchor_spans": [ [ 1, 19 ] ] } ]

[ "Teletraffic" ]

[]

[ { "plaintext": "A dispersion-limited operation is an operation of a communications link in which signal waveform degradation attributable to the dispersive effects of the communications medium is the dominant mechanism that limits link performance. The dispersion is the filter-like effect which a link has on the signal, due to the different propagation speeds of the eigenmodes of the link. Practically, this means that the waveform at the input will be different from the waveform at the output of the link.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 47772, 47867, 40996, 41703, 47592, 7876158, 41812, 2161429 ], "anchor_spans": [ [ 37, 46 ], [ 52, 66 ], [ 67, 71 ], [ 81, 87 ], [ 88, 96 ], [ 97, 108 ], [ 170, 176 ], [ 353, 362 ] ] }, { "plaintext": "Note that the amount of allowable degradation is dependent on the quality of the receiver. In fiber optic communications, dispersion-limited operation is often confused with distortion-limited operation.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 172333, 41053 ], "anchor_spans": [ [ 122, 132 ], [ 174, 202 ] ] } ]

[ "Fiber-optic_communications" ]

[]

[ { "plaintext": "In signal processing, distortion is the alteration of the original shape (or other characteristic) of a signal. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio signal representing sound or a video signal representing images, in an electronic device or communication channel.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 29324, 275871, 5177, 9663, 47592, 275871, 12812363, 32441, 156700 ], "anchor_spans": [ [ 3, 20 ], [ 104, 110 ], [ 116, 130 ], [ 135, 146 ], [ 178, 186 ], [ 213, 219 ], [ 232, 244 ], [ 269, 281 ], [ 330, 351 ] ] }, { "plaintext": "Distortion is usually unwanted, and so engineers strive to eliminate or minimize it. In some situations, however, distortion may be desirable. For example, in noise reduction systems like the Dolby system, an audio signal is deliberately distorted in ways that emphasize aspects of the signal that are subject to electrical noise, then it is symmetrically \"undistorted\" after passing through a noisy communication channel, reducing the noise in the received signal. Distortion is also used as a musical effect, particularly with electric guitars.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 476836, 87710, 3966982, 6325194, 10272 ], "anchor_spans": [ [ 160, 175 ], [ 193, 205 ], [ 314, 330 ], [ 497, 511 ], [ 531, 546 ] ] }, { "plaintext": "The addition of noise or other outside signals (hum, interference) is not considered distortion, though the effects of quantization distortion are sometimes included in noise. Quality measures that reflect both noise and distortion include the signal-to-noise and distortion (SINAD) ratio and total harmonic distortion plus noise (THD+N).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3966982, 2227992, 2889864, 317018, 41714, 41802 ], "anchor_spans": [ [ 16, 21 ], [ 48, 51 ], [ 53, 65 ], [ 119, 142 ], [ 244, 274 ], [ 293, 329 ] ] }, { "plaintext": "In telecommunication and signal processing, a noise-free system can be characterised by a transfer function, such that the output can be written as a function of the input as", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 33094374, 29324, 8286675, 31146 ], "anchor_spans": [ [ 3, 20 ], [ 25, 42 ], [ 57, 63 ], [ 90, 107 ] ] }, { "plaintext": "When the transfer function comprises only a perfect gain constant A and perfect delay T", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 41968, 1275395 ], "anchor_spans": [ [ 52, 56 ], [ 80, 85 ] ] }, { "plaintext": "the output is undistorted. Distortion occurs when the transfer function F is more complicated than this. If F is a linear function, for instance a filter whose gain and/or delay varies with frequency, the signal suffers linear distortion. Linear distortion does not introduce new frequency components to a signal but does alter the balance of existing ones.", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 152111 ], "anchor_spans": [ [ 115, 130 ] ] }, { "plaintext": "This diagram shows the behaviour of a signal (made up of a square wave followed by a sine wave) as it is passed through various distorting functions.", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 314652, 324749 ], "anchor_spans": [ [ 59, 70 ], [ 85, 94 ] ] }, { "plaintext": " The first trace (in black) shows the input. It also shows the output from a non-distorting transfer function (straight line).", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A high-pass filter (green trace) distorts the shape of a square wave by reducing its low frequency components. This is the cause of the \"droop\" seen on the top of the pulses. This \"pulse distortion\" can be very significant when a train of pulses must pass through an AC-coupled (high-pass filtered) amplifier. As the sine wave contains only one frequency, its shape is unaltered.", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 56486 ], "anchor_spans": [ [ 3, 19 ] ] }, { "plaintext": " A low-pass filter (blue trace) rounds the pulses by removing the high frequency components. All systems are low pass to some extent. Note that the phase of the sine wave is different for the lowpass and the highpass cases, due to the phase distortion of the filters.", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 56484, 24047 ], "anchor_spans": [ [ 3, 18 ], [ 148, 153 ] ] }, { "plaintext": " A slightly non-linear transfer function (purple), this one gently compresses the peaks of the sine wave, as may be typical of a tube audio amplifier. This generates small amounts of low order harmonics.", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 146103, 4689286 ], "anchor_spans": [ [ 12, 22 ], [ 129, 149 ] ] }, { "plaintext": " A hard-clipping transfer function (red) generates high order harmonics. Parts of the transfer function are flat, which indicates that all information about the input signal has been lost in this region.", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 3375566 ], "anchor_spans": [ [ 8, 16 ] ] }, { "plaintext": "The transfer function of an ideal amplifier, with perfect gain and delay, is only an approximation. The true behavior of the system is usually different. Nonlinearities in the transfer function of an active device (such as vacuum tubes, transistors, and operational amplifiers) are a common source of non-linear distortion; in passive components (such as a coaxial cable or optical fiber), linear distortion can be caused by inhomogeneities, reflections, and so on in the propagation path.", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 146103, 30874071, 32496, 30011, 22804, 1886820, 46380, 3372377, 42728, 5017866 ], "anchor_spans": [ [ 154, 163 ], [ 200, 213 ], [ 223, 234 ], [ 237, 247 ], [ 254, 275 ], [ 335, 345 ], [ 357, 370 ], [ 374, 387 ], [ 442, 453 ], [ 472, 483 ] ] }, { "plaintext": "Amplitude distortion is distortion occurring in a system, subsystem, or device when the output amplitude is not a linear function of the input amplitude under specified conditions.", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Harmonic distortion adds overtones that are whole number multiples of a sound wave's frequencies. Nonlinearities that give rise to amplitude distortion in audio systems are most often measured in terms of the harmonics (overtones) added to a pure sinewave fed to the system. Harmonic distortion may be expressed in terms of the relative strength of individual components, in decibels, or the root mean square of all harmonic components: Total harmonic distortion (THD), as a percentage. The level at which harmonic distortion becomes audible depends on the exact nature of the distortion. Different types of distortion (like crossover distortion) are more audible than others (like soft clipping) even if the THD measurements are identical. Harmonic distortion in radio frequency applications is rarely expressed as THD.", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 41480, 14563, 41232, 324749, 8410, 66819, 41802, 2774930, 3951487, 42852 ], "anchor_spans": [ [ 25, 33 ], [ 44, 56 ], [ 209, 217 ], [ 247, 255 ], [ 375, 382 ], [ 392, 408 ], [ 437, 462 ], [ 627, 647 ], [ 684, 697 ], [ 767, 782 ] ] }, { "plaintext": "Non-flat frequency response is a form of distortion that occurs when different frequencies are amplified by different amounts in a filter. For example, the non-uniform frequency response curve of AC-coupled cascade amplifier is an example of frequency distortion. In the audio case, this is mainly caused by room acoustics, poor loudspeakers and microphones, long loudspeaker cables in combination with frequency dependent loudspeaker impedance, etc.", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 23434533, 6144394, 41957 ], "anchor_spans": [ [ 131, 137 ], [ 207, 224 ], [ 435, 444 ] ] }, { "plaintext": "This form of distortion mostly occurs due to electrical reactance. Here, all the components of the input signal are not amplified with the same phase shift, hence making some parts of the output signal out of phase with the rest of the output.", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 140710 ], "anchor_spans": [ [ 45, 65 ] ] }, { "plaintext": "Can be found only in dispersive media. In a waveguide, phase velocity varies with frequency. In a filter, group delay tends to peak near the cut-off frequency, resulting in pulse distortion. When analog long distance trunks were commonplace, for example in 12 channel carrier, group delay distortion had to be corrected in repeaters.", "section_idx": 1, "section_name": "Electronic signals", "target_page_ids": [ 172333, 41863, 25098, 40986, 7092388, 41655 ], "anchor_spans": [ [ 21, 37 ], [ 44, 53 ], [ 55, 69 ], [ 141, 158 ], [ 258, 276 ], [ 324, 332 ] ] }, { "plaintext": "As the system output is given by y(t) = F(x(t)), then if the inverse function F−1 can be found, and used intentionally to distort either the input or the output of the system, then the distortion is corrected.", "section_idx": 2, "section_name": "Correction of distortion", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An example of a similar correction is where LP/vinyl recordings or FM audio transmissions are deliberately pre-emphasised by a linear filter, the reproducing system applies an inverse filter to make the overall system undistorted.", "section_idx": 2, "section_name": "Correction of distortion", "target_page_ids": [ 172121, 1607203, 9975 ], "anchor_spans": [ [ 47, 52 ], [ 67, 75 ], [ 127, 140 ] ] }, { "plaintext": "Correction is not possible if the inverse does not exist—for instance if the transfer function has flat spots (the inverse would map multiple input points to a single output point). This produces an uncorrectable loss of information. Such a situation can occur when an amplifier is overdriven—causing clipping or slew rate distortion when, for a moment, the amplifier characteristics alone and not the input signal determine the output.", "section_idx": 2, "section_name": "Correction of distortion", "target_page_ids": [ 31146, 3375566, 544672 ], "anchor_spans": [ [ 77, 94 ], [ 301, 309 ], [ 313, 322 ] ] }, { "plaintext": "Many symmetrical electronic circuits reduce the magnitude of even harmonics generated by the non-linearities of the amplifier's components, by combining two signals from opposite halves of the circuit where distortion components that are roughly the same magnitude but out of phase. Examples include push-pull amplifiers and long-tailed pairs.", "section_idx": 2, "section_name": "Correction of distortion", "target_page_ids": [ 8707643, 856798, 326647 ], "anchor_spans": [ [ 17, 36 ], [ 301, 321 ], [ 326, 342 ] ] }, { "plaintext": "In binary signaling such as FSK, distortion is the shifting of the significant instants of the signal pulses from their proper positions relative to the beginning of the start pulse. The magnitude of the distortion is expressed in percent of an ideal unit pulse length. This is sometimes called bias distortion.", "section_idx": 3, "section_name": "Teletypewriter or modem signaling", "target_page_ids": [ 41703, 41193, 41600, 41600 ], "anchor_spans": [ [ 10, 19 ], [ 28, 31 ], [ 176, 181 ], [ 256, 261 ] ] }, { "plaintext": "Telegraphic distortion is a similar and older problem, distorting the ratio between mark and space intervals.", "section_idx": 3, "section_name": "Teletypewriter or modem signaling", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In the art world, a distortion is any change made by an artist to the size, shape or visual character of a form in order to express an idea, convey a feeling, or enhance visual impact. Such distortions or \"abstractions\" primarily refer to purposeful deviations from photorealistic perspective or from realistic proportionality. Examples include \"The Weeping Woman\" by Picasso and \"The Adoration of the Shepherds\" by El Greco, whose human subject matters are irregularly and (as is often with physical distortions) asymmetrically proportioned in a way that is not possible in standard perspective. ", "section_idx": 4, "section_name": "Distortion in art", "target_page_ids": [ 466798, 9440855, 7902980, 380405 ], "anchor_spans": [ [ 267, 281 ], [ 348, 365 ], [ 383, 413 ], [ 586, 597 ] ] }, { "plaintext": "With respect to audio, distortion refers to any kind of deformation of an output waveform compared to its input, usually clipping, harmonic distortion, or intermodulation distortion (mixing phenomena) caused by non-linear behavior of electronic components and power supply limitations. Terms for specific types of nonlinear audio distortion include: crossover distortion and slew-induced distortion (SID).", "section_idx": 5, "section_name": "Audio distortion", "target_page_ids": [ 3375566, 41052, 590995, 546444, 146103, 2774930, 26089310 ], "anchor_spans": [ [ 121, 129 ], [ 131, 150 ], [ 155, 181 ], [ 183, 189 ], [ 211, 221 ], [ 350, 370 ], [ 375, 398 ] ] }, { "plaintext": "Other forms of audio distortion are non-flat frequency response, compression, modulation, aliasing, quantization noise, wow and flutter from analog media such as vinyl records and magnetic tape. The human ear cannot hear phase distortion, except that it may affect the stereo imaging.", "section_idx": 5, "section_name": "Audio distortion", "target_page_ids": [ 302033, 262733, 20637, 151474, 317018, 1642055, 41160, 172121, 20505, 41510, 2371888 ], "anchor_spans": [ [ 45, 63 ], [ 65, 76 ], [ 78, 88 ], [ 90, 98 ], [ 100, 118 ], [ 120, 123 ], [ 128, 135 ], [ 163, 176 ], [ 181, 194 ], [ 222, 238 ], [ 270, 284 ] ] }, { "plaintext": "In most fields, distortion is characterized as unwanted change to a signal. Distortion in music is often intentionally used as an effect when applied to an electric guitar signal in styles of rock music such as heavy metal and punk rock.", "section_idx": 5, "section_name": "Audio distortion", "target_page_ids": [ 6325194, 23714384, 10272, 25423, 13869, 23037 ], "anchor_spans": [ [ 76, 95 ], [ 105, 136 ], [ 156, 171 ], [ 192, 202 ], [ 211, 222 ], [ 227, 236 ] ] }, { "plaintext": "In optics, image/optical distortion is a divergence from rectilinear projection caused by a change in magnification with increasing distance from the optical axis of an optical system.", "section_idx": 6, "section_name": "Optics", "target_page_ids": [ 22483, 1331480, 603273, 41456 ], "anchor_spans": [ [ 3, 9 ], [ 57, 79 ], [ 102, 115 ], [ 150, 162 ] ] }, { "plaintext": "In cartography, a distortion is the misrepresentation of the area or shape of a feature. The Mercator projection, for example, distorts by exaggerating the size of regions at high latitude.", "section_idx": 7, "section_name": "Map projections", "target_page_ids": [ 7294, 20771, 17616 ], "anchor_spans": [ [ 3, 14 ], [ 93, 112 ], [ 180, 188 ] ] }, { "plaintext": " Aliasing", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 151474 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Attenuation distortion", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 6031554 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Audio system measurements", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 302052 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Bias distortion", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 40788 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Distortion synthesis", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 5215142 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Fading", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 81211 ], "anchor_spans": [ [ 1, 7 ] ] }, { "plaintext": " Image warping", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 10403335 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Lossy compression", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 18208 ], "anchor_spans": [ [ 1, 18 ] ] } ]

[ "Audio_amplifier_specifications", "Audio_effects", "Cartography", "Geometrical_optics", "Effects_units" ]

[]

[ { "plaintext": "In telecommunication, distortion-limited operation is the condition prevailing when distortion of a received signal, rather than its attenuated amplitude (or power), limits performance under stated operational conditions and limits. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 41052, 41703, 24236 ], "anchor_spans": [ [ 3, 20 ], [ 84, 94 ], [ 109, 115 ], [ 158, 163 ] ] }, { "plaintext": "Note: Distortion-limited operation is reached when the system distorts the shape of the waveform beyond specified limits. For linear systems, distortion-limited operation is equivalent to bandwidth-limited operation.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8286675, 47592 ], "anchor_spans": [ [ 56, 62 ], [ 89, 97 ] ] } ]

[ "Telecommunications_engineering" ]

[]

[ { "plaintext": "A distributed database is a database in which data is stored across different physical locations. It may be stored in multiple computers located in the same physical location (e.g. a data centre); or maybe dispersed over a network of interconnected computers. Unlike parallel systems, in which the processors are tightly coupled and constitute a single database system, a distributed database system consists of loosely coupled sites that share no physical components.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 7878457, 4122592, 145162 ], "anchor_spans": [ [ 127, 136 ], [ 223, 230 ], [ 267, 283 ] ] }, { "plaintext": "System administrators can distribute collections of data (e.g. in a database) across multiple physical locations. A distributed database can reside on organised network servers or decentralised independent computers on the Internet, on corporate intranets or extranets, or on other organisation networks. Because distributed databases store data across multiple computers, distributed databases may improve performance at end-user worksites by allowing transactions to be processed on many machines, instead of being limited to one.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 42116, 44065971, 14539, 37481, 131823, 4122592, 127759 ], "anchor_spans": [ [ 161, 176 ], [ 180, 215 ], [ 223, 231 ], [ 246, 255 ], [ 259, 268 ], [ 295, 303 ], [ 422, 430 ] ] }, { "plaintext": "Two processes ensure that the distributed databases remain up-to-date and current: replication and duplication.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2722905, 42168 ], "anchor_spans": [ [ 83, 94 ], [ 99, 110 ] ] }, { "plaintext": " Replication involves using specialized software that looks for changes in the distributive database. Once the changes have been identified, the replication process makes all the databases look the same. The replication process can be complex and time-consuming, depending on the size and number of the distributed databases. This process can also require much time and computer resources. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Duplication, on the other hand, has less complexity. It identifies one database as a master and then duplicates that database. The duplication process is normally done at a set time after hours. This is to ensure that each distributed location has the same data. In the duplication process, users may change only the master database. This ensures that local data will not be overwritten.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 379287 ], "anchor_spans": [ [ 86, 92 ] ] }, { "plaintext": "Both replication and duplication can keep the data current in all distributive locations.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Besides distributed database replication and fragmentation, there are many other distributed database design technologies. For example, local autonomy, synchronous, and asynchronous distributed database technologies. The implementation of these technologies can and do depend on the needs of the business and the sensitivity/confidentiality of the data stored in the database and the price the business is willing to spend on ensuring data security, consistency and integrity.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 353859, 1157832, 6888292, 40995 ], "anchor_spans": [ [ 325, 340 ], [ 435, 448 ], [ 450, 461 ], [ 466, 475 ] ] }, { "plaintext": "When discussing access to distributed databases, Microsoft favors the term distributed query, which it defines in protocol-specific manner as \"[a]ny SELECT, INSERT, UPDATE, or DELETE statement that references tables and rowsets from one or more external OLE DB data sources\".", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 19001 ], "anchor_spans": [ [ 49, 58 ] ] }, { "plaintext": "Oracle provides a more language-centric view in which distributed queries and distributed transactions form part of distributed SQL.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 323725, 619053 ], "anchor_spans": [ [ 0, 6 ], [ 78, 101 ] ] }, { "plaintext": "Centralized database", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 22871783 ], "anchor_spans": [ [ 0, 20 ] ] }, { "plaintext": "Data grid", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 35951900 ], "anchor_spans": [ [ 0, 9 ] ] }, { "plaintext": "Distributed cache", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 35273620 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Distributed data store", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 870094 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "Distributed hash table", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 192141 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "Routing protocol", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 10123059 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "M. T. Özsu and P. Valduriez, Principles of Distributed Databases (3rd edition) (2011), Springer, ", "section_idx": 2, "section_name": "References", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Elmasri and Navathe, Fundamentals of database systems (3rd edition), Addison-Wesley Longman, ", "section_idx": 2, "section_name": "References", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Oracle Database Administrator's Guide 10g (Release 1), ", "section_idx": 2, "section_name": "References", "target_page_ids": [], "anchor_spans": [] } ]

[ "Data_management", "Types_of_databases", "Distributed_computing_architecture", "Applications_of_distributed_computing", "Database_management_systems" ]

[]

[ { "plaintext": "In telecommunication, a distributed-queue dual-bus network (DQDB) is a distributed multi-access network that (a) supports integrated communications using a dual bus and distributed queuing, (b) provides access to local or metropolitan area networks, and (c) supports connectionless data transfer, connection-oriented data transfer, and isochronous communications, such as voice communications.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 46545, 33094374, 17739, 43326, 42168, 346001, 41293 ], "anchor_spans": [ [ 3, 20 ], [ 96, 103 ], [ 133, 147 ], [ 213, 218 ], [ 222, 248 ], [ 282, 295 ], [ 297, 307 ], [ 336, 347 ] ] }, { "plaintext": "IEEE 802.6 is an example of a network providing DQDB access methods.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 262259 ], "anchor_spans": [ [ 0, 10 ] ] }, { "plaintext": "The DQDB Medium Access Control (MAC) algorithm is generally credited to Robert Newman who developed this algorithm in his PhD thesis in the 1980s at the University of Western Australia. To appreciate the innovative value of the DQDB MAC algorithm, it must be seen against the background of LAN protocols at that time, which were based on broadcast (such as ethernet IEEE 802.3) or a ring (like Token Ring IEEE 802.5 and FDDI). The DQDB may be thought of as two token rings, one carrying data in each direction around the ring. This improves reliability which is important in Metropolitan Area Networks (MAN), where repairs may take longer than in a LAN and Wi-Fi because the damage may be inaccessible.", "section_idx": 1, "section_name": "Concept of operation", "target_page_ids": [ 207472, 231031, 17739, 7016168, 41149, 43326 ], "anchor_spans": [ [ 32, 35 ], [ 153, 184 ], [ 290, 293 ], [ 394, 404 ], [ 420, 424 ], [ 576, 602 ] ] }, { "plaintext": "The DQDB standard IEEE 802.6 was developed while ATM (Broadband ISDN) was still in early development, but there was strong interaction between the two standards. ATM cells and DQDB frames were harmonized. They both settled on essentially a 48-byte data frame with a 5-byte header. In the DQDB algorithm, a distributed queue was implemented by communicating queue state information via the header. Each node in a DQDB network maintains a pair of state variables which represent its position in the distributed queue and the size of the queue. The headers on the reverse bus communicated requests to be inserted in the distributed queue so that upstream nodes would know that they should allow DQDB cells to pass unused on the forward bus. The algorithm was remarkable for its extreme simplicity.", "section_idx": 1, "section_name": "Concept of operation", "target_page_ids": [ 2499, 38514, 2499 ], "anchor_spans": [ [ 49, 52 ], [ 54, 68 ], [ 162, 171 ] ] }, { "plaintext": "Currently DQDB systems are being installed by many carriers in entire cities, with lengths that reach up to with speeds of a DS3 line (44.736 Mbit/s). Other implementations use optical fiber for a length of up to 100km and speeds around 150 Mbit/s.", "section_idx": 1, "section_name": "Concept of operation", "target_page_ids": [ 1219567 ], "anchor_spans": [ [ 127, 130 ] ] } ]

[ "Metropolitan_area_networks", "Local_area_networks", "Link_protocols" ]

[ "DQDB" ]

[ { "plaintext": "Distributed switching is an architecture in which multiple processor-controlled switching units are distributed. There is often a hierarchy of switching elements, with a centralized host switch and with remote switches located close to concentrations of users.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5218, 42116, 7092252 ], "anchor_spans": [ [ 59, 68 ], [ 183, 187 ], [ 188, 194 ] ] }, { "plaintext": "Distributed switching is often used in telephone networks, though it is often called host-remote switching.", "section_idx": 1, "section_name": "Use in telephony networks", "target_page_ids": [ 1966111 ], "anchor_spans": [ [ 39, 56 ] ] }, { "plaintext": "In rural areas, population centers tend to be too small for economical deployment of a full-featured dedicated telephone exchange, and distances between these centers make transmission costs relatively high. Normal telephone traffic patterns show that most calling is done between people in a community of interest, in this case a geographical one: the population center. Use of distributed switching allows for the majority of calls that are local to that population center to be switched there without needing to be transported to and from the host switch.", "section_idx": 1, "section_name": "Use in telephony networks", "target_page_ids": [ 26668156, 609152, 1161073 ], "anchor_spans": [ [ 111, 129 ], [ 172, 184 ], [ 294, 315 ] ] }, { "plaintext": "The host switch provides connectivity between the remote switches and to the larger network, and the host may also directly handle some rare and complex call types (conference calling, for example) that the remote itself is not equipped to handle. Host switches also perform OAM&P (Operation, Administration, Maintenance, and Provisioning) functions, including billing, for the entire cluster of the host and its remote switches.", "section_idx": 1, "section_name": "Use in telephony networks", "target_page_ids": [ 406758, 7131166 ], "anchor_spans": [ [ 165, 180 ], [ 276, 281 ] ] }, { "plaintext": "A key capability of a remote switch is the ability to act in emergency standalone (ESA) mode, wherein local calls can still be placed even in the event that the connection between that remote and the host has been lost. In this mode, only local calling is available anyway, so the billing capability of the host switch is not required. ESA is increasingly available on digital loop carrier platforms as well as on purpose-built remote switches in order to improve the scope of their utility.", "section_idx": 1, "section_name": "Use in telephony networks", "target_page_ids": [ 1878839 ], "anchor_spans": [ [ 371, 391 ] ] }, { "plaintext": "Many data-centric telecommunications platforms such as routers and Ethernet switches utilize distributed switching on separate cards within an equipment chassis. Even when this is used, it is common to have a centralized switching fabric to interconnect the distributed switches. This architecture has become less common as backplane bus speeds and centralized switch fabric capacities have increased.", "section_idx": 2, "section_name": "Use within telecommunications equipment platforms", "target_page_ids": [ 25748, 9499, 183330, 1919022, 4352, 6631 ], "anchor_spans": [ [ 55, 61 ], [ 67, 75 ], [ 153, 160 ], [ 222, 238 ], [ 326, 335 ], [ 336, 339 ] ] }, { "plaintext": "Remote Digital Terminal", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 1835717 ], "anchor_spans": [ [ 0, 23 ] ] }, { "plaintext": "Remote concentrator", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 61136 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": " From Host-Remote to Next-Generation - a white paper by MetaSwitch", "section_idx": 4, "section_name": "References", "target_page_ids": [ 291336, 21020839 ], "anchor_spans": [ [ 41, 52 ], [ 56, 66 ] ] }, { "plaintext": " Nortel RSC-S Overview", "section_idx": 4, "section_name": "References", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Lucent 5E-XC Standalone Remote Switches description", "section_idx": 4, "section_name": "References", "target_page_ids": [], "anchor_spans": [] } ]

[ "Local_loop", "Telephone_exchanges" ]

[]

[ { "plaintext": "In telecommunication, a disturbance voltage is an unwanted voltage induced in a system by natural or man-made sources.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 32549, 65888 ], "anchor_spans": [ [ 3, 20 ], [ 59, 66 ], [ 67, 74 ] ] }, { "plaintext": "In telecommunications systems, the disturbance voltage creates currents that limit or interfere with the interchange of information. An example of a disturbance voltage is a voltage that produces (a) false signals in a telephone, (b) Noise (radio) in a radio receiver, or (c) distortion in a received signal.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 6207, 18985062, 30003, 41415, 491851, 41052, 41703 ], "anchor_spans": [ [ 63, 70 ], [ 120, 131 ], [ 219, 228 ], [ 234, 247 ], [ 253, 267 ], [ 276, 286 ], [ 301, 307 ] ] } ]

[ "Electrical_parameters", "Telecommunications_engineering", "Noise_(electronics)" ]

[]

[ { "plaintext": "In telecommunication, diurnal phase shift is the phase shift of electromagnetic signals associated with daily changes in the ionosphere. The major changes usually occur during the period of time when sunrise or sunset is present at critical points along the path. Significant phase shifts may occur on paths wherein a reflection area of the path is subject to a large tidal range. In cable systems, significant phase shifts can be occasioned by diurnal temperature variance.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 24047, 15097, 30012, 42418 ], "anchor_spans": [ [ 3, 20 ], [ 49, 60 ], [ 125, 135 ], [ 190, 194 ], [ 384, 389 ] ] }, { "plaintext": "Terminator (solar) - \"grey line\"", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 87945 ], "anchor_spans": [ [ 0, 18 ] ] } ]

[ "Radio_frequency_propagation" ]

[]

[ { "plaintext": "The Department of Defense master clock is the atomic master clock to which time and frequency measurements for the United States Department of Defense are referenced.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 25453985, 6890306, 30012, 10779, 7279897 ], "anchor_spans": [ [ 46, 52 ], [ 53, 65 ], [ 75, 79 ], [ 84, 93 ], [ 115, 150 ] ] }, { "plaintext": "Located in Washington D.C., the U.S. Naval Observatory master clock is designated as the \"DOD Master Clock\". It is one of the two standard time and frequency references for the U.S. Government in accordance with Federal Standard 1002-A. The other standard time and frequency reference for the U.S. Government is the National Institute of Standards and Technology (NIST) master clock.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 43596, 27065, 195149, 21888 ], "anchor_spans": [ [ 32, 54 ], [ 130, 138 ], [ 177, 192 ], [ 316, 362 ] ] }, { "plaintext": "In 2018, it was proposed to replace the existing Clock House building it's housed in, designed by Richard Morris Hunt, with a new facility.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 612549 ], "anchor_spans": [ [ 99, 118 ] ] }, { "plaintext": "The U.S. Naval Observatory also maintains an alternate clock designated \"USNO Alternate Master Clock\" at Schriever Air Force Base, Colorado.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1658649, 5399 ], "anchor_spans": [ [ 105, 129 ], [ 131, 139 ] ] } ]

[ "Clocks_in_the_United_States", "United_States_Department_of_Defense" ]

[]

[ { "plaintext": "For two connected exchanges in a communications network, a double-ended synchronization (also called double-ended control) is a synchronization control scheme in which the phase error signals used to control the clock at one telephone exchange are derived by comparison with the phase of the incoming digital signal and the phase of the internal clocks at both exchanges.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 46545, 28738, 24047, 41118, 182693, 26668156, 30889569 ], "anchor_spans": [ [ 33, 55 ], [ 128, 143 ], [ 172, 177 ], [ 178, 183 ], [ 212, 217 ], [ 225, 243 ], [ 301, 315 ] ] } ]

[ "Telecommunications_techniques", "Synchronization" ]

[]

[ { "plaintext": "Double-sideband reduced carrier transmission (DSB-RC): transmission in which (a) the frequencies produced by amplitude modulation are symmetrically spaced above and below the carrier and (b) the carrier level is reduced for transmission at a fixed level below that which is provided to the modulator. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 609152, 1140, 153217, 20637 ], "anchor_spans": [ [ 56, 68 ], [ 110, 130 ], [ 176, 183 ], [ 291, 300 ] ] }, { "plaintext": "Note: In DSB-RC transmission, the carrier is usually transmitted at a level suitable for use as a reference by the receiver, except for the case in which it is reduced to the minimum practical level, i.e. the carrier is suppressed.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Double-sideband suppressed-carrier transmission", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 41064 ], "anchor_spans": [ [ 0, 47 ] ] } ]

[ "Radio_modulation_modes" ]

[]

[ { "plaintext": "Double-sideband suppressed-carrier transmission (DSB-SC) is transmission in which frequencies produced by amplitude modulation (AM) are symmetrically spaced above and below the carrier frequency and the carrier level is reduced to the lowest practical level, ideally being completely suppressed.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 609152, 1140, 153217 ], "anchor_spans": [ [ 61, 73 ], [ 107, 127 ], [ 179, 196 ] ] }, { "plaintext": "In the DSB-SC modulation, unlike in AM, the wave carrier is not transmitted; thus, much of the power is distributed between the side bands, which implies an increase of the cover in DSB-SC, compared to AM, for the same power use.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "DSB-SC transmission is a special case of double-sideband reduced carrier transmission. It is used for radio data systems. This mode is frequently used in Amateur radio voice communications, especially on High-Frequency bands.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41063, 225112, 23275402 ], "anchor_spans": [ [ 41, 85 ], [ 102, 119 ], [ 154, 167 ] ] }, { "plaintext": "DSB-SC is basically an amplitude modulation wave without the carrier, therefore reducing power waste, giving it a 50% efficiency. This is an increase compared to normal AM transmission (DSB) that has a maximum efficiency of 33.333%, since 2/3 of the power is in the carrier which conveys no useful information and both sidebands containing identical copies of the same information. Single Side Band Suppressed Carrier (SSB-SC) is 100% efficient.", "section_idx": 1, "section_name": "Spectrum", "target_page_ids": [ 1140, 29048 ], "anchor_spans": [ [ 23, 43 ], [ 382, 417 ] ] }, { "plaintext": "Spectrum plot of a DSB-SC signal:", "section_idx": 1, "section_name": "Spectrum", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "DSB-SC is generated by a mixer. This consists of a message signal multiplied by a carrier signal. The mathematical representation of this process is shown below, where the product-to-sum trigonometric identity is used.", "section_idx": 2, "section_name": "Generation", "target_page_ids": [ 1842477 ], "anchor_spans": [ [ 172, 209 ] ] }, { "plaintext": "For DSBSC, Coherent Demodulation is done by multiplying the DSB-SC signal with the carrier signal (with the same phase as in the modulation process) just like the modulation process. This resultant signal is then passed through a low pass filter to produce a scaled version of the original message signal.", "section_idx": 3, "section_name": "Demodulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The equation above shows that by multiplying the modulated signal by the carrier signal, the result is a scaled version of the original message signal plus a second term. Since , this second term is much higher in frequency than the original message. Once this signal passes through a low pass filter, the higher frequency component is removed, leaving just the original message.", "section_idx": 3, "section_name": "Demodulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For demodulation, the demodulation oscillator's frequency and phase must be exactly the same as the modulation oscillator's, otherwise, distortion and/or attenuation will occur.", "section_idx": 3, "section_name": "Demodulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "To see this effect, take the following conditions:", "section_idx": 3, "section_name": "Demodulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Message signal to be transmitted: ", "section_idx": 3, "section_name": "Demodulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Modulation (carrier) signal: ", "section_idx": 3, "section_name": "Demodulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Demodulation signal (with small frequency and phase deviations from the modulation signal): ", "section_idx": 3, "section_name": "Demodulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The resultant signal can then be given by", "section_idx": 3, "section_name": "Demodulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The terms results in distortion and attenuation of the original message signal. In particular, if the frequencies are correct, but the phase is wrong, contribution from is a constant attenuation factor, also represents a cyclic inversion of the recovered signal, which is a serious form of distortion.", "section_idx": 3, "section_name": "Demodulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This is best shown graphically. Below is a message signal that one may wish to modulate onto a carrier, consisting of a couple of sinusoidal components with frequencies respectively 800 Hz and 1200 Hz.", "section_idx": 4, "section_name": "How it works", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The equation for this message signal is .", "section_idx": 4, "section_name": "How it works", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The carrier, in this case, is a plain 5kHz () sinusoid—pictured below.", "section_idx": 4, "section_name": "How it works", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The modulation is performed by multiplication in the time domain, which yields a 5kHz carrier signal, whose amplitude varies in the same manner as the message signal.", "section_idx": 4, "section_name": "How it works", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The name \"suppressed carrier\" comes about because the carrier signal component is suppressed—it does not appear in the output signal. This is apparent when the spectrum of the output signal is viewed. In the picture shown below we see four peaks, the two peaks below 5000 Hz are the lower sideband (LSB) and the two peaks above 5000 Hz are the upper sideband (USB), but there is no peak at the 5000 Hz mark, which is the frequency of the suppressed carrier.", "section_idx": 4, "section_name": "How it works", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A DSBSC generation and demodulation instrument is described as side application of a commercial lock-in amplifier in Double-sideband Suppressed-carrier Modulation.", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Radio_modulation_modes" ]

[ "DSB-SC" ]

[ { "plaintext": "Drift or Drifts may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Drift or ford (crossing) of a river", "section_idx": 1, "section_name": "Geography", "target_page_ids": [ 30432825 ], "anchor_spans": [ [ 10, 25 ] ] }, { "plaintext": " Drift, Kentucky, unincorporated community in the United States", "section_idx": 1, "section_name": "Geography", "target_page_ids": [ 23183163 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " In Cornwall, England:", "section_idx": 1, "section_name": "Geography", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Drift, Cornwall, village", "section_idx": 1, "section_name": "Geography", "target_page_ids": [ 4777814 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Drift Reservoir, associated with the village", "section_idx": 1, "section_name": "Geography", "target_page_ids": [ 2819101 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Directional Recoil Identification from Tracks, a dark matter experiment", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 18769542 ], "anchor_spans": [ [ 1, 46 ] ] }, { "plaintext": " Drift (video gaming), a typical game controller malfunction", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 41568624 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Drift pin, metalworking tool for localizing hammer blows and for aligning holes", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 2584013 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Drift (geology), deposited material of glacial origin", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 2583979 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Drift, linear term of a stochastic process", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 47895 ], "anchor_spans": [ [ 25, 43 ] ] }, { "plaintext": " Drift (motorsport), the controlled sliding of a vehicle through a sharp turn, either via over-steering with sudden sharp braking, or counter-steering with a sudden \"clutch kick\" acceleration", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 1390192 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Incremental changes:", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Drift (linguistics), a type of language change", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 2583905 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Genetic drift, change in allele frequency", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 72016 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Drift (telecommunication), long-term change in an attribute of a system or equipment", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 2583906 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": "Clock drift", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 6083924 ], "anchor_spans": [ [ 0, 11 ] ] }, { "plaintext": "Frequency drift", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 5439832 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "Drift (data science)", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 70435489 ], "anchor_spans": [ [ 0, 20 ] ] }, { "plaintext": "Concept drift", "section_idx": 2, "section_name": "Science, technology, and physics", "target_page_ids": [ 3118600 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": " Drift (film series), 2006–2008 film series by Futoshi Jinno", "section_idx": 3, "section_name": "Film and television", "target_page_ids": [ 26982256 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Drift, 2006 TV crime drama film directed by Paul W.S. Anderson", "section_idx": 3, "section_name": "Film and television", "target_page_ids": [ 946163 ], "anchor_spans": [ [ 45, 63 ] ] }, { "plaintext": " Drift, fictional technology system that links the minds of two Jaeger pilots in the 2013 sci-fi film Pacific Rim and its sequel", "section_idx": 3, "section_name": "Film and television", "target_page_ids": [ 32112949, 43696932 ], "anchor_spans": [ [ 102, 113 ], [ 122, 128 ] ] }, { "plaintext": " Drift (2013 Australian film), film starring Sam Worthington", "section_idx": 3, "section_name": "Film and television", "target_page_ids": [ 39446209 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " Drift (2013 Belgian film), art house film", "section_idx": 3, "section_name": "Film and television", "target_page_ids": [ 43856178 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Drift (2015 film), Swiss film", "section_idx": 3, "section_name": "Film and television", "target_page_ids": [ 49042949 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Drift (2017 film), German film", "section_idx": 3, "section_name": "Film and television", "target_page_ids": [ 55023716 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Drift, 2007 experimental short film by Max Hattler", "section_idx": 3, "section_name": "Film and television", "target_page_ids": [ 18282558 ], "anchor_spans": [ [ 40, 51 ] ] }, { "plaintext": " Drift (novel), a 2002 Doctor Who novel", "section_idx": 4, "section_name": "Books", "target_page_ids": [ 5317537 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " The Unmooring of American Military Power, a book by Rachel Maddow", "section_idx": 4, "section_name": "Books", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Plot drift, when a story deviates unexpectedly from its initial direction, in writing, television, or other media.", "section_idx": 4, "section_name": "Books", "target_page_ids": [ 7999309 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " The Drift (band), American post-rock band", "section_idx": 5, "section_name": "Music", "target_page_ids": [ 32181959 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Songs:", "section_idx": 5, "section_name": "Music", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " \"Drift\", 1985 song from work ‘’Secret’’", "section_idx": 5, "section_name": "Music", "target_page_ids": [ 12775626 ], "anchor_spans": [ [ 33, 39 ] ] }, { "plaintext": " \"Drift\" (Emily Osment song) (2011)", "section_idx": 5, "section_name": "Music", "target_page_ids": [ 1873388 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " \"Drift\", end credits song of 2013 film Pacific Rim", "section_idx": 5, "section_name": "Music", "target_page_ids": [ 32112949 ], "anchor_spans": [ [ 40, 51 ] ] }, { "plaintext": " Albums/EPs:", "section_idx": 5, "section_name": "Music", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Drift (Flotsam and Jetsam album) (1995)", "section_idx": 5, "section_name": "Music", "target_page_ids": [ 8132386 ], "anchor_spans": [ [ 1, 33 ] ] }, { "plaintext": " The Drift, album by Scott Walker (2006)", "section_idx": 5, "section_name": "Music", "target_page_ids": [ 4322997 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Drift (Ken Block album) (2008)", "section_idx": 5, "section_name": "Music", "target_page_ids": [ 526478 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " Drift (Nosaj Thing album) (2009)", "section_idx": 5, "section_name": "Music", "target_page_ids": [ 32436710 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " The Drift (EP), by Michelle Channel and Arjun Singh (2014)", "section_idx": 5, "section_name": "Music", "target_page_ids": [ 41573412 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Drift (Erra album) (2016)", "section_idx": 5, "section_name": "Music", "target_page_ids": [ 51454476 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Drift (Underworld project), ongoing music-and-video experiment by that band", "section_idx": 5, "section_name": "Music", "target_page_ids": [ 60529663 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Daventry International Rail Freight Terminal (DIRFT), a rail-road intermodal freight terminal in Northamptonshire, England", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 4081053 ], "anchor_spans": [ [ 1, 45 ] ] }, { "plaintext": " Dérive, an unplanned journey through a landscape", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 714602 ], "anchor_spans": [ [ 1, 7 ] ] }, { "plaintext": " Drifter (disambiguation)", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 4589623 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Drifting (disambiguation)", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 535633 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Velddrif, a town in South Africa", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 27761018 ], "anchor_spans": [ [ 1, 9 ] ] } ]

[]

[]

[ { "plaintext": "A drop or droplet is a small column of liquid, bounded completely or almost completely by free surfaces. A drop may form when liquid accumulates at the lower end of a tube or other surface boundary, producing a hanging drop called a pendant drop. Drops may also be formed by the condensation of a vapor or by atomization of a larger mass of solid.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 18993825, 14463033, 247167, 47521, 32505, 18918232 ], "anchor_spans": [ [ 39, 45 ], [ 90, 102 ], [ 233, 240 ], [ 279, 291 ], [ 297, 302 ], [ 309, 320 ] ] }, { "plaintext": "Liquid forms drops because it exhibits surface tension.", "section_idx": 1, "section_name": "Surface tension", "target_page_ids": [ 113302 ], "anchor_spans": [ [ 39, 54 ] ] }, { "plaintext": "A simple way to form a drop is to allow liquid to flow slowly from the lower end of a vertical tube of small diameter. The surface tension of the liquid causes the liquid to hang from the tube, forming a pendant. When the drop exceeds a certain size it is no longer stable and detaches itself. The falling liquid is also a drop held together by surface tension.", "section_idx": 1, "section_name": "Surface tension", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Some substances that appear to be solid, can be shown to instead be extremely viscous liquids, because they form drops and display droplet behavior. In the famous pitch drop experiments, pitch – a substance somewhat like solid bitumen – is shown to be a liquid in this way. Pitch in a funnel slowly forms droplets, each droplet taking about 10 years to form and break off.", "section_idx": 1, "section_name": "Surface tension", "target_page_ids": [ 18963754, 250107, 323371, 657 ], "anchor_spans": [ [ 78, 85 ], [ 163, 184 ], [ 187, 192 ], [ 227, 234 ] ] }, { "plaintext": "In the pendant drop test, a drop of liquid is suspended from the end of a tube or by any surface by surface tension. The force due to surface tension is proportional to the length of the boundary between the liquid and the tube, with the proportionality constant usually denoted . Since the length of this boundary is the circumference of the tube, the force due to surface tension is given by", "section_idx": 2, "section_name": "Pendant drop test", "target_page_ids": [ 113302 ], "anchor_spans": [ [ 100, 115 ] ] }, { "plaintext": "where d is the tube diameter.", "section_idx": 2, "section_name": "Pendant drop test", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The mass m of the drop hanging from the end of the tube can be found by equating the force due to gravity () with the component of the surface tension in the vertical direction () giving the formula", "section_idx": 2, "section_name": "Pendant drop test", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where α is the angle of contact with the tube's front surface, and g is the acceleration due to gravity.", "section_idx": 2, "section_name": "Pendant drop test", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The limit of this formula, as α goes to 90°, gives the maximum weight of a pendant drop for a liquid with a given surface tension, .", "section_idx": 2, "section_name": "Pendant drop test", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This relationship is the basis of a convenient method of measuring surface tension, commonly used in the petroleum industry. More sophisticated methods are available to take account of the developing shape of the pendant as the drop grows. These methods are used if the surface tension is unknown.", "section_idx": 2, "section_name": "Pendant drop test", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The drop adhesion to a solid can be divided into two categories: lateral adhesion and normal adhesion. Lateral adhesion resembles friction (though tribologically lateral adhesion is a more accurate term) and refers to the force required to slide a drop on the surface, namely the force to detach the drop from its position on the surface only to translate it to another position on the surface. Normal adhesion is the adhesion required to detach a drop from the surface in the normal direction, namely the force to cause the drop to fly off from the surface. The measurement of both adhesion forms can be done with the Centrifugal Adhesion Balance (CAB). The CAB uses a combination of centrifugal and gravitational forces to obtain any ratio of lateral and normal forces. For example, it can apply a normal force at zero lateral force for the drop to fly off away from the surface in the normal direction or it can induce a lateral force at zero normal force (simulating zero gravity).", "section_idx": 3, "section_name": "Drop adhesion to a solid", "target_page_ids": [ 835157, 489228, 38579 ], "anchor_spans": [ [ 9, 17 ], [ 147, 161 ], [ 976, 983 ] ] }, { "plaintext": "The term droplet is a diminutive form of 'drop' – and as a guide is typically used for liquid particles of less than 500μm diameter. In spray application, droplets are usually described by their perceived size (i.e., diameter) whereas the dose (or number of infective particles in the case of biopesticides) is a function of their volume. This increases by a cubic function relative to diameter; thus a 50μm droplet represents a dose in 65pl and a 500μm drop represents a dose in 65 nanometers.", "section_idx": 4, "section_name": "Droplet", "target_page_ids": [ 30778041, 16334333, 2065799, 27859 ], "anchor_spans": [ [ 94, 102 ], [ 137, 154 ], [ 294, 306 ], [ 359, 375 ] ] }, { "plaintext": "A droplet with a diameter of 3mm has a terminal velocity of approximately 8m/s.", "section_idx": 5, "section_name": "Speed", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Drops smaller than in diameter will attain 95% of their terminal velocity within . But above this size the distance to get to terminal velocity increases sharply. An example is a drop with a diameter of that may achieve this at .", "section_idx": 5, "section_name": "Speed", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Due to the different refractive index of water and air, refraction and reflection occur on the surfaces of raindrops, leading to rainbow formation.", "section_idx": 6, "section_name": "Optics", "target_page_ids": [ 25880, 33306, 202898, 25948, 521267, 19009110, 3871014 ], "anchor_spans": [ [ 21, 37 ], [ 41, 46 ], [ 51, 54 ], [ 56, 66 ], [ 71, 81 ], [ 107, 111 ], [ 129, 136 ] ] }, { "plaintext": "The major source of sound when a droplet hits a liquid surface is the resonance of excited bubbles trapped underwater. These oscillating bubbles are responsible for most liquid sounds, such as running water or splashes, as they actually consist of many drop-liquid collisions.", "section_idx": 7, "section_name": "Sound", "target_page_ids": [ 6529735 ], "anchor_spans": [ [ 70, 98 ] ] }, { "plaintext": "Reducing the surface tension of a body of liquid makes possible to reduce or prevent noise due to droplets falling into it. This would involve adding soap, detergent or a similar substance to water. The reduced surface tension reduces the noise from dripping.", "section_idx": 7, "section_name": "Sound", "target_page_ids": [ 57875, 92514 ], "anchor_spans": [ [ 150, 154 ], [ 156, 165 ] ] }, { "plaintext": "The classic shape associated with a drop (with a pointy end in its upper side) comes from the observation of a droplet clinging to a surface. The shape of a drop falling through a gas is actually more or less spherical for drops less than 2mm in diameter. Larger drops tend to be flatter on the bottom part due to the pressure of the gas they move through. As a result, as drops get larger, a concave depression forms which leads to the eventual breakup of the drop.", "section_idx": 8, "section_name": "Shape", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The capillary length is a length scaling factor that relates gravity and surface tension, and is directly responsible for the shape a droplet for a specific fluid will take. The capillary length stems from the Laplace pressure, using the radius of the droplet.", "section_idx": 8, "section_name": "Shape", "target_page_ids": [ 12092048, 38579, 113302, 19840237 ], "anchor_spans": [ [ 4, 20 ], [ 61, 68 ], [ 73, 88 ], [ 210, 226 ] ] }, { "plaintext": "Using the capillary length we can define microdrops and macrodrops. Microdrops are droplets with radius smaller than the capillary length, where the shape of the droplet is governed solely by surface tension and they form a spherical cap shape. If a droplet has a radius larger than the capillary length, they are known as macrodrops and the gravitational forces will dominate. Macrodrops will be 'flattened' by gravity and the height of the droplet will be reduced.", "section_idx": 8, "section_name": "Shape", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Raindrop sizes typically range from 0.5mm to 4mm, with size distributions quickly decreasing past diameters larger than 2-2.5mm.", "section_idx": 9, "section_name": "Size", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Scientists traditionally thought that the variation in the size of raindrops was due to collisions on the way down to the ground. In 2009, French researchers succeeded in showing that the distribution of sizes is due to the drops' interaction with air, which deforms larger drops and causes them to fragment into smaller drops, effectively limiting the largest raindrops to about 6mm diameter. However, drops up to 10mm (equivalent in volume to a sphere of radius 4.5mm) are theoretically stable and could be levitated in a wind tunnel.", "section_idx": 9, "section_name": "Size", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The largest recorded raindrop was 8.8mm in diameter, located at the base of a cumulus congestus cloud in the vicinity of Kwajalein Atoll in July 1999. A raindrop of identical size was detected over northern Brazil in September 1995.", "section_idx": 9, "section_name": "Size", "target_page_ids": [ 2367035, 204244 ], "anchor_spans": [ [ 78, 101 ], [ 121, 136 ] ] }, { "plaintext": "In medicine, this property is used to create droppers and IV infusion sets which have a standardized diameter, in such a way that 1 millilitre is equivalent to 20 drops. When smaller amounts are necessary (such as paediatrics), microdroppers or paediatric infusion sets are used, in which 1 millilitre = 60 microdrops.", "section_idx": 9, "section_name": "Size", "target_page_ids": [ 18957, 7716620, 18934904, 8007, 18094, 1348006 ], "anchor_spans": [ [ 3, 11 ], [ 45, 52 ], [ 88, 100 ], [ 101, 109 ], [ 132, 142 ], [ 163, 168 ] ] }, { "plaintext": " Pitch drop experiment", "section_idx": 11, "section_name": "See also", "target_page_ids": [ 250107 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Rain", "section_idx": 11, "section_name": "See also", "target_page_ids": [ 19009110 ], "anchor_spans": [ [ 1, 5 ] ] }, { "plaintext": "Water droplet erosion", "section_idx": 11, "section_name": "See also", "target_page_ids": [ 67025945 ], "anchor_spans": [ [ 0, 21 ] ] }, { "plaintext": " Liquid Sculpture – pictures of drops", "section_idx": 13, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Liquid Art – Galleries of fine art droplet photography", "section_idx": 13, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " (Greatly varying) calculation of water waste from dripping tap: , ", "section_idx": 13, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "څاڅکې", "section_idx": 13, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Liquids", "Fluid_dynamics", "Articles_containing_video_clips", "Alcohol_measurement" ]

[ "metric drop" ]

[ { "plaintext": "In a multichannel transmission system, drop and insert is a process that diverts (drop) a portion of the multiplexed aggregate signal at an intermediate point, and introduces (insert) a different signal for subsequent transmission in the same position.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 4051799, 46982, 41703 ], "anchor_spans": [ [ 5, 17 ], [ 18, 37 ], [ 127, 133 ] ] }, { "plaintext": "Drop and insert is practiced, for example, in time-division multiplexing (TDM) when a time slot or frequency band is replaced from another source. The diverted signal may be demodulated or reinserted into another transmission system in the same or another time slot or frequency band. The time slot or frequency band vacated by the diverted signal need not necessarily be reoccupied by another signal. Likewise, a previously unoccupied time slot or frequency band may be occupied by a signal inserted at the drop-and-insert point.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41796, 10779, 634183, 66926 ], "anchor_spans": [ [ 46, 72 ], [ 99, 108 ], [ 109, 113 ], [ 174, 184 ] ] }, { "plaintext": "Signals not of interest at the drop-and-insert point are not diverted.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] } ]

[ "Multiplexing" ]

[]

[ { "plaintext": "Dropout or drop out may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Dropping out, prematurely leaving school, college or university", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2925542 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Dropout (film), a 1970 Italian drama ", "section_idx": 1, "section_name": "Arts and entertainment", "target_page_ids": [ 28581081 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " \"The Dropout\", an 1970 episode of The Brady Bunch", "section_idx": 1, "section_name": "Arts and entertainment", "target_page_ids": [ 2342078 ], "anchor_spans": [ [ 16, 50 ] ] }, { "plaintext": " The Dropout (podcast), 2019 true crime podcast", "section_idx": 1, "section_name": "Arts and entertainment", "target_page_ids": [ 63708289 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " The Dropout, a 2022 American miniseries based on the podcast", "section_idx": 1, "section_name": "Arts and entertainment", "target_page_ids": [ 60489638 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " \"Drop Out\" (song), by Lil Pump, 2019", "section_idx": 1, "section_name": "Arts and entertainment", "target_page_ids": [ 60026872 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " \"Drop Out,\" a song by Rocket from the Crypt from the 1995 album Scream, Dracula, Scream! ", "section_idx": 1, "section_name": "Arts and entertainment", "target_page_ids": [ 2544923 ], "anchor_spans": [ [ 65, 89 ] ] }, { "plaintext": " \"Drop Out\", a song by Converge from the 2004 album You Fail Me ", "section_idx": 1, "section_name": "Arts and entertainment", "target_page_ids": [ 4942255 ], "anchor_spans": [ [ 52, 63 ] ] }, { "plaintext": " \"Drop Out\", music of Dance Dance Revolution Extreme", "section_idx": 1, "section_name": "Arts and entertainment", "target_page_ids": [ 23291373 ], "anchor_spans": [ [ 13, 52 ] ] }, { "plaintext": " Drop Out with The Barracudas, by The Barracudas, 1981", "section_idx": 1, "section_name": "Arts and entertainment", "target_page_ids": [ 11389783 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " The Dropouts, an early incarnation of Priestess (band)", "section_idx": 1, "section_name": "Arts and entertainment", "target_page_ids": [ 6130606 ], "anchor_spans": [ [ 39, 55 ] ] }, { "plaintext": " Dropout (astronomy), a radiation source whose radiation intensity falls off sharply", "section_idx": 2, "section_name": "Science and technology", "target_page_ids": [ 4583640 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Dropout (bicycle part), a type of fork end", "section_idx": 2, "section_name": "Science and technology", "target_page_ids": [ 2073660 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Dropout (communications), a momentary loss of signal ", "section_idx": 2, "section_name": "Science and technology", "target_page_ids": [ 10672320 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Dropout (neural networks), a regularization technique for reducing overfitting ", "section_idx": 2, "section_name": "Science and technology", "target_page_ids": [ 47349395 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Dropout (streaming platform), an American subscription media service provider", "section_idx": 3, "section_name": "Other uses", "target_page_ids": [ 60556859 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " Drop out ceiling, beneath existing fire sprinklers ", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 2403966 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Turn on, tune in, drop out, a counterculture-era phrase popularized by Timothy Leary in 1966.", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 18302783 ], "anchor_spans": [ [ 1, 27 ] ] } ]

[]

[]

[ { "plaintext": "DTE may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Data terminal equipment, an end instrument used in telecommunication and data transmission", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 74041 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " Distance to empty, a feature in an automobile electronic instrument cluster", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 12073853 ], "anchor_spans": [ [ 47, 76 ] ] }, { "plaintext": " Dithioerythritol, a chemical", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5391903 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " DTE (direct to edit), a digital video recording method", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 30493882 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " DTE Energy, a Detroit, Michigan-based utility", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2651392 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Dora the Explorer, a children's animated television show.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 357030 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Dual-Tile encoding, another name for byte pair encoding", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5825526 ], "anchor_spans": [ [ 38, 56 ] ] }, { "plaintext": " Directorate of Technical Education, Maharashtra, an Indian state government agency for higher education.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 51623484 ], "anchor_spans": [ [ 1, 48 ] ] }, { "plaintext": " Department of Technical Education, a higher education governance body under the government of Kerala, India", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33137190 ], "anchor_spans": [ [ 1, 34 ] ] }, { "plaintext": " Down to Earth (disambiguation)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 197008 ], "anchor_spans": [ [ 1, 31 ] ] } ]

[]

[]

[ { "plaintext": "In telecommunication, the term dual access has the following meanings: ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": "The connection of a user to two switching centers by separate access lines using a single message routing indicator or telephone number.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 346001, 2052479, 26668156, 810183, 41367, 41673, 18790468 ], "anchor_spans": [ [ 4, 14 ], [ 20, 24 ], [ 32, 48 ], [ 62, 68 ], [ 90, 97 ], [ 98, 115 ], [ 119, 135 ] ] }, { "plaintext": "In satellite communications, the transmission of two carriers simultaneously through a single communication satellite repeater.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 45207, 609152, 41655 ], "anchor_spans": [ [ 3, 27 ], [ 33, 45 ], [ 118, 126 ] ] }, { "plaintext": "Also, network hardware company D-Link has named technology which allows two simultaneous connections over one cable, for example 1) Internet and 2) provider's local FTP or game servers or IPTV data flow.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1024742 ], "anchor_spans": [ [ 31, 37 ] ] } ]

[ "Network_access" ]

[]

[ { "plaintext": "In microelectronics, a dual in-line package (DIP or DIL), is an electronic component package with a rectangular housing and two parallel rows of electrical connecting pins. The package may be through-hole mounted to a printed circuit board (PCB) or inserted in a socket. The dual-inline format was invented by Don Forbes, Rex Rice and Bryant Rogers at Fairchild R&D in 1964, when the restricted number of leads available on circular transistor-style packages became a limitation in the use of integrated circuits. Increasingly complex circuits required more signal and power supply leads (as observed in Rent's rule); eventually microprocessors and similar complex devices required more leads than could be put on a DIP package, leading to development of higher-density chip carriers. Furthermore, square and rectangular packages made it easier to route printed-circuit traces beneath the packages.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 19377, 23889797, 1528972, 65910, 180263, 15150, 3010458, 34147043 ], "anchor_spans": [ [ 3, 19 ], [ 64, 92 ], [ 192, 212 ], [ 218, 239 ], [ 352, 361 ], [ 493, 511 ], [ 604, 615 ], [ 770, 782 ] ] }, { "plaintext": "A DIP is usually referred to as a DIPn, where n is the total number of pins. For example, a microcircuit package with two rows of seven vertical leads would be a DIP14. The photograph at the upper right shows three DIP14 ICs. Common packages have as few as three and as many as 64 leads. Many analog and digital integrated circuit types are available in DIP packages, as are arrays of transistors, switches, light emitting diodes, and resistors. DIP plugs for ribbon cables can be used with standard IC sockets.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "DIP packages are usually made from an opaque molded epoxy plastic pressed around a tin-, silver-, or gold-plated lead frame that supports the device die and provides connection pins. Some types of IC are made in ceramic DIP packages, where high temperature or high reliability is required, or where the device has an optical window to the interior of the package. Most DIP packages are secured to a PCB by inserting the pins through holes in the board and soldering them in place. Where replacement of the parts is necessary, such as in test fixtures or where programmable devices must be removed for changes, a DIP socket is used. Some sockets include a zero insertion force (ZIF) mechanism.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 42443688, 175735 ], "anchor_spans": [ [ 113, 123 ], [ 655, 675 ] ] }, { "plaintext": "Variations of the DIP package include those with only a single row of pins, e.g. a resistor array, possibly including a heat sink tab in place of the second row of pins, and types with four rows of pins, two rows, staggered, on each side of the package. DIP packages have been mostly displaced by surface-mount package types, which avoid the expense of drilling holes in a PCB and which allow higher density of interconnections.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1886820 ], "anchor_spans": [ [ 83, 97 ] ] }, { "plaintext": "DIPs are commonly used for integrated circuits (ICs). Other devices in DIP packages include resistor networks, DIP switches, LED segmented and bar graph displays, and electromechanical relays.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 15150, 317918, 18290, 450703, 26590 ], "anchor_spans": [ [ 27, 45 ], [ 111, 121 ], [ 125, 128 ], [ 129, 138 ], [ 185, 190 ] ] }, { "plaintext": "DIP connector plugs for ribbon cables are common in computers and other electronic equipment.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Dallas Semiconductor manufactured integrated DIP real-time clock (RTC) modules which contained an IC chip and a non-replaceable 10-year lithium battery.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 535191 ], "anchor_spans": [ [ 49, 64 ] ] }, { "plaintext": "DIP header blocks on to which discrete components could be soldered were used where groups of components needed to be easily removed, for configuration changes, optional features or calibration.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 34331107 ], "anchor_spans": [ [ 4, 10 ] ] }, { "plaintext": "The original dual-in-line package was invented by Bryant \"Buck\" Rogers in 1964 while working for Fairchild Semiconductor. The first devices had 14 pins and looked much like they do today. The rectangular shape allowed integrated circuits to be packaged more densely than previous round packages. The package was well-suited to automated assembly equipment; a PCB could be populated with scores or hundreds of ICs, then all the components on the circuit board could be soldered at one time on a wave soldering machine and passed on to automated testing machines, with very little human labor required. DIP packages were still large with respect to the integrated circuits within them. By the end of the 20th century, surface-mount packages allowed further reduction in the size and weight of systems. DIP chips are still popular for circuit prototyping on a breadboard because of how easily they can be inserted and utilized there.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 1005128, 232333, 80799 ], "anchor_spans": [ [ 494, 508 ], [ 716, 729 ], [ 857, 867 ] ] }, { "plaintext": "DIPs were the mainstream of the microelectronics industry in the 1970s and 1980s. Their use has declined in the first decade of the 21st century due to the emerging new surface-mount technology (SMT) packages such as plastic leaded chip carrier (PLCC) and small-outline integrated circuit (SOIC), though DIPs continued in extensive use through the 1990s, and still continue to be used substantially as the year 2011 passes. Because some modern chips are available only in surface-mount package types, a number of companies sell various prototyping adapters to allow those surface-mount devices (SMD) to be used like DIP devices with through-hole breadboards and soldered prototyping boards (such as stripboard and perfboard). (SMT can pose quite a problem, at least an inconvenience, for prototyping in general; most of the characteristics of SMT that are advantages for mass production are difficulties for prototyping.)", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 232333, 34147043, 2555717, 351216, 5889117 ], "anchor_spans": [ [ 169, 193 ], [ 217, 244 ], [ 256, 288 ], [ 699, 709 ], [ 714, 723 ] ] }, { "plaintext": "For programmable devices like EPROMs and GALs, DIPs remained popular for many years due to their easy handling with external programming circuitry (i.e., the DIP devices could be simply plugged into a socket on the programming device.) However, with In-System Programming (ISP) technology now state of the art, this advantage of DIPs is rapidly losing importance as well.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 73333, 2839649, 2824030 ], "anchor_spans": [ [ 30, 35 ], [ 41, 44 ], [ 250, 271 ] ] }, { "plaintext": "Through the 1990s, devices with fewer than 20 leads were manufactured in a DIP format in addition to the newer formats. Since about 2000, newer devices are often unavailable in the DIP format.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "DIPs can be mounted either by through-hole soldering or in sockets. Sockets allow easy replacement of a device and eliminates the risk of damage from overheating during soldering. Generally sockets were used for high-value or large ICs, which cost much more than the socket. Where devices would be frequently inserted and removed, such as in test equipment or EPROM programmers, a zero insertion force socket would be used.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 1528972, 175735 ], "anchor_spans": [ [ 30, 52 ], [ 381, 401 ] ] }, { "plaintext": "DIPs are also used with breadboards, a temporary mounting arrangement for education, design development or device testing. Some hobbyists, for one-off construction or permanent prototyping, use point-to-point wiring with DIPs, and their appearance when physically inverted as part of this method inspires the informal term \"dead bug style\" for the method.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 65919 ], "anchor_spans": [ [ 194, 208 ] ] }, { "plaintext": "The body (housing) of a DIP containing an IC chip is usually made from molded plastic or ceramic. The hermetic nature of a ceramic housing is preferred for extremely high reliability devices. However, the vast majority of DIPs are manufactured via a thermoset molding process in which an epoxy mold compound is heated and transferred under pressure to encapsulate the device. Typical cure cycles for the resins are less than 2 minutes and a single cycle may produce hundreds of devices.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The leads emerge from the longer sides of the package along the seam, parallel to the top and bottom planes of the package, and are bent downward approximately 90 degrees (or slightly less, leaving them angled slightly outward from the centerline of the package body). (The SOIC, the SMT package that most resembles a typical DIP, appears essentially the same, notwithstanding size scale, except that after being bent down the leads are bent upward again by an equal angle to become parallel with the bottom plane of the package.) In ceramic (CERDIP) packages, an epoxy or grout is used to hermetically seal the two halves together, providing an air and moisture tight seal to protect the IC die inside. Plastic DIP (PDIP) packages are usually sealed by fusing or cementing the plastic halves around the leads, but a high degree of hermeticity is not achieved because the plastic itself is usually somewhat porous to moisture and the process cannot ensure a good microscopic seal between the leads and the plastic at all points around the perimeter. However, contaminants are usually still kept out well enough that the device can operate reliably for decades with reasonable care in a controlled environment.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [ 2555717, 202898, 591470, 7736707, 1683711 ], "anchor_spans": [ [ 274, 278 ], [ 646, 649 ], [ 654, 662 ], [ 692, 695 ], [ 832, 843 ] ] }, { "plaintext": "Inside the package, the lower half has the leads embedded, and at the center of the package is a rectangular space, chamber, or void into which the IC die is cemented. The leads of the package extend diagonally inside the package from their positions of emergence along the periphery to points along a rectangular perimeter surrounding the die, tapering as they go to become fine contacts at the die. Ultra-fine bond wires (barely visible to the naked human eye) are welded between these die periphery contacts and bond pads on the die itself, connecting one lead to each bond pad, and making the final connection between the microcircuits and the external DIP leads. The bond wires are not usually taut but loop upward slightly to allow slack for thermal expansion and contraction of the materials; if a single bond wire breaks or detaches, the entire IC may become useless. The top of the package covers all of this delicate assemblage without crushing the bond wires, protecting it from contamination by foreign materials.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [ 230283 ], "anchor_spans": [ [ 412, 421 ] ] }, { "plaintext": "Usually, a company logo, alphanumeric codes and sometimes words are printed on top of the package to identify its manufacturer and type, when it was made (usually as a year and a week number), sometimes where it was made, and other proprietary information (perhaps revision numbers, manufacturing plant codes, or stepping ID codes.)", "section_idx": 2, "section_name": "Construction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The necessity of laying out all of the leads in a basically radial pattern in a single plane from the die perimeter to two rows on the periphery of the package is the main reason that DIP packages with higher lead counts must have wider spacing between the lead rows, and it effectively limits the number of leads which a practical DIP package may have. Even for a very small die with many bond pads (e.g. a chip with 15 inverters, requiring 32 leads), a wider DIP would still be required to accommodate the radiating leads internally. This is one of the reasons that four-sided and multiple rowed packages, such as PGAs, were introduced (around the early 1980s).", "section_idx": 2, "section_name": "Construction", "target_page_ids": [ 233017 ], "anchor_spans": [ [ 616, 620 ] ] }, { "plaintext": "A large DIP package (such as the DIP64 used for the Motorola 68000 CPU) has long leads inside the package between pins and the die, making such a package unsuitable for high speed devices.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [ 20270 ], "anchor_spans": [ [ 52, 66 ] ] }, { "plaintext": "Some other types of DIP devices are built very differently. Most of these have molded plastic housings and straight leads or leads that extend directly out of the bottom of the package. For some, LED displays particularly, the housing is usually a hollow plastic box with the bottom/back open, filled (around the contained electronic components) with a hard translucent epoxy material from which the leads emerge. Others, such as DIP switches, are composed of two (or more) plastic housing parts snapped, welded, or glued together around a set of contacts and tiny mechanical parts, with the leads emerging through molded-in holes or notches in the plastic.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Several DIP variants for ICs exist, mostly distinguished by packaging material:", "section_idx": 2, "section_name": "Construction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Ceramic Dual In-line Package (CERDIP or CDIP)", "section_idx": 2, "section_name": "Construction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Plastic Dual In-line Package (PDIP)", "section_idx": 2, "section_name": "Construction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Shrink Plastic Dual In-line Package (SPDIP) A denser version of the PDIP with a 0.07 in (1.778mm) lead pitch.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Skinny Dual In-line Package (SDIP or SPDIP) Sometimes used to refer to a \"narrow\" 0.300 in. (or 300 mil) wide DIP, normally when clarification is needed e.g. for DIP with 24 pins or more, which usually come in \"wide\" 0.600in wide DIP package. An example of a typical proper full spec for a \"narrow\" DIP package would be 300mil body width, pin pitch.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [ 5978127 ], "anchor_spans": [ [ 102, 105 ] ] }, { "plaintext": "EPROMs were sold in ceramic DIPs manufactured with a circular window of clear quartz over the chip die to allow the part to be erased by ultraviolet light. Often, the same chips were also sold in less expensive windowless PDIP or CERDIP packages as one-time programmable (OTP) versions. Windowed and windowless packages were also used for microcontrollers, and other devices, containing EPROM memory. Windowed CERDIP-packaged EPROMs were used for the BIOS ROM of many early IBM PC clones with an adhesive label covering the window to prevent inadvertent erasure through exposure to ambient light.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [ 73333, 31990, 73333, 4473 ], "anchor_spans": [ [ 0, 5 ], [ 137, 154 ], [ 249, 270 ], [ 451, 455 ] ] }, { "plaintext": "Molded plastic DIPs are much lower in cost than ceramic packages; one 1979 study showed that a plastic 14 pin DIP cost around US$0.063 and a ceramic package cost US$0.82.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A single in-line package (SIP or SIL) has one row of connecting pins. It is not as popular as the DIP, but has been used for packaging RAM chips and multiple resistors with a common pin. As compared to DIPs with a typical maximum pin count of 64, SIPs have a typical maximum pin count of 24 with lower package costs.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [ 21306150 ], "anchor_spans": [ [ 135, 138 ] ] }, { "plaintext": "One variant of the single in-line package uses part of the lead frame for a heat sink tab. This multi-leaded power package is useful for such applications as audio power amplifiers, for example.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [ 22282608 ], "anchor_spans": [ [ 96, 122 ] ] }, { "plaintext": "The QIP, sometimes called a QIL package, has the same dimensions as a DIL package, but the leads on each side are bent into an alternating zigzag configuration so as to fit four lines of solder pads (instead of two with a DIL). The QIL design increased the spacing between solder pads without increasing package size, for two reasons: \t", "section_idx": 2, "section_name": "Construction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " First it allowed more reliable soldering. This may seem odd today, given the far closer solder pad spacing in use now, but in the 1970s, the heyday of the QIL, bridging of neighbouring solder pads on DIL chips was an issue at times,", "section_idx": 2, "section_name": "Construction", "target_page_ids": [ 25067088, 9209184 ], "anchor_spans": [ [ 32, 41 ], [ 161, 169 ] ] }, { "plaintext": " QIL also increased the possibility of running a copper track between 2 solder pads. This was very handy on the then standard single sided single layer PCBs.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [ 125293 ], "anchor_spans": [ [ 49, 55 ] ] }, { "plaintext": "Commonly found DIP packages that conform to JEDEC standards use an inter-lead spacing (lead pitch) of (JEDEC MS-001BA). Row spacing varies depending on lead counts, with 0.3 in. (7.62mm) (JEDEC MS-001) or 0.6inch (15.24mm) (JEDEC MS-011) the most common. Less common standardized row spacings include 0.4inch (10.16mm) (JEDEC MS-010) and 0.9inch (22.86mm), as well as a row spacing of 0.3inch, 0.6inch or 0.75inch with a 0.07inch (1.778mm) lead pitch.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [ 184092 ], "anchor_spans": [ [ 44, 49 ] ] }, { "plaintext": "The former Soviet Union and Eastern bloc countries used similar packages, but with a metric pin-to-pin spacing of 2.5mm rather than .", "section_idx": 2, "section_name": "Construction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The number of leads is always even. For 0.3inch spacing, typical lead counts are 8, 14, 16, 18, and 28; less common are 4, 6, 20, and 24 lead counts. To have an even number of leads some DIPs have unused not connected (NC) leads to the internal chip, or are duplicated, e.g. two ground pins. For 0.6inch spacing, typical lead counts are 24, 28, 32, and 40; less common are 36, 48, 52, and 64 lead counts. Some microprocessors, such as the Motorola 68000 and Zilog Z180, used lead counts as high as 64; this is typically the maximum number of leads for a DIP package.", "section_idx": 2, "section_name": "Construction", "target_page_ids": [ 20270, 612247 ], "anchor_spans": [ [ 439, 453 ], [ 458, 468 ] ] }, { "plaintext": "As shown in the diagram, leads are numbered consecutively from Pin 1. When the identifying notch in the package is at the top, Pin 1 is the top left corner of the device. Sometimes Pin 1 is identified with an indent or paint dot mark.", "section_idx": 3, "section_name": "Orientation and lead numbering", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For example, for a 14-lead DIP, with the notch at the top, the left leads are numbered from 1 to 7 (top to bottom) and the right row of leads are numbered 8 to 14 (bottom to top).", "section_idx": 3, "section_name": "Orientation and lead numbering", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Some DIP devices, such as segmented LED displays, relays, or those that replace leads with a heat sink fin, skip some leads; the remaining leads are numbered as if all positions had leads.", "section_idx": 3, "section_name": "Orientation and lead numbering", "target_page_ids": [ 450703 ], "anchor_spans": [ [ 26, 47 ] ] }, { "plaintext": "In addition to providing for human visual identification of the orientation of the package, the notch allows automated chip-insertion machinery to confirm correct orientation of the chip by mechanical sensing.", "section_idx": 3, "section_name": "Orientation and lead numbering", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The SOIC (Small Outline IC), a surface-mount package which is currently very popular, particularly in consumer electronics and personal computers, is essentially a shrunk version of the standard IC PDIP, the fundamental difference which makes it an SMT device being a second bend in the leads to flatten them parallel to the bottom plane of the plastic housing. The SOJ (Small Outline J-lead) and other SMT packages with \"SOP\" (for \"Small Outline Package\") in their names can be considered further relatives of the DIP, their original ancestor. SOIC packages tend to have half the pitch of DIP, and SOP are half that, a fourth of DIP. (0.1\"/2.54mm, 0.05\"/1.27mm, and 0.025\"/0.635mm, respectively)", "section_idx": 4, "section_name": "Descendants", "target_page_ids": [ 2555717 ], "anchor_spans": [ [ 4, 8 ] ] }, { "plaintext": "Pin grid array (PGA) packages may be considered to have evolved from the DIP. PGAs with the same pin centers as most DIPs were popular for microprocessors from the early to mid-1980s through the 1990s. Owners of personal computers containing Intel 80286 through P5 Pentium processors may be most familiar with these PGA packages, which were often inserted into ZIF sockets on motherboards. The similarity is such that a PGA socket may be physically compatible with some DIP devices, though the converse is rarely true.", "section_idx": 4, "section_name": "Descendants", "target_page_ids": [ 233017, 15054, 24668, 5144840, 175735, 19945 ], "anchor_spans": [ [ 0, 14 ], [ 249, 254 ], [ 263, 265 ], [ 266, 273 ], [ 362, 365 ], [ 377, 388 ] ] }, { "plaintext": " Chip carrier", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 34147043 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " DIP switch", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 317918 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Flatpack (electronics)", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 20514106 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " List of integrated circuit package dimensions", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 3920625 ], "anchor_spans": [ [ 1, 46 ] ] }, { "plaintext": " NORBIT 2 (a larger 19-pin DIP, introduced in 1967)", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 13370236 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Pin grid array", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 233017 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " QFP", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 848200 ], "anchor_spans": [ [ 1, 4 ] ] }, { "plaintext": " Surface-mount_technology", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 232333 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Zig-zag in-line package", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 233019 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " DIP packages documentation, photos and videos", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Chip_carriers", "CPU_sockets" ]

[ "DIL package", "DIP", "Dual inline packages" ]

[ { "plaintext": "The word duct is derived from the Latin word for led/leading. It may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Duct (anatomy), various ducts in anatomy and physiology", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 7130789 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Tear duct, which carry tears to the eyes", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 848560 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Duct (HVAC), for transfer of air between spaces in a structure", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 6280965 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Duct tape, a kind of adhesive tape", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 43707 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Ducted fan, motor for aircraft", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 477437 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Electrical bus duct, a metal enclosure for busbars", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1029195 ], "anchor_spans": [ [ 44, 50 ] ] }, { "plaintext": " Duct (industrial exhaust), industrial exhaust duct system designed for low pressure-pneumatic convey of gas, fumes, dusts, shavings, and other pollutants from works space to atmosphere after cleaning and removal of contaminants", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 23977696 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Atmospheric duct, a horizontal layer in the lower atmosphere in which the vertical refractive index gradients are such that radio signals (a) are guided or ducted, (b) tend to follow the curvature of the Earth, and (c) experience less attenuation in the ducts than they would if the ducts were not present", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40732 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Tropospheric ducting, a type of radio propagation in the troposphere that allows signals to travel unusually long distances", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22416553 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Earth–ionosphere waveguide, a type of atmospheric duct", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 11047538 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Surface duct, a sound propagation phenomenon at sea", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 29438 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Duct bank, a set of electrical conduits or telecommunications conduits, entering a building underground", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 43657450, 17912042 ], "anchor_spans": [ [ 21, 39 ], [ 44, 70 ] ] }, { "plaintext": " Duct Publishing, an imprint of the German group VDM Publishing devoted to the reproduction of Wikipedia content", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22904873 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Dispatchable Unit Control Table (DUCT) in z/Architecture", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1856144 ], "anchor_spans": [ [ 43, 57 ] ] }, { "plaintext": " Flexible Ducting", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 6280965 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Ducked", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 1488795 ], "anchor_spans": [ [ 1, 7 ] ] } ]

[]

[]

[ { "plaintext": "A duplexer is an electronic device that allows bi-directional (duplex) communication over a single path. In radar and radio communications systems, it isolates the receiver from the transmitter while permitting them to share a common antenna. Most radio repeater systems include a duplexer. Duplexers can be based on frequency (often a waveguide filter), polarization (such as an orthomode transducer), or timing (as is typical in radar).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2112491, 25676, 491851, 61164, 187317, 4149041, 25000433, 2103852 ], "anchor_spans": [ [ 63, 69 ], [ 108, 113 ], [ 164, 172 ], [ 182, 193 ], [ 234, 241 ], [ 248, 262 ], [ 336, 352 ], [ 380, 400 ] ] }, { "plaintext": "In radar, a transmit/receive (TR) switch alternately connects the transmitter and receiver to a shared antenna. In the simplest arrangement, the switch consists of a gas-discharge tube across the input terminals of the receiver. When the transmitter is active, the resulting high voltage causes the tube to conduct, shorting together the receiver terminals to protect it, while its complementary, the anti-transmit/receive (ATR) switch, is a similar discharge tube which decouples the transmitter from the antenna while not operating, to prevent it from wasting received energy.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 42131483 ], "anchor_spans": [ [ 166, 184 ] ] }, { "plaintext": "A hybrid, such as a magic T, may be used as a duplexer by terminating the fourth port in a matched load.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 41246, 21546542, 344136 ], "anchor_spans": [ [ 2, 8 ], [ 20, 27 ], [ 91, 103 ] ] }, { "plaintext": "This arrangement suffers from the disadvantage that half of the transmitter power is lost in the matched load, while thermal noise in the load is delivered to the receiver.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 182745 ], "anchor_spans": [ [ 117, 130 ] ] }, { "plaintext": "In radio communications (as opposed to radar), the transmitted and received signals can occupy different frequency bands, and so may be separated by frequency-selective filters. These are effectively a higher-performance version of a diplexer, typically with a narrow split between the two frequencies in question (typically around 2%-5% for a commercial two-way radio system).", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 948432 ], "anchor_spans": [ [ 234, 242 ] ] }, { "plaintext": "With a duplexer the high- and low-frequency signals are traveling in opposite directions at the shared port of the duplexer.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 42920842 ], "anchor_spans": [ [ 103, 107 ] ] }, { "plaintext": "Modern duplexers often use nearby frequency bands, so the frequency separation between the two ports is also much less. For example, the transition between the uplink and downlink bands in the GSM frequency bands may be about one percent (915MHz to 925MHz). Significant attenuation (isolation) is needed to prevent the transmitter's output from overloading the receiver's input, so such duplexers employ multi-pole filters. Duplexers are commonly made for use on the 30-50 MHz (\"low band\"), 136-174 MHz (\"high band\"), 380-520 MHz (\"UHF\"), plus the 790–862 MHz (\"800\"), 896-960 MHz (\"900\") and 1215-1300 MHz (\"1200\") bands.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 1080823 ], "anchor_spans": [ [ 193, 212 ] ] }, { "plaintext": "There are two predominant types of duplexer in use - \"notch duplexers\", which exhibit sharp notches at the \"unwanted\" frequencies and only pass through a narrow band of wanted frequencies and \"bandpass duplexers\", which have wide-pass frequency ranges and high out-of-band attenuation.", "section_idx": 1, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "On shared-antenna sites, the bandpass duplexer variety is greatly preferred because this virtually eliminates interference between transmitters and receivers by removing out-of-band transmit emissions and considerably improving the selectivity of receivers. Most professionally engineered sites ban the use of notch duplexers and insist on bandpass duplexers for this reason.", "section_idx": 1, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Note 1: A duplexer must be designed for operation in the frequency band used by the receiver and transmitter, and must be capable of handling the output power of the transmitter.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 10779, 634183, 24236 ], "anchor_spans": [ [ 58, 67 ], [ 68, 72 ], [ 154, 159 ] ] }, { "plaintext": "Note 2: A duplexer must provide adequate rejection of transmitter noise occurring at the receive frequency, and must be designed to operate at, or less than, the frequency separation between the transmitter and receiver.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 41415 ], "anchor_spans": [ [ 67, 72 ] ] }, { "plaintext": "Note 3: A duplexer must provide sufficient isolation to prevent receiver desensitization.", "section_idx": 1, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Source: from Federal Standard 1037C", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 37310 ], "anchor_spans": [ [ 13, 35 ] ] }, { "plaintext": "The first duplexers were invented for use on the electric telegraph and were known as duplex rather than duplexer. They were an early form of the hybrid coil. The telegraph companies were keen to have such a device since the ability to have simultaneous traffic in both directions had the potential to save the cost of thousands of miles of telegraph wire. The first of these devices was designed in 1853 by Julius Wilhelm Gintl of the Austrian State Telegraph. Gintl's design was not very successful. Further attempts were made by Carl Frischen of Hanover with an artificial line to balance the real line as well as by Siemens & Halske, who bought and modified Frischen's design. The first truly successful duplex was designed by Joseph Barker Stearns of Boston in 1872. This was further developed into the quadruplex telegraph by Thomas Edison. The device is estimated to have saved Western Union $500,000 per year in construction of new telegraph lines.", "section_idx": 2, "section_name": "History", "target_page_ids": [ 9450, 41246, 11193275, 4444747, 22463012, 11126672, 29778, 193207 ], "anchor_spans": [ [ 49, 67 ], [ 146, 157 ], [ 408, 428 ], [ 620, 636 ], [ 731, 752 ], [ 808, 828 ], [ 832, 845 ], [ 885, 898 ] ] } ]

[ "Broadcast_engineering", "Radio_electronics", "Electronic_circuits", "Telegraphy" ]

[]

[ { "plaintext": "A duty cycle or power cycle is the fraction of one period in which a signal or system is active. Duty cycle is commonly expressed as a percentage or a ratio. A period is the time it takes for a signal to complete an on-and-off cycle. As a formula, a duty cycle (%) may be expressed as:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 10779, 855329 ], "anchor_spans": [ [ 51, 57 ], [ 228, 233 ] ] }, { "plaintext": "Equally, a duty cycle (ratio) may be expressed as:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where is the duty cycle, is the pulse width (pulse active time), and is the total period of the signal. Thus, a 60% duty cycle means the signal is on 60% of the time but off 40% of the time. The \"on time\" for a 60% duty cycle could be a fraction of a second, a day, or even a week, depending on the length of the period.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Duty cycles can be used to describe the percent time of an active signal in an electrical device such as the power switch in a switching power supply or the firing of action potentials by a living system such as a neuron.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 223407, 156998, 21120 ], "anchor_spans": [ [ 127, 149 ], [ 167, 184 ], [ 214, 220 ] ] }, { "plaintext": "The duty factor for periodic signal expresses the same notion, but is usually scaled to a maximum of one rather than 100%.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The duty cycle can also be notated as .", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In electronics, duty cycle is the percentage of the ratio of pulse duration, or pulse width (PW) to the total period (T) of the waveform. It is generally used to represent time duration of a pulse when it is high (1). In digital electronics, signals are used in rectangular waveform which are represented by logic 1 and logic 0. Logic 1 stands for presence of an electric pulse and 0 for absence of an electric pulse. For example, a signal (10101010) has 50% duty cycle, because the pulse remains high for 1/2 of the period or low for 1/2 of the period. Similarly, for pulse (10001000) the duty cycle will be 25% because the pulse remains high only for 1/4 of the period and remains low for 3/4 of the period.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Electrical motors typically use less than a 100% duty cycle. For example, if a motor runs for one out of 100 seconds, or 1/100 of the time, then, its duty cycle is 1/100, or 1 percent.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 76086 ], "anchor_spans": [ [ 80, 85 ] ] }, { "plaintext": "Pulse-width modulation (PWM) is used in a variety of electronic situations, such as power delivery and voltage regulation.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 81242 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "In electronic music, music synthesizers vary the duty cycle of their audio-frequency oscillators to obtain a subtle effect on the tone colors. This technique is known as pulse-width modulation.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 10791746, 77892 ], "anchor_spans": [ [ 27, 39 ], [ 130, 140 ] ] }, { "plaintext": "In the printer / copier industry, the duty cycle specification refers to the rated throughput (that is, printed pages) of a device per month.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In a welding power supply, the maximum duty cycle is defined as the percentage of time in a 10-minute period that it can be operated continuously before overheating.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 1546777 ], "anchor_spans": [ [ 5, 25 ] ] }, { "plaintext": "The concept of duty cycles is also used to describe the activity of neurons and muscle fibers. In neural circuits for example, a duty cycle specifically refers to the proportion of a cycle period in which a neuron remains active.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 571549, 1726672 ], "anchor_spans": [ [ 80, 93 ], [ 98, 112 ] ] }, { "plaintext": "One way to generate fairly accurate square wave signals with 1/n duty factor, where n is an integer, is to vary the duty cycle until the nth-harmonic is significantly suppressed. For audio-band signals, this can even be done \"by ear\"; for example, a -40dB reduction in the 3rd harmonic corresponds to setting the duty factor to 1/3 with a precision of 1% and -60dB reduction corresponds to a precision of 0.1%.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [ 314652, 41232, 8410 ], "anchor_spans": [ [ 36, 47 ], [ 141, 149 ], [ 253, 255 ] ] }, { "plaintext": " Mark-space ratio, or mark-to-space ratio, is another term for the same concept, to describe the temporal relationship between two alternating periods of a waveform. However, whereas the duty cycle relates the duration of one period to the duration of the entire cycle, the mark-space ratio relates the durations of the two individual periods:", "section_idx": 1, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where and are the durations of the two alternating periods.", "section_idx": 1, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] } ]

[ "Mechanical_engineering", "Timing_in_electronic_circuits", "Articles_containing_video_clips" ]

[ "duty factor", "on time", "power cycle" ]

[ { "plaintext": "Dynamic range (abbreviated DR, DNR, or DYR) is the ratio between the largest and smallest values that a certain quantity can assume. It is often used in the context of signals, like sound and light. It is measured either as a ratio or as a base-10 (decibel) or base-2 (doublings, bits or stops) logarithmic value of the difference between the smallest and largest signal values.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 87837, 275871, 18994087, 17939, 8214, 8410, 238686, 3364, 7184839, 164055 ], "anchor_spans": [ [ 51, 56 ], [ 168, 174 ], [ 182, 187 ], [ 192, 197 ], [ 240, 247 ], [ 249, 256 ], [ 261, 267 ], [ 280, 283 ], [ 288, 292 ], [ 295, 306 ] ] }, { "plaintext": "Electronically reproduced audio and video is often processed to fit the original material with a wide dynamic range into a narrower recorded dynamic range that can more easily be stored and reproduced; this processing is called dynamic range compression.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 262733 ], "anchor_spans": [ [ 228, 253 ] ] }, { "plaintext": "The human senses of sight and hearing have a relatively high dynamic range. However, a human cannot perform these feats of perception at both extremes of the scale at the same time. The human eye takes time to adjust to different light levels, and its dynamic range in a given scene is actually quite limited due to optical glare. The instantaneous dynamic range of human audio perception is similarly subject to masking so that, for example, a whisper cannot be heard in loud surroundings.", "section_idx": 1, "section_name": "Human perception", "target_page_ids": [ 21280496, 21282020, 7497745, 9736652 ], "anchor_spans": [ [ 20, 25 ], [ 30, 37 ], [ 324, 329 ], [ 413, 420 ] ] }, { "plaintext": "A human is capable of hearing (and usefully discerning) anything from a quiet murmur in a soundproofed room to the loudest heavy metal concert. Such a difference can exceed 100dB which represents a factor of 100,000 in amplitude and a factor 10,000,000,000 in power. The dynamic range of human hearing is roughly 140dB, varying with frequency, from the threshold of hearing (around −9dB SPL at 3kHz) to the threshold of pain (from 120–140dB SPL). This wide dynamic range cannot be perceived all at once, however; the tensor tympani, stapedius muscle, and outer hair cells all act as mechanical dynamic range compressors to adjust the sensitivity of the ear to different ambient levels.", "section_idx": 1, "section_name": "Human perception", "target_page_ids": [ 340201, 8410, 37649, 297595, 575347, 2186011, 2111321, 890232, 262733 ], "anchor_spans": [ [ 90, 102 ], [ 176, 178 ], [ 219, 228 ], [ 353, 373 ], [ 407, 424 ], [ 518, 532 ], [ 534, 550 ], [ 556, 572 ], [ 595, 620 ] ] }, { "plaintext": "A human can see objects in starlight or in bright sunlight, even though on a moonless night objects receive one billionth (10−9) of the illumination they would on a bright sunny day; a dynamic range of 90dB.", "section_idx": 1, "section_name": "Human perception", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In practice, it is difficult for humans to achieve the full dynamic experience using electronic equipment. For example, a good quality liquid-crystal display (LCD) has a dynamic range limited to around 1000:1, and some of the latest image sensors now have measured dynamic ranges of about 23,000:1. Paper reflectance can produce a dynamic range of about 100:1. A professional video camera such as the Sony Digital Betacam achieves a dynamic range of greater than 90dB in audio recording.", "section_idx": 1, "section_name": "Human perception", "target_page_ids": [ 17932, 464103 ], "anchor_spans": [ [ 135, 157 ], [ 365, 390 ] ] }, { "plaintext": "Audio engineers use dynamic range to describe the ratio of the amplitude of the loudest possible undistorted signal to the noise floor, say of a microphone or loudspeaker. Dynamic range is therefore the signal-to-noise ratio (SNR) for the case where the signal is the loudest possible for the system. For example, if the ceiling of a device is 5V (rms) and the noise floor is 10µV (rms) then the dynamic range is 500000:1, or 114dB:", "section_idx": 2, "section_name": "Audio", "target_page_ids": [ 21189305, 41052, 795170, 65886, 45871, 41706 ], "anchor_spans": [ [ 0, 14 ], [ 97, 108 ], [ 123, 134 ], [ 145, 155 ], [ 159, 170 ], [ 203, 224 ] ] }, { "plaintext": "In digital audio theory the dynamic range is limited by quantization error. The maximum achievable dynamic range for a digital audio system with Q-bit uniform quantization is calculated as the ratio of the largest sine-wave rms to rms noise is:", "section_idx": 2, "section_name": "Audio", "target_page_ids": [ 317018 ], "anchor_spans": [ [ 56, 74 ] ] }, { "plaintext": "However, the usable dynamic range may be greater, as a properly dithered recording device can record signals well below the noise floor.", "section_idx": 2, "section_name": "Audio", "target_page_ids": [ 1243526 ], "anchor_spans": [ [ 64, 70 ] ] }, { "plaintext": "The 16-bit compact disc has a theoretical undithered dynamic range of about 96dB; however, the perceived dynamic range of 16-bit audio can be 120dB or more with noise-shaped dither, taking advantage of the frequency response of the human ear.", "section_idx": 2, "section_name": "Audio", "target_page_ids": [ 6429, 1244240, 1243526, 1046687 ], "anchor_spans": [ [ 11, 23 ], [ 161, 173 ], [ 174, 180 ], [ 202, 241 ] ] }, { "plaintext": "Digital audio with undithered 20-bit quantization is theoretically capable of 120dB dynamic range, while 24-bit digital audio affords 144dB dynamic range. Most Digital audio workstations process audio with 32-bit floating-point representation which affords even higher dynamic range and so loss of dynamic range is no longer a concern in terms of digital audio processing. Dynamic range limitations typically result from improper gain staging, recording technique including ambient noise and intentional application of dynamic range compression.", "section_idx": 2, "section_name": "Audio", "target_page_ids": [ 431270, 11376, 2322, 37390436, 3296057, 262733 ], "anchor_spans": [ [ 160, 185 ], [ 213, 227 ], [ 347, 371 ], [ 430, 442 ], [ 474, 487 ], [ 519, 544 ] ] }, { "plaintext": "Dynamic range in analog audio is the difference between low-level thermal noise in the electronic circuitry and high-level signal saturation resulting in increased distortion and, if pushed higher, clipping. Multiple noise processes determine the noise floor of a system. Noise can be picked up from microphone self-noise, preamp noise, wiring and interconnection noise, media noise, etc.", "section_idx": 2, "section_name": "Audio", "target_page_ids": [ 3375566 ], "anchor_spans": [ [ 198, 206 ] ] }, { "plaintext": "Early 78 rpm phonograph discs had a dynamic range of up to 40dB, soon reduced to 30dB and worse due to wear from repeated play. Vinyl microgroove phonograph records typically yield 55-65dB, though the first play of the higher-fidelity outer rings can achieve a dynamic range of 70dB.", "section_idx": 2, "section_name": "Audio", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "German magnetic tape in 1941 was reported to have had a dynamic range of 60dB, though modern day restoration experts of such tapes note 45-50dB as the observed dynamic range. Ampex tape recorders in the 1950s achieved 60dB in practical usage, In the 1960s, improvements in tape formulation processes resulted in 7dB greater range, and Ray Dolby developed the Dolby A-Type noise reduction system that increased low- and mid-frequency dynamic range on magnetic tape by 10dB, and high-frequency by 15dB, using companding (compression and expansion) of four frequency bands. The peak of professional analog magnetic recording tape technology reached 90dB dynamic range in the midband frequencies at 3% distortion, or about 80dB in practical broadband applications. The Dolby SR noise reduction system gave a 20dB further increased range resulting in 110dB in the midband frequencies at 3% distortion.", "section_idx": 2, "section_name": "Audio", "target_page_ids": [ 249854, 87710, 40927, 87710 ], "anchor_spans": [ [ 175, 180 ], [ 359, 394 ], [ 507, 517 ], [ 765, 796 ] ] }, { "plaintext": "Compact Cassette tape performance ranges from 50 to 56dB depending on tape formulation, with type IV tape tapes giving the greatest dynamic range, and systems such as XDR, dbx and Dolby noise reduction system increasing it further. Specialized bias and record head improvements by Nakamichi and Tandberg combined with Dolby C noise reduction yielded 72dB dynamic range for the cassette.", "section_idx": 2, "section_name": "Audio", "target_page_ids": [ 65880, 65880, 2723575, 426407, 87710 ], "anchor_spans": [ [ 0, 16 ], [ 93, 105 ], [ 167, 170 ], [ 172, 175 ], [ 180, 208 ] ] }, { "plaintext": "A dynamic microphone is able to withstand high sound intensity and can have a dynamic range of up to 140dB. Condenser microphones are also rugged but their dynamic range may be limited by the overloading of their associated electronic circuitry. Practical considerations of acceptable distortion levels in microphones combined with typical practices in a recording studio result in a useful dynamic range of 125dB.", "section_idx": 2, "section_name": "Audio", "target_page_ids": [ 65886 ], "anchor_spans": [ [ 2, 20 ] ] }, { "plaintext": "In 1981, researchers at Ampex determined that a dynamic range of 118dB on a dithered digital audio stream was necessary for subjective noise-free playback of music in quiet listening environments.", "section_idx": 2, "section_name": "Audio", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Since the early 1990s, it has been recommended by several authorities, including the Audio Engineering Society, that measurements of dynamic range be made with an audio signal present, which is then filtered out in the noise floor measurement used in determining dynamic range. This avoids questionable measurements based on the use of blank media, or muting circuits.", "section_idx": 2, "section_name": "Audio", "target_page_ids": [ 1237052 ], "anchor_spans": [ [ 85, 110 ] ] }, { "plaintext": "The term dynamic range may be confusing in audio production because it has two conflicting definitions, particularly in the understanding of the loudness war phenomenon. Dynamic range may refer to micro-dynamics, related to crest factor, whereas the European Broadcasting Union, in EBU3342 Loudness Range, defines dynamic range as the difference between the quietest and loudest volume, a matter of macro-dynamics.", "section_idx": 2, "section_name": "Audio", "target_page_ids": [ 3576625, 1432608, 10380 ], "anchor_spans": [ [ 145, 157 ], [ 224, 236 ], [ 250, 277 ] ] }, { "plaintext": "In electronics dynamic range is used in the following contexts: ", "section_idx": 3, "section_name": "Electronics", "target_page_ids": [ 9663 ], "anchor_spans": [ [ 3, 14 ] ] }, { "plaintext": " Specifies the ratio of a maximum level of a parameter, such as power, current, voltage or frequency, to the minimum detectable value of that parameter. (See Audio system measurements.)", "section_idx": 3, "section_name": "Electronics", "target_page_ids": [ 25065, 24236, 6207, 32549, 10779, 302052 ], "anchor_spans": [ [ 45, 54 ], [ 64, 69 ], [ 71, 78 ], [ 80, 87 ], [ 91, 100 ], [ 158, 183 ] ] }, { "plaintext": " In a transmission system, the ratio of the overload level (the maximum signal power that the system can tolerate without distortion of the signal) to the noise level of the system. ", "section_idx": 3, "section_name": "Electronics", "target_page_ids": [ 46982, 275871, 41052, 3966982 ], "anchor_spans": [ [ 6, 25 ], [ 72, 78 ], [ 122, 132 ], [ 155, 166 ] ] }, { "plaintext": " In digital systems or devices, the ratio of maximum and minimum signal levels required to maintain a specified bit error ratio.", "section_idx": 3, "section_name": "Electronics", "target_page_ids": [ 8276, 40794 ], "anchor_spans": [ [ 4, 11 ], [ 112, 127 ] ] }, { "plaintext": " Optimization of bit width of digital data path (according to the dynamic ranges of signal) can reduce the area, cost, and power consumption of digital circuits and systems while improving their performance. Optimal bit width for a digital data path is the smallest bit width that can satisfy the required signal-to-noise ratio and also avoid overflow.", "section_idx": 3, "section_name": "Electronics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In audio and electronics applications, the ratio involved is often large enough that it is converted to a logarithm and specified in decibels.", "section_idx": 3, "section_name": "Electronics", "target_page_ids": [ 17860, 8410 ], "anchor_spans": [ [ 106, 115 ], [ 133, 140 ] ] }, { "plaintext": "In metrology, such as when performed in support of science, engineering or manufacturing objectives, dynamic range refers to the range of values that can be measured by a sensor or metrology instrument. Often this dynamic range of measurement is limited at one end of the range by saturation of a sensing signal sensor or by physical limits that exist on the motion or other response capability of a mechanical indicator. The other end of the dynamic range of measurement is often limited by one or more sources of random noise or uncertainty in signal levels that may be described as defining the sensitivity of the sensor or metrology device. When digital sensors or sensor signal converters are a component of the sensor or metrology device, the dynamic range of measurement will be also related to the number of binary digits (bits) used in a digital numeric representation in which the measured value is linearly related to the digital number. For example, a 12-bit digital sensor or converter can provide a dynamic range in which the ratio of the maximum measured value to the minimum measured value is up to 212 = 4096.", "section_idx": 4, "section_name": "Metrology", "target_page_ids": [ 65637, 41415, 455092 ], "anchor_spans": [ [ 3, 12 ], [ 522, 527 ], [ 598, 609 ] ] }, { "plaintext": "Metrology systems and devices may use several basic methods to increase their basic dynamic range. These methods include averaging and other forms of filtering, correction of receivers characteristics, repetition of measurements, nonlinear transformations to avoid saturation, etc. In more advance forms of metrology, such as multiwavelength digital holography, interferometry measurements made at different scales (different wavelengths) can be combined to retain the same low-end resolution while extending the upper end of the dynamic range of measurement by orders of magnitude.", "section_idx": 4, "section_name": "Metrology", "target_page_ids": [ 7814821, 166689 ], "anchor_spans": [ [ 342, 360 ], [ 362, 376 ] ] }, { "plaintext": "In music, dynamic range describes the difference between the quietest and loudest volume of an instrument, part or piece of music. In modern recording, this range is often limited through dynamic range compression, which allows for louder volume, but can make the recording sound less exciting or live.", "section_idx": 5, "section_name": "Music", "target_page_ids": [ 18839, 27406894, 16157429, 262733 ], "anchor_spans": [ [ 3, 8 ], [ 95, 105 ], [ 107, 111 ], [ 188, 213 ] ] }, { "plaintext": "The dynamic range of music as normally perceived in a concert hall does not exceed 80dB, and human speech is normally perceived over a range of about 40dB.", "section_idx": 5, "section_name": "Music", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Photographers use dynamic range to describe the luminance range of a scene being photographed, or the limits of luminance range that a given digital camera or film can capture, or the opacity range of developed film images, or the reflectance range of images on photographic papers.", "section_idx": 6, "section_name": "Photography", "target_page_ids": [ 23604, 18365, 52797, 21556842, 3581788, 41644 ], "anchor_spans": [ [ 0, 12 ], [ 48, 57 ], [ 141, 155 ], [ 159, 163 ], [ 184, 191 ], [ 231, 242 ] ] }, { "plaintext": "The dynamic range of digital photography is comparable to the capabilities of photographic film and both are comparable to the capabilities of the human eye.", "section_idx": 6, "section_name": "Photography", "target_page_ids": [ 3616597, 21556842 ], "anchor_spans": [ [ 21, 40 ], [ 78, 95 ] ] }, { "plaintext": "There are photographic techniques that support even higher dynamic range. ", "section_idx": 6, "section_name": "Photography", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Graduated neutral density filters are used to decrease the dynamic range of scene luminance that can be captured on photographic film (or on the image sensor of a digital camera): The filter is positioned in front of the lens at the time the exposure is made; the top half is dark and the bottom half is clear. The dark area is placed over a scene's high-intensity region, such as the sky. The result is more even exposure in the focal plane, with increased detail in the shadows and low-light areas. Though this doesn't increase the fixed dynamic range available at the film or sensor, it stretches usable dynamic range in practice.", "section_idx": 6, "section_name": "Photography", "target_page_ids": [ 2567334, 21556842, 3788466, 52797 ], "anchor_spans": [ [ 0, 32 ], [ 116, 133 ], [ 145, 157 ], [ 163, 177 ] ] }, { "plaintext": "High-dynamic-range imaging overcomes the limited dynamic range of the sensor by selectively combining multiple exposures of the same scene in order to retain detail in light and dark areas. Tone mapping maps the image differently in shadow and highlights in order to better distribute the lighting range across the image. The same approach has been used in chemical photography to capture an extremely wide dynamic range: A three-layer film with each underlying layer at one hundredth (10−2) the sensitivity of the next higher one has, for example, been used to record nuclear-weapons tests.", "section_idx": 6, "section_name": "Photography", "target_page_ids": [ 173272, 2153191 ], "anchor_spans": [ [ 0, 26 ], [ 190, 202 ] ] }, { "plaintext": "Consumer-grade image file formats sometimes restrict dynamic range. The most severe dynamic-range limitation in photography may not involve encoding, but rather reproduction to, say, a paper print or computer screen. In that case, not only local tone mapping but also dynamic range adjustment can be effective in revealing detail throughout light and dark areas: The principle is the same as that of dodging and burning (using different lengths of exposures in different areas when making a photographic print) in the chemical darkroom. The principle is also similar to gain riding or automatic level control in audio work, which serves to keep a signal audible in a noisy listening environment and to avoid peak levels that overload the reproducing equipment, or which are unnaturally or uncomfortably loud.", "section_idx": 6, "section_name": "Photography", "target_page_ids": [ 2679981, 877792 ], "anchor_spans": [ [ 15, 33 ], [ 400, 419 ] ] }, { "plaintext": "If a camera sensor is incapable of recording the full dynamic range of a scene, high-dynamic-range (HDR) techniques may be used in postprocessing, which generally involve combining multiple exposures using software.", "section_idx": 6, "section_name": "Photography", "target_page_ids": [ 173272 ], "anchor_spans": [ [ 80, 98 ] ] }, { "plaintext": "Loudness war", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 3576625 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": "High dynamic range", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 4688909 ], "anchor_spans": [ [ 0, 18 ] ] }, { "plaintext": "High-dynamic-range imaging", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 173272 ], "anchor_spans": [ [ 0, 26 ] ] }, { "plaintext": "High-dynamic-range rendering", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 2114941 ], "anchor_spans": [ [ 0, 28 ] ] }, { "plaintext": "High-dynamic-range video", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 51174837 ], "anchor_spans": [ [ 0, 24 ] ] }, { "plaintext": "Highlight headroom", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 6888696 ], "anchor_spans": [ [ 0, 18 ] ] }, { "plaintext": "Range fractionation", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 1148992 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": "Spurious-free dynamic range", "section_idx": 7, "section_name": "See also", "target_page_ids": [ 14615532 ], "anchor_spans": [ [ 0, 27 ] ] }, { "plaintext": " Audible dynamic range (online test)", "section_idx": 10, "section_name": "External list", "target_page_ids": [], "anchor_spans": [] } ]

[ "Signal_processing", "Audio_amplifier_specifications", "Electronics_concepts", "Engineering_ratios" ]

[ "DNR", "DR", "DYR" ]

[ { "plaintext": "In Greek mythology, Echo (; , Ēkhō, \"echo\", from ἦχος (ēchos), \"sound\") was an Oread who resided on Mount Cithaeron. Zeus loved consorting with beautiful nymphs and often visited them on Earth. Eventually, Zeus's wife, Hera, became suspicious, and came from Mount Olympus in an attempt to catch Zeus with the nymphs. Echo, by trying to protect Zeus (as he had ordered her to do), endured Hera's wrath, and Hera made her only able to speak the last words spoken to her. So when Echo met Narcissus and fell in love with him, she was unable to tell him how she felt and was forced to watch him as he fell in love with himself.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 23416994, 238901, 82849, 83660, 34398, 22058, 13208, 12418604, 22099 ], "anchor_spans": [ [ 3, 18 ], [ 37, 41 ], [ 79, 84 ], [ 100, 115 ], [ 117, 121 ], [ 154, 159 ], [ 219, 223 ], [ 258, 271 ], [ 486, 495 ] ] }, { "plaintext": "In Metamorphoses (8 AD), the poet Ovid tells of Juno (Hera in Greek mythology) and the jealousy she felt over her husband Jupiter's (Zeus in Greek mythology) many affairs. Though vigilant, whenever she was about to catch him, Echo distracted her with lengthy conversations. When at last Juno realized the truth, she cursed Echo. From that moment on, the once loquacious nymph could only repeat the most recently spoken words of another person.", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [ 83101, 37802, 668594, 40255 ], "anchor_spans": [ [ 3, 16 ], [ 34, 38 ], [ 48, 52 ], [ 122, 129 ] ] }, { "plaintext": "Sometime after being cursed, Echo spied a young man, Narcissus, while he was out hunting deer with his companions. She immediately fell in love with him and, infatuated, followed quietly. The more she looked at the young man, the more she longed for him. Though she wished with all her heart to call out to Narcissus, Juno's curse prevented her.", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [ 22099, 2741013 ], "anchor_spans": [ [ 53, 62 ], [ 119, 152 ] ] }, { "plaintext": "During the hunt, Narcissus became separated from his companions and called out, ‘is anyone there,’ and heard the nymph repeat his words. Startled, Narcissus answered the voice, ‘come here,’ only to be told the same. When Narcissus saw that nobody had emerged from the glade, he concluded that the owner of the voice must be running away from him and called out again. Finally, he shouted, \"This way, we must come together.\" Taking this to be a reciprocation of her love, Echo concurred ecstatically, \"We must come together!\"", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In her delight, Echo rushed to Narcissus ready to throw her arms around her beloved. Narcissus, however, was appalled and, spurning her, exclaimed, ‘Hands off! May I die before you enjoy my body.’ All Echo could whisper in reply was, ‘enjoy my body’ and having done so she fled, scorned, humiliated, and shamed.", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Despite the harshness of his rejection, Echo's love for Narcissus only grew. When Narcissus died, wasting away before his own reflection, consumed by a love that could not be, Echo mourned over his body. When Narcissus, looking one last time into the pool uttered, \"Oh marvellous boy, I loved you in vain, farewell\", Echo too chorused, \"Farewell.\"", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Eventually, Echo, too, began to waste away. Her beauty faded, her skin shrivelled, and her bones turned to stone. Today, all that remains of Echo is the sound of her voice.", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The tale of Daphnis and Chloe is a 2nd-century romance by Greek author Longus. At one point in the novel, Daphnis and Chloe are staring out at the boats gliding across the sea. Chloe, having never heard an echo before, is confused on hearing the fisherman's song repeated in a nearby valley. Daphnis promises to tell her the story of Echo in exchange for ten more kisses.", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [ 1047924, 343273 ], "anchor_spans": [ [ 12, 29 ], [ 71, 77 ] ] }, { "plaintext": "Daphnis’ rendition differs radically from Ovid's account. According to Daphnis, Echo was raised among the Nymphæ because her mother was a nymph. Her father, however, was merely a man and hence Echo was not herself a nymph but mortal. Echo spent her days dancing with the Nymphæ and singing with the Muses who taught her all manner of musical instruments. Pan then grew angry with her, envious of her musical virtuosity and covetous of her virginity, which she would yield neither to men nor gods. Pan drove the men of the fields mad, and, like wild animals, they tore Echo apart and scattered the still singing fragments of her body across the earth.", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [ 71180, 78881 ], "anchor_spans": [ [ 299, 304 ], [ 355, 358 ] ] }, { "plaintext": "Showing favour to the Nymphæ, Gaia hid the shreds of Echo within herself providing shelter for her music and at the Muses’ command, Echo's body will still sing, imitating with perfect likeness the sound of any earthly thing. Daphnis recounts that Pan himself often hears his very own pipes and, giving chase across the mountains, looks in vain for the secret student he can never find.", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [ 19272020 ], "anchor_spans": [ [ 30, 34 ] ] }, { "plaintext": "Both the Homeric and Orphic Hymns to Pan reiterate Longus’ tale of Pan chasing Echo's secret voice across the mountains.", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [ 185320, 22877693 ], "anchor_spans": [ [ 9, 16 ], [ 21, 33 ] ] }, { "plaintext": "Codex 190 of Photius' Bibliotheca states that Pan's unrequited love for Echo was placed there by Aphrodite, angry at his verdict in a beauty contest.", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [ 50371, 3219132, 1174 ], "anchor_spans": [ [ 13, 21 ], [ 22, 33 ], [ 97, 106 ] ] }, { "plaintext": "Nonnus’ Dionysiaca contains a number of references to Echo. In Nonnus’ account, though Pan frequently chased Echo, he never won her affection. Book VI also makes reference to Echo in the context of the Great Deluge. Nonnus states that the waters rose so far that even high on the hills Echo was forced to swim. Having escaped the advances of Pan, she feared now the lust of Poseidon.", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [ 164259, 1331888, 601839, 22948 ], "anchor_spans": [ [ 0, 6 ], [ 8, 18 ], [ 202, 214 ], [ 374, 382 ] ] }, { "plaintext": "Whereas Nonnus is adamant that Pan never wins Echo, in Apuleius' The Golden Ass Pan is described with Echo in his arms, teaching the nymph to repeat all manner of songs. Similarly in the Suda Echo is described as bearing Pan a child, Iynx. Other fragments mention a second daughter, Iambe.", "section_idx": 1, "section_name": "Classical depiction", "target_page_ids": [ 1789, 759793, 78815, 856472, 80616 ], "anchor_spans": [ [ 55, 63 ], [ 65, 79 ], [ 187, 191 ], [ 234, 238 ], [ 283, 288 ] ] }, { "plaintext": "The Lay of Narcissus, one of many titles by which the work is known, is Norman-French verse narrative written towards the end of the 12th century. In the four manuscripts that remain, an unknown author borrows from the Echo and Narcissus of Ovid to create a story better suited to the needs of his time.", "section_idx": 2, "section_name": "Medieval depiction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This medieval account alters the characters of both Echo and Narcissus. In Ovid's account Echo is a beautiful nymph residing with the Muses, and Narcissus is a haughty prince. In The Lay of Narcissus, Echo is replaced by the princess Dané. Conversely, Narcissus loses the royal status he bore in Ovid's account: in this rendition he is no more than a commoner, a vassal of Dané's father, the King.", "section_idx": 2, "section_name": "Medieval depiction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In the Lay, Dané is pierced by the arrows of Amor and falls madly in love with Narcissus. Though aware that she should first consult her father, she nonetheless shares her feelings with Narcissus. Despite her emphasising her royal lineage, Narcissus spurns her just as he spurns and flees from all women.", "section_idx": 2, "section_name": "Medieval depiction", "target_page_ids": [ 20924853 ], "anchor_spans": [ [ 31, 49 ] ] }, { "plaintext": "Humiliated, Dané calls out to Amor, and, in response, the god curses Narcissus. In a classic example of poetic justice, Narcissus is forced to suffer the same pain he inflicted on others, namely the pain of unrequited love. The vehicle of this justice is a pool of water in which Narcissus falls in love with his own reflection, which he at first mistakes for a woman. Deranged by lust, Dané searches for Narcissus, naked but for a cloak, and finds him at the point of death. Devastated, Dané repents ever calling to Amor. Dané expresses her love for the last time, pulls close to her beloved and dies in his arms. The poet warns men and women alike not to disdain suitors lest they suffer a similar fate.", "section_idx": 2, "section_name": "Medieval depiction", "target_page_ids": [ 20924853, 484540 ], "anchor_spans": [ [ 30, 34 ], [ 104, 118 ] ] }, { "plaintext": "While Ovid's story is still recognisable, many of the details have changed considerably. Almost all references to pagan deities are gone, save Amor who is little more than a personification of love. Narcissus is demoted to the status of a commoner while Echo is elevated to the status of princess. Allusions to Narcissus’ homosexuality are expunged. While Ovid talks of Narcissus' disdain for both male and female suitors, the Lay only mentions his hatred of women. Similarly, in the Lay, Narcissus mistakes his reflection for that of a woman, whereas no mention is made of this in Ovid's account. Finally, the tale is overtly moralized with messages about courtly love. Such exhortations were entirely absent from the Metamorphoses rendition.", "section_idx": 2, "section_name": "Medieval depiction", "target_page_ids": [ 63792 ], "anchor_spans": [ [ 657, 669 ] ] }, { "plaintext": "The Romance of the Rose is a medieval French poem, the first section of which was written by Guillaume de Lorris in around 1230. The poem was completed by Jean de Meun in around 1275. Part of a much larger narrative, the tale of Echo and Narcissus is relayed when the central figure stumbles across the pool wherein Narcissus first glimpsed his own reflection.", "section_idx": 2, "section_name": "Medieval depiction", "target_page_ids": [ 213563, 755496, 1344561 ], "anchor_spans": [ [ 0, 23 ], [ 93, 112 ], [ 155, 167 ] ] }, { "plaintext": "In this rendition, Echo is not a nymph, or a princess, but a noble lady. She fell madly in love with Narcissus, so much so that she declared that she would die should he fail to love her in turn. Narcissus refuses, not because he despises all women, but merely because he is haughty and excessively proud of his own beauty.", "section_idx": 2, "section_name": "Medieval depiction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Guillaume relays that on hearing Narcissus’ rejection, Echo's grief and anger were so great that she died at once. However, in a similar vein to the Lay of Narcissus, just before she dies, Echo calls out to Deus. She asks that Narcissus might one day be tormented by unrequited love as she had been, and, in so doing, understand how the spurned suffer.", "section_idx": 2, "section_name": "Medieval depiction", "target_page_ids": [ 5662336 ], "anchor_spans": [ [ 207, 211 ] ] }, { "plaintext": "As in the classical myth, Narcissus comes across a pool following a hunt. Though Echo prayed to Deus, and the tale notes that he answered her prayer, it is Amor who waits for Narcissus by the water. Amor causes Narcissus to fall for his own reflection, leading quickly to his death. The tale makes clear that this is not merely justice for Echo, but also punishment for Narcissus’ slight against love itself.", "section_idx": 2, "section_name": "Medieval depiction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The tale concludes with an exhortation to all men warning them that, should they scorn their lovers, God will repay the offence.", "section_idx": 2, "section_name": "Medieval depiction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Guillaume's rendition builds on the themes of courtly love emphasised in the Lay and moves further away from Ovid's initial account. The curse of Athena is absent entirely, and the tale is overtly moralised. Unlike in the Lay, however, this moral message is aimed solely at women; this despite the fact that the offending behaviour is perpetrated by Narcissus not Echo.", "section_idx": 2, "section_name": "Medieval depiction", "target_page_ids": [], "anchor_spans": [] } ]

[ "Metamorphoses_in_Greek_mythology", "Oreads", "Metamorphoses_characters", "Deeds_of_Hera", "Nymphs" ]

[]

[ { "plaintext": "In telecommunication, effective data transfer rate is the average number of units of data, such as bits, characters, blocks, or frames, transferred per unit time from a source and accepted as valid by a sink.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 18985040, 30012, 5040275 ], "anchor_spans": [ [ 3, 20 ], [ 85, 89 ], [ 157, 161 ], [ 203, 207 ] ] }, { "plaintext": "Note: The effective data transfer rate is usually expressed in bits, characters, blocks, or frames per second. The effective data transfer rate may be averaged over a period of seconds, minutes, or hours.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 272290 ], "anchor_spans": [ [ 20, 38 ] ] } ]

[ "Data_transmission", "Units_of_information" ]

[]

[ { "plaintext": "In telecommunication, the effective height of an antenna is the height of the antenna's center of radiation above the ground. It is defined as the ratio of the induced voltage to the incident field .", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 187317, 25856 ], "anchor_spans": [ [ 3, 20 ], [ 49, 56 ], [ 98, 107 ] ] }, { "plaintext": "In low-frequency applications involving loaded or nonloaded vertical antennas, the effective height is the moment of the current distribution in the vertical section, divided by the input current. For an antenna with a symmetrical current distribution, the center of radiation is the center of the distribution. For an antenna with asymmetrical current distribution, the center of radiation is the center of current moments when viewed from points near the direction of maximum radiation.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 10779 ], "anchor_spans": [ [ 7, 16 ] ] }, { "plaintext": " Antenna effective length", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 1470583 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Antenna factor", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 2530833 ], "anchor_spans": [ [ 1, 15 ] ] } ]

[ "Antennas" ]

[]

[ { "plaintext": "In telecommunications, effective input noise temperature is the source noise temperature in a two-port network or amplifier that will result in the same output noise power, when connected to a noise-free network or amplifier, as that of the actual network or amplifier connected to a noise-free source. If F is the noise figure numeric and 290K the standard noise temperature, then the effective noise temperature is given by T n = 290(''F' − 1).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 41420, 1301093, 9931, 41419, 41417 ], "anchor_spans": [ [ 3, 20 ], [ 71, 88 ], [ 94, 110 ], [ 114, 123 ], [ 160, 171 ], [ 316, 328 ] ] } ]

[ "Noise_(electronics)", "Equivalent_units" ]

[]

[ { "plaintext": "For an optical fiber, the effective mode volume is the square of the product of the diameter of the near-field pattern and the sine of the radiation angle of the far-field pattern. The diameter of the near-field radiation pattern is defined here as the full width at half maximum and the radiation angle at half maximum radiant intensity. Effective mode volume is proportional to the breadth of the relative distribution of power amongst the modes in a multimode fiber. It is not truly a spatial volume but rather an \"optical volume\" equal to the product of area and solid angle. The power divided by the effective mode volume is proportional to the radiance of the light emitted by the fiber.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3372377, 271708, 41618, 271708, 41620, 41200, 1215732, 516150, 81863, 24236, 532592 ], "anchor_spans": [ [ 7, 20 ], [ 100, 110 ], [ 139, 154 ], [ 162, 171 ], [ 212, 229 ], [ 253, 279 ], [ 320, 337 ], [ 349, 353 ], [ 364, 376 ], [ 424, 429 ], [ 650, 658 ] ] } ]

[ "Fiber_optics" ]

[]

[ { "plaintext": "Effective power may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Active power or real power, a concept in AC power", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1780823, 1780823 ], "anchor_spans": [ [ 0, 26 ], [ 41, 49 ] ] }, { "plaintext": "A measurement of horsepower", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 14019 ], "anchor_spans": [ [ 17, 27 ] ] }, { "plaintext": "\"effective power\" bug, an iPhone bug", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 16280492 ], "anchor_spans": [ [ 0, 21 ] ] }, { "plaintext": "Mean effective pressure", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 3102609 ], "anchor_spans": [ [ 0, 23 ] ] } ]

[]

[]

[ { "plaintext": "In telecommunications, effective transmission rate (average rate of transmission, effective speed of transmission) is the rate at which information is processed by a transmission facility. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 18985062, 609152 ], "anchor_spans": [ [ 3, 20 ], [ 136, 147 ], [ 166, 178 ] ] }, { "plaintext": "The effective transmission rate is calculated as (a) the measured number of units of data, such as bits, characters, blocks, or frames, transmitted during a significant measurement time interval divided by (b) the measurement time interval.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 18985040, 3364, 73443, 3608159, 41172, 30012 ], "anchor_spans": [ [ 85, 89 ], [ 99, 102 ], [ 105, 114 ], [ 117, 123 ], [ 128, 133 ], [ 181, 185 ] ] }, { "plaintext": "The effective transmission rate is usually expressed as a number of units of data per unit time, such as bits per second or characters per second.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 272290, 5272 ], "anchor_spans": [ [ 105, 120 ], [ 124, 145 ] ] }, { "plaintext": "Downloadgram Homepage", "section_idx": 2, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Data_transmission", "Units_of_information", "Temporal_rates" ]

[]

[ { "plaintext": "Efficiency factor is a ratio of some measure of performance to an expected value.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In data communications, the factor is the ratio of the time to transmit a text automatically at a specified modulation rate to the time actually required to receive the same text at a specified maximum error rate. All of the communication facilities are assumed to be in the normal condition of adjustment and operation. The practical conditions of measurement should be specified, especially the duration of the measurement.", "section_idx": 1, "section_name": "Data communication", "target_page_ids": [ 42168, 30012, 2518170, 40794 ], "anchor_spans": [ [ 3, 22 ], [ 55, 59 ], [ 108, 123 ], [ 202, 212 ] ] }, { "plaintext": "Telegraph communications may have different temporal efficiency factors for the two directions of transmission.", "section_idx": 1, "section_name": "Data communication", "target_page_ids": [ 609152 ], "anchor_spans": [ [ 98, 110 ] ] }, { "plaintext": "In industrial engineering, the efficiency factor is the relationship between the allowance time and the time taken, in the form of percentage.", "section_idx": 2, "section_name": "Industrial engineering", "target_page_ids": [ 23535218 ], "anchor_spans": [ [ 3, 25 ] ] }, { "plaintext": "Efficiency factors are used in performance rating and remuneration calculation exercises. The efficiency factor is an extremely simple to use and readily comprehensible index, the prerequisite being exact time management for maintaining the allowed times.", "section_idx": 2, "section_name": "Industrial engineering", "target_page_ids": [ 31092 ], "anchor_spans": [ [ 205, 220 ] ] } ]

[ "Data_transmission", "Industrial_engineering", "Time_management" ]

[]

[ { "plaintext": "In telecommunications and electrical engineering, electrical length (or phase length)", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 9531 ], "anchor_spans": [ [ 3, 20 ], [ 26, 48 ] ] }, { "plaintext": "refers to the length of an electrical conductor in terms of the phase shift introduced by transmission over that conductor at some frequency.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 24047 ], "anchor_spans": [ [ 64, 75 ] ] }, { "plaintext": "Depending on the specific context, the term \"electrical length\" is used rather than simple physical length to incorporate one or more of the following three concepts:", "section_idx": 1, "section_name": "Use of the term", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "When one is concerned with the number of wavelengths, or phase, involved in a wave's transit across a segment of transmission line especially, one may simply specify that electrical length, while specification of a physical length, frequency, or velocity factor is omitted. The electrical length is then typically expressed as N wavelengths or as the phase φ expressed in degrees or radians. Thus in a microstrip design one might specify a shorted stub of 60° phase length, which will correspond to different physical lengths when applied to different frequencies. Or one might consider a 2meter section of coax which has an electrical length of one quarter wavelength (90°) at 37.5MHz and ask what its electrical length becomes when the circuit is operated at a different frequency.", "section_idx": 1, "section_name": "Use of the term", "target_page_ids": [ 24047, 41811, 2022356, 2770268 ], "anchor_spans": [ [ 57, 62 ], [ 113, 130 ], [ 402, 412 ], [ 448, 452 ] ] }, { "plaintext": "Due to the velocity factor of a particular transmission line, for instance, the transit time of a signal in a certain length of cable is equal to the transit time over a longer distance when travelling at the speed of light. So a pulse sent down a 2meter section of coax (whose velocity factor is 67%) would arrive at the end of the coax at the same time that the same pulse arrives at the end of a bare wire of length 3meters (over which it propagates at the speed of light), and one might refer to the 2meter section of coax as having an electrical length of 3meters, or an electrical length of wavelength at 50MHz (since a 50MHz radio wave has a wavelength of 6meters).", "section_idx": 1, "section_name": "Use of the term", "target_page_ids": [ 1072520 ], "anchor_spans": [ [ 11, 26 ] ] }, { "plaintext": "Since resonant antennas are usually specified in terms of the electrical length of their conductors (such as the half wave dipole), the attainment of such an electrical length is loosely equated with electrical resonance, that is, a purely resistive impedance at the antenna's input, as is usually desired. An antenna that has been made slightly too long, for instance, will present an inductive reactance, which can be corrected by physically shortening the antenna. Based on this understanding, a common jargon in the antenna trade refers to the achievement of resonance (cancellation of reactance) at the antenna terminals as electrically shortening that too-long antenna (or electrically lengthening a too-short antenna) when an electrical matching network (or antenna tuner) has performed that task without physically altering the antenna's length. Although the terminology is very inexact, this use is widespread, especially as applied to the use of a loading coil at the bottom of a short monopole (a vertical, or whip antenna) to \"electrically lengthen\" it and achieve electrical resonance as seen through the loading coil.", "section_idx": 1, "section_name": "Use of the term", "target_page_ids": [ 465156, 582127, 41326, 465189 ], "anchor_spans": [ [ 123, 129 ], [ 765, 778 ], [ 958, 970 ], [ 1021, 1033 ] ] }, { "plaintext": "The first use of the term \"electrical length\" assumes a sine wave of some frequency, or at least a narrowband waveform centered around some frequency f. The sine wave will repeat with a period of . The frequency f will correspond to a particular wavelength λ along a particular conductor. For conductors (such as bare wire or air-filled coax) which transmit signals at the speed of light c, the wavelength is given by . A distance L along that conductor corresponds to N wavelengths where .", "section_idx": 2, "section_name": "Phase length", "target_page_ids": [ 324749, 274798, 33125, 46380 ], "anchor_spans": [ [ 56, 65 ], [ 99, 109 ], [ 246, 256 ], [ 337, 341 ] ] }, { "plaintext": "In the figure at the right, the wave shown is seen to be wavelengths long. A wave crest at the beginning of the graph, moving towards the right, will arrive at the end after a time . The electrical length of that segment is said to be \"1.5wavelengths\" or, expressed as a phase angle, 540 \"electrical degrees\" (or ) where N wavelengths corresponds to (or ). In radio frequency applications, when a delay is introduced due to a transmission line, it is often the phase shift φ that is of importance, so specifying a design in terms of the phase or electrical length allows one to adapt that design to an arbitrary frequency by employing the wavelength λ applying to that frequency.", "section_idx": 2, "section_name": "Phase length", "target_page_ids": [ 42852 ], "anchor_spans": [ [ 361, 376 ] ] }, { "plaintext": "In a transmission line, a signal travels at a rate controlled by the effective capacitance and inductance per unit of length of the transmission line. Some transmission lines consist only of bare conductors, in which case their signals propagate at the speed of light, c. More often the signal travels at a reduced velocity κc, where κ is the velocity factor, a number less than 1, representing the ratio of that velocity to the speed of light.", "section_idx": 3, "section_name": "Velocity factor", "target_page_ids": [ 41811, 140711, 165146 ], "anchor_spans": [ [ 5, 22 ], [ 79, 90 ], [ 95, 105 ] ] }, { "plaintext": "Most transmission lines contain a dielectric material (insulator) filling some or all of the space in between the conductors. The relative permittivity or dielectric constant of that material increases the distributed capacitance in the cable, which reduces the velocity factor below unity. It is also possible for κ to be reduced due to a relative permeability () of that material, which increases the distributed inductance, but this is almost never the case. Now, if one fills a space with a dielectric of relative permittivity , then the velocity of an electromagnetic plane wave is reduced by the velocity factor:", "section_idx": 3, "section_name": "Velocity factor", "target_page_ids": [ 53933, 754487 ], "anchor_spans": [ [ 139, 151 ], [ 349, 361 ] ] }, { "plaintext": "This reduced velocity factor would also apply to propagation of signals along wires immersed in a large space filled with that dielectric. However, with only part of the space around the conductors filled with that dielectric, there is less reduction of the wave velocity. Part of the electromagnetic wave surrounding each conductor \"feels\" the effect of the dielectric, and part is in free space. Then it is possible to define an effective relative permittivity which then predicts the velocity factor according to", "section_idx": 3, "section_name": "Velocity factor", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " is computed as a weighted average of the relative permittivity of free space (1) and that of the dielectric:", "section_idx": 3, "section_name": "Velocity factor", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where the fill factor F expresses the effective proportion of space so affected by the dielectric.", "section_idx": 3, "section_name": "Velocity factor", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In the case of coaxial cable, where all of the volume in between the inner conductor and the shield is filled with a dielectric, the fill factor is unity, since the electromagnetic wave is confined to that region. In other types of cable, such as twin lead, the fill factor can be much smaller. Regardless, any cable intended for radio frequencies will have its velocity factor (as well as its characteristic impedance) specified by the manufacturer. In the case of coaxial cable, where , the velocity factor is solely determined by the sort of dielectric used as specified here.", "section_idx": 3, "section_name": "Velocity factor", "target_page_ids": [ 46380, 321524, 42852, 40866, 46380 ], "anchor_spans": [ [ 15, 28 ], [ 247, 256 ], [ 330, 347 ], [ 394, 418 ], [ 574, 578 ] ] }, { "plaintext": "For example, a typical velocity factor for coaxial cable is .66, corresponding to a dielectric constant of 2.25. Suppose we wish to send a 30MHz signal down a short section of such a cable, and delay it by a quarter wave (90°). In free space, this frequency corresponds to a wavelength of , so a delay of would require an electrical length of 2.5 m. Applying the velocity factor of .66, this results in a physical length of cable 1.67 m long.", "section_idx": 3, "section_name": "Velocity factor", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The velocity factor likewise applies to antennas in cases where the antenna conductors are (partly) surrounded by a dielectric. This particularly applies to microstrip antennas such as the patch antenna. Waves on microstrip are affected mostly by the dielectric of the circuit board beneath them, but also on the air above them (because of trace edge effects). Their velocity factors thus depend not directly on the permittivity of the circuit board material but on the effective permittivity which is often specified for a circuit board material (or can be calculated). Note that the fill factor and therefore are somewhat dependent on the width of the trace compared to the thickness of the board.", "section_idx": 3, "section_name": "Velocity factor", "target_page_ids": [ 2021939, 2415892, 2022356 ], "anchor_spans": [ [ 157, 175 ], [ 189, 202 ], [ 213, 223 ] ] }, { "plaintext": "While there are certain wideband antenna designs, many antennas are classified as resonant and perform according to design around a particular frequency. This applies especially to broadcasting stations and communication systems which are confined to one frequency or narrow frequency band. This includes the dipole and monopole antennas and all of the designs based on them (Yagi, dipole or monopole arrays, folded dipole, etc.). In addition to the directive gain in beam antennas suffering away from the design frequency, the antenna feedpoint impedance is very sensitive to frequency offsets. Especially for transmitting, the antenna is often intended to operate at the resonant frequency. At the resonant frequency, by definition, that impedance is a pure resistance which matches the characteristic impedance of the transmission line and the output (or input) impedance of the transmitter (or receiver). At frequencies away from the resonant frequency, the impedance includes some reactance (capacitance or inductance). It is possible for an antenna tuner to be used to cancel that reactance (and to change the resistance to match the transmission line), however that is often avoided as an extra complication (and needs to be controlled at the antenna side of the transmission line).", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [ 41332, 41660, 465156, 2874126, 296081, 31417095, 465156, 342371, 187317, 61577, 320733, 40866, 41811, 140710, 140711, 165146, 582127 ], "anchor_spans": [ [ 24, 48 ], [ 82, 90 ], [ 309, 315 ], [ 320, 336 ], [ 376, 380 ], [ 401, 407 ], [ 409, 422 ], [ 468, 481 ], [ 536, 555 ], [ 760, 770 ], [ 777, 784 ], [ 789, 813 ], [ 821, 838 ], [ 986, 995 ], [ 997, 1008 ], [ 1012, 1022 ], [ 1047, 1060 ] ] }, { "plaintext": "The condition for resonance in a monopole antenna is for the element to be an odd multiple of a quarter-wavelength, λ/4. In a dipole antenna both driven conductors must be that long, for a total dipole length of (2N+1)λ/2.", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [ 2874126, 465156 ], "anchor_spans": [ [ 33, 49 ], [ 126, 140 ] ] }, { "plaintext": "The electrical length of an antenna element is, in general, different from its physical length", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For example, increasing the diameter of the conductor, or the presence of nearby metal objects, will decrease the velocity of the waves in the element, increasing the electrical length.", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An antenna which is shorter than its resonant length is described as \"electrically short\", and exhibits capacitive reactance. Similarly, an antenna which is longer than its resonant length is described as \"electrically long\" and exhibits inductive reactance.", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [ 140710, 140710 ], "anchor_spans": [ [ 104, 124 ], [ 238, 257 ] ] }, { "plaintext": "An antenna's effective electrical length can be changed without changing its physical length by adding reactance, (inductance or capacitance) in series with it. This is called lumped-impedance matching or loading.", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [ 140710, 165146, 140711 ], "anchor_spans": [ [ 103, 112 ], [ 115, 125 ], [ 129, 140 ] ] }, { "plaintext": "For example, a monopole antenna such as a metal rod fed at one end, will be resonant when its electrical length is equal to a quarter wavelength, λ/4, of the frequency used. If the antenna is shorter than a quarter wavelength, the feedpoint impedance will include a capacitive reactance; this causes reflections on the feedline and a mismatch at the transmitter or receiver, even if the resistive component of the impedance is correct. To cancel the capacitive reactance, a loading coil, an inductor with a reactance equal in magnitude but opposite in sign to that of the antenna, is used. Such a coil cancels the capacitive reactance seen at the antenna terminal, thus making the antenna system (antenna and coil) resonant. The feedline sees a purely resistive impedance. The addition of a loading coil to an electrically-short antenna to create a resonant antenna-coil system is sometimes referred to as \"electrically lengthening\" the antenna.", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [ 2874126, 140710, 41326 ], "anchor_spans": [ [ 15, 31 ], [ 266, 286 ], [ 474, 486 ] ] }, { "plaintext": "Similarly, the feedpoint impedance of a monopole antenna longer than λ/4 (or a dipole with arms longer than λ/4) will include inductive reactance. A capacitor in series with the antenna can cancel this reactance to make it resonant, which can be referred to as \"electrically shortening\" the antenna.", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Inductive loading is widely used to reduce the length of whip antennas on portable radios such as walkie-talkies and short wave antennas on cars, to meet physical requirements.", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [ 369685 ], "anchor_spans": [ [ 98, 111 ] ] }, { "plaintext": "The electrical lengthening allows the construction of shorter aerials. It is applied in particular for aerials for VLF, longwave and medium-wave transmitters. Because those radio waves are several hundred meters to many kilometers long, mast radiators of the necessary height cannot be realised economically. It is also used widely for whip antennas on portable devices such as walkie-talkies to allow antennas much shorter than the standard quarter-wavelength to be used. The most widely used example is the rubber ducky antenna.", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [ 160505, 168741, 110381, 61164, 2044496, 465189, 369685, 6497307 ], "anchor_spans": [ [ 115, 118 ], [ 120, 128 ], [ 133, 144 ], [ 145, 156 ], [ 237, 241 ], [ 336, 348 ], [ 378, 391 ], [ 509, 529 ] ] }, { "plaintext": "The electrical lengthening reduces the bandwidth of the antenna if other phase control measures are not undertaken. An electrically extended aerial is less efficient than the equivalent, full-length antenna.", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [ 3967, 24047, 327511 ], "anchor_spans": [ [ 39, 48 ], [ 73, 78 ], [ 156, 165 ] ] }, { "plaintext": "There are two possibilities for the realisation of the electric lengthening.", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " switching in inductive coils in series with the aerial", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [ 14896, 270770 ], "anchor_spans": [ [ 14, 29 ], [ 33, 39 ] ] }, { "plaintext": " switching in metal surfaces, known as roof capacitance, at the aerial ends which form capacitors to earth.", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [ 4932111, 41215 ], "anchor_spans": [ [ 87, 96 ], [ 101, 106 ] ] }, { "plaintext": "Often both measures are combined. The coils switched in series must sometimes be placed in the middle of the aerial construction. The cabin installed at a height of 150-metres on the Blosenbergturm in Beromünster is such a construction, in which a lengthening coil is installed for the supply of the upper tower part (the Blosenbergturm has in addition a ring-shaped roof capacitor on its top)", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [ 580343, 1343695 ], "anchor_spans": [ [ 183, 197 ], [ 201, 212 ] ] }, { "plaintext": "Transmission aerials of transmitters working at frequencies below the longwave broadcasting band always apply electric lengthening. Broadcasting aerials of longwave broadcasting stations apply it often. However, for transmission aerials of NDBs electrical lengthening is extensively applied, because these use antennas which are considerably less tall than a quarter of the radiated wavelength.", "section_idx": 4, "section_name": "Antennas", "target_page_ids": [ 316405 ], "anchor_spans": [ [ 240, 243 ] ] }, { "plaintext": " Antenna tuner", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 582127 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Electrically small antenna", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 39213154 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Loading coil", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 41326 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Monopole antenna", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 2874126 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": "A. Nickle, , \"Antenna\". (Filed May 25, 1934; Issued Aug 2, 1938)", "section_idx": 7, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "William W. Brown, , \"Antenna structure\". (Filed May 25, 1934; Issued Oct 27, 1936).", "section_idx": 7, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Robert B. Dome, , \"Antenna\". (Filed May 25, 1934; Issued Dec 7, 1937)", "section_idx": 7, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Slyusar V. I. 60 Years of Electrically Small Antennas Theory.//Proceedings of the 6-th International Conference on Antenna Theory and Techniques, 17-21 September, 2007, Sevastopol, Ukraine. - Pp. 116 - 118. ", "section_idx": 7, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] } ]

[ "Telecommunication_theory", "Antennas" ]

[]

[ { "plaintext": "An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field for a system of charged particles. Electric fields originate from electric charges and time-varying electric currents. Electric fields and magnetic fields are both manifestations of the electromagnetic field, one of the four fundamental interactions (also called forces) of nature.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 26998617, 352541, 6207, 9532, 10890 ], "anchor_spans": [ [ 45, 59 ], [ 88, 104 ], [ 342, 358 ], [ 428, 449 ], [ 467, 490 ] ] }, { "plaintext": "Electric fields are important in many areas of physics, and are exploited in electrical technology. In atomic physics and chemistry, for instance, the electric field is the attractive force holding the atomic nucleus and electrons together in atoms. It is also the force responsible for chemical bonding between atoms that result in molecules.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22939, 1200, 5180, 19916559, 9476, 5993, 19555 ], "anchor_spans": [ [ 47, 54 ], [ 103, 117 ], [ 122, 131 ], [ 202, 216 ], [ 221, 229 ], [ 287, 303 ], [ 333, 341 ] ] }, { "plaintext": "The electric field is defined as a vector field that associates to each point in space the (electrostatic or Coulomb) force per unit of charge exerted on an infinitesimal positive test charge at rest at that point. The derived SI unit for the electric field is the volt per meter (V/m), which is equal to the newton per coulomb (N/C).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 62641, 26288711, 9804, 2679845, 26876, 32567, 18947, 72540, 47719 ], "anchor_spans": [ [ 35, 47 ], [ 109, 116 ], [ 136, 142 ], [ 180, 191 ], [ 219, 229 ], [ 265, 269 ], [ 274, 279 ], [ 309, 315 ], [ 320, 327 ] ] }, { "plaintext": "The electric field is defined at each point in space as the force per unit charge that would be experienced by a vanishingly small positive test charge if held stationary at that point. As the electric field is defined in terms of force, and force is a vector (i.e. having both magnitude and direction), it follows that an electric field is a vector field. Fields that may be defined in this manner are sometimes referred to as force fields. The electric field acts between two charges similarly to the way the gravitational field acts between two masses, as they both obey an inverse-square law with distance. This is the basis for Coulomb's law, which states that, for stationary charges, the electric field varies with the source charge and varies inversely with the square of the distance from the source. This means that if the source charge were doubled, the electric field would double, and if you move twice as far away from the source, the field at that point would be only one-quarter its original strength.", "section_idx": 1, "section_name": "Description", "target_page_ids": [ 160990, 2679845, 10902, 32533, 577301, 2544098, 62641, 2916607, 174782, 19048, 41288, 26288711 ], "anchor_spans": [ [ 113, 130 ], [ 140, 151 ], [ 231, 236 ], [ 253, 259 ], [ 278, 287 ], [ 292, 301 ], [ 343, 355 ], [ 428, 440 ], [ 511, 530 ], [ 548, 552 ], [ 577, 595 ], [ 633, 646 ] ] }, { "plaintext": "The electric field can be visualized with a set of lines whose direction at each point is the same as the field's, a concept introduced by Michael Faraday, whose term 'lines of force' is still sometimes used. This illustration has the useful property that the field's strength is proportional to the density of the lines. The field lines are the paths that a point positive charge would follow as it is forced to move within the field, similar to trajectories that masses follow within a gravitational field. Field lines due to stationary charges have several important properties, including always originating from positive charges and terminating at negative charges, they enter all good conductors at right angles, and they never cross or close in on themselves. The field lines are a representative concept; the field actually permeates all the intervening space between the lines. More or fewer lines may be drawn depending on the precision to which it is desired to represent the field. The study of electric fields created by stationary charges is called electrostatics.", "section_idx": 1, "section_name": "Description", "target_page_ids": [ 5000404, 19727, 3024068, 41150, 200115, 368328 ], "anchor_spans": [ [ 51, 56 ], [ 139, 154 ], [ 168, 182 ], [ 260, 276 ], [ 447, 459 ], [ 1062, 1076 ] ] }, { "plaintext": "Faraday's law describes the relationship between a time-varying magnetic field and the electric field. One way of stating Faraday's law is that the curl of the electric field is equal to the negative time derivative of the magnetic field. In the absence of time-varying magnetic field, the electric field is therefore called conservative (i.e. curl-free). This implies there are two kinds of electric fields: electrostatic fields and fields arising from time-varying magnetic fields. While the curl-free nature of the static electric field allows for a simpler treatment using electrostatics, time-varying magnetic fields are generally treated as a component of a unified electromagnetic field. The study of time varying magnetic and electric fields is called electrodynamics.", "section_idx": 1, "section_name": "Description", "target_page_ids": [ 742288, 6123, 1783069, 461454, 9735, 9532 ], "anchor_spans": [ [ 0, 13 ], [ 148, 152 ], [ 200, 215 ], [ 325, 337 ], [ 672, 693 ], [ 760, 775 ] ] }, { "plaintext": "Electric fields are caused by electric charges, described by Gauss's law, and time varying magnetic fields, described by Faraday's law of induction. Together, these laws are enough to define the behavior of the electric field. However, since the magnetic field is described as a function of electric field, the equations of both fields are coupled and together form Maxwell's equations that describe both fields as a function of charges and currents.", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 9804, 74964, 36563, 742288, 19737, 6207 ], "anchor_spans": [ [ 30, 46 ], [ 61, 72 ], [ 91, 106 ], [ 121, 147 ], [ 366, 385 ], [ 441, 449 ] ] }, { "plaintext": "In the special case of a steady state (stationary charges and currents), the Maxwell-Faraday inductive effect disappears. The resulting two equations (Gauss's law and Faraday's law with no induction term ), taken together, are equivalent to Coulomb's law, which states that a particle with electric charge at position exerts a force on a particle with charge at position of:", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 1326107, 26288711 ], "anchor_spans": [ [ 25, 37 ], [ 242, 255 ] ] }, { "plaintext": "where is the unit vector in the direction from point to point , and is the electric constant (also known as \"the absolute permittivity of free space\") with the unit C2⋅m−2⋅N−1.", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 167053, 2582879 ], "anchor_spans": [ [ 14, 25 ], [ 78, 95 ] ] }, { "plaintext": "Note that , the vacuum electric permittivity, must be substituted with , permittivity, when charges are in non-empty media.", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 2582879, 53933 ], "anchor_spans": [ [ 16, 44 ], [ 73, 85 ] ] }, { "plaintext": "When the charges and have the same sign this force is positive, directed away from the other charge, indicating the particles repel each other. When the charges have unlike signs the force is negative, indicating the particles attract.", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "To make it easy to calculate the Coulomb force on any charge at position this expression can be divided by leaving an expression that only depends on the other charge (the source charge)", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 26288711 ], "anchor_spans": [ [ 33, 46 ] ] }, { "plaintext": "This is the electric field at point due to the point charge ; it is a vector-valued function equal to the Coulomb force per unit charge that a positive point charge would experience at the position .", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 3675281 ], "anchor_spans": [ [ 71, 93 ] ] }, { "plaintext": "Since this formula gives the electric field magnitude and direction at any point in space (except at the location of the charge itself, , where it becomes infinite) it defines a vector field.", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 62641 ], "anchor_spans": [ [ 179, 191 ] ] }, { "plaintext": "From the above formula it can be seen that the electric field due to a point charge is everywhere directed away from the charge if it is positive, and toward the charge if it is negative, and its magnitude decreases with the inverse square of the distance from the charge.", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 41288 ], "anchor_spans": [ [ 225, 239 ] ] }, { "plaintext": "The Coulomb force on a charge of magnitude at any point in space is equal to the product of the charge and the electric field at that point", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The SI unit of the electric field is the newton per coulomb (N/C), or volt per meter (V/m); in terms of the SI base units it is kg⋅m⋅s−3⋅A−1.", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 26764, 72540, 47719, 32567, 18947, 26872 ], "anchor_spans": [ [ 4, 6 ], [ 41, 47 ], [ 52, 59 ], [ 70, 74 ], [ 79, 84 ], [ 108, 120 ] ] }, { "plaintext": "Due to the linearity of Maxwell's equations, electric fields satisfy the superposition principle, which states that the total electric field, at a point, due to a collection of charges is equal to the vector sum of the electric fields at that point due to the individual charges. This principle is useful in calculating the field created by multiple point charges. If charges are stationary in space at points , in the absence of currents, the superposition principle says that the resulting field is the sum of fields generated by each particle as described by Coulomb's law:", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 379868, 19737, 1201321 ], "anchor_spans": [ [ 11, 20 ], [ 24, 43 ], [ 73, 96 ] ] }, { "plaintext": "where is the unit vector in the direction from point to point .", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 167053 ], "anchor_spans": [ [ 14, 25 ] ] }, { "plaintext": "The superposition principle allows for the calculation of the electric field due to a continuous distribution of charge (where is the charge density in coulombs per cubic meter). By considering the charge in each small volume of space at point as a point charge, the resulting electric field, , at point can be calculated as ", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 3134585 ], "anchor_spans": [ [ 136, 150 ] ] }, { "plaintext": "where is the unit vector pointing from to . The total field is then found by \"adding up\" the contributions from all the increments of volume by integrating over the volume of the charge distribution :", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 15532 ], "anchor_spans": [ [ 146, 157 ] ] }, { "plaintext": "Similar equations follow for a surface charge with continuous charge distribution where is the charge density in coulombs per square meter", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "and for line charges with continuous charge distribution where is the charge density in coulombs per meter.", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "If a system is static, such that magnetic fields are not time-varying, then by Faraday's law, the electric field is curl-free. In this case, one can define an electric potential, that is, a function such that This is analogous to the gravitational potential. The difference between the electric potential at two points in space is called the potential difference (or voltage) between the two points.", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 461454, 59615, 579026, 32549 ], "anchor_spans": [ [ 116, 125 ], [ 159, 177 ], [ 236, 259 ], [ 344, 364 ] ] }, { "plaintext": "In general, however, the electric field cannot be described independently of the magnetic field. Given the magnetic vector potential, , defined so that one can still define an electric potential such that:", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 1191067 ], "anchor_spans": [ [ 107, 132 ] ] }, { "plaintext": "where is the gradient of the electric potential and is the partial derivative of A with respect to time.", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 12461, 52565 ], "anchor_spans": [ [ 14, 22 ], [ 61, 79 ] ] }, { "plaintext": "Faraday's law of induction can be recovered by taking the curl of that equation ", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 742288, 6123 ], "anchor_spans": [ [ 0, 26 ], [ 58, 62 ] ] }, { "plaintext": "which justifies, a posteriori, the previous form for .", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The equations of electromagnetism are best described in a continuous description. However, charges are sometimes best described as discrete points; for example, some models may describe electrons as point sources where charge density is infinite on an infinitesimal section of space.", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 9476 ], "anchor_spans": [ [ 186, 194 ] ] }, { "plaintext": "A charge located at can be described mathematically as a charge density , where the Dirac delta function (in three dimensions) is used. Conversely, a charge distribution can be approximated by many small point charges.", "section_idx": 2, "section_name": "Mathematical formulation", "target_page_ids": [ 37021 ], "anchor_spans": [ [ 86, 106 ] ] }, { "plaintext": "Electrostatic fields are electric fields that do not change with time. Such fields are present when systems of charged matter are stationary, or when electric currents are unchanging. In that case, Coulomb's law fully describes the field.", "section_idx": 3, "section_name": "Electrostatic fields", "target_page_ids": [ 18859574, 26288711 ], "anchor_spans": [ [ 150, 167 ], [ 198, 211 ] ] }, { "plaintext": "Coulomb's law, which describes the interaction of electric charges:", "section_idx": 3, "section_name": "Electrostatic fields", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "is similar to Newton's law of universal gravitation:", "section_idx": 3, "section_name": "Electrostatic fields", "target_page_ids": [ 244611 ], "anchor_spans": [ [ 14, 51 ] ] }, { "plaintext": "(where ).", "section_idx": 3, "section_name": "Electrostatic fields", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This suggests similarities between the electric field E and the gravitational field g, or their associated potentials. Mass is sometimes called \"gravitational charge\".", "section_idx": 3, "section_name": "Electrostatic fields", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Electrostatic and gravitational forces both are central, conservative and obey an inverse-square law.", "section_idx": 3, "section_name": "Electrostatic fields", "target_page_ids": [ 1888817, 44158, 41288 ], "anchor_spans": [ [ 48, 55 ], [ 57, 69 ], [ 82, 100 ] ] }, { "plaintext": "A uniform field is one in which the electric field is constant at every point. It can be approximated by placing two conducting plates parallel to each other and maintaining a voltage (potential difference) between them; it is only an approximation because of boundary effects (near the edge of the planes, electric field is distorted because the plane does not continue). Assuming infinite planes, the magnitude of the electric field E is:", "section_idx": 3, "section_name": "Electrostatic fields", "target_page_ids": [ 4932111, 32549 ], "anchor_spans": [ [ 128, 134 ], [ 176, 183 ] ] }, { "plaintext": "where ΔV is the potential difference between the plates and d is the distance separating the plates. The negative sign arises as positive charges repel, so a positive charge will experience a force away from the positively charged plate, in the opposite direction to that in which the voltage increases. In micro- and nano-applications, for instance in relation to semiconductors, a typical magnitude of an electric field is in the order of , achieved by applying a voltage of the order of 1 volt between conductors spaced 1µm apart.", "section_idx": 3, "section_name": "Electrostatic fields", "target_page_ids": [ 32549 ], "anchor_spans": [ [ 16, 36 ] ] }, { "plaintext": "Electrodynamic fields are electric fields which do change with time, for instance when charges are in motion. In this case, a magnetic field is produced in accordance with Ampère's circuital law (with Maxwell's addition), which, along with Maxwell's other equations, defines the magnetic field, , in terms of its curl:", "section_idx": 4, "section_name": "Electrodynamic fields", "target_page_ids": [ 199304, 19737 ], "anchor_spans": [ [ 172, 194 ], [ 196, 219 ] ] }, { "plaintext": "where is the current density, is the vacuum permeability, and is the vacuum permittivity.", "section_idx": 4, "section_name": "Electrodynamic fields", "target_page_ids": [ 5498706, 4602964, 2582879 ], "anchor_spans": [ [ 14, 29 ], [ 39, 58 ], [ 72, 91 ] ] }, { "plaintext": "That is, both electric currents (i.e. charges in uniform motion) and the (partial) time derivative of the electric field directly contributes to the magnetic field. In addition, the Maxwell–Faraday equation states ", "section_idx": 4, "section_name": "Electrodynamic fields", "target_page_ids": [ 6207, 742288 ], "anchor_spans": [ [ 14, 31 ], [ 182, 206 ] ] }, { "plaintext": "These represent two of Maxwell's four equations and they intricately link the electric and magnetic fields together, resulting in the electromagnetic field. The equations represent a set of four coupled multi-dimensional partial differential equations which, when solved for a system, describe the combined behavior of the electromagnetic fields. In general, the force experienced by a test charge in an electromagnetic field is given by the Lorentz force law:", "section_idx": 4, "section_name": "Electrodynamic fields", "target_page_ids": [ 19737, 9735, 18631 ], "anchor_spans": [ [ 23, 47 ], [ 134, 155 ], [ 442, 459 ] ] }, { "plaintext": "The total energy per unit volume stored by the electromagnetic field is", "section_idx": 5, "section_name": "Energy in the electric field", "target_page_ids": [ 9735 ], "anchor_spans": [ [ 47, 68 ] ] }, { "plaintext": "where is the permittivity of the medium in which the field exists, its magnetic permeability, and and are the electric and magnetic field vectors.", "section_idx": 5, "section_name": "Energy in the electric field", "target_page_ids": [ 53933, 754487 ], "anchor_spans": [ [ 14, 26 ], [ 73, 94 ] ] }, { "plaintext": "As and fields are coupled, it would be misleading to split this expression into \"electric\" and \"magnetic\" contributions. In particular, an electrostatic field in any given frame of reference in general transforms into a field with a magnetic component in a relatively moving frame. Accordingly, decomposing the electromagnetic field into an electric and magnetic component is frame-specific, and similarly for the associated energy.", "section_idx": 5, "section_name": "Energy in the electric field", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The total energy U stored in the electromagnetic field in a given volume V is", "section_idx": 5, "section_name": "Energy in the electric field", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In the presence of matter, it is helpful to extend the notion of the electric field into three vector fields:", "section_idx": 6, "section_name": "The electric displacement field", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where P is the electric polarization – the volume density of electric dipole moments, and is the electric displacement field. Since E and P are defined separately, this equation can be used to define . The physical interpretation of D is not as clear as E (effectively the field applied to the material) or (induced field due to the dipoles in the material), but still serves as a convenient mathematical simplification, since Maxwell's equations can be simplified in terms of free charges and currents.", "section_idx": 6, "section_name": "The electric displacement field", "target_page_ids": [ 698648, 30876071, 1191101, 19737 ], "anchor_spans": [ [ 15, 36 ], [ 61, 83 ], [ 98, 125 ], [ 479, 504 ] ] }, { "plaintext": "The E and D fields are related by the permittivity of the material, ε.", "section_idx": 6, "section_name": "The electric displacement field", "target_page_ids": [ 53933 ], "anchor_spans": [ [ 38, 50 ] ] }, { "plaintext": "For linear, homogeneous, isotropic materials E and D are proportional and constant throughout the region, there is no position dependence: ", "section_idx": 6, "section_name": "The electric displacement field", "target_page_ids": [ 3180547, 14865 ], "anchor_spans": [ [ 12, 23 ], [ 25, 34 ] ] }, { "plaintext": "For inhomogeneous materials, there is a position dependence throughout the material:", "section_idx": 6, "section_name": "The electric displacement field", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For anisotropic materials the and fields are not parallel, and so and are related by the permittivity tensor (a 2nd order tensor field), in component form:", "section_idx": 6, "section_name": "The electric displacement field", "target_page_ids": [ 53933, 256738 ], "anchor_spans": [ [ 93, 112 ], [ 126, 138 ] ] }, { "plaintext": "For non-linear media, and are not proportional. Materials can have varying extents of linearity, homogeneity and isotropy.", "section_idx": 6, "section_name": "The electric displacement field", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The electric field given by Coulomb's law for a point charge particle at rest is found to preserve the form of Gauss's law under Lorentz transformation consistent with the first postulate of relativity. The invariance of form of Maxwell's equations can be used to derive the electric field of point charges. Alternatively the electric field of non-accelerating point particles can be derived from the Lorentz transformation of four-force experienced by charges in the source's rest frame and assigning electric field and magnetic field as per their definition given by the form of Lorentz force. The electric field of a non-accelerating point charge is given by:", "section_idx": 7, "section_name": "In relativity", "target_page_ids": [ 74964, 18404, 1607648, 19737, 18404, 230072, 18631 ], "anchor_spans": [ [ 111, 122 ], [ 129, 151 ], [ 178, 201 ], [ 229, 248 ], [ 401, 423 ], [ 427, 437 ], [ 581, 594 ] ] }, { "plaintext": "where is the charge of the point source, is the position vector from the point source to the point in space, is the ratio of observed speed of the charge particle to the speed of light and is the angle between and the observed velocity of the charged particle. ", "section_idx": 7, "section_name": "In relativity", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The charge of the particle is considered invariant of inertial frame in relativity, as supported by experimental evidence. The above equation reduces to that given by Coulomb's law for non-relativistic speeds of the point charge.", "section_idx": 7, "section_name": "In relativity", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For arbitrarily moving point charges, propagation of potential fields such as Lorenz gauge fields at the speed of light needs to be accounted for using Liénard–Wiechert potential. Since the electric and magnetic fields may be expressed in terms of retarded potentials, the fields derived for point charge also satisfy Maxwell's equations. The electric field is expressed as:", "section_idx": 7, "section_name": "In relativity", "target_page_ids": [ 9999827, 11230759, 19737 ], "anchor_spans": [ [ 152, 178 ], [ 248, 267 ], [ 318, 337 ] ] }, { "plaintext": "where is the charge of the point source, is retarded time or the time at which the source's contribution of the electric field originated, is the position vector of the particle, is a unit vector pointing from charged particle to the point in space, is the velocity of the particle divided by the speed of light, and is the corresponding Lorentz factor. The retarded time is given as solution of:", "section_idx": 7, "section_name": "In relativity", "target_page_ids": [ 2511080, 732446 ], "anchor_spans": [ [ 46, 59 ], [ 344, 358 ] ] }, { "plaintext": "The uniqueness of solution for for given , and is valid for charged particles moving slower than speed of light. Electromagnetic radiation of accelerating charges is known to be caused by the acceleration dependent term in the electric field from which relativistic correction for Larmor formula is obtained.", "section_idx": 7, "section_name": "In relativity", "target_page_ids": [ 9426, 2817855 ], "anchor_spans": [ [ 116, 141 ], [ 284, 298 ] ] }, { "plaintext": "The equations, although consistent with that of non-accelerating charges as well as its non-relativistic limit, are not corrected for quantum-mechanical effects.", "section_idx": 7, "section_name": "In relativity", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Classical electromagnetism", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 426219 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Electricity", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 9550 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " History of electromagnetic theory", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 5951576 ], "anchor_spans": [ [ 1, 34 ] ] }, { "plaintext": " Optical field", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 9735 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Magnetism", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 19716 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Teltron tube", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 2024566 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Teledeltos, a conductive paper that may be used as a simple analog computer for modelling fields", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 36080790 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Electric field in \"Electricity and Magnetism\", R Nave – Hyperphysics, Georgia State University", "section_idx": 10, "section_name": "External links", "target_page_ids": [ 799988, 503118 ], "anchor_spans": [ [ 57, 69 ], [ 71, 95 ] ] }, { "plaintext": " Frank Wolfs's lectures at University of Rochester, chapters 23 and 24", "section_idx": 10, "section_name": "External links", "target_page_ids": [ 31918 ], "anchor_spans": [ [ 27, 50 ] ] }, { "plaintext": " Fields – a chapter from an online textbook", "section_idx": 10, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Electrostatics", "Physical_quantities", "Electromagnetism" ]

[]

[ { "plaintext": "Electromagnetic compatibility (EMC) is the ability of electrical equipment and systems to function acceptably in their electromagnetic environment, by limiting the unintentional generation, propagation and reception of electromagnetic energy which may cause unwanted effects such as electromagnetic interference (EMI) or even physical damage in operational equipment. The goal of EMC is the correct operation of different equipment in a common electromagnetic environment. It is also the name given to the associated branch of electrical engineering.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41094, 1072324 ], "anchor_spans": [ [ 119, 146 ], [ 283, 311 ] ] }, { "plaintext": "EMC pursues three main classes of issue. Emission is the generation of electromagnetic energy, whether deliberate or accidental, by some source and its release into the environment. EMC studies the unwanted emissions and the countermeasures which may be taken in order to reduce unwanted emissions. The second class, susceptibility, is the tendency of electrical equipment, referred to as the victim, to malfunction or break down in the presence of unwanted emissions, which are known as Radio frequency interference (RFI). Immunity is the opposite of susceptibility, being the ability of equipment to function correctly in the presence of RFI, with the discipline of \"hardening\" equipment being known equally as susceptibility or immunity. A third class studied is coupling, which is the mechanism by which emitted interference reaches the victim.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Interference mitigation and hence electromagnetic compatibility may be achieved by addressing any or all of these issues, i.e., quieting the sources of interference, inhibiting coupling paths and/or hardening the potential victims. In practice, many of the engineering techniques used, such as grounding and shielding, apply to all three issues.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "\"Electromagnetic interference\" (EMI) is defined as the \"degradation in the performance of equipment or transmission channel or a system caused by an electromagnetic disturbance\" ( 161-01-06) while \"electromagnetic disturbance\" is defined as \"an electromagnetic phenomenon that can degrade the performance of a device, equipment or system, or adversely affect living or inert matter (IEV 161-01-05). The terms \"electromagnetic disturbance\" and \"electromagnetic interference\" designate respectively the cause and the effect, ", "section_idx": 1, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Electromagnetic compatibility (EMC) is an equipment characteristic or property and is defined as \" the ability of equipment or a system to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbances to anything in that environment \" (IEV 161-01-07).", "section_idx": 1, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "EMC ensures the correct operation, in the same electromagnetic environment, of different equipment items which use or respond to electromagnetic phenomena, and the avoidance of any interference. Another way of saying this is that EMC is the control of EMI so that unwanted effects are prevented.", "section_idx": 1, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Besides understanding the phenomena in themselves, EMC also addresses the countermeasures, such as control regimes, design and measurement, which should be taken in order to prevent emissions from causing any adverse effect.", "section_idx": 1, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Electromagnetic interference divides into several categories according to the source and signal characteristics.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 1072324 ], "anchor_spans": [ [ 0, 28 ] ] }, { "plaintext": "The origin of interference, often called \"noise\" in this context, can be man-made (artificial) or natural.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Continuous, or continuous wave (CW), interference arises where the source continuously emits at a given range of frequencies. This type is naturally divided into sub-categories according to frequency range, and as a whole is sometimes referred to as \"DC to daylight\".", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Audio frequency, from very low frequencies up to around 20kHz. Frequencies up to 100kHz may sometimes be classified as audio. Sources include:", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Mains hum from: power supply units, nearby power supply wiring, transmission lines and substations.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Audio processing equipment, such as audio power amplifiers and loudspeakers.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 92791, 45871 ], "anchor_spans": [ [ 43, 58 ], [ 64, 75 ] ] }, { "plaintext": " Demodulation of a high-frequency carrier wave such as an FM radio transmission.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 1607203 ], "anchor_spans": [ [ 58, 66 ] ] }, { "plaintext": " Radio frequency interference (RFI), from typically 20kHz to an upper limit which constantly increases as technology pushes it higher. Sources include:", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Wireless and radio frequency transmissions", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Television and radio receivers", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Industrial, scientific and medical equipment (ISM)", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Digital processing circuitry such as microcontrollers", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 21017 ], "anchor_spans": [ [ 38, 53 ] ] }, { "plaintext": "Switched-mode power supplies (SMPS)", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 223407 ], "anchor_spans": [ [ 0, 28 ] ] }, { "plaintext": " Broadband noise may be spread across parts of either or both frequency ranges, with no particular frequency accentuated. Sources include:", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Solar activity", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 206555 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Continuously operating spark gaps such as arc welders", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 294989 ], "anchor_spans": [ [ 24, 33 ] ] }, { "plaintext": " CDMA (spread-spectrum) mobile telephony", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 7143 ], "anchor_spans": [ [ 1, 5 ] ] }, { "plaintext": "An electromagnetic pulse (EMP), sometimes called a transient disturbance, arises where the source emits a short-duration pulse of energy. The energy is usually broadband by nature, although it often excites a relatively narrow-band damped sine wave response in the victim.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 39519079, 4622312, 1744868 ], "anchor_spans": [ [ 3, 24 ], [ 51, 60 ], [ 232, 248 ] ] }, { "plaintext": "Sources divide broadly into isolated and repetitive events.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Sources of isolated EMP events include:", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Switching action of electrical circuitry, including inductive loads such as relays, solenoids, or electric motors.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Power line surges/pulses", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 38824 ], "anchor_spans": [ [ 0, 10 ] ] }, { "plaintext": "Electrostatic discharge (ESD), as a result of two charged objects coming into close proximity or contact.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 75049 ], "anchor_spans": [ [ 0, 23 ] ] }, { "plaintext": "Lightning electromagnetic pulse (LEMP), although typically a short series of pulses.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 61344, 39519079 ], "anchor_spans": [ [ 0, 9 ], [ 10, 31 ] ] }, { "plaintext": " Nuclear electromagnetic pulse (NEMP), as a result of a nuclear explosion. A variant of this is the high altitude EMP (HEMP) nuclear weapon, designed to create the pulse as its primary destructive effect.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 41097 ], "anchor_spans": [ [ 1, 30 ] ] }, { "plaintext": "Non-nuclear electromagnetic pulse (NNEMP) weapons.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Sources of repetitive EMP events, sometimes as regular pulse trains, include:", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 319613 ], "anchor_spans": [ [ 55, 60 ] ] }, { "plaintext": "Electric motors", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [ 76086 ], "anchor_spans": [ [ 0, 14 ] ] }, { "plaintext": "Electrical ignition systems, such as in gasoline engines.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Continual switching actions of digital electronic circuitry.", "section_idx": 2, "section_name": "Types of interference", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Some of the technical terms which are employed can be used with differing meanings. Some phenomena may be referred to by various different terms. These terms are used here in a widely accepted way, which is consistent with other articles in the encyclopedia.", "section_idx": 3, "section_name": "Coupling mechanisms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The basic arrangement of noise emitter or source, coupling path and victim, receptor or sink is shown in the figure below. Source and victim are usually electronic hardware devices, though the source may be a natural phenomenon such as a lightning strike, electrostatic discharge (ESD) or, in one famous case, the Big Bang at the origin of the Universe.", "section_idx": 3, "section_name": "Coupling mechanisms", "target_page_ids": [ 3966982, 950012, 491851, 3213396, 2449741, 75049, 639790, 4116 ], "anchor_spans": [ [ 25, 30 ], [ 50, 58 ], [ 76, 84 ], [ 153, 172 ], [ 238, 254 ], [ 256, 279 ], [ 293, 308 ], [ 314, 322 ] ] }, { "plaintext": "There are four basic coupling mechanisms: conductive, capacitive, magnetic or inductive, and radiative. Any coupling path can be broken down into one or more of these coupling mechanisms working together. For example the lower path in the diagram involves inductive, conductive and capacitive modes.", "section_idx": 3, "section_name": "Coupling mechanisms", "target_page_ids": [ 198984, 4932111, 65888, 9426 ], "anchor_spans": [ [ 42, 52 ], [ 54, 64 ], [ 66, 74 ], [ 93, 102 ] ] }, { "plaintext": "Conductive coupling occurs when the coupling path between the source and victim is formed by direct electrical contact with a conducting body, for example a transmission line, wire, cable, PCB trace or metal enclosure.", "section_idx": 3, "section_name": "Coupling mechanisms", "target_page_ids": [ 5258912, 65910 ], "anchor_spans": [ [ 0, 19 ], [ 189, 192 ] ] }, { "plaintext": "Conducted noise is also characterised by the way it appears on different conductors:", "section_idx": 3, "section_name": "Coupling mechanisms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Common-mode coupling: noise appears in phase (in the same direction) on two conductors.", "section_idx": 3, "section_name": "Coupling mechanisms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Differential-mode coupling: noise appears out of phase (in opposite directions) on two conductors.", "section_idx": 3, "section_name": "Coupling mechanisms", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Inductive coupling occurs where the source and victim are separated by a short distance (typically less than a wavelength). Strictly, \"Inductive coupling\" can be of two kinds, electrical induction and magnetic induction. It is common to refer to electrical induction as capacitive coupling, and to magnetic induction as inductive coupling.", "section_idx": 3, "section_name": "Coupling mechanisms", "target_page_ids": [ 33125 ], "anchor_spans": [ [ 111, 121 ] ] }, { "plaintext": "Capacitive coupling occurs when a varying electrical field exists between two adjacent conductors typically less than a wavelength apart, inducing a change in voltage on the receiving conductor.", "section_idx": 3, "section_name": "Coupling mechanisms", "target_page_ids": [ 40843, 41092, 32549 ], "anchor_spans": [ [ 0, 19 ], [ 42, 58 ], [ 159, 166 ] ] }, { "plaintext": "Inductive coupling or magnetic coupling occurs when a varying magnetic field exists between two parallel conductors typically less than a wavelength apart, inducing a change in voltage along the receiving conductor.", "section_idx": 3, "section_name": "Coupling mechanisms", "target_page_ids": [ 41258, 36563, 32549 ], "anchor_spans": [ [ 0, 18 ], [ 62, 76 ], [ 177, 184 ] ] }, { "plaintext": "Radiative coupling or electromagnetic coupling occurs when source and victim are separated by a large distance, typically more than a wavelength. Source and victim act as radio antennas: the source emits or radiates an electromagnetic wave which propagates across the space in between and is picked up or received by the victim.", "section_idx": 3, "section_name": "Coupling mechanisms", "target_page_ids": [ 9426 ], "anchor_spans": [ [ 219, 239 ] ] }, { "plaintext": "The damaging effects of electromagnetic interference pose unacceptable risks in many areas of technology, and it is necessary to control such interference and reduce the risks to acceptable levels.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The control of electromagnetic interference (EMI) and assurance of EMC comprises a series of related disciplines:", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Characterising the threat.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Setting standards for emission and susceptibility levels.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Design for standards compliance.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Testing for standards compliance.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The risk posed by the threat is usually statistical in nature, so much of the work in threat characterisation and standards setting is based on reducing the probability of disruptive EMI to an acceptable level, rather than its assured elimination.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For a complex or novel piece of equipment, this may require the production of a dedicated EMC control plan summarizing the application of the above and specifying additional documents required.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Characterisation of the problem requires understanding of:", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The interference source and signal.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The coupling path to the victim.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The nature of the victim both electrically and in terms of the significance of malfunction.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Several organizations, both national and international, work to promote international co-operation on standardization (harmonization), including publishing various EMC standards. Where possible, a standard developed by one organization may be adopted with little or no change by others. This helps for example to harmonize national standards across Europe.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 45545426 ], "anchor_spans": [ [ 119, 132 ] ] }, { "plaintext": "International standards organizations include:", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " International Electrotechnical Commission (IEC), which has several committees working full-time on EMC issues. These are:", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 15144 ], "anchor_spans": [ [ 1, 42 ] ] }, { "plaintext": " Technical Committee 77 (TC77), working on electromagnetic compatibility between equipment including networks.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Comité International Spécial des Perturbations Radioélectriques (CISPR), or International Special Committee on Radio Interference.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 2830944 ], "anchor_spans": [ [ 1, 64 ] ] }, { "plaintext": " The Advisory Committee on Electromagnetic Compatibility (ACEC) co-ordinates the IEC's work on EMC between these committees.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " International Organization for Standardization (ISO), which publishes standards for the automotive industry.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 14934 ], "anchor_spans": [ [ 1, 47 ] ] }, { "plaintext": "Among the main national organizations are:", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Europe:", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Comité Européen de Normalisation (CEN) or European Committee for Standardization).", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 627291 ], "anchor_spans": [ [ 1, 33 ] ] }, { "plaintext": " Comité Européen de Normalisation Electrotechniques (CENELEC) or European Committee for Electrotechnical Standardisation.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 468466 ], "anchor_spans": [ [ 1, 51 ] ] }, { "plaintext": " European Telecommunications Standards Institute (ETSI).", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 18934452 ], "anchor_spans": [ [ 1, 48 ] ] }, { "plaintext": " United States:", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The Federal Communications Commission (FCC).", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 55974 ], "anchor_spans": [ [ 5, 38 ] ] }, { "plaintext": " The Society of Automotive Engineers (SAE).", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 341646 ], "anchor_spans": [ [ 5, 36 ] ] }, { "plaintext": " The Radio Technical Commission for Aeronautics (RTCA); see DO-160", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 5758972, 20592740 ], "anchor_spans": [ [ 6, 48 ], [ 61, 67 ] ] }, { "plaintext": " Britain: The British Standards Institution (BSI).", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 4775 ], "anchor_spans": [ [ 14, 43 ] ] }, { "plaintext": " Germany: The Verband der Elektrotechnik, Elektronik und Informationstechnik (VDE) or Association for Electrical, Electronic and Information Technologies.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 1835588 ], "anchor_spans": [ [ 14, 76 ] ] }, { "plaintext": "Compliance with national or international standards is usually laid down by laws passed by individual nations. Different nations can require compliance with different standards.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In European law, EU directive 2014/30/EU (previously 2004/108/EC) on EMC defines the rules for the placing on the market/putting into service of electric/electronic equipment within the European Union. The Directive applies to a vast range of equipment including electrical and electronic appliances, systems and installations. Manufacturers of electric and electronic devices are advised to run EMC tests in order to comply with compulsory CE-labeling. More are given in the list of EMC directives. Compliance with the applicable harmonised standards whose reference is listed in the OJEU under the EMC Directive gives presumption of conformity with the corresponding essential requirements of the EMC Directive.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 276436, 9317, 9663, 1278559, 43161284 ], "anchor_spans": [ [ 3, 15 ], [ 186, 200 ], [ 345, 376 ], [ 441, 451 ], [ 476, 498 ] ] }, { "plaintext": "In 2019, the USA adopted a program for the protection of critical infrastructure against an electromagnetic pulse, whether caused by a geomagnetic storm or a high-altitude nuclear weapon.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 147685 ], "anchor_spans": [ [ 135, 152 ] ] }, { "plaintext": "Electromagnetic noise is produced in the source due to rapid current and voltage changes, and spread via the coupling mechanisms described earlier.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 1072324, 6207, 32549 ], "anchor_spans": [ [ 0, 21 ], [ 61, 68 ], [ 73, 80 ] ] }, { "plaintext": "Breaking a coupling path is equally effective at either the start or the end of the path, therefore many aspects of good EMC design practice apply equally to potential sources and to potential victims.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A design which easily couples energy to the outside world will equally easily couple energy in and will be susceptible. A single improvement will often reduce both emissions and susceptibility.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Grounding and shielding aim to reduce emissions or divert EMI away from the victim by providing an alternative, low-impedance path. Techniques include:", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Grounding or earthing schemes such as star earthing for audio equipment or ground planes for RF. The scheme must also satisfy safety regulations.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Shielded cables, where the signal wires are surrounded by an outer conductive layer that is grounded at one or both ends.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 1564394 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Shielded housings. A conductive metal housing will act as an interference shield. In order to access the interior, such a housing is typically made in sections (such as a box and lid); an RF gasket may be used at the joints to reduce the amount of interference that leaks through. RF gaskets come in various types. A plain metal gasket may be either braided wire or a flat strip slotted to create many springy \"fingers\". Where a waterproof seal is required, a flexible elastomeric base may be impregnated with chopped metal fibers dispersed into the interior or long metal fibers covering the surface or both.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 842224 ], "anchor_spans": [ [ 470, 479 ] ] }, { "plaintext": " Decoupling or filtering at critical points such as cable entries and high-speed switches, using RF chokes and/or RC elements. A line filter implements these measures between a device and a line.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 34782809, 3382576, 299801, 12663338 ], "anchor_spans": [ [ 1, 11 ], [ 97, 106 ], [ 114, 125 ], [ 129, 140 ] ] }, { "plaintext": " Transmission line techniques for cables and wiring, such as balanced differential signal and return paths, and impedance matching.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 41811 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Avoidance of antenna structures such as loops of circulating current, resonant mechanical structures, unbalanced cable impedances or poorly grounded shielding.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Eliminating spurious rectifying junctions that can form between metal structures around and near transmitter installations. Such junctions in combination with unintentional antenna structures can radiate harmonics of the transmitter frequency.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Additional measures to reduce emissions include:", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Avoid unnecessary switching operations. Necessary switching should be done as slowly as is technically possible.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 28284 ], "anchor_spans": [ [ 19, 25 ] ] }, { "plaintext": " Noisy circuits (e. g. with a lot of switching activity) should be physically separated from the rest of the design.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " High peaks at single frequencies can be avoided by using the spread spectrum method, in which different parts of the circuit emit at different frequencies.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 41734 ], "anchor_spans": [ [ 62, 77 ] ] }, { "plaintext": " Harmonic wave filters.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 41232 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Design for operation at lower signal levels, reducing the energy available for emission.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Additional measures to reduce susceptibility include:", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Fuses, trip switches and circuit breakers.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Transient absorbers.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Design for operation at higher signal levels, reducing the relative noise level in comparison.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Error-correction techniques in digital circuitry. These may be implemented in hardware, software or a combination of both.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Differential signaling or other common-mode noise techniques for signal routing", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Testing is required to confirm that a particular device meets the required standards. It divides broadly into emissions testing and susceptibility testing.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Open-area test sites, or OATS, are the reference sites in most standards. They are especially useful for emissions testing of large equipment systems.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "However RF testing of a physical prototype is most often carried out indoors, in a specialised EMC test chamber. Types of chamber include anechoic, reverberation and the gigahertz transverse electromagnetic cell (GTEM cell).", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 300082, 3211121, 25312728 ], "anchor_spans": [ [ 138, 146 ], [ 148, 161 ], [ 170, 211 ] ] }, { "plaintext": "Sometimes computational electromagnetics simulations are used to test virtual models.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 3849994 ], "anchor_spans": [ [ 10, 40 ] ] }, { "plaintext": "Like all compliance testing, it is important that the test equipment, including the test chamber or site and any software used, be properly calibrated and maintained.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Typically, a given run of tests for a particular piece of equipment will require an EMC test plan and follow-up test report. The full test program may require the production of several such documents.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Emissions are typically measured for radiated field strength and where appropriate for conducted emissions along cables and wiring. Inductive (magnetic) and capacitive (electric) field strengths are near-field effects, and are only important if the device under test (DUT) is designed for location close to other electrical equipment.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For conducted emissions, typical transducers include the LISN (line impedance stabilisation network) or AMN (artificial mains network) and the RF current clamp.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 10979583, 4468348 ], "anchor_spans": [ [ 57, 61 ], [ 146, 159 ] ] }, { "plaintext": "For radiated emission measurement, antennas are used as transducers. Typical antennas specified include dipole, biconical, log-periodic, double ridged guide and conical log-spiral designs. Radiated emissions must be measured in all directions around the DUT.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 465156, 234918, 41332 ], "anchor_spans": [ [ 104, 110 ], [ 112, 121 ], [ 123, 135 ] ] }, { "plaintext": "Specialized EMI test receivers or EMI analysers are used for EMC compliance testing. These incorporate bandwidths and detectors as specified by international EMC standards. An EMI receiver may be based on a spectrum analyser to measure the emission levels of the DUT across a wide band of frequencies (frequency domain), or on a tunable narrower-band device which is swept through the desired frequency range. EMI receivers along with specified transducers can often be used for both conducted and radiated emissions. Pre-selector filters may also be used to reduce the effect of strong out-of-band signals on the front-end of the receiver.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 313416 ], "anchor_spans": [ [ 207, 224 ] ] }, { "plaintext": "Some pulse emissions are more usefully characterized using an oscilloscope to capture the pulse waveform in the time domain.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 15361791 ], "anchor_spans": [ [ 62, 74 ] ] }, { "plaintext": "Radiated field susceptibility testing typically involves a high-powered source of RF or EM energy and a radiating antenna to direct the energy at the potential victim or device under test (DUT).", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Conducted voltage and current susceptibility testing typically involves a high-powered signal generator, and a current clamp or other type of transformer to inject the test signal.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 4468348, 30906 ], "anchor_spans": [ [ 111, 124 ], [ 142, 153 ] ] }, { "plaintext": "Transient or EMP signals are used to test the immunity of the DUT against powerline disturbances including surges, lightning strikes and switching noise. In motor vehicles, similar tests are performed on battery and signal lines. The transient pulse may be generated digitally and passed through a broadband pulse amplifier, or applied directly to the transducer from a specialised pulse generator.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Electrostatic discharge testing is typically performed with a piezo spark generator called an \"ESD pistol\". Higher energy pulses, such as lightning or nuclear EMP simulations, can require a large current clamp or a large antenna which completely surrounds the DUT. Some antennas are so large that they are located outdoors, and care must be taken not to cause an EMP hazard to the surrounding environment.", "section_idx": 4, "section_name": "EMC control", "target_page_ids": [ 75049, 4249509, 22250817, 4468348 ], "anchor_spans": [ [ 0, 23 ], [ 62, 83 ], [ 95, 105 ], [ 196, 209 ] ] }, { "plaintext": "The earliest EMC issue was lightning strike (lightning electromagnetic pulse, or LEMP) on ships and buildings. Lightning rods or lightning conductors began to appear in the mid-18th century. With the advent of widespread electricity generation and power supply lines from the late 19th century on, problems also arose with equipment short-circuit failure affecting the power supply, and with local fire and shock hazard when the power line was struck by lightning. Power stations were provided with output circuit breakers. Buildings and appliances would soon be provided with input fuses, and later in the 20th century miniature circuit breakers (MCB) would come into use.", "section_idx": 5, "section_name": "History", "target_page_ids": [ 61344, 39519079, 20646679, 9540, 235898, 235899, 683342 ], "anchor_spans": [ [ 27, 36 ], [ 55, 76 ], [ 111, 124 ], [ 221, 243 ], [ 333, 346 ], [ 506, 521 ], [ 583, 588 ] ] }, { "plaintext": "It may be said that radio interference and its correction arose with the first spark-gap experiment of Marconi in the late 1800s. As radio communications developed in the first half of the 20th century, interference between broadcast radio signals began to occur and an international regulatory framework was set up to ensure interference-free communications.", "section_idx": 5, "section_name": "History", "target_page_ids": [ 12104, 113604 ], "anchor_spans": [ [ 103, 110 ], [ 224, 233 ] ] }, { "plaintext": "Switching devices became commonplace through the middle of the 20th century, typically in petrol powered cars and motorcycles but also in domestic appliances such as thermostats and refrigerators. This caused transient interference with domestic radio and (after World War II) TV reception, and in due course laws were passed requiring the suppression of such interference sources.", "section_idx": 5, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "ESD problems first arose with accidental electric spark discharges in hazardous environments such as coal mines and when refuelling aircraft or motor cars. Safe working practices had to be developed.", "section_idx": 5, "section_name": "History", "target_page_ids": [ 3924362 ], "anchor_spans": [ [ 41, 55 ] ] }, { "plaintext": "After World War II the military became increasingly concerned with the effects of nuclear electromagnetic pulse (NEMP), lightning strike, and even high-powered radar beams, on vehicle and mobile equipment of all kinds, and especially aircraft electrical systems.", "section_idx": 5, "section_name": "History", "target_page_ids": [ 25676 ], "anchor_spans": [ [ 160, 165 ] ] }, { "plaintext": "When high RF emission levels from other sources became a potential problem (such as with the advent of microwave ovens), certain frequency bands were designated for Industrial, Scientific and Medical (ISM) use, allowing emission levels limited only by thermal safety standards. Later, the International Telecommunication Union adopted a Recommendation providing limits of radiation from ISM devices in order to protect radiocommunications. A variety of issues such as sideband and harmonic emissions, broadband sources, and the ever-increasing popularity of electrical switching devices and their victims, resulted in a steady development of standards and laws.", "section_idx": 5, "section_name": "History", "target_page_ids": [ 58017 ], "anchor_spans": [ [ 103, 117 ] ] }, { "plaintext": "From the late 1970s, the popularity of modern digital circuitry rapidly grew. As the technology developed, with ever-faster switching speeds (increasing emissions) and lower circuit voltages (increasing susceptibility), EMC increasingly became a source of concern. Many more nations became aware of EMC as a growing problem and issued directives to the manufacturers of digital electronic equipment, which set out the essential manufacturer requirements before their equipment could be marketed or sold. Organizations in individual nations, across Europe and worldwide, were set up to maintain these directives and associated standards. In 1979, the American FCC published a regulation that required the electromagnetic emissions of all \"digital devices\" to be below certain limits. This regulatory environment led to a sharp growth in the EMC industry supplying specialist devices and equipment, analysis and design software, and testing and certification services. Low-voltage digital circuits, especially CMOS transistors, became more susceptible to ESD damage as they were miniaturised and, despite the development of on-chip hardening techniques, a new ESD regulatory regime had to be developed.", "section_idx": 5, "section_name": "History", "target_page_ids": [ 55974 ], "anchor_spans": [ [ 659, 662 ] ] }, { "plaintext": "From the 1980s on the explosive growth in mobile communications and broadcast media channels put huge pressure on the available airspace. Regulatory authorities began squeezing band allocations closer and closer together, relying on increasingly sophisticated EMC control methods, especially in the digital communications domain, to keep cross-channel interference to acceptable levels. Digital systems are inherently less susceptible than analogue systems, and also offer far easier ways (such as software) to implement highly sophisticated protection and error-correction measures.", "section_idx": 5, "section_name": "History", "target_page_ids": [ 1145887, 10375 ], "anchor_spans": [ [ 42, 62 ], [ 557, 573 ] ] }, { "plaintext": "In 1985, the USA released the ISM bands for low-power mobile digital communications, leading to the development of Wi-Fi and remotely-operated car door keys. This approach relies on the intermittent nature of ISM interference and use of sophisticated error-correction methods to ensure lossless reception during the quiet gaps between any bursts of interference.", "section_idx": 5, "section_name": "History", "target_page_ids": [ 63973 ], "anchor_spans": [ [ 115, 120 ] ] }, { "plaintext": " Conducted electromagnetic interference", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 1072324 ], "anchor_spans": [ [ 1, 39 ] ] }, { "plaintext": " Crosstalk", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 2995499 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " EMC-aware programming", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 8006531 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " IEEE Electromagnetic Compatibility Society", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 56938 ], "anchor_spans": [ [ 1, 43 ] ] }, { "plaintext": " International Commission on Non-Ionizing Radiation Protection (ICNIRP)", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 28858009 ], "anchor_spans": [ [ 1, 62 ] ] }, { "plaintext": " List of common EMC test standards", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 43161284 ], "anchor_spans": [ [ 1, 34 ] ] }, { "plaintext": " Television interference", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 3385905 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " EMC-Directive European Commission – Harmonised standards for EMC", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " European EMI and EMC Conformity Assessment", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Federal Communications Commission", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "IEEE/EMC Society", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " News and information on Electromagnetic Compatibility regulations", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Radio Technical Commission for Aeronautics", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Summary of EU standards by equipment type", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " What is EMC? YouTube video.", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Introduction to EMC", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Basics in EMC/EMI and Powerquality", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Analog, RF and EMC Considerations in Printed Wiring Board (PWB) Design", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Application Note: Design for EMC Compliance", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Design for EMC - Effects of Via Slots, Split Planes,Gaps and Return Paths on Clock Signal", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " EMC Design Fundamentals", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " EMC Design Guidelines", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " EMC engineering practices for panel builders", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " EMC Resources (Clemson University)", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Fundamentals of the Plane Electromagnetic Shield", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Electromagnetic_compatibility" ]

[ "EMC" ]

[ { "plaintext": "In telecommunication, the term electromagnetic environment (EME) has the following meanings:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": "For a telecommunications system, the spatial distribution of electromagnetic fields surrounding a given site. The electromagnetic environment may be expressed in terms of the spatial and temporal distribution of electric field strength (volts per metre), irradiance (watts per square metre), or energy density (joules per cubic metre).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8286675, 9735, 41150, 32567, 556970, 21347693, 16327 ], "anchor_spans": [ [ 25, 31 ], [ 61, 82 ], [ 222, 236 ], [ 238, 242 ], [ 256, 266 ], [ 268, 272 ], [ 312, 317 ] ] }, { "plaintext": "The resulting product of the power and time distribution, in various frequency ranges, of the radiated or conducted electromagnetic emission levels that may be encountered by a military force, system, or platform when performing its assigned mission in its intended operational environment. It is the sum of electromagnetic interference; electromagnetic pulse; hazards of electromagnetic radiation to personnel, ordnance, and volatile materials; and natural phenomena effects of lightning and p-static.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 24236, 30012, 10779, 292420, 1072324, 39519079, 9426, 61344 ], "anchor_spans": [ [ 29, 34 ], [ 39, 43 ], [ 69, 78 ], [ 132, 140 ], [ 308, 336 ], [ 338, 359 ], [ 372, 397 ], [ 479, 488 ] ] }, { "plaintext": " All electromagnetic phenomena observable in a given location.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] } ]

[ "Electromagnetic_radiation", "Telecommunications_engineering", "Electromagnetic_compatibility", "Reliability_engineering" ]

[]

[ { "plaintext": "In Electrical systems, such as telecommunication, power electronics, industrial electronics, power engineering; electromagnetic interference (EMI) control is the control of radiated and conducted energy such that emissions that are unnecessary for system, subsystem, or equipment operation are reduced, minimized, or eliminated. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9550, 33094374, 1001628, 1001628, 618077, 8286675 ], "anchor_spans": [ [ 3, 21 ], [ 31, 48 ], [ 50, 67 ], [ 69, 91 ], [ 93, 110 ], [ 249, 255 ] ] }, { "plaintext": "Note: Electromagnetic radiated and conducted emissions are controlled regardless of their origin within the system, subsystem, or equipment. Successful EMI control with effective susceptibility control leads to electromagnetic compatibility.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 64345796, 187360, 41093 ], "anchor_spans": [ [ 36, 55 ], [ 180, 194 ], [ 212, 241 ] ] }, { "plaintext": " Radio resource management", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 7856907 ], "anchor_spans": [ [ 1, 26 ] ] } ]

[ "Interference" ]

[]

[ { "plaintext": "A nuclear electromagnetic pulse (commonly abbreviated as nuclear EMP, or NEMP) is a burst of electromagnetic radiation created by a nuclear explosion. The resulting rapidly varying electric and magnetic fields may couple with electrical and electronic systems to produce damaging current and voltage surges. The specific characteristics of a particular nuclear EMP event vary according to a number of factors, the most important of which is the altitude of the detonation.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9426, 4380587, 41092, 36563, 319613, 59211 ], "anchor_spans": [ [ 93, 118 ], [ 132, 149 ], [ 181, 189 ], [ 194, 208 ], [ 292, 306 ], [ 445, 453 ] ] }, { "plaintext": "The term \"electromagnetic pulse\" generally excludes optical (infrared, visible, ultraviolet) and ionizing (such as X-ray and gamma radiation) ranges. In military terminology, a nuclear warhead detonated tens to hundreds of miles above the Earth's surface is known as a high-altitude electromagnetic pulse (HEMP) device. Effects of a HEMP device depend on factors including the altitude of the detonation, energy yield, gamma ray output, interactions with the Earth's magnetic field and electromagnetic shielding of targets.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3973438, 3145631, 18616290, 146983, 1564394 ], "anchor_spans": [ [ 269, 304 ], [ 405, 417 ], [ 419, 428 ], [ 459, 481 ], [ 486, 511 ] ] }, { "plaintext": "The fact that an electromagnetic pulse is produced by a nuclear explosion was known in the earliest days of nuclear weapons testing. The magnitude of the EMP and the significance of its effects were not immediately realized.", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "During the first United States nuclear test on 16 July 1945, electronic equipment was shielded because Enrico Fermi expected the electromagnetic pulse. The official technical history for that first nuclear test states, \"All signal lines were completely shielded, in many cases doubly shielded. In spite of this many records were lost because of spurious pickup at the time of the explosion that paralyzed the recording equipment.\" During British nuclear testing in 1952–1953, instrumentation failures were attributed to \"radioflash\", which was their term for EMP.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 60033, 10264, 1372970, 31349263 ], "anchor_spans": [ [ 11, 43 ], [ 103, 115 ], [ 438, 461 ], [ 521, 531 ] ] }, { "plaintext": "The first openly reported observation of the unique aspects of high-altitude nuclear EMP occurred during the helium balloon-lofted Yucca nuclear test of the Hardtack I series on 28 April 1958. In that test, the electric field measurements from the 1.7 kiloton weapon exceeded the range to which the test instruments were adjusted and was estimated to be about five times the limits to which the oscilloscopes were set. ", "section_idx": 1, "section_name": "History", "target_page_ids": [ 1244402, 1107058 ], "anchor_spans": [ [ 109, 123 ], [ 157, 167 ] ] }, { "plaintext": "The Yucca EMP was initially positive-going, whereas low-altitude bursts were negative going pulses. Also, the polarization of the Yucca EMP signal was horizontal, whereas low-altitude nuclear EMP was vertically polarized. In spite of these many differences, the unique EMP results were dismissed as a possible wave propagation anomaly.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 41564, 5017866 ], "anchor_spans": [ [ 110, 122 ], [ 310, 326 ] ] }, { "plaintext": "The high-altitude nuclear tests of 1962, as discussed below, confirmed the unique results of the Yucca high-altitude test and increased the awareness of high-altitude nuclear EMP beyond the original group of defense scientists. The larger scientific community became aware of the significance of the EMP problem after a three-article series on nuclear EMP was published in 1981 by William J. Broad in Science.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 3973438, 7327848, 193513 ], "anchor_spans": [ [ 4, 31 ], [ 381, 397 ], [ 401, 408 ] ] }, { "plaintext": "In July 1962, the US carried out the Starfish Prime test, exploding a bomb above the mid-Pacific Ocean. This demonstrated that the effects of a high-altitude nuclear explosion were much larger than had been previously calculated. Starfish Prime made those effects known to the public by causing electrical damage in Hawaii, about away from the detonation point, disabling approximately 300 streetlights, triggering numerous burglar alarms and damaging a microwave link.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 2173797, 3973438, 13270 ], "anchor_spans": [ [ 37, 51 ], [ 146, 177 ], [ 318, 324 ] ] }, { "plaintext": "Starfish Prime was the first success in the series of United States high-altitude nuclear tests in 1962 known as Operation Fishbowl. Subsequent tests gathered more data on the high-altitude EMP phenomenon.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 3036860 ], "anchor_spans": [ [ 113, 131 ] ] }, { "plaintext": "The Bluegill Triple Prime and Kingfish high-altitude nuclear tests of October and November 1962 in Operation Fishbowl provided data that was clear enough to enable physicists to accurately identify the physical mechanisms behind the electromagnetic pulses.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 3036860, 3036860 ], "anchor_spans": [ [ 4, 25 ], [ 30, 38 ] ] }, { "plaintext": "The EMP damage of the Starfish Prime test was quickly repaired due, in part, to the fact that the EMP over Hawaii was relatively weak compared to what could be produced with a more intense pulse, and in part due to the relative ruggedness (compared to today) of Hawaii's electrical and electronic infrastructure in 1962.", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The relatively small magnitude of the Starfish Prime EMP in Hawaii (about 5.6 kilovolts/metre) and the relatively small amount of damage (for example, only 1% to 3% of streetlights extinguished) led some scientists to believe, in the early days of EMP research, that the problem might not be significant. Later calculations showed that if the Starfish Prime warhead had been detonated over the northern continental United States, the magnitude of the EMP would have been much larger (22 to 30 kV/m) because of the greater strength of the Earth's magnetic field over the United States, as well as its different orientation at high latitudes. These calculations, combined with the accelerating reliance on EMP-sensitive microelectronics, heightened awareness that EMP could be a significant problem.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 146983 ], "anchor_spans": [ [ 538, 560 ] ] }, { "plaintext": "In 1962, the Soviet Union performed three EMP-producing nuclear tests in space over Kazakhstan, the last in the \"Soviet Project K nuclear tests\". Although these weapons were much smaller (300 kiloton) than the Starfish Prime test, they were over a populated, large landmass and at a location where the Earth's magnetic field was greater. The damage caused by the resulting EMP was reportedly much greater than in Starfish Prime. The geomagnetic storm–like E3 pulse from Test 184 induced a current surge in a long underground power line that caused a fire in the power plant in the city of Karaganda.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 26779, 41369768, 3145631, 147685, 1355057, 212141, 267899 ], "anchor_spans": [ [ 13, 25 ], [ 113, 143 ], [ 192, 199 ], [ 433, 450 ], [ 525, 535 ], [ 562, 573 ], [ 589, 598 ] ] }, { "plaintext": "After the collapse of the Soviet Union, the level of this damage was communicated informally to US scientists. For a few years US and Russian scientists collaborated on the HEMP phenomenon. Funding was secured to enable Russian scientists to report on some of the Soviet EMP results in international scientific journals. As a result, formal documentation of some of the EMP damage in Kazakhstan exists but is still sparse in the open scientific literature.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 40494892, 6277878 ], "anchor_spans": [ [ 10, 38 ], [ 429, 444 ] ] }, { "plaintext": "For one of the K Project tests, Soviet scientists instrumented a section of telephone line in the area that they expected to be affected by the pulse. The monitored telephone line was divided into sub-lines of in length, separated by repeaters. Each sub-line was protected by fuses and by gas-filled overvoltage protectors. The EMP from the 22 October (K-3) nuclear test (also known as Test 184) blew all of the fuses and destroyed all of the overvoltage protectors in all of the sub-lines.", "section_idx": 1, "section_name": "History", "target_page_ids": [ 41655, 683342, 548308, 2074176 ], "anchor_spans": [ [ 236, 244 ], [ 278, 283 ], [ 291, 301 ], [ 302, 313 ] ] }, { "plaintext": "Published reports, including a 1998 IEEE article, have stated that there were significant problems with ceramic insulators on overhead electrical power lines during the tests. A 2010 technical report written for Oak Ridge National Laboratory stated that \"Power line insulators were damaged, resulting in a short circuit on the line and some lines detaching from the poles and falling to the ground.\"", "section_idx": 1, "section_name": "History", "target_page_ids": [ 38147 ], "anchor_spans": [ [ 212, 241 ] ] }, { "plaintext": "Nuclear EMP is a complex multi-pulse, usually described in terms of three components, as defined by the International Electrotechnical Commission (IEC).", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [ 15144 ], "anchor_spans": [ [ 104, 145 ] ] }, { "plaintext": "The three components of nuclear EMP, as defined by the IEC, are called \"E1\", \"E2\" and \"E3\".", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The E1 pulse is a very fast component of nuclear EMP. E1 is a brief but intense electromagnetic field that induces high voltages in electrical conductors. E1 causes most of its damage by causing electrical breakdown voltages to be exceeded. E1 can destroy computers and communications equipment and it changes too quickly (nanoseconds) for ordinary surge protectors to provide effective protection from it. Fast-acting surge protectors (such as those using TVS diodes) will block the E1 pulse.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [ 1224250, 414738, 414738 ], "anchor_spans": [ [ 206, 223 ], [ 349, 364 ], [ 457, 467 ] ] }, { "plaintext": "E1 is produced when gamma radiation from the nuclear detonation ionizes (strips electrons from) atoms in the upper atmosphere. This is known as the Compton effect and the resulting current is called the \"Compton current\". The electrons travel in a generally downward direction at relativistic speeds (more than 90 per cent of the speed of light). In the absence of a magnetic field, this would produce a large, radial pulse of electric current propagating outward from the burst location confined to the source region (the region over which the gamma photons are attenuated). The Earth's magnetic field exerts a force on the electron flow at a right angle to both the field and the particles' original vector, which deflects the electrons and leads to synchrotron radiation. Because the outward traveling gamma pulse is propagating at the speed of light, the synchrotron radiation of the Compton electrons adds coherently, leading to a radiated electromagnetic signal. This interaction produces a large, brief, pulse.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [ 18616290, 59611, 55236, 26962, 6207, 170808, 240011 ], "anchor_spans": [ [ 20, 35 ], [ 64, 71 ], [ 148, 162 ], [ 280, 299 ], [ 427, 443 ], [ 752, 773 ], [ 911, 921 ] ] }, { "plaintext": "Several physicists worked on the problem of identifying the mechanism of the HEMP E1 pulse. The mechanism was finally identified by Conrad Longmire of Los Alamos National Laboratory in 1963.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [ 31859474, 38145 ], "anchor_spans": [ [ 132, 147 ], [ 151, 181 ] ] }, { "plaintext": "Longmire gives numerical values for a typical case of E1 pulse produced by a second-generation nuclear weapon such as those of Operation Fishbowl. The typical gamma rays given off by the weapon have an energy of about 2MeV (mega electron-volts). The gamma rays transfer about half of their energy to the ejected free electrons, giving an energy of about 1MeV.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [ 3036860, 9598, 19938 ], "anchor_spans": [ [ 127, 145 ], [ 219, 222 ], [ 224, 228 ] ] }, { "plaintext": "In a vacuum and absent a magnetic field, the electrons would travel with a current density of tens of amperes per square metre. Because of the downward tilt of the Earth's magnetic field at high latitudes, the area of peak field strength is a U-shaped region to the equatorial side of the detonation. As shown in the diagram, for nuclear detonations in the Northern Hemisphere, this U-shaped region is south of the detonation point. Near the equator, where the Earth's magnetic field is more nearly horizontal, the E1 field strength is more nearly symmetrical around the burst location.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [ 5498706, 772, 17616, 22126, 20611356 ], "anchor_spans": [ [ 75, 90 ], [ 102, 109 ], [ 195, 204 ], [ 357, 376 ], [ 442, 449 ] ] }, { "plaintext": "At geomagnetic field strengths typical of the mid-latitudes, these initial electrons spiral around the magnetic field lines with a typical radius of about . These initial electrons are stopped by collisions with air molecules at an average distance of about . This means that most of the electrons are stopped by collisions with air molecules before completing a full spiral around the field lines.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This interaction of the negatively charged electrons with the magnetic field radiates a pulse of electromagnetic energy. The pulse typically rises to its peak value in some five nanoseconds. Its magnitude typically decays by half within 200 nanoseconds. (By the IEC definition, this E1 pulse ends 1000 nanoseconds after it begins.) This process occurs simultaneously on about 1025 electrons. The simultaneous action of the electrons causes the resulting pulse from each electron to radiate coherently, adding to produce a single large amplitude, but narrow, radiated pulse.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Secondary collisions cause subsequent electrons to lose energy before they reach ground level. The electrons generated by these subsequent collisions have so little energy that they do not contribute significantly to the E1 pulse.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "These 2 MeV gamma rays typically produce an E1 pulse near ground level at moderately high latitudes that peaks at about 50,000 volts per metre. The ionization process in the mid-stratosphere causes this region to become an electrical conductor, a process that blocks the production of further electromagnetic signals and causes the field strength to saturate at about 50,000 volts per metre. The strength of the E1 pulse depends upon the number and intensity of the gamma rays and upon the rapidity of the gamma-ray burst. Strength is also somewhat dependent upon altitude.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [ 47454 ], "anchor_spans": [ [ 178, 190 ] ] }, { "plaintext": "There are reports of \"super-EMP\" nuclear weapons that are able to exceed the 50,000 volts per metre limit by unspecified mechanisms. The reality and possible construction details of these weapons are classified and are, therefore, unconfirmed in the open scientific literature", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The E2 component is generated by scattered gamma rays and inelastic gammas produced by neutrons. This E2 component is an \"intermediate time\" pulse that, by IEC definition, lasts from about one microsecond to one second after the explosion. E2 has many similarities to lightning, although lightning-induced E2 may be considerably larger than a nuclear E2. Because of the similarities and the widespread use of lightning protection technology, E2 is generally considered to be the easiest to protect against.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [ 21272, 61344 ], "anchor_spans": [ [ 87, 94 ], [ 268, 277 ] ] }, { "plaintext": "According to the United States EMP Commission, the main problem with E2 is that it immediately follows E1, which may have damaged the devices that would normally protect against E2.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The EMP Commission Executive Report of 2004 states, \"In general, it would not be an issue for critical infrastructure systems since they have existing protective measures for defense against occasional lightning strikes. The most significant risk is synergistic because the E2 component follows a small fraction of a second after the first component's insult, which has the ability to impair or destroy many protective and control features. The energy associated with the second component thus may be allowed to pass into and damage systems.\"", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The E3 component is different from E1 and E2. E3 is a much slower pulse, lasting tens to hundreds of seconds. It is caused by the nuclear detonation's temporary distortion of the Earth's magnetic field. The E3 component has similarities to a geomagnetic storm. Like a geomagnetic storm, E3 can produce geomagnetically induced currents in long electrical conductors, damaging components such as power line transformers.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [ 147685, 30906 ], "anchor_spans": [ [ 242, 259 ], [ 405, 416 ] ] }, { "plaintext": "Because of the similarity between solar-induced geomagnetic storms and nuclear E3, it has become common to refer to solar-induced geomagnetic storms as \"Solar EMP\". \"Solar EMP\" does not include E1 or E2 components.", "section_idx": 2, "section_name": "Characteristics", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Factors that control weapon effectiveness include altitude, yield, construction details, target distance, intervening geographical features, and local strength of the Earth's magnetic field.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 3145631 ], "anchor_spans": [ [ 60, 65 ] ] }, { "plaintext": "According to an internet primer published by the Federation of American Scientists:", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 158172 ], "anchor_spans": [ [ 49, 82 ] ] }, { "plaintext": " A high-altitude nuclear detonation produces an immediate flux of gamma rays from the nuclear reactions within the device. These photons in turn produce high energy free electrons by Compton scattering at altitudes between (roughly) 20 and 40 km. These electrons are then trapped in the Earth's magnetic field, giving rise to an oscillating electric current. This current is asymmetric in general and gives rise to a rapidly rising radiated electromagnetic field called an electromagnetic pulse (EMP). Because the electrons are trapped essentially simultaneously, a very large electromagnetic source radiates coherently.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 43590, 23535, 22522, 240011 ], "anchor_spans": [ [ 58, 62 ], [ 129, 135 ], [ 329, 340 ], [ 609, 619 ] ] }, { "plaintext": " The pulse can easily span continent-sized areas, and this radiation can affect systems on land, sea, and air. ... A large device detonated at 400–500 km (250 to 312 miles) over Kansas would affect all of the continental U.S. The signal from such an event extends to the visual horizon as seen from the burst point.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 16716 ], "anchor_spans": [ [ 179, 185 ] ] }, { "plaintext": "Thus, for equipment to be affected, the weapon needs to be above the visual horizon.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 60455 ], "anchor_spans": [ [ 69, 83 ] ] }, { "plaintext": "The altitude indicated above is greater than that of the International Space Station and many low Earth orbit satellites. Large weapons could have a dramatic impact on satellite operations and communications such as occurred during Operation Fishbowl. The damaging effects on orbiting satellites are usually due to factors other than EMP. In the Starfish Prime nuclear test, most damage was to the satellites' solar panels while passing through radiation belts created by the explosion.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 15043, 47568, 27683, 2173797 ], "anchor_spans": [ [ 57, 84 ], [ 94, 109 ], [ 168, 177 ], [ 346, 360 ] ] }, { "plaintext": "For detonations within the atmosphere, the situation is more complex. Within the range of gamma ray deposition, simple laws no longer hold as the air is ionised and there are other EMP effects, such as a radial electric field due to the separation of Compton electrons from air molecules, together with other complex phenomena. For a surface burst, absorption of gamma rays by air would limit the range of gamma-ray deposition to approximately , while for a burst in the lower-density air at high altitudes, the range of deposition would be far greater.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 59611, 55236 ], "anchor_spans": [ [ 153, 160 ], [ 251, 267 ] ] }, { "plaintext": "Typical nuclear weapon yields used during Cold War planning for EMP attacks were in the range of . This is roughly 50 to 500 times the size of the Hiroshima and Nagasaki bombs. Physicists have testified at United States Congressional hearings that weapons with yields of or less can produce a large EMP.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 3145631, 325329 ], "anchor_spans": [ [ 8, 28 ], [ 42, 50 ] ] }, { "plaintext": "The EMP at a fixed distance from an explosion increases at most as the square root of the yield (see the illustration to the right). This means that although a weapon has only of the energy release of the Starfish Prime test, the EMP will be at least as powerful. Since the E1 component of nuclear EMP depends on the prompt gamma-ray output, which was only 0.1% of yield in Starfish Prime but can be of yield in low-yield pure nuclear fission weapons, a bomb can easily be as powerful as the Starfish Prime at producing EMP.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 22054 ], "anchor_spans": [ [ 432, 447 ] ] }, { "plaintext": "The total prompt gamma-ray energy in a fission explosion is of the yield, but in a detonation the triggering explosive around the bomb core absorbs about of the prompt gamma rays, so the output is only about of the yield. In the thermonuclear Starfish Prime the fission yield was less than 100% and the thicker outer casing absorbed about 95% of the prompt gamma rays from the pusher around the fusion stage. Thermonuclear weapons are also less efficient at producing EMP because the first stage can pre-ionize the air which becomes conductive and hence rapidly shorts out the Compton currents generated by the fusion stage. Hence, small pure fission weapons with thin cases are far more efficient at causing EMP than most megaton bombs.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 21544, 172911, 59611, 55236, 21544 ], "anchor_spans": [ [ 233, 246 ], [ 413, 434 ], [ 504, 514 ], [ 581, 596 ], [ 615, 621 ] ] }, { "plaintext": "This analysis, however, only applies to the fast E1 and E2 components of nuclear EMP. The geomagnetic storm-like E3 component of nuclear EMP is more closely proportional to the total energy yield of the weapon.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 147685 ], "anchor_spans": [ [ 90, 107 ] ] }, { "plaintext": "In nuclear EMP all of the components of the electromagnetic pulse are generated outside of the weapon.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For high-altitude nuclear explosions, much of the EMP is generated far from the detonation (where the gamma radiation from the explosion hits the upper atmosphere). This electric field from the EMP is remarkably uniform over the large area affected.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 3973438 ], "anchor_spans": [ [ 4, 35 ] ] }, { "plaintext": "According to the standard reference text on nuclear weapons effects published by the U.S. Department of Defense, \"The peak electric field (and its amplitude) at the Earth's surface from a high-altitude burst will depend upon the explosion yield, the height of the burst, the location of the observer, and the orientation with respect to the geomagnetic field. As a general rule, however, the field strength may be expected to be tens of kilovolts per metre over most of the area receiving the EMP radiation.\"", "section_idx": 3, "section_name": "Generation", "target_page_ids": [ 146983 ], "anchor_spans": [ [ 341, 358 ] ] }, { "plaintext": "The text also states that, \"...over most of the area affected by the EMP the electric field strength on the ground would exceed 0.5Emax. For yields of less than a few hundred kilotons, this would not necessarily be true because the field strength at the Earth's tangent could be substantially less than 0.5Emax.\"", "section_idx": 3, "section_name": "Generation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "(Emax refers to the maximum electric field strength in the affected area.)", "section_idx": 3, "section_name": "Generation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In other words, the electric field strength in the entire area that is affected by the EMP will be fairly uniform for weapons with a large gamma-ray output. For smaller weapons, the electric field may fall at a faster rate as distance increases.", "section_idx": 3, "section_name": "Generation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Also known as an \"Enhanced-EMP\", a super-electromagnetic pulse is a relatively new type of warfare in which a nuclear weapon is designed to create a far greater electromagnetic pulse in comparison to standard nuclear weapons of mass destruction. These weapons capitalize on the E1 pulse component of a detonation involving gamma rays, creating an EMP yield of potentially up to 200,000 volts per meter. For decades, numerous countries have experimented with the creation of such weapons, most notably China and Russia.", "section_idx": 4, "section_name": "Super-EMP", "target_page_ids": [ 21785, 39519079, 53136, 18616290, 5405, 25391 ], "anchor_spans": [ [ 110, 124 ], [ 161, 182 ], [ 217, 244 ], [ 323, 332 ], [ 502, 507 ], [ 512, 518 ] ] }, { "plaintext": "According to a statement made in writing by the Chinese military, the country has super-EMPs and has discussed their use in attacking Taiwan. Such an attack would debilitate information systems in the nation, allowing China to move in and attack it directly using soldiers. The Taiwanese military has subsequently confirmed Chinese possession of super-EMPs and their possible destruction to power grids.", "section_idx": 4, "section_name": "Super-EMP", "target_page_ids": [ 25734, 20344155 ], "anchor_spans": [ [ 134, 140 ], [ 391, 402 ] ] }, { "plaintext": "In addition to Taiwan, the possible implications of attacking the United States with these weapons was examined by China. While the United States also possess nuclear weapons, the country has not experimented with super-EMPs and is hypothetically highly vulnerable to any future attacks by nations. This is due to the country's reliance on computers to control much of the government and economy. Abroad, U.S. aircraft carriers stationed within a reasonable range of an exploding bomb could potentially be subject to complete destruction of missiles on board, as well as telecommunication systems that would allow them to communicate with nearby vessels and controllers on land.", "section_idx": 4, "section_name": "Super-EMP", "target_page_ids": [ 3434750, 33094374 ], "anchor_spans": [ [ 66, 79 ], [ 571, 596 ] ] }, { "plaintext": "Since the Cold War, Russia has experimented with the design and effects of EMP bombs. More recently, the country has performed several cyberattacks on the United States, which some analysts believe suggests possible future nationwide blackouts caused by super-EMPs, since Russia is known to possess them. Along with ordinary warheads equipped with Super-EMP capabilities, Russia has been developing hypersonic missiles that, in 2021, are far more difficult for U.S. defenses in the form of radars and satellites to detect in a timely manner. This method makes the act of nuclear deterrence, which is a key strategy for the United States in preventing nuclear war, nearly impossible.", "section_idx": 4, "section_name": "Super-EMP", "target_page_ids": [ 37925700, 55244, 735661, 36880 ], "anchor_spans": [ [ 135, 146 ], [ 400, 410 ], [ 572, 590 ], [ 652, 663 ] ] }, { "plaintext": "Plans of a device that is capable of placing a nuclear weapon into space were first introduced by the Soviet Union in 1962 when they developed a system, known as Fractional Orbital Bombardment System, to deliver nuclear weapons from above the Earth's atmosphere. Compared to super-EMPs that target ground operations, proposals have been made by Russia to develop satellites supplied with similar EMP capabilities. This would call for detonations up to above the Earth's surface, with the potential to disrupt the electronic systems of U.S. satellites suspended in orbit around the planet, many of which are vital for deterrence and alerting the country of possible incoming missiles.", "section_idx": 4, "section_name": "Super-EMP", "target_page_ids": [ 26779, 894303, 202898, 27683 ], "anchor_spans": [ [ 102, 114 ], [ 162, 199 ], [ 243, 261 ], [ 363, 372 ] ] }, { "plaintext": "An energetic EMP can temporarily upset or permanently damage electronic equipment by generating high voltage and high current surges; semiconductor components are particularly at risk. The effects of damage can range from imperceptible to the eye, to devices literally blowing apart. Cables, even if short, can act as antennas to transmit pulse energy to the equipment.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Older, vacuum tube (valve)-based equipment is generally much less vulnerable to nuclear EMP than solid state equipment, which is much more susceptible to damage by large, brief voltage and current surges. Soviet Cold War-era military aircraft often had avionics based on vacuum tubes because solid-state capabilities were limited and vacuum-tube gear was believed to be more likely to survive.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [ 32496, 3656002, 26779, 325329, 2039 ], "anchor_spans": [ [ 7, 18 ], [ 97, 108 ], [ 205, 211 ], [ 212, 220 ], [ 253, 261 ] ] }, { "plaintext": "Other components in vacuum tube circuitry can be damaged by EMP. Vacuum tube equipment was damaged in the 1962 testing. The solid state PRC-77 VHF manpackable two-way radio survived extensive EMP testing. The earlier PRC-25, nearly identical except for a vacuum tube final amplification stage, was tested in EMP simulators, but was not certified to remain fully functional.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [ 160494, 69480 ], "anchor_spans": [ [ 136, 142 ], [ 143, 146 ] ] }, { "plaintext": "Equipment that is running at the time of an EMP is more vulnerable. Even a low-energy pulse has access to the power source, and all parts of the system are illuminated by the pulse. For example, a high-current arcing path may be created across the power supply, burning out some device along that path. Such effects are hard to predict and require testing to assess potential vulnerabilities.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Many nuclear detonations have taken place using aerial bombs. The B-29 aircraft that delivered the nuclear weapons at Hiroshima and Nagasaki did not lose power from electrical damage, because electrons (ejected from the air by gamma rays) are stopped quickly in normal air for bursts below roughly , so they are not significantly deflected by the Earth's magnetic field.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [ 19681450, 53179, 59062, 21790, 9476 ], "anchor_spans": [ [ 48, 59 ], [ 66, 70 ], [ 118, 127 ], [ 132, 140 ], [ 192, 200 ] ] }, { "plaintext": "If the aircraft carrying the Hiroshima and Nagasaki bombs had been within the intense nuclear radiation zone when the bombs exploded over those cities, then they would have suffered effects from the charge separation (radial) EMP. But this only occurs within the severe blast radius for detonations below about altitude.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [ 59062, 21790, 3370908 ], "anchor_spans": [ [ 29, 38 ], [ 43, 51 ], [ 199, 216 ] ] }, { "plaintext": "During Operation Fishbowl, EMP disruptions were suffered aboard a KC-135 photographic aircraft flying from the detonations at burst altitudes. The vital electronics were less sophisticated than today's and the aircraft was able to land safely.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [ 3036860, 17441 ], "anchor_spans": [ [ 7, 25 ], [ 66, 72 ] ] }, { "plaintext": "Modern aircraft are heavily reliant on solid state electronics which are very susceptible to EMP blasts. Therefore, airline authorities are creating high intensity radiated fields (HIRF) requirements for new air planes to help prevent the chance of crashes caused by EMPs or electromagnetic interference (EMI). To do this all parts of the airplane must be conductive. This is the main shield from EMP blasts as long as there are no holes for the waves to penetrate into the interior of the airplane. Also, by insulating some of the main computers inside the plane also add an extra layer of protection from EMP blasts.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An EMP would probably not affect most cars, despite modern cars' heavy use of electronics, because cars' electronic circuits and cabling are likely too short to be affected. In addition, cars' metallic frames provide some protection. However, even a small percentage of cars breaking down due to an electronic malfunction would cause temporary traffic jams.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An EMP has a smaller effect the shorter the length of an electrical conductor; though other factors affect the vulnerability of electronics as well, so no cutoff length determines whether some piece of equipment will survive. However, small electronic devices, such as wristwatches and cell phones, would most likely withstand an EMP.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This is true only if they are not plugged into or in operation. Electronics plugged into the grid could see a massive surge and end up sustaining permanent damage to the devices similarly, if there was a lightning strike. EMPs could also blow all the breakers in a home and damage devices not connected to a surge protector. Or if the house has a proper whole house surge protector that can negate the effects of an EMP attack, and other protective devices that will protect the house.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Though electric potential difference can accumulate in electrical conductors after an EMP, it will generally not flow out into human or animal bodies, and thus contact is safe.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "EMPs of sufficient magnitude and length have the potential to affect the human body. Possible side effects include cellular mutations, nervous system damages, internal burns, brain damage, and temporary problems with thinking and memory. However, this would be in extreme cases like being near the center of the blast and being exposed to a large amount of radiation and EMP waves.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A study found that exposure to 200–400 pulses of EMP caused the leaking of vessels in the brain, leakage that has been linked to small problems with thinking and memory recollection. These effects could last up to 12 hours after the exposure. Due to the long exposure time needed to see any of these effects it is unlikely that anyone would see these effects even if exposed for a small period of time. Also, the human body will see little effect as signals are passed chemically and not electrically making it hard to be affected by EMP waves.", "section_idx": 5, "section_name": "Effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The United States EMP Commission was created by the United States Congress in 2001. The commission is formally known as the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack.", "section_idx": 6, "section_name": "Post–Cold War attack scenarios", "target_page_ids": [ 31756 ], "anchor_spans": [ [ 52, 74 ] ] }, { "plaintext": "The Commission brought together notable scientists and technologists to compile several reports. In 2008, the Commission released the \"Critical National Infrastructures Report\". This report describes the likely consequences of a nuclear EMP on civilian infrastructure. Although this report covered the United States, most of the information is applicable to other industrialized countries. The 2008 report was a follow-up to a more generalized report issued by the commission in 2004.", "section_idx": 6, "section_name": "Post–Cold War attack scenarios", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In written testimony delivered to the United States Senate in 2005, an EMP Commission staff member reported:", "section_idx": 6, "section_name": "Post–Cold War attack scenarios", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The United States EMP Commission determined that long-known protections are almost completely absent in the civilian infrastructure of the United States and that large parts of US military services were less-protected against EMP than during the Cold War. In public statements, the Commission recommended making electronic equipment and electrical components resistant to EMP – and maintaining spare parts inventories that would enable prompt repairs. The United States EMP Commission did not look at other nations.", "section_idx": 6, "section_name": "Post–Cold War attack scenarios", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In 2011, the Defense Science Board published a report about the ongoing efforts to defend critical military and civilian systems against EMP and other nuclear weapons effects.", "section_idx": 6, "section_name": "Post–Cold War attack scenarios", "target_page_ids": [ 1374790 ], "anchor_spans": [ [ 13, 34 ] ] }, { "plaintext": "The United States military services developed, and in some cases published, hypothetical EMP attack scenarios.", "section_idx": 6, "section_name": "Post–Cold War attack scenarios", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In 2016, the Los Alamos Laboratory started phase 0 of a multi-year study (through to phase 3) to investigate EMPs which prepared the strategy to be followed for the rest of the study.", "section_idx": 6, "section_name": "Post–Cold War attack scenarios", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In 2017, the US Department of Energy published the \"DOE Electromagnetic Pulse Resilience Action Plan\", Edwin Boston published a dissertation on the topic and the EMP Commission published \"Assessing the threat from electromagnetic pulse (EMP)\". The EMP commission was closed in summer 2017. They found that earlier reports had underestimated the effects of an EMP attack on the national infrastructure, highlighted issues with communications from the DoD due to the classified nature of the material, and recommended that the DHS instead of going to the DOE for guidance and direction should directly cooperate with the more knowledgeable parts of the DOE. Several reports are in process of being released to the general public.", "section_idx": 6, "section_name": "Post–Cold War attack scenarios", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The problem of protecting civilian infrastructure from electromagnetic pulse has been intensively studied throughout the European Union, and in particular by the United Kingdom.", "section_idx": 7, "section_name": "Protecting infrastructure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "As of 2017, several power utility companies in the United States had been involved in a three-year research program on the impact of HEMP to the United States power grid led by an industry non-profit organization, Electric Power Research Institute (EPRI).", "section_idx": 7, "section_name": "Protecting infrastructure", "target_page_ids": [ 171136, 8531714 ], "anchor_spans": [ [ 20, 43 ], [ 214, 247 ] ] }, { "plaintext": "In 2018, the US Department of Homeland Security released the Strategy for Protecting and Preparing the Homeland against Threats from Electromagnetic Pulse (EMP) and Geomagnetic Disturbance (GMD), which was the Department’s first articulation of a holistic, long-term, partnership-based approach to protecting critical infrastructure and preparing to respond and recover from potentially catastrophic electromagnetic incidents. Progress on that front is described in the EMP Program Status Report.", "section_idx": 7, "section_name": "Protecting infrastructure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "NuScale, the small modular nuclear reactor company from Oregon, US, has made their reactor resistant to EMP.", "section_idx": 7, "section_name": "Protecting infrastructure", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Automated monitoring and controlled systems also known as supervisory control and data acquisition (SCADA) systems are the backbone of the computer age. They are critical for mass data transformation across the globe. These systems control fuel lines, water management, and controlling the grid. These systems are not usually in populated environments, but in remote locations and operate autonomously. By being in remote operation it leaves them heavily susceptible to EMP attacks. Due to the nature of these systems companies are investing billions of dollars each year into developing safer SCADA systems to protect them from EMP blasts to prevent massive infrastructure damages. With the protection of these systems EMP attacks would pose little threat to the infrastructure as water, fuel, and electricity would still be able to flow. However, this is a huge cost as the systems are highly complex and integrated throughout each system and would take years to replace.", "section_idx": 7, "section_name": "Protecting infrastructure", "target_page_ids": [ 62437 ], "anchor_spans": [ [ 100, 105 ] ] }, { "plaintext": "Especially since the 1980s, nuclear EMP weapons have gained a significant presence in fiction and popular culture.", "section_idx": 8, "section_name": "In fiction and popular culture", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The popular media often depict EMP effects incorrectly, causing misunderstandings among the public and even professionals, and official efforts have been made in the United States to set the record straight. The United States Space Command commissioned science educator Bill Nye to produce a video called \"Hollywood vs. EMP\" so that inaccurate Hollywood fiction would not confuse those who must deal with real EMP events. The video is not available to the general public.", "section_idx": 8, "section_name": "In fiction and popular culture", "target_page_ids": [ 742825, 10276064 ], "anchor_spans": [ [ 212, 239 ], [ 270, 278 ] ] }, { "plaintext": " A 21st Century Complete Guide to Electromagnetic Pulse (EMP) Attack Threats, Report of the Commission to Assess the Threat to the United States from Electromagnetic ... High-Altitude Nuclear Weapon EMP Attacks (CD-ROM), ", "section_idx": 11, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Threat posed by electromagnetic pulse (EMP) to U.S. military systems and civil infrastructure: Hearing before the Military Research and Development Subcommittee – first session, hearing held July 16, 1997, ", "section_idx": 11, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Electromagnetic Pulse Radiation and Protective Techniques, ", "section_idx": 11, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " GlobalSecurity.org – Electromagnetic Pulse: From chaos to a manageable solution", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Electromagnetic Pulse (EMP) and Tempest Protection for Facilities U.S. Army Corps of Engineers", "section_idx": 12, "section_name": "External links", "target_page_ids": [ 83180 ], "anchor_spans": [ [ 68, 96 ] ] }, { "plaintext": " EMP data from Starfish nuclear test measured by Richard Wakefield of LANL, and review of evidence pertaining to the effects 1,300 km away in Hawaii, also review of Russian EMP tests of 1962", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Read Congressional Research Service (CRS) Reports regarding HEMP", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " MIL-STD-188-125-1", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " How E-Bombs Work", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " NEMP and Nuclear plant", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " U.S. Presidential Executive Order concerning EMP", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Protecting Electrical Equipment: good practice for preventing high altitude electromagnetic pulse impacts, De Gruyter, 2019", "section_idx": 12, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Electromagnetic_radiation", "Energy_weapons", "Nuclear_weapons", "Electromagnetic_compatibility", "Bombs", "Electronic_warfare", "Pulsed_power" ]

[ "electromagnetic pulse", "EMP", "NEMP", "nuclear EMP" ]

[ { "plaintext": "Electromagnetic radiation can be classified into two types: ionizing radiation and non-ionizing radiation, based on the capability of a single photon with more than 10eV energy to ionize atoms or break chemical bonds. Extreme ultraviolet and higher frequencies, such as X-rays or gamma rays are ionizing, and these pose their own special hazards: see radiation poisoning.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9426, 202522, 30872182, 23535, 9598, 5993, 3436141, 34197, 18616290, 151196 ], "anchor_spans": [ [ 0, 25 ], [ 60, 78 ], [ 83, 105 ], [ 143, 149 ], [ 167, 169 ], [ 202, 215 ], [ 218, 237 ], [ 270, 275 ], [ 280, 289 ], [ 351, 370 ] ] }, { "plaintext": "The most common health hazard of radiation is sunburn, which causes between approximately 100,000 and 1 million new skin cancers annually in the United States.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 20647810 ], "anchor_spans": [ [ 46, 53 ] ] }, { "plaintext": "In 2011, the World Health Organization (WHO) and the International Agency for Research on Cancer (IARC) have classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (Group 2B).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33583, 1855289, 6445 ], "anchor_spans": [ [ 13, 38 ], [ 53, 96 ], [ 170, 182 ] ] }, { "plaintext": "Dielectric heating from electromagnetic fields can create a biological hazard. For example, touching or standing around an antenna while a high-power transmitter is in operation can cause burns (the mechanism is the same as that used in a microwave oven).", "section_idx": 1, "section_name": "Hazards", "target_page_ids": [ 1916136, 187317, 61164, 58017 ], "anchor_spans": [ [ 0, 18 ], [ 123, 130 ], [ 150, 161 ], [ 239, 253 ] ] }, { "plaintext": "The heating effect varies with the power and the frequency of the electromagnetic energy, as well as the inverse square of distance to the source. The eyes and testes are particularly susceptible to radio frequency heating due to the paucity of blood flow in these areas that could otherwise dissipate the heat buildup.", "section_idx": 1, "section_name": "Hazards", "target_page_ids": [ 10779, 41288 ], "anchor_spans": [ [ 49, 58 ], [ 105, 119 ] ] }, { "plaintext": "Radio frequency (RF) energy at power density levels of 1–10mW/cm2 or higher can cause measurable heating of tissues. Typical RF energy levels encountered by the general public are well below the level needed to cause significant heating, but certain workplace environments near high power RF sources may exceed safe exposure limits. A measure of the heating effect is the specific absorption rate or SAR, which has units of watts per kilogram (W/kg). The IEEE and many national governments have established safety limits for exposure to various frequencies of electromagnetic energy based on SAR, mainly based on ICNIRP Guidelines, which guard against thermal damage.", "section_idx": 1, "section_name": "Hazards", "target_page_ids": [ 970650, 56938, 970650 ], "anchor_spans": [ [ 372, 396 ], [ 455, 459 ], [ 592, 595 ] ] }, { "plaintext": "The World Health Organization (WHO) began a research effort in 1996 to study the health effects from the ever-increasing exposure of people to a diverse range of EMR sources. In 2011, the WHO/International Agency for Research on Cancer (IARC) has classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (Group 2B), based on an increased risk for glioma, a malignant type of brain cancer, associated with wireless phone use.", "section_idx": 1, "section_name": "Hazards", "target_page_ids": [ 33583 ], "anchor_spans": [ [ 4, 35 ] ] }, { "plaintext": "Epidemiological studies look for statistical correlations between EM exposure in the field and specific health effects. As of 2019, much of the current work is focused on the study of EM fields in relation to cancer. There are publications which support the existence of complex biological and neurological effects of weaker non-thermal electromagnetic fields (see Bioelectromagnetics), including weak ELF electromagnetic fields and modulated RF and microwave fields.", "section_idx": 1, "section_name": "Hazards", "target_page_ids": [ 3108062, 366253, 42852, 20097 ], "anchor_spans": [ [ 365, 384 ], [ 402, 405 ], [ 443, 445 ], [ 450, 459 ] ] }, { "plaintext": "While the most acute exposures to harmful levels of electromagnetic radiation are immediately realized as burns, the health effects due to chronic or occupational exposure may not manifest effects for months or years.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Extremely low frequency EM waves can span from 0 Hz to 3 kHz, though definitions vary across disciplines. The maximum recommended exposure for the general public is 5 kV/m.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 366253 ], "anchor_spans": [ [ 0, 23 ] ] }, { "plaintext": "ELF waves around 50 Hz to 60 Hz are emitted by power generators, transmission lines and distribution lines, power cables, and electric appliances. Typical household exposure to ELF waves ranges in intensity from 5 V/m for a light bulb to 180 V/m for a stereo, measured at and using 240V power. (120V power systems would be unable to reach this intensity unless an appliance has an internal voltage transformer.) Overhead power lines range from 1kV for local distribution to 1,150 kV for ultra high voltage lines. These can produce electric fields up to 10kV/m on the ground directly underneath, but 50 m to 100 m away these levels return to approximately ambient. Metal equipment must be maintained at a safe distance from energized high-voltage lines.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 9540, 38824, 212253, 1480601, 185982, 1355057 ], "anchor_spans": [ [ 47, 62 ], [ 65, 83 ], [ 88, 106 ], [ 108, 119 ], [ 126, 144 ], [ 413, 432 ] ] }, { "plaintext": "Exposure to ELF waves can induce an electric current. Because the human body is conductive, electric currents and resulting voltages differences typically accumulate on the skin but do not reach interior tissues. People can start to perceive high-voltage charges as tingling when hair or clothing in contact with the skin stands up or vibrates. In scientific tests, only about 10% of people could detect a field intensity in the range of 2-5 kV/m. Such voltage differences can also create electric sparks, similar to a discharge of static electricity when nearly touching a grounded object. When receiving such a shock at 5 kV/m, it was reported as painful by only 7% of test participants and by 50% of participants at 10 kV/m.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 200136 ], "anchor_spans": [ [ 532, 550 ] ] }, { "plaintext": "The International Agency for Research on Cancer (IARC) finds \"inadequate evidence\" for human carcinogenicity.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Shortwave (1.6 to 30MHz) diathermy (where EM waves are used to produce heat) can be used as a therapeutic technique for its analgesic effect and deep muscle relaxation, but has largely been replaced by ultrasound. Temperatures in muscles can increase by 4–6°C, and subcutaneous fat by 15°C. The FCC has restricted the frequencies allowed for medical treatment, and most machines in the US use 27.12MHz. Shortwave diathermy can be applied in either continuous or pulsed mode. The latter came to prominence because the continuous mode produced too much heating too rapidly, making patients uncomfortable. The technique only heats tissues that are good electrical conductors, such as blood vessels and muscle. Adipose tissue (fat) receives little heating by induction fields because an electrical current is not actually going through the tissues.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 57980, 712377, 2246, 31780, 48530, 380541, 419094 ], "anchor_spans": [ [ 0, 9 ], [ 25, 34 ], [ 124, 133 ], [ 202, 212 ], [ 681, 694 ], [ 699, 705 ], [ 707, 721 ] ] }, { "plaintext": "Studies have been performed on the use of shortwave radiation for cancer therapy and promoting wound healing, with some success. However, at a sufficiently high energy level, shortwave energy can be harmful to human health, potentially causing damage to biological tissues, for example by overheating or inducing electrical currents. The FCC limits for maximum permissible workplace exposure to shortwave radio frequency energy in the range of 3–30MHz has a plane-wave equivalent power density of (900/f2)mW/cm2 where f is the frequency in MHz, and 100mW/cm2 from 0.3 to 3.0MHz. For uncontrolled exposure to the general public, the limit is 180/f2 between 1.34 and 30MHz.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 2207861 ], "anchor_spans": [ [ 480, 493 ] ] }, { "plaintext": "The designation of mobile phone signals as \"possibly carcinogenic to humans\" by the World Health Organization (WHO) (e.g. its IARC, see below) has often been misinterpreted as indicating that some measure of risk has been observed however the designation indicates only that the possibility could not be conclusively ruled out using the available data.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 6445, 33583 ], "anchor_spans": [ [ 53, 63 ], [ 84, 109 ] ] }, { "plaintext": "In 2011, International Agency for Research on Cancer (IARC) classified mobile phone radiation as Group 2B \"possibly carcinogenic\" (rather than Group 2A \"probably carcinogenic\" nor the \"is carcinogenic\" Group 1). That means that there \"could be some risk\" of carcinogenicity, so additional research into the long-term, heavy use of mobile phones needs to be conducted. The WHO concluded in 2014 that \"A large number of studies have been performed over the last two decades to assess whether mobile phones pose a potential health risk. To date, no adverse health effects have been established as being caused by mobile phone use.\"", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 1855289, 1917748, 1882377, 33583 ], "anchor_spans": [ [ 9, 59 ], [ 97, 105 ], [ 143, 151 ], [ 372, 375 ] ] }, { "plaintext": "Since 1962, the microwave auditory effect or tinnitus has been shown from radio frequency exposure at levels below significant heating. Studies during the 1960s in Europe and Russia claimed to show effects on humans, especially the nervous system, from low energy RF radiation; the studies were disputed at the time.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 57331 ], "anchor_spans": [ [ 16, 41 ] ] }, { "plaintext": "In 2019, reporters from the Chicago Tribune tested the level of radiation from smartphones and found that certain models emitted more than reported by the manufacturers and in some cases more than the U.S. Federal Communications Commission exposure limit. It is unclear if this resulted in any harm to consumers. Some problems apparently involved the phone's ability to detect proximity to a human body and lower the radio power. In response, the FCC began testing some phones itself rather than relying solely on manufacturer certifications.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 60961, 55974 ], "anchor_spans": [ [ 28, 43 ], [ 206, 239 ] ] }, { "plaintext": "Microwave and other radio frequencies cause heating, and this can cause burns or eye damage if delivered in high intensity, or hyperthermia as with any powerful heat source. Microwave ovens use this form of radiation, and have shielding to prevent it from leaking out and unintentionally heating nearby objects or people.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 20097, 27625957, 75654, 58017 ], "anchor_spans": [ [ 0, 9 ], [ 72, 77 ], [ 127, 139 ], [ 174, 188 ] ] }, { "plaintext": "In 2009, the US TSA introduced full-body scanners as a primary screening modality in airport security, first as backscatter X-ray scanners, which use ionizing radiation and which the European Union banned in 2011 due to health and safety concerns. These were followed by non-ionizing millimeter wave scanners . Likewise WiGig for personal area networks have opened the 60GHz and above microwave band to SAR exposure regulations. Previously, microwave applications in these bands were for point-to-point satellite communication with minimal human exposure.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 284770, 1203072, 16959357, 22781658, 23303 ], "anchor_spans": [ [ 85, 101 ], [ 112, 137 ], [ 284, 307 ], [ 320, 325 ], [ 330, 351 ] ] }, { "plaintext": "Infrared wavelengths longer than 750nm can produce changes in the lens of the eye. Glassblower's cataract is an example of a heat injury that damages the anterior lens capsule among unprotected glass and iron workers. Cataract-like changes can occur in workers who observe glowing masses of glass or iron without protective eyewear for prolonged periods over many years.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 15022, 41672221, 3940682 ], "anchor_spans": [ [ 0, 8 ], [ 83, 105 ], [ 154, 167 ] ] }, { "plaintext": "Exposing skin to infrared radiation near visible light (IR-A) leads to increased production of free radicals. Short-term exposure can be beneficial (activating protective responses), while prolonged exposure can lead to photoaging.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 19916613, 22290971 ], "anchor_spans": [ [ 95, 108 ], [ 220, 230 ] ] }, { "plaintext": "Another important factor is the distance between the worker and the source of radiation. In the case of arc welding, infrared radiation decreases rapidly as a function of distance, so that farther than three feet away from where welding takes place, it does not pose an ocular hazard anymore but, ultraviolet radiation still does. This is why welders wear tinted glasses and surrounding workers only have to wear clear ones that filter UV.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 440996 ], "anchor_spans": [ [ 104, 115 ] ] }, { "plaintext": "Photic retinopathy is damage to the macular area of the eye's retina that results from prolonged exposure to sunlight, particularly with dilated pupils. This can happen, for example, while observing a solar eclipse without suitable eye protection. The Sun's radiation creates a photochemical reaction that can result in visual dazzling and a scotoma. The initial lesions and edema will disappear after several weeks, but may leave behind a permanent reduction in visual acuity.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 51178220, 252035, 207737, 5024887, 53090773, 849874, 70426 ], "anchor_spans": [ [ 0, 18 ], [ 36, 68 ], [ 137, 150 ], [ 201, 214 ], [ 320, 335 ], [ 342, 349 ], [ 375, 380 ] ] }, { "plaintext": "Moderate and high-power lasers are potentially hazardous because they can burn the retina of the eye, or even the skin. To control the risk of injury, various specifications – for example ANSI Z136 in the US, EN 60825-1/A2 in Europe, and IEC 60825 internationally – define \"classes\" of lasers depending on their power and wavelength. Regulations prescribe required safety measures, such as labeling lasers with specific warnings, and wearing laser safety goggles during operation (see laser safety).", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 48334, 27978, 1101848 ], "anchor_spans": [ [ 83, 89 ], [ 114, 118 ], [ 485, 497 ] ] }, { "plaintext": "As with its infrared and ultraviolet radiation dangers, welding creates an intense brightness in the visible light spectrum, which may cause temporary flash blindness. Some sources state that there is no minimum safe distance for exposure to these radiation emissions without adequate eye protection.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 6922153 ], "anchor_spans": [ [ 151, 166 ] ] }, { "plaintext": "Sunlight includes sufficient ultraviolet power to cause sunburn within hours of exposure, and the burn severity increases with the duration of exposure. This effect is a response of the skin called erythema, which is caused by a sufficient strong dose of UV-B. The Sun's UV output is divided into UV-A and UV-B: solar UV-A flux is 100 times that of UV-B, but the erythema response is 1,000 times higher for UV-B. This exposure can increase at higher altitudes and when reflected by snow, ice, or sand. The UV-B flux is 2–4 times greater during the middle 4–6 hours of the day, and is not significantly absorbed by cloud cover or up to a meter of water.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 20647810, 532849, 31990, 31990 ], "anchor_spans": [ [ 56, 63 ], [ 198, 206 ], [ 255, 259 ], [ 297, 301 ] ] }, { "plaintext": "Ultraviolet light, specifically UV-B, has been shown to cause cataracts and there is some evidence that sunglasses worn at an early age can slow its development in later life. Most UV light from the sun is filtered out by the atmosphere and consequently airline pilots often have high rates of cataracts because of the increased levels of UV radiation in the upper atmosphere. It is hypothesized that depletion of the ozone layer and a consequent increase in levels of UV light on the ground may increase future rates of cataracts. Note that the lens filters UV light, so if it is removed via surgery, one may be able to see UV light.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 88931, 44183 ], "anchor_spans": [ [ 62, 71 ], [ 402, 430 ] ] }, { "plaintext": "Prolonged exposure to ultraviolet radiation from the sun can lead to melanoma and other skin malignancies. Clear evidence establishes ultraviolet radiation, especially the non-ionizing medium wave UVB, as the cause of most non-melanoma skin cancers, which are the most common forms of cancer in the world. UV rays can also cause wrinkles, liver spots, moles, and freckles. In addition to sunlight, other sources include tanning beds, and bright desk lights. Damage is cumulative over one's lifetime, so that permanent effects may not be evident for some time after exposure.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 31990, 26751, 716631, 31990, 64993, 653750, 4286150, 50524, 58180, 541499 ], "anchor_spans": [ [ 22, 43 ], [ 53, 56 ], [ 69, 77 ], [ 197, 200 ], [ 236, 247 ], [ 330, 338 ], [ 340, 350 ], [ 353, 358 ], [ 364, 372 ], [ 421, 433 ] ] }, { "plaintext": "Ultraviolet radiation of wavelengths shorter than 300nm (actinic rays) can damage the corneal epithelium. This is most commonly the result of exposure to the sun at high altitude, and in areas where shorter wavelengths are readily reflected from bright surfaces, such as snow, water, and sand. UV generated by a welding arc can similarly cause damage to the cornea, known as \"arc eye\" or welding flash burn, a form of photokeratitis.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 31990, 5306317, 44883, 240096 ], "anchor_spans": [ [ 57, 69 ], [ 86, 104 ], [ 314, 321 ], [ 420, 434 ] ] }, { "plaintext": "Fluorescent light bulbs and tubes internally produce ultraviolet light. Normally this is converted to visible light by the phosphor film inside a protective coating. When the film is cracked by mishandling or faulty manufacturing then UV may escape at levels that could cause sunburn or even skin cancer.", "section_idx": 2, "section_name": "Effects by frequency", "target_page_ids": [ 144056, 31990, 88444 ], "anchor_spans": [ [ 0, 17 ], [ 53, 64 ], [ 123, 131 ] ] }, { "plaintext": "In the United States, nonionizing radiation is regulated in the Radiation Control for Health and Safety Act of 1968 and the Occupational Safety and Health Act of 1970.", "section_idx": 3, "section_name": "Regulation", "target_page_ids": [ 44838369, 461036 ], "anchor_spans": [ [ 64, 115 ], [ 124, 166 ] ] }, { "plaintext": " Background radiation", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 4882 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " BioInitiative Report", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 25180841 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Biological effects of radiation on the epigenome", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 56379488 ], "anchor_spans": [ [ 1, 49 ] ] }, { "plaintext": " Central nervous system effects from radiation exposure during spaceflight", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 39761773 ], "anchor_spans": [ [ 1, 74 ] ] }, { "plaintext": " Cosmic ray", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 47687 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " COSMOS cohort study", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 27075748 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Electromagnetic hypersensitivity", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 4217297 ], "anchor_spans": [ [ 1, 33 ] ] }, { "plaintext": " Electromagnetism", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 9532 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " EMF measurements", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 23547932 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Health threat from cosmic rays", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 14415787 ], "anchor_spans": [ [ 1, 31 ] ] }, { "plaintext": " Light ergonomics", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 14047716 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Magnetobiology", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 11991342 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Microwave", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 20097 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Mobile phone radiation and health", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 1272748 ], "anchor_spans": [ [ 1, 34 ] ] }, { "plaintext": " Personal RF safety monitors", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 35152779 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Specific absorption rate", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 970650 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Wireless electronic devices and health", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 1272748 ], "anchor_spans": [ [ 1, 39 ] ] }, { "plaintext": " (over 100 pages)", "section_idx": 6, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Information page on electromagnetic fields at the World Health Organization web site", "section_idx": 7, "section_name": "External links", "target_page_ids": [ 33583 ], "anchor_spans": [ [ 51, 76 ] ] }, { "plaintext": " CDC – Electric and Magnetic Fields – NIOSH Workplace Safety and Health Topic", "section_idx": 7, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Environmental_controversies", "Medical_physics", "Radiation_health_effects", "Radiobiology", "Health_effects_by_subject" ]

[ "electromagnetic radiation and health", "Microwave Sickness" ]

[ { "plaintext": "In telecommunication, electromagnetic survivability is the ability of a system, subsystem, or equipment to resume functioning without evidence of degradation following temporary exposure to an adverse electromagnetic environment. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 8286675, 7876158, 41094 ], "anchor_spans": [ [ 3, 20 ], [ 72, 78 ], [ 146, 157 ], [ 201, 228 ] ] }, { "plaintext": "The system, subsystem, or equipment performance may be degraded during exposure to the adverse electromagnetic environment, but the system will not experience permanent damage, such as component burnout, that will prevent proper operation when the adverse electromagnetic environment is removed.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1886820 ], "anchor_spans": [ [ 185, 194 ] ] } ]

[ "Telecommunications_engineering", "Fault_tolerance" ]

[]

[ { "plaintext": "In telecommunication, the term electronic deception means the deliberate radiation, reradiation, alteration, suppression, absorption, denial, enhancement, or reflection of electromagnetic energy in a manner intended to convey misleading information and to deny valid information to an enemy or to enemy electronics-dependent weapons.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 25856, 41658, 1384005, 521267, 18985062 ], "anchor_spans": [ [ 3, 20 ], [ 73, 82 ], [ 84, 95 ], [ 122, 132 ], [ 158, 168 ], [ 237, 248 ] ] }, { "plaintext": "Among the types of electronic deception are:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Manipulative electronic deception – Actions to eliminate revealing or convey misleading, telltale indicators that may be used by hostile forces", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Simulative electronic deception – Actions to represent friendly notional or actual capabilities to mislead hostile forces", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Imitative electronic deception – The introduction of electromagnetic energy into enemy systems that imitates enemy emissions.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Simulated reality", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 247365 ], "anchor_spans": [ [ 0, 17 ] ] } ]

[ "Deception" ]

[]

[ { "plaintext": "In telecommunications, an electronic switching system (ESS) is a telephone switch that uses solid-state electronics, such as digital electronics and computerized common control, to interconnect telephone circuits for the purpose of establishing telephone calls.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 26668156, 3656002, 39068, 7878457, 40911 ], "anchor_spans": [ [ 3, 20 ], [ 65, 81 ], [ 92, 115 ], [ 125, 144 ], [ 149, 157 ], [ 162, 176 ] ] }, { "plaintext": "The generations of telephone switches before the advent of electronic switching in the 1950s used purely electro-mechanical relay systems and analog voice paths. These early machines typically utilized the step-by-step technique. The first generation of electronic switching systems in the 1960s were not entirely digital in nature, but used reed relay-operated metallic paths or crossbar switches operated by stored program control (SPC) systems.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 31322120, 831609, 7145306, 45456, 7092252 ], "anchor_spans": [ [ 105, 123 ], [ 206, 218 ], [ 342, 352 ], [ 380, 395 ], [ 410, 432 ] ] }, { "plaintext": "First announced in 1955, the first customer trial installation of an all-electronic central office commenced in Morris, Illinois in November 1960 by Bell Laboratories. The first large-scale electronic switching system was the Number One Electronic Switching System (1ESS) of the Bell System, cut over in Succasunna, New Jersey, in May 1965.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 26668156, 111243, 14849, 3712, 8340179, 21347591, 629310, 21648 ], "anchor_spans": [ [ 84, 98 ], [ 112, 118 ], [ 120, 128 ], [ 149, 166 ], [ 226, 264 ], [ 279, 290 ], [ 304, 314 ], [ 316, 326 ] ] }, { "plaintext": "The adoption of metal–oxide–semiconductor (MOS) and pulse-code modulation (PCM) technologies in the 1970s led to the transition from analog to digital telephony. Later electronic switching systems implemented the digital representation of the electrical audio signals on subscriber loops by digitizing the analog signals and processing the resulting data for transmission between central offices. Time-division multiplexing (TDM) technology permitted the simultaneous transmission of multiple telephone calls on a single wire connection between central offices or other electronic switches, resulting in dramatic capacity improvements of the telephone network.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40345, 25513330, 41831, 59602, 41796, 468436 ], "anchor_spans": [ [ 16, 41 ], [ 52, 73 ], [ 143, 160 ], [ 271, 286 ], [ 397, 423 ], [ 642, 659 ] ] }, { "plaintext": "With the advances of digital electronics starting in the 1960s telephone switches employed semiconductor device components in increasing measure.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40344 ], "anchor_spans": [ [ 91, 111 ] ] }, { "plaintext": "In the late 20th century most telephone exchanges without TDM processing were eliminated and the term electronic switching system became largely a historical distinction for the older SPC systems.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "List of telephone switches", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 737780 ], "anchor_spans": [ [ 0, 26 ] ] }, { "plaintext": "Stored program control", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 7092252 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "5ESS Switching System", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 35511 ], "anchor_spans": [ [ 0, 21 ] ] } ]

[ "Telephone_exchanges" ]

[]

[ { "plaintext": "In military telecommunications, electronic support (ES) or electronic support measures (ESM) gather intelligence through passive \"listening\" to electromagnetic radiations of military interest. They are an aspect of electronic warfare involving actions taken under direct control of an operational commander to detect, intercept, identify, locate, record, and/or analyze sources of radiated electromagnetic energy for the purposes of immediate threat recognition (such as warning that fire control RADAR has locked on a combat vehicle, ship, or aircraft) or longer-term operational planning. Thus, electronic support provides a source of information required for decisions involving electronic protection (EP), electronic attack (EA), avoidance, targeting, and other tactical employment of forces. Electronic support data can be used to produce signals intelligence (SIGINT), communications intelligence (COMINT) and electronics intelligence (ELINT).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 82272, 29122, 720630, 25676, 18985062, 1376411, 879940, 18985040, 29122, 29122, 29122 ], "anchor_spans": [ [ 12, 29 ], [ 215, 233 ], [ 318, 327 ], [ 443, 449 ], [ 497, 502 ], [ 638, 649 ], [ 683, 704 ], [ 711, 728 ], [ 817, 821 ], [ 845, 865 ], [ 876, 903 ], [ 917, 941 ] ] }, { "plaintext": "Electronic support measures can provide (1) initial detection or knowledge of foreign systems, (2) a library of technical and operational data on foreign systems, and (3) tactical combat information utilizing that library. ESM collection platforms can remain electronically silent and detect and analyze RADAR transmissions beyond the RADAR detection range because of the greater power of the transmitted electromagnetic pulse with respect to a reflected echo of that pulse. United States airborne ESM receivers are designated in the AN/ALR series.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 39519079 ], "anchor_spans": [ [ 406, 427 ] ] }, { "plaintext": "Desirable characteristics for electromagnetic surveillance and collection equipment include (1) wide-spectrum or bandwidth capability because foreign frequencies are initially unknown, (2) wide dynamic range because signal strength is initially unknown, (3) narrow bandpass to discriminate the signal of interest from other electromagnetic radiation on nearby frequencies, and (4) good angle-of arrival measurement for bearings to locate the transmitter. The frequency spectrum of interest ranges from 30MHz to 50GHz. Multiple receivers are typically required for surveillance of the entire spectrum, but tactical receivers may be functional within a specific signal strength threshold of a smaller frequency range.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " AWACS", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 236466 ], "anchor_spans": [ [ 1, 6 ] ] }, { "plaintext": " Boeing E-3 Sentry", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 10384 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Boeing E-4", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 440894 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Electronic warfare", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 82272 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Electronic countermeasure", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 879940 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Lockheed Orion", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 162863 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Low-probability-of-intercept radar", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 1382559 ], "anchor_spans": [ [ 1, 35 ] ] }, { "plaintext": " MGARJS", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 4687087 ], "anchor_spans": [ [ 1, 7 ] ] } ]

[ "Military_technology", "Military_communications", "Electronic_warfare" ]

[ "electronic support measures", "ESM", "Electronic warfare Support, ES" ]

[ { "plaintext": "An electro–optic effect is a change in the optical properties of a material in response to an electric field that varies slowly compared with the frequency of light. The term encompasses a number of distinct phenomena, which can be subdivided into", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41092 ], "anchor_spans": [ [ 94, 108 ] ] }, { "plaintext": " a) change of the absorption", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1384005 ], "anchor_spans": [ [ 18, 28 ] ] }, { "plaintext": " Electroabsorption: general change of the absorption constants", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Franz–Keldysh effect: change in the absorption shown in some bulk semiconductors", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 4204003 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Quantum-confined Stark effect: change in the absorption in some semiconductor quantum wells", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22236319, 642886 ], "anchor_spans": [ [ 1, 30 ], [ 79, 91 ] ] }, { "plaintext": " Electrochromic effect: creation of an absorption band at some wavelengths, which gives rise to a change in colour", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1586159 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " b) change of the refractive index and permittivity", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 25880, 53933 ], "anchor_spans": [ [ 18, 34 ], [ 39, 51 ] ] }, { "plaintext": " Pockels effect (or linear electro-optic effect): change in the refractive index linearly proportional to the electric field. Only certain crystalline solids show the Pockels effect, as it requires lack of inversion symmetry", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 637733 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Kerr effect (or quadratic electro-optic effect, QEO effect): change in the refractive index proportional to the square of the electric field. All materials display the Kerr effect, with varying magnitudes, but it is generally much weaker than the Pockels effect", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 661039 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " electro-gyration: change in the optical activity.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 39774 ], "anchor_spans": [ [ 33, 49 ] ] }, { "plaintext": " Electron-refractive effect or EIPM", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 39846248 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": "In December 2015, two further electro-optic effects of type (b) were theoretically predicted to exist but have not, as yet, been experimentally observed.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Changes in absorption can have a strong effect on refractive index for wavelengths near the absorption edge, due to the Kramers–Kronig relation.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2481686 ], "anchor_spans": [ [ 120, 143 ] ] }, { "plaintext": "Using a less strict definition of the electro-optic effect allowing also electric fields oscillating at optical frequencies, one could also include nonlinear absorption (absorption depends on the light intensity) to category a) and the optical Kerr effect (refractive index depends on the light intensity) to category b). Combined with the photoeffect and photoconductivity, the electro-optic effect gives rise to the photorefractive effect.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 661039, 23579, 60885, 625318 ], "anchor_spans": [ [ 236, 255 ], [ 340, 351 ], [ 356, 373 ], [ 418, 440 ] ] }, { "plaintext": "The term \"electro-optic\" is often erroneously used as a synonym for \"optoelectronic\".", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 132883 ], "anchor_spans": [ [ 69, 83 ] ] }, { "plaintext": "Electro-optic modulators are usually built with electro-optic crystals exhibiting the Pockels effect. The transmitted beam is phase modulated with the electric signal applied to the crystal. Amplitude modulators can be built by putting the electro-optic crystal between two linear polarizers or in one path of a Mach–Zehnder interferometer.", "section_idx": 1, "section_name": "Main applications", "target_page_ids": [ 20637, 24772, 1140, 2722105, 579755 ], "anchor_spans": [ [ 14, 23 ], [ 126, 141 ], [ 191, 210 ], [ 281, 290 ], [ 312, 339 ] ] }, { "plaintext": "Additionally, Amplitude modulators can be constructed by deflecting the beam into and out of a small aperture such as a fiber. This design can be low loss (<3dB) and polarization independent depending on the crystal configuration.", "section_idx": 1, "section_name": "Main applications", "target_page_ids": [ 1140 ], "anchor_spans": [ [ 14, 33 ] ] }, { "plaintext": "Electro-optic deflectors utilize prisms of electro-optic crystals. The index of refraction is changed by the Pockels effect, thus changing the direction of propagation of the beam inside the prism. Electro-optic deflectors have only a small number of resolvable spots, but possess a fast response time. There are few commercial models available at this time. This is because of competing acousto-optic deflectors, the small number of resolvable spots and the relatively high price of electro-optic crystals.", "section_idx": 1, "section_name": "Main applications", "target_page_ids": [ 282998, 8906668 ], "anchor_spans": [ [ 33, 39 ], [ 388, 401 ] ] }, { "plaintext": "The electro-optic Pockels effect in nonlinear crystals (e.g. KDP, BSO, K*DP) can be used for electric field sensing via polarisation state modulation techniques. In this scenario, an unknown electric field results in polarisation rotation of a laser beam propagating through the electro-optic crystal; through inclusion of polarisers to modulate the light intensity incident on a photodiode, a time-resolved electric field measurement can be reconstructed from the obtained voltage trace. As the signals obtained from vgccthe crystalline probes are optical, they are inherently resistant to electrical noise pickup, hence can be used for low-noise field measurement even in areas with high levels of electromagnetic noise in the vicinity of the probe. Furthermore, as the polarisation rotation due to the Pockels effect scales linearly with electric field, absolute field measurements are obtained, with no need for numerical integration to reconstruct electric fields, as is the case with conventional probes sensitive to the time-derivative of the electric field. ", "section_idx": 1, "section_name": "Main applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Electro-optic measurements of strong electromagnetic pulses from intense laser-matter interactions have been demonstrated in both the nanosecond and picosecond (sub-petawatt) laser pulse driver regimes. ", "section_idx": 1, "section_name": "Main applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " AdvR - Electro-optic Devices & Research", "section_idx": 3, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Nonlinear_optics" ]

[]

[ { "plaintext": "An electro-optic modulator (EOM) is an optical device in which a signal-controlled element exhibiting an electro-optic effect is used to modulate a beam of light. The modulation may be imposed on the phase, frequency, amplitude, or polarization of the beam. Modulation bandwidths extending into the gigahertz range are possible with the use of laser-controlled modulators.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41103, 1612888, 20637, 24047, 10779, 37649, 41564, 14121, 17556 ], "anchor_spans": [ [ 105, 125 ], [ 148, 161 ], [ 167, 177 ], [ 200, 205 ], [ 207, 216 ], [ 218, 227 ], [ 232, 244 ], [ 299, 308 ], [ 344, 349 ] ] }, { "plaintext": "The electro-optic effect is the change in the refractive index of a material resulting from the application of a DC or low-frequency electric field. This is caused by forces that distort the position, orientation, or shape of the molecules constituting the material. Generally, a nonlinear optical material (organic polymers have the fastest response rates, and thus are best for this application) with an incident static or low frequency optical field will see a modulation of its refractive index.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41103, 21723, 23001, 9735, 25880 ], "anchor_spans": [ [ 4, 24 ], [ 280, 297 ], [ 308, 323 ], [ 439, 452 ], [ 482, 498 ] ] }, { "plaintext": "The simplest kind of EOM consists of a crystal, such as lithium niobate (LiNbO3), whose refractive index is a function of the strength of the local electric field. That means that if lithium niobate is exposed to an electric field, light will travel more slowly through it. But the phase of the light leaving the crystal is directly proportional to the length of time it takes that light to pass through it. Therefore, the phase of the laser light exiting an EOM can be controlled by changing the electric field in the crystal.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3243489, 41092, 3243489 ], "anchor_spans": [ [ 56, 71 ], [ 148, 162 ], [ 183, 198 ] ] }, { "plaintext": "Note that the electric field can be created by placing a parallel plate capacitor across the crystal. Since the field inside a parallel plate capacitor depends linearly on the potential, the index of refraction depends linearly on the field (for crystals where Pockels effect dominates), and the phase depends linearly on the index of refraction, the phase modulation must depend linearly on the potential applied to the EOM.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 4932111, 91591, 637733 ], "anchor_spans": [ [ 72, 81 ], [ 160, 168 ], [ 261, 275 ] ] }, { "plaintext": "The voltage required for inducing a phase change of is called the half-wave voltage (). For a Pockels cell, it is usually hundreds or even thousands of volts, so that a high-voltage amplifier is required. Suitable electronic circuits can switch such large voltages within a few nanoseconds, allowing the use of EOMs as fast optical switches.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 637733 ], "anchor_spans": [ [ 95, 107 ] ] }, { "plaintext": "Liquid crystal devices are electro-optical phase modulators if no polarizers are used.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 17932 ], "anchor_spans": [ [ 0, 22 ] ] }, { "plaintext": "Phase modulation (PM) is a modulation pattern that encodes information as variations in the instantaneous phase of a carrier wave.", "section_idx": 1, "section_name": "Phase modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The phase of a carrier signal is modulated to follow the changing voltage level (amplitude) of modulation signal. The peak amplitude and frequency of the carrier signal remain constant, but as the amplitude of the information signal changes, the phase of the carrier changes correspondingly. The analysis and the final result (modulated signal) are similar to those of frequency modulation.", "section_idx": 1, "section_name": "Phase modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A very common application of EOMs is for creating sidebands in a monochromatic laser beam. To see how this works, first imagine that the strength of a laser beam with frequency entering the EOM is given by", "section_idx": 1, "section_name": "Phase modulation", "target_page_ids": [ 41701, 261993, 10779 ], "anchor_spans": [ [ 50, 58 ], [ 65, 78 ], [ 168, 177 ] ] }, { "plaintext": "Now suppose we apply a sinusoidally varying potential voltage to the EOM with frequency and small amplitude . This adds a time dependent phase to the above expression,", "section_idx": 1, "section_name": "Phase modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Since is small, we can use the Taylor expansion for the exponential", "section_idx": 1, "section_name": "Phase modulation", "target_page_ids": [ 30448 ], "anchor_spans": [ [ 32, 48 ] ] }, { "plaintext": "to which we apply a simple identity for sine,", "section_idx": 1, "section_name": "Phase modulation", "target_page_ids": [ 5010838 ], "anchor_spans": [ [ 40, 44 ] ] }, { "plaintext": "This expression we interpret to mean that we have the original carrier signal plus two small sidebands, one at and another at . Notice however that we only used the first term in the Taylor expansion – in truth there are an infinite number of sidebands. There is a useful identity involving Bessel functions called the Jacobi–Anger expansion which can be used to derive", "section_idx": 1, "section_name": "Phase modulation", "target_page_ids": [ 153217, 4700, 13985992 ], "anchor_spans": [ [ 63, 77 ], [ 294, 310 ], [ 322, 344 ] ] }, { "plaintext": "which gives the amplitudes of all the sidebands. Notice that if one modulates the amplitude instead of the phase, one gets only the first set of sidebands, ", "section_idx": 1, "section_name": "Phase modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A phase modulating EOM can also be used as an amplitude modulator by using a Mach–Zehnder interferometer. This alternative technique is often used in integrated optics where the requirements of phase stability is more easily achieved. The beam splitter divides the laser light into two paths, one of which has a phase modulator as described above. The beams are then recombined. Changing the electric field on the phase modulating path will then determine whether the two beams interfere constructively or destructively at the output, and thereby control the amplitude or intensity of the exiting light. This device is called a Mach–Zehnder modulator.", "section_idx": 2, "section_name": "Amplitude modulation", "target_page_ids": [ 579755, 579755 ], "anchor_spans": [ [ 77, 104 ], [ 630, 652 ] ] }, { "plaintext": "Depending on the type and orientation of the nonlinear crystal, and on the direction of the applied electric field, the phase delay can depend on the polarization direction. A Pockels cell can thus be seen as a voltage-controlled waveplate, and it can be used for modulating the polarization state. For a linear input polarization (often oriented at 45° to the crystal axis), the output polarization will in general be elliptical, rather than simply a linear polarization state with a rotated direction.", "section_idx": 3, "section_name": "Polarization modulation", "target_page_ids": [ 637733 ], "anchor_spans": [ [ 176, 188 ] ] }, { "plaintext": "Polarization modulation in electro-optic crystals can also be used as a technique for time-resolved measurement of unknown electric fields. ", "section_idx": 3, "section_name": "Polarization modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Compared to conventional techniques using conductive field probes and cabling for signal transport to read-out systems, electro-optical measurement is inherently noise resistant as signals are carried by fiber-optics, preventing distortion of the signal by electrical noise sources. The polarization change measured by such techniques is linearly dependent on the electric field applied to the crystal, hence providing absolute measurements of the field, without the need for numerical integration of voltage traces, as is the case for conductive probes sensitive to the time-derivative of the electric field.", "section_idx": 3, "section_name": "Polarization modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Pockels effect", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 637733 ], "anchor_spans": [ [ 0, 14 ] ] }, { "plaintext": "Acousto-optic modulator", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 1855722 ], "anchor_spans": [ [ 0, 23 ] ] }, { "plaintext": "Phase modulation", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 24772 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Dielectric wireless receiver", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 13350759 ], "anchor_spans": [ [ 0, 28 ] ] }, { "plaintext": "Notes", "section_idx": 5, "section_name": "References", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Encyclopedia of Laser Physics and Technology", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Interactive visualization of the transfer characteristic of a Mach–Zehnder modulator for phase and amplitude modulation", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Optical_devices", "Nonlinear_optics", "Optoelectronics" ]

[ "EOM" ]

[ { "plaintext": "Electro–optics is a branch of electrical engineering, electronic engineering, materials science, and material physics involving components, devices (e.g. lasers, LEDs, waveguides, etc.) and systems which operate by the propagation and interaction of light with various tailored materials. It is essentially the same as what is popularly described today as photonics. It is not only concerned with the \"electro–optic effect\". Thus it concerns the interaction between the electromagnetic (optical) and the electrical (electronic) states of materials.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9531, 28923910, 19622, 19622, 17556, 18290, 41863, 184904, 41103, 9532, 22483, 9550, 9476 ], "anchor_spans": [ [ 30, 52 ], [ 54, 76 ], [ 78, 95 ], [ 101, 117 ], [ 154, 159 ], [ 162, 166 ], [ 168, 177 ], [ 356, 365 ], [ 402, 422 ], [ 470, 485 ], [ 487, 494 ], [ 504, 514 ], [ 516, 524 ] ] }, { "plaintext": "The electro-optic effect is a change in the optical properties of an optically active material due to interaction with light. This interaction usually results in a change in the birefringence, and not simply the refractive index of the medium. In a Kerr cell, the change in birefringence is proportional to the square of the optical electric field, and the material is usually a liquid. In a Pockels cell, the change in birefringence varies linearly with the electric field, and the material is usually a crystal. Non-crystalline, solid electro-optical materials have generated interest because of their low cost of production. These organic, polymer-based materials are also known as organic EO material, plastic EO material, or polymer EO material. They consist of nonlinear optical chromophores in a polymer lattice. The nonlinear optical chromophores can produce Pockels effect.", "section_idx": 1, "section_name": "Electro-optical devices", "target_page_ids": [ 41103, 174412, 661039, 637733, 2193362, 637733 ], "anchor_spans": [ [ 4, 24 ], [ 178, 191 ], [ 249, 258 ], [ 393, 405 ], [ 787, 799 ], [ 869, 883 ] ] }, { "plaintext": " Introduction to Electro-Optical Systems in Unmanned Vehicle Applications - Unmanned Systems Technology", "section_idx": 3, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Atomic,_molecular,_and_optical_physics", "Optoelectronics", "Nonlinear_optics" ]

[]

[ { "plaintext": "In electrodynamics, elliptical polarization is the polarization of electromagnetic radiation such that the tip of the electric field vector describes an ellipse in any fixed plane intersecting, and normal to, the direction of propagation. An elliptically polarized wave may be resolved into two linearly polarized waves in phase quadrature, with their polarization planes at right angles to each other. Since the electric field can rotate clockwise or counterclockwise as it propagates, elliptically polarized waves exhibit chirality.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9532, 41564, 9426, 41092, 32533, 9277, 173224, 41316, 24047, 1170169 ], "anchor_spans": [ [ 3, 18 ], [ 51, 63 ], [ 67, 92 ], [ 118, 132 ], [ 133, 139 ], [ 153, 160 ], [ 198, 204 ], [ 295, 318 ], [ 323, 339 ], [ 524, 533 ] ] }, { "plaintext": "Circular polarization and linear polarization can be considered to be special cases of elliptical polarization. This terminology was introduced by Augustin-Jean Fresnel in 1822, before the electromagnetic nature of light waves was known.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40875, 41316, 1141 ], "anchor_spans": [ [ 0, 21 ], [ 26, 45 ], [ 147, 168 ] ] }, { "plaintext": "The classical sinusoidal plane wave solution of the electromagnetic wave equation for the electric and magnetic fields is (Gaussian units)", "section_idx": 1, "section_name": "Mathematical description", "target_page_ids": [ 151066, 324749, 2924436, 41092, 36563, 1101364 ], "anchor_spans": [ [ 4, 13 ], [ 14, 24 ], [ 52, 81 ], [ 90, 98 ], [ 103, 111 ], [ 123, 137 ] ] }, { "plaintext": "for the magnetic field, where k is the wavenumber,", "section_idx": 1, "section_name": "Mathematical description", "target_page_ids": [ 164570 ], "anchor_spans": [ [ 39, 49 ] ] }, { "plaintext": "is the angular frequency of the wave propagating in the +z direction, and is the speed of light.", "section_idx": 1, "section_name": "Mathematical description", "target_page_ids": [ 199829, 28736 ], "anchor_spans": [ [ 7, 24 ], [ 82, 96 ] ] }, { "plaintext": "Here is the amplitude of the field and", "section_idx": 1, "section_name": "Mathematical description", "target_page_ids": [ 37649 ], "anchor_spans": [ [ 13, 22 ] ] }, { "plaintext": "is the normalized Jones vector. This is the most complete representation of polarized electromagnetic radiation and corresponds in general to elliptical polarization.", "section_idx": 1, "section_name": "Mathematical description", "target_page_ids": [ 16565 ], "anchor_spans": [ [ 18, 30 ] ] }, { "plaintext": "At a fixed point in space (or for fixed z), the electric vector traces out an ellipse in the x-y plane. The semi-major and semi-minor axes of the ellipse have lengths A and B, respectively, that are given by", "section_idx": 2, "section_name": "Polarization ellipse", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "and ", "section_idx": 2, "section_name": "Polarization ellipse", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": ",", "section_idx": 2, "section_name": "Polarization ellipse", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "where with the phases and .", "section_idx": 2, "section_name": "Polarization ellipse", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The orientation of the ellipse is given by the angle the semi-major axis makes with the x-axis. This angle can be calculated from", "section_idx": 2, "section_name": "Polarization ellipse", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": ".", "section_idx": 2, "section_name": "Polarization ellipse", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "If , the wave is linearly polarized. The ellipse collapses to a straight line ) oriented at an angle . This is the case of superposition of two simple harmonic motions (in phase), one in the x direction with an amplitude , and the other in the y direction with an amplitude . When increases from zero, i.e., assumes positive values, the line evolves into an ellipse that is being traced out in the counterclockwise direction (looking in the direction of the propagating wave); this then corresponds to left-handed elliptical polarization; the semi-major axis is now oriented at an angle . Similarly, if becomes negative from zero, the line evolves into an ellipse that is being traced out in the clockwise direction; this corresponds to right-handed elliptical polarization.", "section_idx": 2, "section_name": "Polarization ellipse", "target_page_ids": [ 41316 ], "anchor_spans": [ [ 17, 35 ] ] }, { "plaintext": "If and , , i.e., the wave is circularly polarized. When , the wave is left-circularly polarized, and when , the wave is right-circularly polarized.", "section_idx": 2, "section_name": "Polarization ellipse", "target_page_ids": [ 40875 ], "anchor_spans": [ [ 30, 50 ] ] }, { "plaintext": " Any fixed polarization can be described in terms of the shape and orientation of the polarization ellipse, which is defined by two parameters: axial ratio AR and tilt angle . The axial ratio is the ratio of the lengths of the major and minor axes of the ellipse, and is always greater than or equal to one.", "section_idx": 2, "section_name": "Polarization ellipse", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Alternatively, polarization can be represented as a point on the surface of the Poincaré sphere, with as the longitude and as the latitude, where . The sign used in the argument of the depends on the handedness of the polarization. Positive indicates left hand polarization, while negative indicates right hand polarization, as defined by IEEE.", "section_idx": 2, "section_name": "Polarization ellipse", "target_page_ids": [ 41564, 17617, 17616 ], "anchor_spans": [ [ 80, 95 ], [ 110, 119 ], [ 132, 140 ] ] }, { "plaintext": "For the special case of circular polarization, the axial ratio equals 1 (or 0 dB) and the tilt angle is undefined. For the special case of linear polarization, the axial ratio is infinite.", "section_idx": 2, "section_name": "Polarization ellipse", "target_page_ids": [ 40875, 41316 ], "anchor_spans": [ [ 24, 45 ], [ 140, 159 ] ] }, { "plaintext": "The reflected light from some beetles (e.g. Cetonia aurata) is elliptical polarized.", "section_idx": 3, "section_name": "In nature", "target_page_ids": [ 72033 ], "anchor_spans": [ [ 44, 58 ] ] }, { "plaintext": "Ellipsometry", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 1177592 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": "Fresnel rhomb", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 8323351 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Photon polarization", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 6432722 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": "Sinusoidal plane-wave solutions of the electromagnetic wave equation", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 6420246 ], "anchor_spans": [ [ 0, 68 ] ] }, { "plaintext": " Henri Poincaré (1889) Théorie Mathématique de la Lumière, volume 1 and Volume 2 (1892) via Internet Archive.", "section_idx": 5, "section_name": "References", "target_page_ids": [ 48740, 176931 ], "anchor_spans": [ [ 1, 15 ], [ 92, 108 ] ] }, { "plaintext": " H. Poincaré (1901) Électricité et Optique : La Lumière et les Théories Électrodynamiques, via Internet Archive", "section_idx": 5, "section_name": "References", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Animation of Elliptical Polarization (on YouTube)", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Comparison of Elliptical Polarization with Linear and Circular Polarizations (YouTube Animation)", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "楕円偏光", "section_idx": 6, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Polarization_(waves)" ]

[]

[ { "plaintext": "Typically, prior to some process, such as transmission over cable, or recording to phonograph record or tape, the input frequency range most susceptible to noise is boosted. This is referred to as \"pre-emphasis\"before the process the signal will undergo. Later, when the signal is received, or retrieved from recording, the reverse transformation is applied (\"de-emphasis\") so that the output accurately reproduces the original input. Any noise added by transmission or record/playback, to the frequency range previously boosted, is now attenuated in the de-emphasis stage.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The high-frequency signal components are emphasized to produce a more equal modulation index for the transmitted frequency spectrum, and therefore a better signal-to-noise ratio for the entire frequency range.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1131440, 41706, 5167862 ], "anchor_spans": [ [ 76, 92 ], [ 156, 177 ], [ 193, 208 ] ] }, { "plaintext": "Emphasis is commonly used in FM broadcasting and vinyl (e.g. LP) records.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1607203, 172121, 8975473 ], "anchor_spans": [ [ 29, 44 ], [ 49, 54 ], [ 61, 63 ] ] }, { "plaintext": "In processing electronic audio signals, pre-emphasis refers to a system process designed to increase (within a frequency band) the magnitude of some (usually higher) frequencies with respect to the magnitude of other (usually lower) frequencies in order to improve the overall signal-to-noise ratio by minimizing the adverse effects of such phenomena as attenuation distortion or saturation of recording media in subsequent parts of the system. The mirror operation is called de-emphasis, and the system as a whole is called emphasis.", "section_idx": 1, "section_name": "In waveform signals", "target_page_ids": [ 12812363, 5167862, 6031554, 3375566 ], "anchor_spans": [ [ 25, 37 ], [ 111, 125 ], [ 354, 376 ], [ 380, 390 ] ] }, { "plaintext": "Pre-emphasis is achieved with a pre-emphasis network which is essentially a calibrated filter. The frequency response is decided by special time constants. The cutoff frequency can be calculated from that value.", "section_idx": 1, "section_name": "In waveform signals", "target_page_ids": [ 23434533, 302033, 19770252, 40986 ], "anchor_spans": [ [ 87, 93 ], [ 99, 117 ], [ 140, 153 ], [ 160, 176 ] ] }, { "plaintext": "Pre-emphasis is commonly used in telecommunications, digital audio recording, record cutting, in FM broadcasting transmissions, and in displaying the spectrograms of speech signals. One example of this is the RIAA equalization curve on 33rpm and 45rpm vinyl records. Another is the Dolby noise-reduction system as used with magnetic tape.", "section_idx": 1, "section_name": "In waveform signals", "target_page_ids": [ 33094374, 53712, 24471, 1607203, 609152, 263317, 3997452, 172121, 87710 ], "anchor_spans": [ [ 33, 50 ], [ 53, 66 ], [ 78, 84 ], [ 97, 112 ], [ 113, 125 ], [ 150, 161 ], [ 209, 226 ], [ 252, 265 ], [ 282, 310 ] ] }, { "plaintext": "Pre-emphasis is employed in frequency modulation or phase modulation transmitters to equalize the modulating signal drive power in terms of deviation ratio. The receiver demodulation process includes a reciprocal network, called a de-emphasis network, to restore the original signal power distribution.", "section_idx": 1, "section_name": "In waveform signals", "target_page_ids": [ 10835, 24772, 41703, 24236, 1131440, 66926 ], "anchor_spans": [ [ 28, 48 ], [ 52, 68 ], [ 109, 115 ], [ 122, 127 ], [ 140, 155 ], [ 170, 182 ] ] }, { "plaintext": "In telecommunication, de-emphasis is the complement of pre-emphasis, in the antinoise system called emphasis. De-emphasis is a system process designed to decrease, (within a band of frequencies), the magnitude of some (usually higher) frequencies with respect to the magnitude of other (usually lower) frequencies in order to improve the overall signal-to-noise ratio by minimizing the adverse effects of such phenomena as attenuation distortion or saturation of recording media in subsequent parts of the system.", "section_idx": 1, "section_name": "In waveform signals", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Special time constants dictate the frequency response curve, from which one can calculate the cutoff frequency.", "section_idx": 1, "section_name": "In waveform signals", "target_page_ids": [ 19770252, 302033, 40986 ], "anchor_spans": [ [ 8, 21 ], [ 35, 53 ], [ 94, 110 ] ] }, { "plaintext": "Although rarely used, there exists the capability for standardized emphasis in Red Book CD mastering. As CDs were originally intended to work on 14-bit audio, a specification for 'pre-emphasis' was included to compensate for quantization noise. After production specifications were instead set to 16 bits, quantization noise became less of a concern, but emphasis remained an option through standards revisions. The pre-emphasis is described as a first-order filter with a gain of 10dB (at 20dB/decade) and time constants 50μs and 15μs.", "section_idx": 1, "section_name": "In waveform signals", "target_page_ids": [ 521572, 317018 ], "anchor_spans": [ [ 79, 90 ], [ 225, 243 ] ] }, { "plaintext": "In high speed digital transmission, pre-emphasis is used to improve signal quality at the output of a data transmission. In transmitting signals at high data rates, the transmission medium may introduce distortions, so pre-emphasis is used to distort the transmitted signal to correct for this distortion. When done properly this produces a received signal which more closely resembles the original or desired signal, allowing the use of higher frequencies or producing fewer bit errors.", "section_idx": 2, "section_name": "In digital transmission", "target_page_ids": [ 3492525, 42168 ], "anchor_spans": [ [ 68, 82 ], [ 102, 119 ] ] }, { "plaintext": "In serial data transmission, de-emphasis has a different meaning, which is to reduce the level of all bits except the first one after a transition. That causes the high frequency content due to the transition to be emphasized compared to the low frequency content which is de-emphasized. This is a form of transmitter equalization; it compensates for losses over the channel which are larger at higher frequencies. Well known serial data standards such as PCI Express, SATA and SAS require transmitted signals to use de-emphasis.", "section_idx": 2, "section_name": "In digital transmission", "target_page_ids": [ 194114, 143320, 174151, 1143131 ], "anchor_spans": [ [ 3, 27 ], [ 457, 468 ], [ 470, 474 ], [ 479, 482 ] ] }, { "plaintext": " EmphasisFrequency response and equalization EQConversion: time constant to cut-off frequency and vice versa", "section_idx": 4, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " DeemphasisFrequency response and equalization EQConversion: time constant to cut-off frequency and vice versa", "section_idx": 4, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Signal_processing", "Broadcast_engineering" ]

[]

[ { "plaintext": "Encode or encoding may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " APL (programming language) dyadic Encode function and its symbol ⊤", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1451 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Binary encoding", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 219202 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Binary-to-text encoding", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3282778 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " Character encoding", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5295 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Coding region of a gene", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 198948 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Encoding, or code", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5225 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Encoding (memory)", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5128182 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Encoding (semiotics)", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2108591 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " ENCODE (Encyclopedia of DNA Elements)", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2140955 ], "anchor_spans": [ [ 1, 7 ] ] }, { "plaintext": " MPEG encoding", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 20055 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " Semantics encoding", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1758417 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Text encoding — see character encoding applied to textual data", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5295 ], "anchor_spans": [ [ 21, 39 ] ] }, { "plaintext": " Video encoding", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8013 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Encoder (disambiguation)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 313461 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " ENCOD, the European Coalition for Just and Effective Drug Policies", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 541377 ], "anchor_spans": [ [ 1, 67 ] ] } ]

[]

[]

[ { "plaintext": "In start-stop teletypewriter operation, end distortion refers to the shifting of the end of all marking pulses, except the stop pulse, from their proper positions in relation to the beginning of the next start pulse. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 200992, 31247, 41600 ], "anchor_spans": [ [ 3, 13 ], [ 14, 28 ], [ 128, 133 ] ] }, { "plaintext": "Shifting of the end of the stop pulse is a deviation in character time and rate rather than an end distortion. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 12579, 30012, 41052 ], "anchor_spans": [ [ 56, 65 ], [ 66, 70 ], [ 99, 109 ] ] }, { "plaintext": "Spacing end distortion is the termination of marking pulses before the proper time. Marking end distortion is the continuation of marking pulses past the proper time. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The magnitude of the distortion is expressed as a percentage of an ideal pulse length.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] } ]

[ "Telegrams" ]

[]

[ { "plaintext": "In telecommunication, an end-of-Transmission character (EOT) is a transmission control character. Its intended use is to indicate the conclusion of a transmission that may have included one or more texts and any associated message headings.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 609152, 5298, 41367 ], "anchor_spans": [ [ 3, 20 ], [ 66, 78 ], [ 79, 96 ], [ 223, 230 ] ] }, { "plaintext": "An EOT is often used to initiate other functions, such as releasing circuits, disconnecting terminals, or placing receive terminals in a standby condition. Its most common use today is to cause a Unix terminal driver to signal end of file and thus exit programs that are awaiting input.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 2183606, 249402, 342322 ], "anchor_spans": [ [ 137, 144 ], [ 201, 209 ], [ 227, 238 ] ] }, { "plaintext": "In ASCII and Unicode, the character is encoded at . It can be referred to as , in caret notation. Unicode provides the character for when EOT needs to be displayed graphically. In addition, can also be used as a graphic representation of EOT; it is defined in Unicode as \"symbol for End of Transmission\".", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 586, 31742, 2265038 ], "anchor_spans": [ [ 3, 8 ], [ 13, 20 ], [ 83, 97 ] ] }, { "plaintext": "The EOT character in Unix is different from the Control-Z in DOS. The DOS Control-Z byte is actually sent and/or placed in files to indicate where the text ends. In contrast, the Control-D causes the Unix terminal driver to signal the EOF condition, which is not a character, while the byte has no special meaning if actually read or written from a file or terminal.", "section_idx": 1, "section_name": "Meaning in Unix", "target_page_ids": [ 3327672, 342322 ], "anchor_spans": [ [ 48, 57 ], [ 235, 238 ] ] }, { "plaintext": "In Unix, the end-of-file character (by default EOT) causes the terminal driver to make available all characters in its input buffer immediately; normally the driver would collect characters until it sees an end-of-line character. If the input buffer is empty (because no characters have been typed since the last end-of-line or end-of-file), a program reading from the terminal reads a count of zero bytes. In Unix, such a condition is understood as having reached the end of the file.", "section_idx": 1, "section_name": "Meaning in Unix", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This can be demonstrated with the program on Unix-like operating systems such as Linux: Run the command with no arguments, so it accepts its input from the keyboard and prints output to the screen. Type a few characters without pressing , then type . The characters typed to that point are sent to cat, which then writes them to the screen. If is typed without typing any characters first, the input stream is terminated and the program ends. An actual EOT is obtained by typing then .", "section_idx": 1, "section_name": "Meaning in Unix", "target_page_ids": [ 21347364, 6097297 ], "anchor_spans": [ [ 46, 50 ], [ 82, 87 ] ] }, { "plaintext": "If the terminal driver is in \"raw\" mode, it no longer interprets control characters, and the EOT character is sent unchanged to the program, which is free to interpret it any way it likes. A program may then decide to handle the EOT byte as an indication that it should end the text; this would then be similar to how is handled by DOS programs.", "section_idx": 1, "section_name": "Meaning in Unix", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The EOT character is used in legacy communications protocols by mainframe computer manufacturers such as IBM, Burroughs Corporation, and the BUNCH. Terminal transmission control protocols such as IBM 3270 Poll/Select, or Burroughs TD830 Contention Mode protocol use the EOT character to terminate a communications sequence between two cooperating stations (such as a host multiplexer or Input/Output terminal).", "section_idx": 2, "section_name": "Usage in mainframe computer system communications protocols", "target_page_ids": [ 20266, 40379651, 4524, 1737023, 15154 ], "anchor_spans": [ [ 64, 82 ], [ 105, 108 ], [ 110, 131 ], [ 141, 146 ], [ 196, 204 ] ] }, { "plaintext": "A single Poll (ask the station for data) or Select (send data to the station) operation will include two round-trip send-reply operations between the polling station and the station being polled, the final operation being transmission of a single EOT character to the initiating station.", "section_idx": 2, "section_name": "Usage in mainframe computer system communications protocols", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "C0 and C1 control codes", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 2371820 ], "anchor_spans": [ [ 0, 23 ] ] }, { "plaintext": "ASCII", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 586 ], "anchor_spans": [ [ 0, 5 ] ] }, { "plaintext": "Keyboard shortcut", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 423419 ], "anchor_spans": [ [ 0, 17 ] ] } ]

[ "Control_characters" ]

[ "EOT", "U+0004", "0x04", "Control+D", "END OF TRANSMISSION" ]

[ { "plaintext": "In telecommunication, endurability is the property of a system, subsystem, equipment, or process that enables it to continue to function within specified performance limits for an extended period of time, usually months, despite a severe natural or man-made disturbance, such as a nuclear attack, or a loss of external logistic or utility support. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 8286675, 30012 ], "anchor_spans": [ [ 3, 20 ], [ 56, 62 ], [ 199, 203 ] ] }, { "plaintext": "Endurability is not compromised by temporary failures when the local capability exists to restore and maintain the system, subsystem, equipment, or process to an acceptable performance level.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Federal Standard 1037C", "section_idx": 1, "section_name": "References", "target_page_ids": [ 37310 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " MIL-STD-188", "section_idx": 1, "section_name": "References", "target_page_ids": [ 41882 ], "anchor_spans": [ [ 1, 12 ] ] } ]

[ "Telecommunications_engineering", "Fault_tolerance" ]

[]

[ { "plaintext": "Enhanced service is service offered over commercial carrier transmission facilities used in interstate communications, that employs computer processing applications that act on the format, content, code, protocol, or similar aspects of the subscriber's transmitted information; provides the subscriber with additional, different, or restructured information; or involves subscriber interaction with stored information.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40910, 609152, 33094374, 7878457, 5225, 28030850, 259338, 18985062 ], "anchor_spans": [ [ 52, 59 ], [ 60, 72 ], [ 103, 117 ], [ 132, 140 ], [ 198, 202 ], [ 204, 212 ], [ 240, 250 ], [ 265, 276 ] ] } ]

[ "Telephone_service_enhanced_features" ]

[]

[ { "plaintext": "In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The \"epoch\" serves as a reference point from which time is measured.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 55931, 23733, 13371925, 442948 ], "anchor_spans": [ [ 3, 13 ], [ 18, 31 ], [ 67, 74 ], [ 120, 132 ] ] }, { "plaintext": "The moment of epoch is usually decided by congruity, or by following conventions understood from the epoch in question. The epoch moment or date is usually defined from a specific, clear event of change, an epoch event. In a more gradual change, a deciding moment is chosen when the epoch criterion was reached.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 142829 ], "anchor_spans": [ [ 248, 263 ] ] }, { "plaintext": " The Yoruba calendar (Kọ́jọ́dá) uses 8042 BC as the epoch, regarded as the year of the creation of Ile-Ife by the god Obatala, also regarded as the creation of the earth.", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 18450460, 400759, 99369 ], "anchor_spans": [ [ 5, 20 ], [ 99, 106 ], [ 118, 125 ] ] }, { "plaintext": " Anno Mundi (years since the creation of the world) is used in the Byzantine calendar (5509 BC).", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 1656672, 7203088 ], "anchor_spans": [ [ 1, 11 ], [ 67, 85 ] ] }, { "plaintext": " Anno Mundi (years since the creation of the world) as used in the Hebrew calendar (3761 BC).", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 1656672, 13782 ], "anchor_spans": [ [ 1, 11 ], [ 67, 82 ] ] }, { "plaintext": " Olympiads, the ancient Greek era of four-year periods between Olympic Games, beginning in 776 BC.", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 332902, 19098431 ], "anchor_spans": [ [ 1, 9 ], [ 63, 76 ] ] }, { "plaintext": " Ab urbe condita (753 BC), used in the Roman imperial period.", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 2553 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Buddhist calendars tend to use the epoch of 544 BC (date of Buddha's parinirvana).", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 1227385, 3395, 559513 ], "anchor_spans": [ [ 2, 19 ], [ 62, 68 ], [ 71, 82 ] ] }, { "plaintext": " The term Hindu calendar may refer to a number of traditional Indian calendars. A notable example of a Hindu epoch is the Vikram Samvat (58 BC), also used in modern times as the national calendars of Nepal and Bangladesh.", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 201400, 1675364, 171166, 3454 ], "anchor_spans": [ [ 10, 24 ], [ 122, 135 ], [ 200, 205 ], [ 210, 220 ] ] }, { "plaintext": " The Anno Domini or Common Era system, still in use with the Julian calendar and Gregorians today, marks the Incarnation of Jesus as calculated in the 6th century by Dionysius Exiguus.", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 1400, 6088, 15651, 23306251, 4789488, 102058 ], "anchor_spans": [ [ 5, 16 ], [ 20, 30 ], [ 61, 76 ], [ 81, 90 ], [ 109, 129 ], [ 166, 183 ] ] }, { "plaintext": " The Islamic calendar counts \"lunar years\" by Anno Hegiræ (in the year of the Hijra) or AH era (AD 622). The year count shifts relative to the solar year as the calendar is purely lunar. The official Iranian calendar (also used in Afghanistan) dates from the Hijra, but as it is a solar calendar, its year numbering does not coincide with the religious calendar.", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 14810, 514023, 18369, 99227, 737, 99211 ], "anchor_spans": [ [ 5, 21 ], [ 78, 83 ], [ 173, 185 ], [ 200, 216 ], [ 231, 242 ], [ 281, 295 ] ] }, { "plaintext": " The Bahá'í calendar is dated from the vernal equinox of the year the Báb proclaimed his religion (AD 1844). Years are grouped in Váḥids of 19 years, and Kull-i-Shay of 361 (19×19) years.", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 206356, 1730537, 28361417 ], "anchor_spans": [ [ 5, 20 ], [ 39, 53 ], [ 70, 73 ] ] }, { "plaintext": " In Thailand in 1888 King Chulalongkorn decreed a National Thai Era dating from the founding of Bangkok on April 6, 1782. In 1912, New Year's Day was shifted to April 1. In 1941, Prime Minister Phibunsongkhram decided to count the years since 543 BC. This is the Thai solar calendar using the Thai Buddhist Era. Except for this era, it is the Gregorian calendar.", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 30128, 202262, 56615, 273644, 203758, 180802 ], "anchor_spans": [ [ 4, 12 ], [ 26, 39 ], [ 96, 103 ], [ 179, 193 ], [ 194, 209 ], [ 263, 282 ] ] }, { "plaintext": " In the French Republican Calendar, a calendar used by the French government for about twelve years from late 1793, the epoch was the beginning of the \"Republican Era\", September 22, 1792 (the day the French First Republic was proclaimed, one day after the Convention abolished the Ancien Regime).", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 11396, 62243, 6637507 ], "anchor_spans": [ [ 8, 34 ], [ 201, 222 ], [ 282, 295 ] ] }, { "plaintext": " The Indian national calendar, introduced in 1957, follows the Saka era (AD 78).", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 1305738, 3041571 ], "anchor_spans": [ [ 5, 29 ], [ 63, 71 ] ] }, { "plaintext": " The Minguo calendar used by officials of Taiwan and its predecessor dates from January 1, 1912, the first year after the Xinhai Revolution, which overthrew the Qing Empire.", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 10310004, 25734, 33167689, 298025, 25310 ], "anchor_spans": [ [ 5, 20 ], [ 42, 48 ], [ 53, 68 ], [ 122, 139 ], [ 161, 172 ] ] }, { "plaintext": " North Korea uses a system that starts in 1912 (= Juche 1), the year of the birth of its founder Kim Il-Sung.", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 21255, 225153, 19718837 ], "anchor_spans": [ [ 1, 12 ], [ 50, 55 ], [ 97, 108 ] ] }, { "plaintext": " The Fascist Era dates to Mussolini's March on Rome in 1922, and was in use only in countries under hegemony of the Fascist regime of Benito Mussolini. It has been defunct since the fall of the Italian Social Republic in 1945. ", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 56545078, 19283178, 613885, 315427 ], "anchor_spans": [ [ 5, 16 ], [ 26, 35 ], [ 38, 51 ], [ 194, 217 ] ] }, { "plaintext": " In the scientific Before Present system of numbering years for purposes of radiocarbon dating, the reference date is January 1, 1950 (though the specific date January 1 is quite unnecessary, as radiocarbon dating has limited precision).", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 971107, 26197 ], "anchor_spans": [ [ 19, 33 ], [ 76, 94 ] ] }, { "plaintext": " Different branches of Freemasonry have selected different years to date their documents according to a Masonic era, such as the Anno Lucis (A.L.).", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 11227, 3759103 ], "anchor_spans": [ [ 23, 34 ], [ 129, 139 ] ] }, { "plaintext": " The Holocene calendar uses 10,000 BC as the epoch, the beginning of the Holocene epoch on the geological time scale.", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 3681668, 13471, 12967 ], "anchor_spans": [ [ 5, 22 ], [ 73, 87 ], [ 95, 116 ] ] }, { "plaintext": "The official Japanese system numbers years from the accession of the current emperor, regarding the calendar year during which the accession occurred as the first year. A similar system existed in China before 1912, being based on the accession year of the emperor (1911 was thus the third year of the Xuantong period). With the establishment of the Republic of China in 1912, the republican era was introduced. It is still very common in Taiwan to date events via the republican era. The People's Republic of China adopted the common era calendar in 1949 (the 38th year of the Chinese Republic).", "section_idx": 1, "section_name": "Calendar eras", "target_page_ids": [ 192415, 10110, 23650107, 5405, 55072, 33167689, 25734 ], "anchor_spans": [ [ 13, 28 ], [ 77, 84 ], [ 179, 185 ], [ 197, 202 ], [ 302, 310 ], [ 350, 367 ], [ 439, 445 ] ] }, { "plaintext": "An epoch in computing is the time at which the representation is zero. For example, Unix time is represented as the number of seconds since 00:00:00 UTC on 1 January 1970, not counting leap seconds. ", "section_idx": 2, "section_name": "Other applications", "target_page_ids": [ 22295187, 1006035, 18472 ], "anchor_spans": [ [ 3, 21 ], [ 84, 93 ], [ 185, 196 ] ] }, { "plaintext": "An epoch in astronomy is a reference time used for consistency in calculation of positions and orbits. A common astronomical epoch is J2000, which is noon on January 1, 2000, Terrestrial Time.", "section_idx": 2, "section_name": "Other applications", "target_page_ids": [ 200006, 31016 ], "anchor_spans": [ [ 3, 21 ], [ 175, 191 ] ] }, { "plaintext": "An epoch in Geochronology is a period of time, typically in the order of tens of millions of years. The current epoch is the Holocene.", "section_idx": 2, "section_name": "Other applications", "target_page_ids": [ 208215, 13471 ], "anchor_spans": [ [ 12, 25 ], [ 125, 133 ] ] } ]

[ "Calendar_eras", "Calendaring_standards", "Chronology" ]

[ "calendar epoch", "reference epoch", "reference time" ]

[ { "plaintext": "In telecommunication, an equivalent noise resistance is a quantitative representation in resistance units of the spectral density of a noise-voltage generator, given by", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 202672, 41415, 32549 ], "anchor_spans": [ [ 3, 20 ], [ 113, 129 ], [ 135, 140 ], [ 141, 148 ] ] }, { "plaintext": "where is the spectral density, is the Boltzmann constant, is the standard noise temperature (290 K), so .", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 53702, 41420 ], "anchor_spans": [ [ 40, 58 ], [ 77, 94 ] ] }, { "plaintext": "Note: The equivalent noise resistance in terms of the mean-square noise-generator voltage, e2, within a frequency increment, Δf, is given by", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 10779 ], "anchor_spans": [ [ 105, 114 ] ] }, { "plaintext": " Equivalent input noise", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 43751582 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Effective input noise temperature", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 41085 ], "anchor_spans": [ [ 1, 34 ] ] } ]

[ "Noise_(electronics)", "Equivalent_units" ]

[]

[ { "plaintext": "In telecommunication, equivalent pulse code modulation (PCM) noise is the amount of noise power on a frequency-division multiplexing (FDM) or wire communication channel necessary to approximate the same judgment of speech quality created by quantization noise in a PCM channel. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 41419, 86376, 156700, 317018, 25513330 ], "anchor_spans": [ [ 3, 20 ], [ 84, 95 ], [ 101, 132 ], [ 147, 168 ], [ 241, 259 ], [ 265, 268 ] ] }, { "plaintext": "Note 1: The speech quality judgment is based on comparative tests.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Note 2: Generally, 33.5 dBrnC ±2.5 dB is considered the approximate equivalent PCM noise of a 7-bit PCM system.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8410, 8410, 3364, 8286675 ], "anchor_spans": [ [ 25, 30 ], [ 36, 38 ], [ 97, 100 ], [ 105, 111 ] ] } ]

[ "Multiplexing", "Noise_(electronics)" ]

[]

[ { "plaintext": "An error (from the Latin error, meaning \"wandering\") is an action which is inaccurate or incorrect. In some usages, an error is synonymous with a mistake.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In statistics, \"error\" refers to the difference between the value which has been computed and the correct value. An error could result in failure or in a deviation from the intended performance or behavior.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 26685, 19005769, 9252911 ], "anchor_spans": [ [ 3, 13 ], [ 138, 145 ], [ 154, 163 ] ] }, { "plaintext": "One reference differentiates between \"error\" and \"mistake\" as follows:", "section_idx": 1, "section_name": "Human behavior", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In human behavior the norms or expectations for behavior or its consequences can be derived from the intention of the actor or from the expectations of other individuals or from a social grouping or from social norms. (See deviance.) Gaffes and faux pas can be labels for certain instances of this kind of error. More serious departures from social norms carry labels such as misbehavior and labels from the legal system, such as misdemeanor and crime. Departures from norms connected to religion can have other labels, such as sin.", "section_idx": 1, "section_name": "Human behavior", "target_page_ids": [ 563299, 43851, 14534297, 20583, 5785, 28307 ], "anchor_spans": [ [ 3, 17 ], [ 204, 216 ], [ 223, 231 ], [ 430, 441 ], [ 446, 451 ], [ 528, 531 ] ] }, { "plaintext": "An individual language user's deviations from standard language norms in grammar, pronunciation and orthography are sometimes referred to as errors. However, in light of the role of language usage in everyday social class distinctions, many feel that linguistics should restrain itself from such prescriptivist judgments to avoid reinforcing dominant class value claims about what linguistic forms should and should not be used. One may distinguish various kinds of linguistic errors – some, such as aphasia or speech disorders, where the user is unable to say what they intend to, are generally considered errors, while cases where natural, intended speech is non-standard (as in vernacular dialects), are considered legitimate speech in scholarly linguistics, but might be considered errors in prescriptivist contexts. See also Error analysis (linguistics).", "section_idx": 1, "section_name": "Human behavior", "target_page_ids": [ 17524, 12569, 192281, 22209, 40016004, 29174, 22760983, 229136, 2088, 148951, 1227659, 30056639 ], "anchor_spans": [ [ 14, 22 ], [ 73, 80 ], [ 82, 95 ], [ 100, 111 ], [ 141, 147 ], [ 209, 221 ], [ 251, 262 ], [ 296, 320 ], [ 500, 507 ], [ 511, 526 ], [ 661, 673 ], [ 830, 858 ] ] }, { "plaintext": "A gaffe is usually made in a social environment and may come from saying something that may be true but inappropriate. It may also be an erroneous attempt to reveal a truth. Gaffes can be malapropisms, grammatical errors or other verbal and gestural weaknesses or revelations through body language. Actually revealing factual or social truth through words or body language, however, can commonly result in embarrassment or, when the gaffe has negative connotations, friction between people involved.", "section_idx": 1, "section_name": "Human behavior", "target_page_ids": [ 558722, 145230, 366663 ], "anchor_spans": [ [ 29, 47 ], [ 188, 199 ], [ 284, 297 ] ] }, { "plaintext": "Philosophers and psychologists interested in the nature of the gaffe include Sigmund Freud (Freudian slip) and Gilles Deleuze. Deleuze, in his The Logic of Sense, places the gaffe in a developmental process that can culminate in stuttering.", "section_idx": 1, "section_name": "Human behavior", "target_page_ids": [ 26743, 195177, 12557, 14705096 ], "anchor_spans": [ [ 77, 90 ], [ 92, 105 ], [ 111, 125 ], [ 143, 161 ] ] }, { "plaintext": "Sportswriters and journalists commonly use \"gaffe\" to refer to any kind of mistake, e.g. a dropped ball (baseball error) by a player in a baseball game.", "section_idx": 1, "section_name": "Human behavior", "target_page_ids": [ 300765 ], "anchor_spans": [ [ 105, 119 ] ] }, { "plaintext": "In statistics, an error (or residual) is not a \"mistake\" but rather a difference between a computed, estimated, or measured value and the accepted true, specified, or theoretically correct value.", "section_idx": 2, "section_name": "Science and engineering", "target_page_ids": [ 26685, 461509 ], "anchor_spans": [ [ 3, 13 ], [ 18, 37 ] ] }, { "plaintext": "In science and engineering in general, an error is defined as a difference between the desired and actual performance or behavior of a system or object. This definition is the basis of operation for many types of control systems, in which error is defined as the difference between a set point and the process value. An example of this would be the thermostat in a home heating system – the operation of the heating equipment is controlled by the difference (the error) between the thermostat setting and the sensed air temperature. Another approach is related to considering a scientific hypothesis as true or false, giving birth to two types of errors: Type 1 and Type 2. The first one is when a true hypothesis is considered false, while the second is the reverse (a false one is considered true).", "section_idx": 2, "section_name": "Science and engineering", "target_page_ids": [ 3689133, 4805, 8286675, 47353, 275473, 5657877 ], "anchor_spans": [ [ 106, 117 ], [ 121, 129 ], [ 135, 141 ], [ 145, 151 ], [ 213, 227 ], [ 655, 672 ] ] }, { "plaintext": "Engineers seek to design devices, machines and systems and in such a way as to mitigate or preferably avoid the effects of error, whether unintentional or not. Such errors in a system can be latent design errors that may go unnoticed for years, until the right set of circumstances arises that cause them to become active. Other errors in engineered systems can arise due to human error, which includes cognitive bias. Human factors engineering is often applied to designs in an attempt to minimize this type of error by making systems more forgiving or error-tolerant.", "section_idx": 2, "section_name": "Science and engineering", "target_page_ids": [ 38223, 533170, 51462, 8286675, 44178, 8560, 4584639, 47278, 36479878, 1683007 ], "anchor_spans": [ [ 0, 8 ], [ 25, 32 ], [ 34, 41 ], [ 47, 53 ], [ 138, 158 ], [ 198, 204 ], [ 375, 386 ], [ 403, 417 ], [ 419, 432 ], [ 554, 568 ] ] }, { "plaintext": "(In computational mechanics, when solving a system such as Ax=b there is a distinction between the \"error\" – the inaccuracy in x – and residual – the inaccuracy in Ax.)", "section_idx": 2, "section_name": "Science and engineering", "target_page_ids": [ 5205878, 6773580 ], "anchor_spans": [ [ 4, 27 ], [ 135, 143 ] ] }, { "plaintext": "A notable result of Engineering and Scientific errors that ocurred in history is the Chernobyl disaster of 1986, which caused a nuclear meltdown in the City of Chernobyl in present day Ukraine, and is used as a case study in many Engineering/Science research ", "section_idx": 2, "section_name": "Science and engineering", "target_page_ids": [ 2589713, 6100, 31750 ], "anchor_spans": [ [ 85, 103 ], [ 160, 169 ], [ 185, 192 ] ] }, { "plaintext": "Numerical analysis provides a variety of techniques to represent (store) and compute approximations to mathematical numerical values. Errors arise from a trade-off between efficiency (space and computation time) and precision, which is limited anyway, since (using common floating-point arithmetic) only a finite amount of values can be represented exactly. The discrepancy between the exact mathematical value and the stored/computed value is called the approximation error.", "section_idx": 3, "section_name": "Numerical analysis", "target_page_ids": [ 21506, 336271, 11376, 640422 ], "anchor_spans": [ [ 0, 18 ], [ 85, 98 ], [ 272, 297 ], [ 455, 474 ] ] }, { "plaintext": "The word cybernetics stems from the Greek Κυβερνήτης (kybernētēs, steersman, governor, pilot, or rudder – the same root as government). In applying corrections to the trajectory or course being steered cybernetics can be seen as the most general approach to error and its correction for the achievement of any goal. The term was suggested by Norbert Wiener to describe a new science of control and information in the animal and the machine. Wiener's early work was on noise.", "section_idx": 4, "section_name": "Cybernetics", "target_page_ids": [ 20786042, 148363, 12229, 63185, 41415 ], "anchor_spans": [ [ 9, 20 ], [ 36, 41 ], [ 123, 133 ], [ 342, 356 ], [ 468, 473 ] ] }, { "plaintext": "The cybernetician Gordon Pask held that the error that drives a servomechanism can be seen as a difference between a pair of analogous concepts in a servomechanism: the current state and the goal state. Later he suggested error can also be seen as an innovation or a contradiction depending on the context and perspective of interacting (observer) participants. The founder of management cybernetics, ", "section_idx": 4, "section_name": "Cybernetics", "target_page_ids": [ 4848621, 325496, 12457518 ], "anchor_spans": [ [ 18, 29 ], [ 64, 78 ], [ 377, 399 ] ] }, { "plaintext": "Stafford Beer, applied these ideas most notably in his viable system model.", "section_idx": 4, "section_name": "Cybernetics", "target_page_ids": [ 142597, 2312170 ], "anchor_spans": [ [ 0, 13 ], [ 55, 74 ] ] }, { "plaintext": "In biology, an error is said to occur when perfect fidelity is lost in the copying of information. For example, in an asexually reproducing species, an error (or mutation) has occurred for each DNA nucleotide that differs between the child and the parent. Many of these mutations can be harmful, but unlike other types of errors, some are neutral or even beneficial. Mutations are an important force driving evolution. Mutations that make organisms more adapted to their environment increase in the population through natural selection as organisms with favorable mutations have more offspring.", "section_idx": 5, "section_name": "Biology", "target_page_ids": [ 9127632, 18985062, 7955, 21505, 128987, 83441, 9236, 17554500, 21147, 96628 ], "anchor_spans": [ [ 3, 10 ], [ 86, 97 ], [ 194, 197 ], [ 198, 208 ], [ 234, 239 ], [ 248, 254 ], [ 408, 417 ], [ 471, 482 ], [ 518, 535 ], [ 584, 593 ] ] }, { "plaintext": "In philately, an error refers to a postage stamp or piece of postal stationery that exhibits a printing or production mistake that differentiates it from a normal specimen or from the intended result. Examples are stamps printed in the wrong color or missing one or more colors, printed with a vignette inverted in relation to its frame, produced without any perforations on one or more sides when the normal stamps are perforated, or printed on the wrong type of paper. Legitimate errors must always be produced and sold unintentionally. Such errors may or may not be scarce or rare. A design error may refer to a mistake in the design of the stamp, such as a mislabeled subject, even if there are no printing or production mistakes.", "section_idx": 6, "section_name": "Philately", "target_page_ids": [ 23681, 25126, 216592, 203316, 1427452 ], "anchor_spans": [ [ 3, 12 ], [ 35, 48 ], [ 61, 78 ], [ 303, 311 ], [ 587, 599 ] ] }, { "plaintext": "In appellate review, error typically refers to mistakes made by a trial court or some other court of first instance in applying the law in a particular legal case. This may involve such mistakes as improper admission of evidence, inappropriate instructions to the jury, or applying the wrong standard of proof.", "section_idx": 7, "section_name": "Law", "target_page_ids": [ 35925403, 306967, 1704112, 2001231, 16365, 44720, 61610 ], "anchor_spans": [ [ 3, 19 ], [ 66, 77 ], [ 152, 162 ], [ 220, 228 ], [ 244, 256 ], [ 264, 268 ], [ 292, 309 ] ] }, { "plaintext": "A stock market error is a stock market transaction that was done due to an error, due to human failure or computer errors.", "section_idx": 8, "section_name": "Stock market", "target_page_ids": [ 19005769, 3388502 ], "anchor_spans": [ [ 95, 102 ], [ 106, 120 ] ] }, { "plaintext": "Within United States government intelligence agencies, such as Central Intelligence Agency agencies, error refers to intelligence error, as previous assumptions that used to exist at a senior intelligence level within senior intelligence agencies, but has since been disproven, and is sometimes eventually listed as unclassified, and therefore more available to the public and citizenry of the United States. The Freedom of information act provides American citizenry with a means to read intelligence reports that were mired in error. Per United States Central Intelligence Agency's website (as of August, 2008) intelligence error is described as:", "section_idx": 9, "section_name": "Governmental policy", "target_page_ids": [ 5183633, 307834, 6784, 590464 ], "anchor_spans": [ [ 63, 90 ], [ 366, 372 ], [ 377, 386 ], [ 413, 439 ] ] }, { "plaintext": "\"Intelligence errors are factual inaccuracies in analysis resulting from poor or missing data; intelligence failure is systemic organizational surprise resulting from incorrect, missing, discarded, or inadequate hypotheses.\"", "section_idx": 9, "section_name": "Governmental policy", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In numismatics, an error refers to a coin or medal that has a minting mistake, similar to errors found in philately. Because the U.S. Bureau of the Mint keeps a careful eye on all potential errors, errors on U.S. coins are very few and usually very scarce. Examples of numismatic errors: extra metal attached to a coin, a clipped coin caused by the coin stamp machine stamping a second coin too early, double stamping of a coin. A coin that has been overdated, e.g. 1942/41, is also considered an error.", "section_idx": 10, "section_name": "Numismatics", "target_page_ids": [ 38212, 7558, 375211, 391329 ], "anchor_spans": [ [ 3, 14 ], [ 37, 41 ], [ 45, 50 ], [ 134, 152 ] ] }, { "plaintext": "In applied linguistics, an error is an unintended deviation from the immanent rules of a language variety made by a second language learner. Such errors result from the learner's lack of knowledge of the correct rules of the target language variety. A significant distinction is generally made between errors (systematic deviations) and mistakes (speech performance errors) which are not treated the same from a linguistic viewpoint. The study of learners' errors has been the main area of investigation by linguists in the history of second-language acquisition research.", "section_idx": 11, "section_name": "Linguistics", "target_page_ids": [ 406551, 255928, 162986, 3449686, 1199964 ], "anchor_spans": [ [ 3, 22 ], [ 89, 105 ], [ 116, 131 ], [ 347, 372 ], [ 535, 562 ] ] }, { "plaintext": "A medical error is a preventable adverse effect of care (\"iatrogenesis\"), whether or not it is evident or harmful to the patient. This might include an inaccurate or incomplete diagnosis or treatment of a disease, injury, syndrome, behavior, infection, or other ailment.", "section_idx": 12, "section_name": "Medicine", "target_page_ids": [ 718324 ], "anchor_spans": [ [ 2, 15 ] ] }, { "plaintext": "The word error in medicine is used as a label for nearly all of the clinical incidents that harm patients. Medical errors are often described as human errors in healthcare. Whether the label is a medical error or human error, one definition used in medicine says that it occurs when a healthcare provider chooses an inappropriate method of care, improperly executes an appropriate method of care, or reads the wrong CT scan. It has been said that the definition should be the subject of more debate. For instance, studies of hand hygiene compliance of physicians in an ICU show that compliance varied from 19% to 85%. The deaths that result from infections caught as a result of treatment providers improperly executing an appropriate method of care by not complying with known safety standards for hand hygiene are difficult to regard as innocent accidents or mistakes.", "section_idx": 12, "section_name": "Medicine", "target_page_ids": [ 4584639, 261925, 50982 ], "anchor_spans": [ [ 145, 156 ], [ 285, 295 ], [ 416, 423 ] ] }, { "plaintext": "There are many types of medical error, from minor to major, and causality is often poorly determined.", "section_idx": 12, "section_name": "Medicine", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "There are many taxonomies for classifying medical errors.", "section_idx": 12, "section_name": "Medicine", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Blooper", "section_idx": 13, "section_name": "See also", "target_page_ids": [ 296116 ], "anchor_spans": [ [ 0, 7 ] ] }, { "plaintext": "Error detection and correction", "section_idx": 13, "section_name": "See also", "target_page_ids": [ 10375 ], "anchor_spans": [ [ 0, 30 ] ] }, { "plaintext": "Fallacy – Error in reasoning", "section_idx": 13, "section_name": "See also", "target_page_ids": [ 53986 ], "anchor_spans": [ [ 0, 7 ] ] }, { "plaintext": "Margin of error", "section_idx": 13, "section_name": "See also", "target_page_ids": [ 277379 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "Nonconformity – Production quality terminology ", "section_idx": 13, "section_name": "See also", "target_page_ids": [ 20197918 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Perfection", "section_idx": 13, "section_name": "See also", "target_page_ids": [ 1928374 ], "anchor_spans": [ [ 0, 10 ] ] }, { "plaintext": "Trial and error", "section_idx": 13, "section_name": "See also", "target_page_ids": [ 245733 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "Errors contained in reference books – Internet Accuracy Project", "section_idx": 15, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Error", "Human_communication", "Measurement" ]

[ "mistake", "incorrect", "wrong", "erroneous", "mistaken", "blunder", "misstep", "goof" ]

[ { "plaintext": "In telecommunication, a burst error or error burst is a contiguous sequence of symbols, received over a communication channel, such that the first and last symbols are in error and there exists no contiguous subsequence of m correctly received symbols within the error burst. The integer parameter m is referred to as the guard band of the error burst. The last symbol in a burst and the first symbol in the following burst are accordingly separated by m correct symbols or more. The parameter m should be specified when describing an error burst.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 27838, 156700, 41118, 40823 ], "anchor_spans": [ [ 3, 20 ], [ 67, 75 ], [ 104, 125 ], [ 171, 176 ], [ 269, 274 ] ] }, { "plaintext": "The Gilbert–Elliott model is a simple channel model introduced by Edgar Gilbert and E. O. Elliott that is widely used for describing burst error patterns in transmission channels and enables simulations of the digital error performance of communications links. It is based on a Markov chain with two states G (for good or gap) and B (for bad or burst). In state G the probability of transmitting a bit correctly is k and in state B it is h. Usually, it is assumed thatk=1. Gilbert provided equations for deriving the other three parameters (G and B state transition probabilities and h) from a given success/failure sequence. In his example, the sequence was too short to correctly find h (a negative probability was found) and so Gilbert assumed thath=0.5.", "section_idx": 1, "section_name": "Channel model", "target_page_ids": [ 156700, 30980291, 60876 ], "anchor_spans": [ [ 38, 51 ], [ 66, 79 ], [ 279, 291 ] ] }, { "plaintext": " The Gilbert-Elliott Model for Packet Loss in Real Time Services on the Internet", "section_idx": 3, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A Markov-Based Channel Model Algorithm for Wireless Networks", "section_idx": 3, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The two-state model for a fading channel", "section_idx": 3, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Markov_models", "Data_transmission" ]

[]

[ { "plaintext": "In computing and telecommunication, an escape character is a character that invokes an alternative interpretation on the following characters in a character sequence. An escape character is a particular case of metacharacters. Generally, the judgement of whether something is an escape character or not depends on the context.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5213, 33094374, 73443, 81959 ], "anchor_spans": [ [ 3, 12 ], [ 17, 34 ], [ 61, 70 ], [ 211, 224 ] ] }, { "plaintext": "In the telecommunications field, escape characters are used to indicate that the following characters are encoded differently. This is used to alter control characters that would otherwise be noticed and acted on by the underlying telecommunications hardware. In this context, the use of escape characters is often referred to as quoting.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 5298 ], "anchor_spans": [ [ 7, 24 ], [ 149, 166 ] ] }, { "plaintext": "An escape character may not have its own meaning, so all escape sequences are of two or more characters.", "section_idx": 1, "section_name": "Definition", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Escape characters are part of the syntax for many programming languages, data formats, and communication protocols. For a given alphabet an escape character's purpose is to start character sequences (so named escape sequences), which have to be interpreted differently from the same characters occurring without the prefixed escape character.", "section_idx": 1, "section_name": "Definition", "target_page_ids": [ 18020716, 4292269, 60114 ], "anchor_spans": [ [ 34, 40 ], [ 128, 136 ], [ 209, 224 ] ] }, { "plaintext": "The functions of escape sequences include:", "section_idx": 1, "section_name": "Definition", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " To encode a syntactic entity, such as device commands or special data, which cannot be directly represented by the alphabet.", "section_idx": 1, "section_name": "Definition", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " To represent characters, referred to as character quoting, which cannot be typed in the current context, or would have an undesired interpretation. In this case, an escape sequence is a digraph consisting of an escape character itself and a \"quoted\" character.", "section_idx": 1, "section_name": "Definition", "target_page_ids": [ 403720 ], "anchor_spans": [ [ 187, 194 ] ] }, { "plaintext": "Generally, an escape character is not a particular case of (device) control characters, nor vice versa. If we define control characters as non-graphic, or as having a special meaning for an output device (e.g. printer or text terminal) then any escape character for this device is a control one. But escape characters used in programming (such as the backslash, \"\\\") are graphic, hence are not control characters. Conversely most (but not all) of the ASCII \"control characters\" have some control function in isolation, therefore they are not escape characters.", "section_idx": 1, "section_name": "Definition", "target_page_ids": [ 5298, 41214, 5272, 249402, 174815, 586 ], "anchor_spans": [ [ 68, 85 ], [ 143, 150 ], [ 210, 217 ], [ 221, 234 ], [ 351, 360 ], [ 451, 456 ] ] }, { "plaintext": "In many programming languages, an escape character also forms some escape sequences which are referred to as control characters. For example, line break has an escape sequence of .", "section_idx": 1, "section_name": "Definition", "target_page_ids": [ 238775 ], "anchor_spans": [ [ 142, 152 ] ] }, { "plaintext": "JavaScript uses the (backslash) as an escape character for:", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " single quote", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " double quote", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " backslash", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " new line", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " carriage return", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " tab", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " backspace", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " form feed", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " vertical tab (Internet Explorer 9 and older treats as instead of a vertical tab (). If cross-browser compatibility is a concern, use instead of .)", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 16247198 ], "anchor_spans": [ [ 16, 35 ] ] }, { "plaintext": " null character (U+0000 NULL) (only if the next character is not a decimal digit; else it is an octal escape sequence)", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " character represented by the hexadecimal byte \"FF\"", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Note that the and escapes are not allowed in JSON strings.", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Example code:", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The ASCII \"escape\" character (octal: , hexadecimal: , or , or, in decimal, ) is used in many output devices to start a series of characters called a control sequence or escape sequence. Typically, the escape character was sent first in such a sequence to alert the device that the following characters were to be interpreted as a control sequence rather than as plain characters, then one or more characters would follow to specify some detailed action, after which the device would go back to interpreting characters normally. For example, the sequence of , followed by the printable characters , would cause a DEC VT102 terminal to move its cursor to the 10th cell of the 2nd line of the screen. This was later developed to ANSI escape codes covered by the ANSI X3.64 standard. The escape character also starts each command sequence in the Hewlett Packard Printer Command Language.", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 22330, 13263, 7952, 56207, 2104830, 65930, 21347024, 2542099 ], "anchor_spans": [ [ 30, 35 ], [ 39, 50 ], [ 612, 615 ], [ 616, 621 ], [ 643, 649 ], [ 726, 743 ], [ 842, 857 ], [ 858, 882 ] ] }, { "plaintext": "An early reference to the term \"escape character\" is found in Bob Bemer's IBM technical publications, who is credited with inventing this mechanism during his work on the ASCII character set.", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 643475, 586 ], "anchor_spans": [ [ 62, 71 ], [ 171, 176 ] ] }, { "plaintext": "The Escape key is usually found on standard PC keyboards. However, it is commonly absent from keyboards for PDAs and other devices not designed primarily for ASCII communications. The DEC VT220 series was one of the few popular keyboards that did not have a dedicated Esc key, instead of using one of the keys above the main keypad. In user interfaces of the 1970s–1980s it was not uncommon to use this key as an escape character, but in modern desktop computers, such use is dropped. Sometimes the key was identified with AltMode (for alternative mode). Even with no dedicated key, the escape character code could be generated by typing while simultaneously holding down .", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 2062485, 310034, 45249 ], "anchor_spans": [ [ 4, 14 ], [ 188, 193 ], [ 336, 350 ] ] }, { "plaintext": "Many modern programming languages specify the double-quote character () as a delimiter for a string literal. The backslash () escape character typically provides two ways to include double-quotes inside a string literal, either by modifying the meaning of the double-quote character embedded in the string ( becomes ), or by modifying the meaning of a sequence of characters including the hexadecimal value of a double-quote character ( becomes ).", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 23015, 564276, 199706, 174815 ], "anchor_spans": [ [ 12, 32 ], [ 77, 86 ], [ 93, 107 ], [ 113, 122 ] ] }, { "plaintext": "C, C++, Java, and Ruby all allow exactly the same two backslash escape styles. The PostScript language and Microsoft Rich Text Format also use backslash escapes. The quoted-printable encoding uses the equals sign as an escape character.", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 6021, 72038, 15881, 25768, 24080, 25739, 525655, 501828 ], "anchor_spans": [ [ 0, 1 ], [ 3, 6 ], [ 8, 12 ], [ 18, 22 ], [ 83, 93 ], [ 117, 133 ], [ 166, 182 ], [ 201, 212 ] ] }, { "plaintext": "URL and URI use %-escapes to quote characters with a special meaning, as for non-ASCII characters. The ampersand () character may be considered as an escape character in SGML and derived formats such as HTML and XML.", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 47817022, 32146, 1712680, 1829286, 59153, 28994, 13191, 34138 ], "anchor_spans": [ [ 0, 3 ], [ 8, 11 ], [ 16, 17 ], [ 18, 25 ], [ 103, 112 ], [ 170, 174 ], [ 203, 207 ], [ 212, 215 ] ] }, { "plaintext": "Some programming languages also provide other ways to represent special characters in literals, without requiring an escape character (see e.g. delimiter collision).", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 564276 ], "anchor_spans": [ [ 144, 163 ] ] }, { "plaintext": "The Point-to-Point Protocol (PPP) uses the octet (, or ASCII: ) as an escape character. The octet immediately following should be XORed by before being passed to a higher level protocol. This is applied to both itself and the control character (which is used in PPP to mark the beginning and end of a frame) when those octets need to be transmitted by a higher level protocol encapsulated by PPP, as well as other octets negotiated when the link is established. That is, when a higher level protocol wishes to transmit , it is transmitted as the sequence , and is transmitted as .", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 23511, 4240997, 105979 ], "anchor_spans": [ [ 4, 27 ], [ 44, 49 ], [ 131, 134 ] ] }, { "plaintext": "In Bourne shell (sh), the asterisk () and question mark () characters are wildcard characters expanded via globbing. Without a preceding escape character, an will expand to the names of all files in the working directory that do not start with a period if and only if there are such files, otherwise remains unexpanded. So to refer to a file literally called \"*\", the shell must be told not to interpret it in this way, by preceding it with a backslash (). This modifies the interpretation of the asterisk (). Compare:", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 92839, 59152, 59348, 41869, 484117, 159129, 14922 ], "anchor_spans": [ [ 3, 15 ], [ 26, 34 ], [ 42, 55 ], [ 74, 92 ], [ 107, 115 ], [ 204, 221 ], [ 254, 268 ] ] }, { "plaintext": "The Windows command-line interpreter uses a caret character () to escape reserved characters that have special meanings (in particular: , , , , , , ). The DOS command-line interpreter, though it has similar syntax, does not support this.", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 1256072, 70250038, 71187 ], "anchor_spans": [ [ 4, 36 ], [ 44, 49 ], [ 155, 183 ] ] }, { "plaintext": "For example, on the Windows Command Prompt, this will result in a syntax error.", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "whereas this will output the string: ", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In Windows, the backslash is used as a path separator; therefore, it generally cannot be used as an escape character. PowerShell uses backtick ( ` ) instead.", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 18890, 14465871, 559838 ], "anchor_spans": [ [ 3, 10 ], [ 118, 128 ], [ 134, 142 ] ] }, { "plaintext": "For example, the following command:", "section_idx": 2, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Quoted-printable, which encodes 8-bit data into 7-bit data of limited line lengths, uses the equals sign () as an escape character.", "section_idx": 2, "section_name": "Examples", "target_page_ids": [ 525655, 501828 ], "anchor_spans": [ [ 1, 17 ], [ 94, 105 ] ] }, { "plaintext": " AltGr key used to type characters that are unusual for the locale of the keyboard layout.", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 668160 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Escape sequences in C", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 32561813 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Leaning toothpick syndrome", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 5552846 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Nested quotation", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 7732659 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Stropping (syntax) – in some conventions a leading character (such as an apostrophe) functions as an escape character", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 3631345 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": "That Powerful ESCAPE Character -- Key and Sequences – Bob Bemer", "section_idx": 5, "section_name": "External links", "target_page_ids": [ 643475 ], "anchor_spans": [ [ 55, 64 ] ] } ]

[ "Pattern_matching", "Control_characters" ]

[]

[ { "plaintext": "In telecommunication, an essential service (critical service) is a network-provided service feature in which a priority dial tone is furnished. Essential service is typically provided to fewer than 10% of network users, and recommended for use in conjunction with NS/EP telecommunications services.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 46545, 417914, 162228, 41427 ], "anchor_spans": [ [ 3, 20 ], [ 67, 74 ], [ 84, 99 ], [ 120, 129 ], [ 264, 288 ] ] } ]

[ "Telecommunication_services" ]

[]

[ { "plaintext": "Exchange may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Gas exchange is the movement of oxygen and carbon dioxide molecules from a region of higher concentration to a region of lower concentration.", "section_idx": 1, "section_name": "Physics", "target_page_ids": [ 379303 ], "anchor_spans": [ [ 0, 12 ] ] }, { "plaintext": " Exchange, Indiana, an unincorporated community", "section_idx": 2, "section_name": "Places", "target_page_ids": [ 15309476 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Exchange, Missouri, an unincorporated community", "section_idx": 2, "section_name": "Places", "target_page_ids": [ 52579563 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Exchange, Pennsylvania, an unincorporated community", "section_idx": 2, "section_name": "Places", "target_page_ids": [ 38973903 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Exchange, West Virginia, an unincorporated community", "section_idx": 2, "section_name": "Places", "target_page_ids": [ 87020 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " Exchange Alley, in London, United Kingdom", "section_idx": 2, "section_name": "Places", "target_page_ids": [ 11820761 ], "anchor_spans": [ [ 1, 15 ] ] }, { "plaintext": " Exchange District, a historic area in Winnipeg, Manitoba, Canada", "section_idx": 2, "section_name": "Places", "target_page_ids": [ 4830665 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": "Bureau de change, a business whose customers exchange one currency for another", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 1949760 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Cryptocurrency exchange, a business that allows customers to trade cryptocurrencies or digital currencies.", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 3330391 ], "anchor_spans": [ [ 0, 23 ] ] }, { "plaintext": "Digital currency exchangers (a.k.a. DCEs or Bitcoin exchanges), businesses that allow customers to trade digital currencies for other assets, such as conventional fiat money, or different digital currencies", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 3330391 ], "anchor_spans": [ [ 0, 26 ] ] }, { "plaintext": "Exchange (economics)", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 48852 ], "anchor_spans": [ [ 0, 20 ] ] }, { "plaintext": "Exchange (organized market)", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 19919873 ], "anchor_spans": [ [ 0, 27 ] ] }, { "plaintext": "Exchange rate (a.k.a. foreign exchange rate), the price for which one currency is exchanged for another", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 180311 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Foreign exchange company, a broker that offers currency exchange and international payments", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 29095083 ], "anchor_spans": [ [ 0, 24 ] ] }, { "plaintext": "Foreign exchange controls, controls imposed by a government on the purchase/sale of foreign currencies", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 1404479 ], "anchor_spans": [ [ 0, 25 ] ] }, { "plaintext": "Foreign exchange market (a.k.a. forex, FX, or currency market), a global decentralized market where one currency is exchanged for another", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 648277 ], "anchor_spans": [ [ 0, 23 ] ] }, { "plaintext": "Foreign-exchange reserves, holdings of other countries' currencies", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 1015869 ], "anchor_spans": [ [ 0, 25 ] ] }, { "plaintext": "Foreign exchange risk, arises from the change in price of one currency against another", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 4421780 ], "anchor_spans": [ [ 0, 21 ] ] }, { "plaintext": "Retail foreign exchange platform, speculative trading of foreign exchange by individuals using electronic trading platforms", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 20593805 ], "anchor_spans": [ [ 0, 32 ] ] }, { "plaintext": "Trade, the exchange of goods or services for money or other goods or services", "section_idx": 3, "section_name": "Business and economy", "target_page_ids": [ 29678 ], "anchor_spans": [ [ 0, 5 ] ] }, { "plaintext": "Post exchange (a.k.a. \"PX\" or base exchange), a retail store operated by Army and Air Force Exchange Service on US military installations worldwide; originally akin to trading posts, they now resemble contemporary department stores or strip malls. ", "section_idx": 4, "section_name": "Military", "target_page_ids": [ 1853352 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": " Prisoner exchange", "section_idx": 4, "section_name": "Military", "target_page_ids": [ 17209653 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " , an American Civil War steamer", "section_idx": 4, "section_name": "Military", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " .exchange, an ICANN-era generic Internet top-level domain", "section_idx": 5, "section_name": "Technology", "target_page_ids": [ 15422 ], "anchor_spans": [ [ 12, 58 ] ] }, { "plaintext": " Internet exchange point (IX), physical infrastructure connecting Internet service providers' networks", "section_idx": 5, "section_name": "Technology", "target_page_ids": [ 359193 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " Microsoft Exchange (disambiguation)", "section_idx": 5, "section_name": "Technology", "target_page_ids": [ 508382 ], "anchor_spans": [ [ 1, 36 ] ] }, { "plaintext": " Telephone exchange, a system that connects telephone calls", "section_idx": 5, "section_name": "Technology", "target_page_ids": [ 26668156 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Exchange (chess), closely related or sequential captures of pieces of both players in a chess game", "section_idx": 6, "section_name": "Art, entertainment, and media", "target_page_ids": [ 15669955 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": "The exchange (chess), a specific type of exchange where a player exchanges a minor piece for an opponent's rook", "section_idx": 6, "section_name": "Art, entertainment, and media", "target_page_ids": [ 2982620 ], "anchor_spans": [ [ 0, 20 ] ] }, { "plaintext": " Exchange (song), a 2015 song by Bryson Tiller", "section_idx": 6, "section_name": "Art, entertainment, and media", "target_page_ids": [ 48907712, 47743693 ], "anchor_spans": [ [ 1, 16 ], [ 33, 46 ] ] }, { "plaintext": " Exchange, a new-age/atmospheric instrumental band composed of Steve Sexton and Gerald O'Brien and also their 1992 self-titled album ", "section_idx": 6, "section_name": "Art, entertainment, and media", "target_page_ids": [ 27141634, 50907375 ], "anchor_spans": [ [ 63, 75 ], [ 80, 94 ] ] }, { "plaintext": " Exchange (album), a 1999 split EP by the punk bands Against All Authority and The Criminals", "section_idx": 6, "section_name": "Art, entertainment, and media", "target_page_ids": [ 1658970 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " \"Exchange\" or \"(Exchange)\", two songs on Massive Attack's Mezzanine (album)", "section_idx": 6, "section_name": "Art, entertainment, and media", "target_page_ids": [ 1791673 ], "anchor_spans": [ [ 59, 76 ] ] }, { "plaintext": " Exchange (film), 2015 South Korean crime thriller", "section_idx": 6, "section_name": "Art, entertainment, and media", "target_page_ids": [ 50649041 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Cultural exchange", "section_idx": 7, "section_name": "Other uses", "target_page_ids": [ 1204525 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Student exchange program", "section_idx": 7, "section_name": "Other uses", "target_page_ids": [ 1076499 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Columbian exchange", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 622746 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " The Exchange (disambiguation)", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 666202 ], "anchor_spans": [ [ 1, 30 ] ] }, { "plaintext": " Exchange Building (disambiguation)", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 21755674 ], "anchor_spans": [ [ 1, 35 ] ] }, { "plaintext": " Exchange Hotel (disambiguation)", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 17377268 ], "anchor_spans": [ [ 1, 32 ] ] }, { "plaintext": " Interchange (disambiguation)", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 664782 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " X-Change (disambiguation)", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 14795473 ], "anchor_spans": [ [ 1, 26 ] ] } ]

[]

[]

[ { "plaintext": "In telecommunication, an exempted addressee is an organization, activity, or person included in the collective address group of a message and deemed by the message originator as having no need for the information in the message.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 8168925, 41367, 18985062 ], "anchor_spans": [ [ 3, 20 ], [ 111, 118 ], [ 130, 137 ], [ 201, 212 ] ] }, { "plaintext": "Exempted addressees may be explicitly excluded from the collective address group for the particular message to which the exemption applies.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] } ]

[ "Data_transmission" ]

[]

[ { "plaintext": "In telecommunications, extinction ratio (re) is the ratio of two optical power levels of a digital signal generated by an optical source, e.g., a laser diode. The extinction ratio may be expressed as a fraction, in dB, or as a percentage. It may be given by", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 87837, 24236, 30889569, 142258, 8410, 64493 ], "anchor_spans": [ [ 3, 20 ], [ 52, 57 ], [ 73, 78 ], [ 91, 105 ], [ 146, 157 ], [ 215, 217 ], [ 227, 237 ] ] }, { "plaintext": "where P1 is the optical power level generated when the light source is on, and P0 is the power level generated when the light source is off.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The polarization extinction ratio (PER) is the ratio of optical powers of perpendicular polarizations, usually called TE (transverse electric) and TM (transverse magnetic). In telecommunications, the PER is used to characterize the degree of polarization in a polarization-maintaining device or fiber. For coherent transmitter and receiver, the PER is a key parameter, since Xpolarization and Ypolarization are coded with different signals.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 176, 193 ] ] }, { "plaintext": " Material also incorporated from MIL-STD-2196.", "section_idx": 1, "section_name": "References", "target_page_ids": [], "anchor_spans": [] } ]

[ "Data_transmission", "Telecommunication_theory", "Engineering_ratios", "Laser_science" ]

[]

[ { "plaintext": "In telecommunication, an eye pattern, also known as an eye diagram, is an oscilloscope display in which a digital signal from a receiver is repetitively sampled and applied to the vertical input, while the data rate is used to trigger the horizontal sweep. It is so called because, for several types of coding, the pattern looks like a series of eyes between a pair of rails. It is a tool for the evaluation of the combined effects of channel noise, dispersion and intersymbol interference on the performance of a baseband pulse-transmission system. The technique was first used with the WWII SIGSALY secure speech transmission system.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 15361791, 30889569, 41287, 32927, 740918 ], "anchor_spans": [ [ 3, 20 ], [ 74, 86 ], [ 106, 120 ], [ 465, 489 ], [ 588, 592 ], [ 593, 600 ] ] }, { "plaintext": "From a mathematical perspective, an eye pattern is a visualization of the probability density function (PDF) of the signal, modulo the unit interval (UI). In other words, it shows the probability of the signal being at each possible voltage across the duration of the UI. Typically a color ramp is applied to the PDF in order to make small brightness differences easier to visualize.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 43487, 20087, 2078753, 912871 ], "anchor_spans": [ [ 74, 102 ], [ 124, 130 ], [ 135, 148 ], [ 284, 294 ] ] }, { "plaintext": "Several system performance measurements can be derived by analyzing the display. If the signals are too long, too short, poorly synchronized with the system clock, too high, too low, too noisy, or too slow to change, or have too much undershoot or overshoot, this can be observed from the eye diagram. An open eye pattern corresponds to minimal signal distortion. Distortion of the signal waveform due to intersymbol interference and noise appears as closure of the eye pattern.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8286675, 3966982, 22376472, 41052, 47592, 41287, 3966982 ], "anchor_spans": [ [ 8, 14 ], [ 187, 192 ], [ 248, 257 ], [ 352, 362 ], [ 389, 397 ], [ 405, 429 ], [ 434, 439 ] ] }, { "plaintext": "The first step of computing an eye pattern is normally to obtain the waveform being analyzed in a quantized form. This may be done by measuring an actual electrical system with an oscilloscope of sufficient bandwidth, or by creating synthetic data with a circuit simulator in order to evaluate the signal integrity of a proposed design. A combination of the two approaches may be used as well: simulating the effects of an arbitrary circuit or transmission line on a measured signal, perhaps to determine whether a signal will still be intelligible after passing through a long cable. Interpolation may also be applied at this time in order to increase the number of samples per UI and produce a smooth, gap-free plot which is more visually appealing and easier to understand.", "section_idx": 1, "section_name": "Calculation", "target_page_ids": [ 10900720, 41811, 14569 ], "anchor_spans": [ [ 255, 272 ], [ 444, 461 ], [ 585, 598 ] ] }, { "plaintext": "Next, the position of each sample within the UI must be determined. There are several methods for doing this depending on the characteristics of the signal and the capabilities of the oscilloscope and software in use. This step is critically important for accurate visualization of jitter in the eye.", "section_idx": 1, "section_name": "Calculation", "target_page_ids": [ 41296 ], "anchor_spans": [ [ 282, 288 ] ] }, { "plaintext": "A very simple method of slicing is to set the oscilloscope display to be slightly more than one UI wide, trigger on both rising and falling edges in the signal, and enable display persistence so that all measured waveforms \"stack\" into a single plot. This has the advantage of being possible on almost any oscilloscope (even fully analog ones) and can provide decent visualization of noise and overall signal shape, but completely destroys the jitter content of the signal since the instrument's trigger re-synchronizes the plot to each UI. The only jitter visible with this method is that of the oscilloscope itself, as well as extremely high frequency jitter (frequencies with period less than the UI).", "section_idx": 1, "section_name": "Calculation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A simple way to have the eye pattern display jitter in the signal is to estimate the symbol rate of the signal (perhaps by counting the average number of zero crossings in a known window of time) and acquiring many UIs in a single oscilloscope capture. The first zero crossing in the capture is located and declared to be the start of the first UI, and the remainder of the waveform is divided into chunks one UI long.", "section_idx": 1, "section_name": "Calculation", "target_page_ids": [ 2518170 ], "anchor_spans": [ [ 85, 96 ] ] }, { "plaintext": "This approach can work adequately for stable signals in which the symbol rate remains exactly the same over time, however inaccuracies in the system mean that some drift is inevitable so it is rarely used in practice. In some protocols, such as SATA, the symbol rate is intentionally varied by use of spread spectrum clocking, so assuming a fixed rate will lead to the eye grossly exaggerating the actual jitter present on the signal. (While spread spectrum modulation on a clock is technically jitter in the strict sense, receivers for these systems are designed to track the modulation. The only jitter of interest to a signal integrity engineer is jitter much faster than the modulation rate, which the receiver cannot track effectively.)", "section_idx": 1, "section_name": "Calculation", "target_page_ids": [ 174151, 41734 ], "anchor_spans": [ [ 245, 249 ], [ 301, 325 ] ] }, { "plaintext": "With some protocols, such as HDMI, a reference clock is supplied along with the signal, either at the symbol rate or at a lower (but synchronized) frequency from which a symbol clock can be reconstructed. Since the actual receiver in the system uses the reference clock to sample the data, using this clock to determine UI boundaries allows the eye pattern to faithfully display the signal as the receiver sees it: only jitter between the signal and the reference clock is displayed.", "section_idx": 1, "section_name": "Calculation", "target_page_ids": [ 537442 ], "anchor_spans": [ [ 29, 33 ] ] }, { "plaintext": "Most high speed serial signals, such as PCIe, DisplayPort, and most variants of Ethernet, use a line code which is intended to allow easy clock recovery by means of a PLL. Since this is how the actual receiver works, the most accurate way to slice data for the eye pattern is to implement a PLL with the same characteristics in software. Correct PLL configuration allows for the eye to conceal the effects of spread spectrum clocking and other long-term variation in the symbol rate which do not contribute to errors at the receiver, while still displaying higher frequency jitter.", "section_idx": 1, "section_name": "Calculation", "target_page_ids": [ 143320, 2515655, 9499, 41317, 6076335, 41548 ], "anchor_spans": [ [ 40, 44 ], [ 46, 57 ], [ 80, 88 ], [ 96, 105 ], [ 138, 152 ], [ 167, 170 ] ] }, { "plaintext": "The samples are then accumulated into a two-dimensional histogram, with the X axis representing time within the UI and the Y axis representing voltage. This is then normalized by dividing the value in each histogram bin by the value in the largest bin. Tone mapping, logarithmic scaling, or other mathematical transformations may be applied in order to emphasize different portions of the distribution, and a color gradient is applied to the final eye for display.", "section_idx": 1, "section_name": "Calculation", "target_page_ids": [ 13266, 34061548, 2153191 ], "anchor_spans": [ [ 56, 65 ], [ 165, 175 ], [ 253, 265 ] ] }, { "plaintext": "Large amounts of data may be needed to provide an accurate representation of the signal; tens to hundreds of millions of UIs are frequently used for a single eye pattern. In the example below, the eye using twelve thousand UIs only shows the basic shape of the eye, while the eye using eight million UIs shows far more nuance on the rising and falling edges.", "section_idx": 1, "section_name": "Calculation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Each form of baseband modulation produces an eye pattern with a unique appearance.", "section_idx": 2, "section_name": "Modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The eye pattern of a NRZ signal should consist of two clearly distinct levels with smooth transitions between them.", "section_idx": 2, "section_name": "Modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The eye pattern of a MLT-3 signal should consist of three clearly distinct levels (nominally -1, 0, +1 from bottom to top). The 0 level should be located at zero volts and the overall shape should be symmetric about the horizontal axis. The +1 and -1 states should have equal amplitude. There should be smooth transitions from the 0 state to the +1 and -1 states, however there should be no direct transitions from the -1 to +1 state.", "section_idx": 2, "section_name": "Modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The eye pattern of a PAM signal should consist of N clearly distinct levels (depending on the PAM order, for example PAM-4 should have four levels). The overall shape should be symmetric about the horizontal axis and the spacing of all levels should be uniform.", "section_idx": 2, "section_name": "Modulation", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Many properties of a channel can be seen in the eye pattern.", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [ 156700 ], "anchor_spans": [ [ 21, 28 ] ] }, { "plaintext": "Emphasis applied to a signal produces an additional level for each value of the signal which is higher (for pre-emphasis) or lower (for de-emphasis) than the nominal value.", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [ 41107 ], "anchor_spans": [ [ 0, 8 ] ] }, { "plaintext": "The eye pattern for a signal with emphasis may be mistaken for that of a PAM signal at first glance, however closer inspection reveals some key differences. Most notably, an emphasized signal has a limited set of legal transitions:", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Strong state to corresponding weak state (1-1 or 0-0 bit pattern)", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Strong state to opposite strong state (second transition of a 1-0-1 or 0-1-0 bit pattern)", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Weak state to opposite strong state (second transition of a 1-1-0 or 0-0-1 bit pattern)", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "An emphasized signal will never transition from a weak state to the corresponding strong state, a weak state to another weak state, or remain in the same strong state for more than one UI. A PAM signal also normally has equally spaced levels while emphasized levels are normally closer to the nominal signal level.", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Loss of printed circuit board traces and cables increases with frequency due to dielectric loss, which causes the channel to behave as a low-pass filter. The effect of this is an increase in signal rise/fall time. If the data rate is high enough or the channel is lossy enough, the signal may not even reach its full value during a fast 0-1-0 or 1-0-1 transition, and only stabilize after a run of several identical bits. This results in vertical closure of the eye.", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [ 7090506, 56484 ], "anchor_spans": [ [ 80, 95 ], [ 137, 152 ] ] }, { "plaintext": "The image below shows a 1.25 Gbit/s NRZ signal after passing through a lossy channel - an RG-188 coaxial cable approximately 12 feet (3.65 meters) in length. This channel has loss increasing in a fairly linear fashion from 0.1 dB at DC to 9 dB at 6 GHz.", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The top and bottom \"rails\" of the eye show the final voltage the signal reaches after several consecutive bits with the same value. Since the channel has minimal loss at DC, the maximum signal amplitude is largely unaffected. Looking at the rising edge of the signal (a 0-1 pattern) we can see that the signal starts to level off around -300 ps, but continues to rise slowly over the duration of the UI. At around +300 ps, the signal either begins falling again (a 0-1-0 pattern) or continues rising slowly (an 0-1-1 pattern).", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [ 77700 ], "anchor_spans": [ [ 342, 344 ] ] }, { "plaintext": "As high frequency losses increase the overall shape of the eye gradually degrades into a sinusoid (once higher frequency harmonics of the data has been eliminated, all that remains is the fundamental) and decreases in amplitude.", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Stubs, impedance mismatches, and other defects in a transmission line can cause reflections visible as defects in the edges of the signal. Reflections with a delay greater than one UI often render the eye completely unreadable due to inter-symbol interference (ISI), however those with a shorter delay can be easily seen in the shape of the eye.", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [ 42728, 41287 ], "anchor_spans": [ [ 80, 91 ], [ 234, 265 ] ] }, { "plaintext": "In the image below, a roughly one inch (25.4 mm) open circuited stub is present in the line, causing an initial low-impedance effect (reduced amplitude) followed by a positive reflection from the end of the stub with a delay of about 320 ps or 0.4 UIs. This can be clearly seen as a \"step\" in the rising edge in which the signal rises to a fraction of the full value, levels off for the round trip delay of the stub, then rises to its full value when the reflection arrives.", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In the image below, an additional three inches of cable is added to the end of the same stub. The same \"step\" is present but is now four times as long, producing reflections at about 1280 ps or 1.6 UI. This produces extreme ISI (since the reflection of each UI arrives during the subsequent UI) which completely closes the eye.", "section_idx": 3, "section_name": "Channel effects", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "There are many measurements that can be obtained from an eye diagram:", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Amplitude measurements", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Eye amplitude", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Eye crossing amplitude", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Eye crossing percentage", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Eye height", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Eye level", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Eye signal-to-noise ratio", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Quality factor", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Vertical eye opening", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Time measurements", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Deterministic jitter", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Eye crossing time", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Eye delay", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Eye fall time", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Eye rise time", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Eye width", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Horizontal eye opening", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Peak-to-peak jitter", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Random jitter", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "RMS jitter", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "CRC jitter", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Total jitter", "section_idx": 4, "section_name": "Measurements", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Constellation diagram", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 2033635 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Signal integrity", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 3492525 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Raised-cosine filter", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 3070805 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Extinction ratio", "section_idx": 5, "section_name": "See also", "target_page_ids": [ 41130 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Gives an example video of construction of an eye pattern", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Understanding Data Eye Diagram Methodology for Analyzing High Speed Digital Signals", "section_idx": 8, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Data_transmission" ]

[]

[ { "plaintext": "In telecommunications, a facility is defined by Federal Standard 1037C as:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 37310 ], "anchor_spans": [ [ 3, 20 ], [ 48, 70 ] ] }, { "plaintext": " A fixed, mobile, or transportable structure, including (a) all installed electrical and electronic wiring, cabling, and equipment and (b) all supporting structures, such as utility, ground network, and electrical supporting structures.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41215, 46545 ], "anchor_spans": [ [ 183, 189 ], [ 190, 197 ] ] }, { "plaintext": " A network-provided service to users or the network operating administration.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " A transmission pathway and associated equipment.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 609152 ], "anchor_spans": [ [ 3, 15 ] ] }, { "plaintext": " In a protocol applicable to a data unit, such as a block or frame, an additional item of information or a constraint encoded within the protocol to provide the required control.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 28030850, 18985040, 3608159, 41172, 18985062 ], "anchor_spans": [ [ 6, 14 ], [ 31, 35 ], [ 52, 57 ], [ 61, 66 ], [ 90, 101 ] ] }, { "plaintext": " A real property entity consisting of one or more of the following: a building, a structure, a utility system, pavement, and underlying land.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 47707505, 8286675 ], "anchor_spans": [ [ 3, 16 ], [ 103, 109 ] ] }, { "plaintext": "Telecommunications facility, is where a service can be offered. A location where a Incumbent Local Exchange Carriers (ILECs) have their Hardware to process Telecom services. A phone call made to Jamaica can not be processed by a Telecom Facility in Canada or USA. If a phone number series belongs to say operator or carriers in Jamaica then only that operator knows if that phone number is valid and further if that phone number is on net to place a valid phone call. So all carriers in the world get the signal from the Telecom Facilities of the Digicel in Jamaica.", "section_idx": 1, "section_name": "Global Telecom Facility", "target_page_ids": [ 979683 ], "anchor_spans": [ [ 547, 554 ] ] }, { "plaintext": "Telecommunications facility, is same as Airport Facility. A location where a Incumbent Local Exchange Carriers (ILECs) have their Hardware to process Telecom services.", "section_idx": 2, "section_name": "In Canada", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Under Canadian federal and Québécois provincial law, a telecommunications facility, for the purposes of determining whether GST applies, is defined by §123(1) of the GST Act to be \"any facility, apparatus, or other thing (including any wire, cable, radio, optical, or other electromagnetic system, or any similar technical system or any part thereof) that is used or is capable of being used for telecommunications\". This is a very broad definition that includes a wide range of things from satellites and earth stations, to telephones and fax machines.", "section_idx": 2, "section_name": "In Canada", "target_page_ids": [ 296406, 1042310, 10826 ], "anchor_spans": [ [ 124, 127 ], [ 507, 520 ], [ 541, 552 ] ] } ]

[ "Telecommunications_buildings" ]

[]

[ { "plaintext": "In telecommunication, the term facsimile converter has the following meanings: ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": "1. In a facsimile receiver, a device that changes the signal modulation from frequency-shift keying (FSK) to amplitude modulation (AM). ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41703, 20637, 41193, 1140 ], "anchor_spans": [ [ 55, 61 ], [ 62, 72 ], [ 78, 100 ], [ 110, 130 ] ] }, { "plaintext": "2. In a facsimile transmitter, a device that changes the signal modulation from amplitude modulation (AM) to frequency-shift keying (FSK).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] } ]

[ "Communication_circuits", "Computing_terminology" ]

[]

[ { "plaintext": "In telecommunication, the term fade margin (fading margin) has the following meanings:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374 ], "anchor_spans": [ [ 3, 20 ] ] }, { "plaintext": "A design allowance that provides for sufficient system gain or sensitivity to accommodate expected fading, for the purpose of ensuring that the required quality of service is maintained.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 8286675, 41968, 455092, 81211, 25315 ], "anchor_spans": [ [ 48, 54 ], [ 55, 59 ], [ 63, 74 ], [ 99, 105 ], [ 153, 171 ] ] }, { "plaintext": "The amount by which a received signal level may be reduced without causing system performance to fall below a specified threshold value. It is mainly used to describe a communication system such as satellite, for example a system like globalstar operates at 25-35dB Fade margin.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 690346, 27683, 256906 ], "anchor_spans": [ [ 22, 43 ], [ 198, 207 ], [ 235, 245 ] ] }, { "plaintext": " Multipath propagation", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 41385 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Link Budget", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 1945347 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": "Attila Hilt, \"Availability and Fade Margin Calculations for 5G Microwave and Millimeter-Wave Anyhaul Links\", Applied Sciences, 2019, 9(23), 5240; .,", "section_idx": 2, "section_name": "References", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Trevor Manning, \"Microwave Radio Transmission Design Guide\", 2nd edition; Artech House: London, UK, 2009.", "section_idx": 2, "section_name": "References", "target_page_ids": [], "anchor_spans": [] } ]

[ "Radio_frequency_propagation_fading" ]

[]

[ { "plaintext": "''' is the probability distribution of the value of signal fading, relative to a specified reference level.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 23543, 41703, 81211 ], "anchor_spans": [ [ 11, 35 ], [ 52, 58 ], [ 59, 65 ] ] }, { "plaintext": "In the case of phase interference fading, the time distribution of the instantaneous field strength usually approximates a Rayleigh distribution when several signal components of equal amplitude are present. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41385, 30012, 41150, 262296 ], "anchor_spans": [ [ 15, 40 ], [ 46, 50 ], [ 85, 99 ], [ 123, 144 ] ] }, { "plaintext": "The field strength is usually measured in volts per meter. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41150 ], "anchor_spans": [ [ 4, 18 ] ] }, { "plaintext": "The fading distribution may also be measured in terms of power level, where the unit of measure is usually watts per square meter and the expression is in decibels.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 24236, 8410 ], "anchor_spans": [ [ 57, 62 ], [ 155, 162 ] ] } ]

[ "Radio_frequency_propagation_fading" ]

[]

[ { "plaintext": "In engineering, a fail-safe is a design feature or practice that in the event of a specific type of failure, inherently responds in a way that will cause minimal or no harm to other equipment, to the environment or to people. Unlike inherent safety to a particular hazard, a system being \"fail-safe\" does not mean that failure is impossible or improbable, but rather that the system's design prevents or mitigates unsafe consequences of the system's failure. That is, if and when a \"fail-safe\" system fails, it remains at least as safe as it was before the failure. Since many types of failure are possible, failure mode and effects analysis is used to examine failure situations and recommend safety design and procedures.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9251, 1227042, 3597879, 981631 ], "anchor_spans": [ [ 3, 14 ], [ 100, 107 ], [ 233, 248 ], [ 608, 641 ] ] }, { "plaintext": "Some systems can never be made fail-safe, as continuous availability is needed. Redundancy, fault tolerance, or contingency plans are used for these situations (e.g. multiple independently controlled and fuel-fed engines).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1953581, 2091393, 9308997 ], "anchor_spans": [ [ 80, 90 ], [ 92, 107 ], [ 112, 128 ] ] }, { "plaintext": "Examples include:", "section_idx": 1, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Roller-shutter fire doors that are activated by building alarm systems or local smoke detectors must close automatically when signaled regardless of power. In case of power outage the coiling fire door does not need to close, but must be capable of automatic closing when given a signal from the building alarm systems or smoke detectors. A temperature-sensitive fusible link may be employed to hold the fire doors open against gravity or a closing spring. In case of fire, the link melts and releases the doors, and they close.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 6156238 ], "anchor_spans": [ [ 363, 375 ] ] }, { "plaintext": "Some airport baggage carts require that the person hold down a given cart's handbrake switch at all times; if the handbrake switch is released, the brake will activate, and assuming that all other portions of the braking system are working properly, the cart will stop. The handbrake-holding requirement thus both operates according to the principles of \"fail-safety\" and contributes to (but does not necessarily ensure) the fail-security of the system. This is an example of a dead man's switch.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 979665, 180735, 351284 ], "anchor_spans": [ [ 13, 20 ], [ 21, 25 ], [ 478, 495 ] ] }, { "plaintext": "Lawnmowers and snow blowers have a hand-closed lever that must be held down at all times. If it is released, it stops the blade's or rotor's rotation. This also functions as a dead man's switch.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 343857, 729339 ], "anchor_spans": [ [ 0, 9 ], [ 15, 26 ] ] }, { "plaintext": "Air brakes on railway trains and air brakes on trucks. The brakes are held in the \"off\" position by air pressure created in the brake system. Should a brake line split, or a carriage become de-coupled, the air pressure will be lost and the brakes applied, by springs in the case of trucks, or by a local air reservoir in trains. It is impossible to drive a truck with a serious leak in the air brake system. (Trucks may also employ wig wags to indicate low air pressure.)", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 192417, 30598, 6889398, 31456, 23619, 6889398 ], "anchor_spans": [ [ 0, 10 ], [ 22, 27 ], [ 33, 43 ], [ 47, 52 ], [ 104, 112 ], [ 432, 440 ] ] }, { "plaintext": "Motorized gates – In case of power outage the gate can be pushed open by hand with no crank or key required. However, as this would allow virtually anyone to go through the gate, a fail-secure design is used: In a power outage, the gate can only be opened by a hand crank that is usually kept in a safe area or under lock and key. When such a gate provides vehicle access to homes, a fail-safe design is used, where the door opens to allow fire department access.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Safety valves – Various devices that operate with fluids use fuses or safety valves as fail-safe mechanisms.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 10915, 2377391, 304612 ], "anchor_spans": [ [ 50, 55 ], [ 61, 66 ], [ 70, 82 ] ] }, { "plaintext": "A railway semaphore signal is specially designed so that, should the cable controlling the signal break, the arm returns to the \"danger\" position, preventing any trains passing the inoperative signal.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 14997747 ], "anchor_spans": [ [ 2, 26 ] ] }, { "plaintext": "Isolation valves, and control valves, that are used for example in systems containing hazardous substances, can be designed to close upon loss of power, for example by spring force. This is known as fail-closed upon loss of power.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 34874358 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "An elevator has brakes that are held off brake pads by the tension of the elevator cable. If the cable breaks, tension is lost and the brakes latch on the rails in the shaft, so that the elevator cabin does not fall.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 19373997 ], "anchor_spans": [ [ 3, 11 ] ] }, { "plaintext": " Vehicle air conditioning – Defrost controls require vacuum for diverter damper operation for all functions except defrost. If vacuum fails, defrost is still available.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Examples include:", "section_idx": 1, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Many devices are protected from short circuit by fuses, circuit breakers, or current limiting circuits. The electrical interruption under overload conditions will prevent damage or destruction of wiring or circuit devices due to overheating.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 235898, 683342, 235899, 4377184 ], "anchor_spans": [ [ 32, 45 ], [ 49, 54 ], [ 56, 71 ], [ 77, 93 ] ] }, { "plaintext": "Avionics using redundant systems to perform the same computation using three different systems. Different results indicate a fault in the system.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 2039, 1953581, 8950361 ], "anchor_spans": [ [ 0, 8 ], [ 15, 32 ], [ 48, 94 ] ] }, { "plaintext": "Drive-by-wire and fly-by-wire controls such as an Accelerator Position Sensor typically have two potentiometers which read in opposite directions, such that moving the control will result in one reading becoming higher, and the other generally equally lower. Mismatches between the two readings indicates a fault in the system, and the ECU can often deduce which of the two readings is faulty.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 1390368, 11522, 2528024 ], "anchor_spans": [ [ 0, 13 ], [ 18, 29 ], [ 337, 340 ] ] }, { "plaintext": "Traffic light controllers use a Conflict Monitor Unit to detect faults or conflicting signals and switch an intersection to an all flashing error signal, rather than displaying potentially dangerous conflicting signals, e.g. showing green in all directions.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 163395, 12460 ], "anchor_spans": [ [ 0, 13 ], [ 233, 238 ] ] }, { "plaintext": "The automatic protection of programs and/or processing systems when a computer hardware or software failure is detected in a computer system. A classic example is a watchdog timer. See Fail-safe (computer).", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 21808348, 5309, 7878457, 862179, 2091393 ], "anchor_spans": [ [ 70, 87 ], [ 91, 99 ], [ 125, 140 ], [ 165, 179 ], [ 185, 205 ] ] }, { "plaintext": "A control operation or function that prevents improper system functioning or catastrophic degradation in the event of circuit malfunction or operator error; for example, the failsafe track circuit used to control railway block signals. The fact that a flashing amber is more permissive than a solid amber on many railway lines is a sign of a failsafe, as the relay, if not working, will revert to a more restrictive setting.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 40961, 1107703, 8707643, 1992196, 276071 ], "anchor_spans": [ [ 2, 19 ], [ 77, 89 ], [ 118, 125 ], [ 183, 196 ], [ 213, 233 ] ] }, { "plaintext": "The iron pellet ballast on the Bathyscaphe is dropped to allow the submarine to ascend. The ballast is held in place by electromagnets. If electrical power fails, the ballast is released, and the submarine then ascends to safety.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 301717, 92377 ], "anchor_spans": [ [ 31, 42 ], [ 120, 133 ] ] }, { "plaintext": "Many nuclear reactor designs have neutron absorbing control rods suspended by electromagnets. If the power fails, they drop under gravity into the core and shut down the chain reaction in seconds by absorbing the neutrons needed for fission to continue.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 22151 ], "anchor_spans": [ [ 5, 20 ] ] }, { "plaintext": "In industrial automation, alarm circuits are usually \"normally closed\". This ensures that in case of a wire break the alarm will be triggered. If the circuit were normally open, a wire failure would go undetected, while blocking actual alarm signals.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 173354, 28284 ], "anchor_spans": [ [ 3, 24 ], [ 54, 69 ] ] }, { "plaintext": "Analog sensors and modulating actuators can usually be installed and wired such that the circuit failure results in an out-of-bound reading – see current loop. For example, a potentiometer indicating pedal position might only travel from 20% to 80% of its full range, such that a cable break or short results in a 0% or 100% reading.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 1174172 ], "anchor_spans": [ [ 146, 158 ] ] }, { "plaintext": "In control systems, critically important signals can be carried by a complementary pair of wires (<signal> and <not_signal>). Only states where the two signals are opposite (one is high, the other low) are valid. If both are high or both are low the control system knows that something is wrong with the sensor or connecting wiring. Simple failure modes (dead sensor, cut or unplugged wires) are thereby detected. An example would be a control system reading both the normally open (NO) and normally closed (NC) poles of a SPDT selector switch against common, and checking them for coherency before reacting to the input.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 28284, 28284, 28284 ], "anchor_spans": [ [ 468, 481 ], [ 491, 506 ], [ 523, 527 ] ] }, { "plaintext": "In HVAC control systems, actuators that control dampers and valves may be fail-safe, for example, to prevent coils from freezing or rooms from overheating. Older pneumatic actuators were inherently fail-safe because if the air pressure against the internal diaphragm failed, the built-in spring would push the actuator to its home position – of course the home position needed to be the \"safe\" position. Newer electrical and electronic actuators need additional components (springs or capacitors) to automatically drive the actuator to home position upon loss of electrical power.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 396508, 293079, 3420076 ], "anchor_spans": [ [ 3, 22 ], [ 25, 34 ], [ 162, 181 ] ] }, { "plaintext": "Programmable logic controllers (PLCs). To make a PLC fail-safe the system does not require energization to stop the drives associated. For example, usually, an emergency stop is a normally closed contact. In the event of a power failure this would remove the power directly from the coil and also the PLC input. Hence, a fail-safe system.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 24992, 28284 ], "anchor_spans": [ [ 0, 29 ], [ 180, 195 ] ] }, { "plaintext": "If a voltage regulator fails, it can destroy connected equipment. A crowbar (circuit) prevents damage by short-circuiting the power supply as soon as it detects overvoltage.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 624231, 1950960 ], "anchor_spans": [ [ 5, 22 ], [ 68, 85 ] ] }, { "plaintext": "As well as physical devices and systems fail-safe procedures can be created so that if a procedure is not carried out or carried out incorrectly no dangerous action results. ", "section_idx": 1, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "For example:", "section_idx": 1, "section_name": "Examples", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Spacecraft trajectory - During early Apollo program missions to the Moon, the spacecraft was put on a free return trajectory— if the engines had failed at lunar orbit insertion, the craft would have safely coasted back to Earth.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 1461, 4435025, 5908941 ], "anchor_spans": [ [ 37, 51 ], [ 102, 124 ], [ 155, 166 ] ] }, { "plaintext": "The pilot of an aircraft landing on an aircraft carrier increases the throttle to full power at touchdown. If the arresting wires fail to capture the aircraft, it is able to take off again; this is an example of fail-safe practice.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 2219, 2771881 ], "anchor_spans": [ [ 39, 55 ], [ 114, 128 ] ] }, { "plaintext": "In railway signalling signals which are not in active use for a train are required to be kept in the 'danger' position. The default position of every controlled absolute signal is therefore \"danger\", and therefore a positive action— setting signals to \"clear\"— is required before a train may pass. This practice also ensures that, in case of a fault in the signalling system, an incapacitated signalman, or the unexpected entry of a train, that a train will never be shown an erroneous \"clear\" signal.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 276071 ], "anchor_spans": [ [ 3, 21 ] ] }, { "plaintext": "Railroad engineers are instructed that a railway signal showing a confusing, contradictory or unfamiliar aspect (for example a colour light signal that has suffered an electrical failure and is showing no light at all) must be treated as showing \"danger\". In this way, the driver contributes to the fail-safety of the system.", "section_idx": 1, "section_name": "Examples", "target_page_ids": [ 276071 ], "anchor_spans": [ [ 127, 146 ] ] }, { "plaintext": "Fail-safe (foolproof) devices are also known as poka-yoke devices. Poka-yoke, a Japanese term, was coined by Shigeo Shingo, a quality expert. \"Safe to fail\" refers to civil engineering designs such as the Room for the River project in Netherlands and the Thames Estuary 2100 Plan which incorporate flexible adaptation strategies or climate change adaptation which provide for, and limit, damage, should severe events such as 500-year floods occur.", "section_idx": 2, "section_name": "Other terminology", "target_page_ids": [ 13898574, 1985954, 15606, 2381197, 15703397, 4607152 ], "anchor_spans": [ [ 11, 20 ], [ 48, 57 ], [ 80, 88 ], [ 109, 122 ], [ 205, 246 ], [ 332, 357 ] ] }, { "plaintext": "Fail-safe and fail-secure are distinct concepts. Fail-safe means that a device will not endanger lives or property when it fails. Fail-secure, also called fail-closed, means that access or data will not fall into the wrong hands in a security failure. Sometimes the approaches suggest opposite solutions. For example, if a building catches fire, fail-safe systems would unlock doors to ensure quick escape and allow firefighters inside, while fail-secure would lock doors to prevent unauthorized access to the building.", "section_idx": 2, "section_name": "Other terminology", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The opposite of fail-closed is called fail-open.", "section_idx": 2, "section_name": "Other terminology", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Fail active operational can be installed on systems that have a high degree of redundancy so that a single failure of any part of the system can be tolerated (fail active operational) and a second failure can be detected – at which point the system will turn itself off (uncouple, fail passive). One way of accomplishing this is to have three identical systems installed, and a control logic which detects discrepancies. An example for this are many aircraft systems, among them inertial navigation systems and pitot tubes.", "section_idx": 2, "section_name": "Other terminology", "target_page_ids": [ 24050869, 25100 ], "anchor_spans": [ [ 479, 505 ], [ 511, 521 ] ] }, { "plaintext": "During the Cold War, \"failsafe point\" was the term used for the point of no return for American Strategic Air Command nuclear bombers, just outside Soviet airspace. In the event of receiving an attack order, the bombers were required to linger at the failsafe point and wait for a second confirming order; until one was received, they would not arm their bombs or proceed further. The design was to prevent any single failure of the American command system causing nuclear war. This sense of the term entered the American popular lexicon with the publishing of the 1962 novel Fail-Safe.", "section_idx": 2, "section_name": "Other terminology", "target_page_ids": [ 325329, 28118, 4951184 ], "anchor_spans": [ [ 11, 19 ], [ 96, 117 ], [ 576, 585 ] ] }, { "plaintext": "(Other nuclear war command control systems have used the opposite scheme, fail-deadly, which requires continuous or regular proof that an enemy first-strike attack has not occurred to prevent the launching of a nuclear strike.)", "section_idx": 2, "section_name": "Other terminology", "target_page_ids": [ 158262 ], "anchor_spans": [ [ 74, 85 ] ] }, { "plaintext": "Fail-fast", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 4611484 ], "anchor_spans": [ [ 0, 9 ] ] }, { "plaintext": "Control theory", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 7039 ], "anchor_spans": [ [ 0, 14 ] ] }, { "plaintext": "Dead man's switch", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 351284 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "EIA-485", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 1179248 ], "anchor_spans": [ [ 0, 7 ] ] }, { "plaintext": "Elegant degradation", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 2608153 ], "anchor_spans": [ [ 0, 19 ] ] }, { "plaintext": "Failing badly", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 6493982 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Fail-deadly", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 158262 ], "anchor_spans": [ [ 0, 11 ] ] }, { "plaintext": "Fault tolerance", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 2091393 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "IEC 61508", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 4069108 ], "anchor_spans": [ [ 0, 9 ] ] }, { "plaintext": "Interlock", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 3089375 ], "anchor_spans": [ [ 0, 9 ] ] }, { "plaintext": "Safe-life design", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 2256597 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Safety engineering", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 29278 ], "anchor_spans": [ [ 0, 18 ] ] } ]

[ "Safety", "Fault-tolerant_computer_systems" ]

[]

[ { "plaintext": "In electronics, fall time (pulse decay time) is the time taken for the amplitude of a pulse to decrease (fall) from a specified value (usually 90% of the peak value exclusive of overshoot or undershoot) to another specified value (usually 10% of the maximum value exclusive of overshoot or undershoot). ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9663, 30012, 527784, 22376472 ], "anchor_spans": [ [ 3, 14 ], [ 53, 57 ], [ 87, 92 ], [ 179, 188 ] ] }, { "plaintext": "Limits on undershoot and oscillation (also known as ringing and hunting) are sometimes additionally stated when specifying fall time limits.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22386942 ], "anchor_spans": [ [ 52, 59 ] ] }, { "plaintext": "Rise time", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 780738 ], "anchor_spans": [ [ 0, 9 ] ] }, { "plaintext": "Transition time", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 780738 ], "anchor_spans": [ [ 0, 15 ] ] } ]

[ "Transient_response_characteristics" ]

[]

[ { "plaintext": "In telecommunications, fast packet switching is a variant of packet switching that increases the throughput by eliminating overhead associated with flow control and error correction functions, which are either offloaded to upper layer networking protocols or removed altogether. ATM and Frame Relay are two major implementations of fast packet switching.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 43339, 30932, 1619428, 10375, 2499, 38340 ], "anchor_spans": [ [ 3, 20 ], [ 61, 77 ], [ 97, 107 ], [ 148, 160 ], [ 165, 181 ], [ 279, 282 ], [ 287, 298 ] ] } ]

[ "Packets_(information_technology)", "Frame_Relay" ]

[]

[ { "plaintext": "Fault commonly refers to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Fault (geology), planar rock fractures showing evidence of relative movement", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 182787 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "Fault (law), blameworthiness or responsibility", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 17995775 ], "anchor_spans": [ [ 0, 11 ] ] }, { "plaintext": "Fault(s) may also refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " \"Fault\", a song by Taproot from Welcome", "section_idx": 1, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 1315270 ], "anchor_spans": [ [ 33, 40 ] ] }, { "plaintext": "Faults (film), 2014 ", "section_idx": 1, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 43170638 ], "anchor_spans": [ [ 0, 13 ] ] }, { "plaintext": "Fault (computing), also called a trap or an exception, a type of interrupt in software or operating systems", "section_idx": 2, "section_name": "Science and technology", "target_page_ids": [ 15289 ], "anchor_spans": [ [ 0, 17 ] ] }, { "plaintext": "Fault (technology), an abnormal condition or defect that may lead to a failure", "section_idx": 2, "section_name": "Science and technology", "target_page_ids": [ 4685393 ], "anchor_spans": [ [ 0, 18 ] ] }, { "plaintext": "Electrical fault, an abnormal current", "section_idx": 2, "section_name": "Science and technology", "target_page_ids": [ 6499752 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Fault (breeding), an undesirable aspect of structure or appearance of an animal", "section_idx": 3, "section_name": "Sport and competition", "target_page_ids": [ 798084 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Fault, in pickleball, any infringement of the rules by a player", "section_idx": 3, "section_name": "Sport and competition", "target_page_ids": [ 70449119 ], "anchor_spans": [ [ 10, 20 ] ] }, { "plaintext": "Fault, in show jumping, a penalty", "section_idx": 3, "section_name": "Sport and competition", "target_page_ids": [ 36871 ], "anchor_spans": [ [ 10, 22 ] ] }, { "plaintext": "Fault, in tennis jargon, a serve that fails to place a tennis ball in the correct area of play", "section_idx": 3, "section_name": "Sport and competition", "target_page_ids": [ 2086074 ], "anchor_spans": [ [ 10, 23 ] ] }, { "plaintext": "Blame", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 319888 ], "anchor_spans": [ [ 0, 5 ] ] }, { "plaintext": "Defect (disambiguation)", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 160903 ], "anchor_spans": [ [ 0, 23 ] ] }, { "plaintext": "Error", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 41118 ], "anchor_spans": [ [ 0, 5 ] ] }, { "plaintext": "Mistake (disambiguation)", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 216475 ], "anchor_spans": [ [ 0, 24 ] ] }, { "plaintext": "Software bug", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 37085 ], "anchor_spans": [ [ 0, 12 ] ] } ]

[]

[]

[ { "plaintext": "In network management, fault management is the set of functions that detect, isolate, and correct malfunctions in a telecommunications network, compensate for environmental changes, and include maintaining and examining error logs, accepting and acting on error detection notifications, tracing and identifying faults, carrying out sequences of diagnostics tests, correcting faults, reporting error conditions, and localizing and tracing faults by examining and manipulating database information.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41410, 310005, 988114, 8377, 18985062 ], "anchor_spans": [ [ 3, 21 ], [ 220, 225 ], [ 226, 230 ], [ 475, 483 ], [ 484, 495 ] ] }, { "plaintext": "When a fault or event occurs, a network component will often send a notification to the network operator using a protocol such as SNMP. An alarm is a persistent indication of a fault that clears only when the triggering condition has been resolved. A current list of problems occurring on the network component is often kept in the form of an active alarm list such as is defined in RFC 3877, the Alarm MIB. A list of cleared faults is also maintained by most network management systems.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41710, 920982, 41410 ], "anchor_spans": [ [ 130, 134 ], [ 403, 406 ], [ 460, 478 ] ] }, { "plaintext": "Fault management systems may use complex filtering systems to assign alarms to severity levels. These can range in severity from debug to emergency, as in the syslog protocol. Alternatively, they could use the ITU X.733 Alarm Reporting Function's perceived severity field. This takes on values of cleared, indeterminate, critical, major, minor or warning. Note that the latest version of the syslog protocol draft under development within the IETF includes a mapping between these two different sets of severities. It is considered good practice to send a notification not only when a problem has occurred, but also when it has been resolved. The latter notification would have a severity of clear.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1590295, 15285 ], "anchor_spans": [ [ 159, 165 ], [ 443, 447 ] ] }, { "plaintext": "A fault management console allows a network administrator or system operator to monitor events from multiple systems and perform actions based on this information. Ideally, a fault management system should be able to correctly identify events and automatically take action, either launching a program or script to take corrective action, or activating notification software that allows a human to take proper intervention (i.e. send e-mail or SMS text to a mobile phone). Some notification systems also have escalation rules that will notify a chain of individuals based on availability and severity of alarm.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1595155, 28576, 9738, 305854, 19644137 ], "anchor_spans": [ [ 36, 57 ], [ 61, 76 ], [ 433, 439 ], [ 443, 451 ], [ 457, 469 ] ] }, { "plaintext": "There are two primary ways to perform fault management - these are active and passive. Passive fault management is done by collecting alarms from devices (normally via SNMP traps) when something happens in the devices. In this mode, the fault management system only knows if a device it is monitoring is intelligent enough to generate an error and report it to the management tool. However, if the device being monitored fails completely or locks up, it won't throw an alarm and the problem will not be detected. Active fault management addresses this issue by actively monitoring devices via tools such as ping to determine if the device is active and responding. If the device stops responding, active monitoring will throw an alarm showing the device as unavailable and allows for the proactive correction of the problem.", "section_idx": 1, "section_name": "Types", "target_page_ids": [ 41710, 24265 ], "anchor_spans": [ [ 171, 175 ], [ 617, 621 ] ] }, { "plaintext": "Fault management includes any tools or procedure for testing, diagnosing or repairing the network when a failure occurs.", "section_idx": 1, "section_name": "Types", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Alarm management", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 963881 ], "anchor_spans": [ [ 0, 16 ] ] }, { "plaintext": "Alarm fatigue", "section_idx": 2, "section_name": "See also", "target_page_ids": [ 40116346 ], "anchor_spans": [ [ 0, 13 ] ] } ]

[ "Network_management" ]

[]

[ { "plaintext": "The FCC, or Federal Communications Commission, is an independent agency of the United States government.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 55974 ], "anchor_spans": [ [ 4, 7 ] ] }, { "plaintext": "FCC may also refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Federated Colored Catholics", "section_idx": 1, "section_name": "Christianity", "target_page_ids": [ 22923671 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Free Church of Scotland (disambiguation)", "section_idx": 1, "section_name": "Christianity", "target_page_ids": [ 3525501 ], "anchor_spans": [ [ 1, 41 ] ] }, { "plaintext": " Franciscan Clarist Congregation", "section_idx": 1, "section_name": "Christianity", "target_page_ids": [ 5583441 ], "anchor_spans": [ [ 1, 32 ] ] }, { "plaintext": " Faujdarhat Cadet College, in Bangladesh", "section_idx": 2, "section_name": "Education", "target_page_ids": [ 4778507 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Federal City College, now merged into the University of the District of Columbia", "section_idx": 2, "section_name": "Education", "target_page_ids": [ 744519 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Felpham Community College, in England", "section_idx": 2, "section_name": "Education", "target_page_ids": [ 20893504 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Florida Christian College, now Johnson University Florida, in Kissimmee, Florida, United States", "section_idx": 2, "section_name": "Education", "target_page_ids": [ 1157508 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Forman Christian College, in Lahore, Pakistan", "section_idx": 2, "section_name": "Education", "target_page_ids": [ 2637414 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Frederick Community College, in Maryland, United States", "section_idx": 2, "section_name": "Education", "target_page_ids": [ 28451276 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Fresno City College, in Fresno, California, United States", "section_idx": 2, "section_name": "Education", "target_page_ids": [ 1601903 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Footscray City College, a high school in Melbourne, Australia", "section_idx": 2, "section_name": "Education", "target_page_ids": [ 9404073 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " freeCodeCamp, a non-profit online course which teaches computer programming", "section_idx": 2, "section_name": "Education", "target_page_ids": [ 52809488 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Face-centered cubic, a crystal system", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 666697 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Female cosmetic coalitions, a theory about the emergence of art, ritual and symbolic culture ", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 39933524 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Fibrocystic change", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 8483785 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Flash column chromatography", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 1514469 ], "anchor_spans": [ [ 1, 28 ] ] }, { "plaintext": " Fluid catalytic cracking", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 3527984 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " Food Chemicals Codex", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 48746314 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Future Circular Collider, a proposed particle collider", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 47278268 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " A hypothetical 3-in-one vaccine, for the flu, common cold, and COVID-19.", "section_idx": 3, "section_name": "Science and technology", "target_page_ids": [ 19572217, 92693, 63030231 ], "anchor_spans": [ [ 42, 45 ], [ 47, 58 ], [ 64, 72 ] ] }, { "plaintext": " Chilean Cycling Federation (Spanish: )", "section_idx": 4, "section_name": "Sport", "target_page_ids": [ 9722935 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Colombian Cycling Federation (Spanish: )", "section_idx": 4, "section_name": "Sport", "target_page_ids": [ 9584031 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " Cuban Cycling Federation (Spanish: )", "section_idx": 4, "section_name": "Sport", "target_page_ids": [ 9639346 ], "anchor_spans": [ [ 1, 25 ] ] }, { "plaintext": " FC Carl Zeiss Jena, a German association football club", "section_idx": 4, "section_name": "Sport", "target_page_ids": [ 2073268 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " FC Chartres, a French association football club", "section_idx": 4, "section_name": "Sport", "target_page_ids": [ 25060761 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " FC Cincinnati, an American soccer club who currently play in MLS", "section_idx": 4, "section_name": "Sport", "target_page_ids": [ 59038812 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " FC Cincinnati (2016–18), predecessor to the above, which played in the league now known as the USL Championship", "section_idx": 4, "section_name": "Sport", "target_page_ids": [ 47500562 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " FIFA Confederations Cup, international association football tournament for men's national teams organised by FIFA", "section_idx": 4, "section_name": "Sport", "target_page_ids": [ 592115 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " Four Continents Championships, a figure skating competition", "section_idx": 4, "section_name": "Sport", "target_page_ids": [ 3290340 ], "anchor_spans": [ [ 1, 30 ] ] }, { "plaintext": " Ferrocarril Central, a former peruvian railway company", "section_idx": 5, "section_name": "Transport", "target_page_ids": [ 5596735 ], "anchor_spans": [ [ 1, 20 ] ] }, { "plaintext": " Ferrocarrils de la Generalitat de Catalunya, Railway operator in Catalonia, Spain", "section_idx": 5, "section_name": "Transport", "target_page_ids": [ 225124 ], "anchor_spans": [ [ 1, 44 ] ] }, { "plaintext": " Ferrocarriles de Cuba, the National Railways of Cuba", "section_idx": 5, "section_name": "Transport", "target_page_ids": [ 15368525 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " First Capital Connect, a defunct United Kingdom train operator", "section_idx": 5, "section_name": "Transport", "target_page_ids": [ 3406715 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Fairfield Community Connection, an American bulletin board system", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 3792017 ], "anchor_spans": [ [ 1, 31 ] ] }, { "plaintext": " Falling Creek Camp, in North Carolina, United States", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 19905755 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Farm Credit Canada, formerly the Farm Credit Corporation, a Canadian crown corporation", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 23814867 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Flying Cunts of Chaos, an American rock band and former backing band of Serj Tankian", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 14805239 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " FCC Environment, a British waste management firm", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 6479887 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " \"FCC Song\", by Eric Idle", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 1030429 ], "anchor_spans": [ [ 2, 10 ] ] }, { "plaintext": " Federal Correctional Complex; see List of U.S. federal prisons", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 412693 ], "anchor_spans": [ [ 35, 63 ] ] }, { "plaintext": " Five Country Conference, a conference of the immigration authorities for English speaking countries", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 51160222 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " Fomento de Construcciones y Contratas, a Spanish construction firm", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 15560578 ], "anchor_spans": [ [ 1, 38 ] ] }, { "plaintext": " Foreign Correspondents' Club, a group of clubs for correspondents and journalists", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 5092140 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " Foreign Correspondents' Club, Hong Kong", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 347516 ], "anchor_spans": [ [ 1, 40 ] ] }, { "plaintext": " Civil Forum for Change (FCC in French), an alliance of civil society groups created in Algeria in 2019", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 62670587 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " The Future Cities Catapult, which in April 2019 became the Connected Places Catapult", "section_idx": 6, "section_name": "Other uses", "target_page_ids": [ 62786804 ], "anchor_spans": [ [ 60, 85 ] ] } ]

[]

[]

[ { "plaintext": "In telecommunication, FCC registration program is the Federal Communications Commission (FCC) program and associated directives intended to assure that all connected terminal equipment and protective circuitry will not harm the public switched telephone network or certain private line services. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 55974, 41786, 468436, 41584 ], "anchor_spans": [ [ 3, 20 ], [ 54, 87 ], [ 166, 184 ], [ 228, 261 ], [ 273, 285 ] ] }, { "plaintext": "Note 1: The FCC registration program requires the registering of terminal equipment and protective circuitry in accordance with Subpart C of part 68, Title 47 of the Code of Federal Regulations. This includes the assignment of identification numbers to the equipment and the testing of the equipment. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41486 ], "anchor_spans": [ [ 142, 149 ] ] }, { "plaintext": "Note 2: The FCC registration program contains no requirement that accepted terminal equipment be compatible with, or function with, the network. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " FCC Equipment Authorization Database Search Facility", "section_idx": 1, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Federal_Communications_Commission" ]

[]

[ { "plaintext": "Feed or The Feed may refer to:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Animal feed, food given to domestic animals in the course of animal husbandry", "section_idx": 1, "section_name": "Animal foodstuffs", "target_page_ids": [ 14193930 ], "anchor_spans": [ [ 1, 12 ] ] }, { "plaintext": " Fodder, foodstuffs manufactured for animal consumption", "section_idx": 1, "section_name": "Animal foodstuffs", "target_page_ids": [ 634526 ], "anchor_spans": [ [ 1, 7 ] ] }, { "plaintext": " Forage, foodstuffs that animals gather themselves, such as by grazing", "section_idx": 1, "section_name": "Animal foodstuffs", "target_page_ids": [ 246828 ], "anchor_spans": [ [ 1, 7 ] ] }, { "plaintext": " Compound feed, foodstuffs that are blended from various raw materials and additives", "section_idx": 1, "section_name": "Animal foodstuffs", "target_page_ids": [ 14193930 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " A straight man who 'feeds' lines to the funny man in a comic dialogue", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 37614657 ], "anchor_spans": [ [ 3, 15 ] ] }, { "plaintext": " Feed (2005 film), a 2005 film directed by Brett Leonard", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 5332316 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Feed (2017 film), a 2017 film directed by Tommy Bertelsen", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 54915389 ], "anchor_spans": [ [ 1, 17 ] ] }, { "plaintext": " Feed (Anderson novel), a 2002 novel by M. T. Anderson", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 1712791 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Feed (Grant novel), a 2010 novel by Seanan McGuire under the name \"Mira Grant\"", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 32156731 ], "anchor_spans": [ [ 1, 19 ] ] }, { "plaintext": " Feed Us, 2007 song by Serj Tankian from Elect the Dead", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 10019744 ], "anchor_spans": [ [ 41, 55 ] ] }, { "plaintext": " Feed Magazine, one of the earliest e-zines that relied entirely on its original online content", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 703514 ], "anchor_spans": [ [ 1, 14 ] ] }, { "plaintext": " \"The Feed\", video game news and blogs, published by G4 Media, an NBCUniversal subsidiary", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 650407 ], "anchor_spans": [ [ 66, 78 ] ] }, { "plaintext": " Web feed or news feed, a data format used for providing users with frequently updated content", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 717016 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Feed (Facebook), a web feed on the social networking site", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 54113587 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " The Feed (Australian TV series), an Australian news TV series", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 42406498 ], "anchor_spans": [ [ 1, 32 ] ] }, { "plaintext": " The Feed (British TV series), a 2019 psychological thriller drama television series", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 56742416 ], "anchor_spans": [ [ 1, 29 ] ] }, { "plaintext": " The Feed, a recurring segment on the American TV series Attack of the Show!", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 1617619 ], "anchor_spans": [ [ 57, 76 ] ] }, { "plaintext": " In video game terminology, to die repeatedly", "section_idx": 2, "section_name": "Arts, entertainment, and media", "target_page_ids": [ 41568624 ], "anchor_spans": [ [ 4, 26 ] ] }, { "plaintext": " Antenna feed, the components of an antenna which feed the radio waves to the rest of the antenna structure", "section_idx": 3, "section_name": "Computing and telecommunications", "target_page_ids": [ 3866029 ], "anchor_spans": [ [ 1, 13 ] ] }, { "plaintext": " Data feed, a mechanism for users to receive updates from data sources", "section_idx": 3, "section_name": "Computing and telecommunications", "target_page_ids": [ 13000371 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " feed URI scheme (), a non-standard URI scheme designed to facilitate subscription to web feeds", "section_idx": 3, "section_name": "Computing and telecommunications", "target_page_ids": [ 3799086 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Relay (disambiguation), any of several technologies for forwarding messages between stations", "section_idx": 3, "section_name": "Computing and telecommunications", "target_page_ids": [ 7177393 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Feed, a broadcasting signal sent from one station to another, or to or from a central facility, intended for retransmission", "section_idx": 3, "section_name": "Computing and telecommunications", "target_page_ids": [ 113604 ], "anchor_spans": [ [ 9, 21 ] ] }, { "plaintext": " FEED (disambiguation)", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 8286790 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Feeder (disambiguation)", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 796115 ], "anchor_spans": [ [ 1, 24 ] ] }, { "plaintext": " Feeding (disambiguation)", "section_idx": 4, "section_name": "See also", "target_page_ids": [ 25286087 ], "anchor_spans": [ [ 1, 25 ] ] } ]

[]

[]

[ { "plaintext": "An optical amplifier is a device that amplifies an optical signal directly, without the need to first convert it to an electrical signal. An optical amplifier may be thought of as a laser without an optical cavity, or one in which feedback from the cavity is suppressed. Optical amplifiers are important in optical communication and laser physics. They are used as optical repeaters in the long distance fiberoptic cables which carry much of the world's telecommunication links.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22483, 275871, 17556, 591513, 11545, 164174, 17878, 3848966, 11234274 ], "anchor_spans": [ [ 51, 58 ], [ 59, 65 ], [ 182, 187 ], [ 199, 213 ], [ 231, 239 ], [ 307, 328 ], [ 333, 346 ], [ 365, 381 ], [ 404, 420 ] ] }, { "plaintext": "There are several different physical mechanisms that can be used to amplify a light signal, which correspond to the major types of optical amplifiers. In doped fiber amplifiers and bulk lasers, stimulated emission in the amplifier's gain medium causes amplification of incoming light. In semiconductor optical amplifiers (SOAs), electron-hole recombination occurs. In Raman amplifiers, Raman scattering of incoming light with phonons in the lattice of the gain medium produces photons coherent with the incoming photons. Parametric amplifiers use parametric amplification.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 28469, 40692, 9476, 142534, 2080260, 2851719, 623870, 85754, 23535, 4902017 ], "anchor_spans": [ [ 194, 213 ], [ 233, 244 ], [ 329, 337 ], [ 338, 342 ], [ 343, 356 ], [ 368, 383 ], [ 386, 402 ], [ 426, 432 ], [ 477, 483 ], [ 521, 541 ] ] }, { "plaintext": "The principle of optical amplification was invented by Gordon Gould on November 13, 1957. He filed patent No. 804,539 on April 6, 1959 titled \"Light Amplifiers Employing Collisions to Produce Population Inversions\" (subsequently amended as a continuation in part and finally issued as No. 4,746,201A on May 4, 1988). The patent covered “the amplification of light by the stimulated emission of photons from ions, atoms or molecules in gaseous, liquid or solid state.” In total, Gould obtained 48 patents related to the optical amplifier that covered 80% of the lasers on the market at the time of issuance.", "section_idx": 1, "section_name": "History", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Gould co-founded an optical telecommunications equipment firm, Optelecom Inc., that helped start Ciena Corp with his former head of Light Optics Research, David Huber. Huber and Steve Alexander of Ciena invented the dual-stage optical amplifier (US Patent 5,159,601) that was a key to the first dense wave division multiplexing (DWDM) system, marking the start of optical networking. Its significance was recognized at the time by optical authority, Shoichi Sudo and technology analyst, George Gilder in 1997, when Sudo wrote that optical amplifiers “will usher in a worldwide revolution called the Information Age” and Gilder compared the optical amplifier to the importance of the integrated circuit, predicting that it would make possible the Age of Information. Today optical amplification WDM systems are the common basis of all local, metro, national, intercontinental and subsea telecommunications networks and the technology of choice for the fiber optic backbones of the Internet (e.g. fiber-optic cables form a basis of modern day computer networking).", "section_idx": 1, "section_name": "History", "target_page_ids": [ 11234274, 4122592 ], "anchor_spans": [ [ 995, 1013 ], [ 1041, 1060 ] ] }, { "plaintext": "Almost any laser active gain medium can be pumped to produce gain for light at the wavelength of a laser made with the same material as its gain medium. Such amplifiers are commonly used to produce high power laser systems. Special types such as regenerative amplifiers and chirped-pulse amplifiers are used to amplify ultrashort pulses.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 40692, 3245664, 10547121, 7835939, 2055287, 1207161 ], "anchor_spans": [ [ 17, 35 ], [ 43, 49 ], [ 61, 65 ], [ 246, 268 ], [ 274, 298 ], [ 319, 335 ] ] }, { "plaintext": "Solid-state amplifiers are optical amplifiers that uses a wide range of doped solid-state materials ( Yb:YAG, Sa) and different geometries (disk, slab, rod) to amplify optical signals. The variety of materials allows the amplification of different wavelength while the shape of the medium can distinguish between more suitable for energy of average power scaling. Beside their use in fundamental research from gravitational wave detection to high energy physics at the National Ignition Facility they can also be found in many of today’s ultra short pulsed lasers.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 3184580, 495725, 8111079, 337301, 11932926 ], "anchor_spans": [ [ 78, 89 ], [ 110, 112 ], [ 410, 428 ], [ 469, 495 ], [ 538, 563 ] ] }, { "plaintext": "Doped fiber amplifiers (DFAs) are optical amplifiers that use a doped optical fiber as a gain medium to amplify an optical signal. They are related to fiber lasers. The signal to be amplified and a pump laser are multiplexed into the doped fiber, and the signal is amplified through interaction with the doping ions. ", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 23777515, 3372377, 4555508, 41389, 18963787 ], "anchor_spans": [ [ 64, 69 ], [ 70, 83 ], [ 151, 162 ], [ 213, 224 ], [ 311, 315 ] ] }, { "plaintext": "Amplification is achieved by stimulated emission of photons from dopant ions in the doped fiber. The pump laser excites ions into a higher energy from where they can decay via stimulated emission of a photon at the signal wavelength back to a lower energy level. The excited ions can also decay spontaneously (spontaneous emission) or even through nonradiative processes involving interactions with phonons of the glass matrix. These last two decay mechanisms compete with stimulated emission reducing the efficiency of light amplification.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 85754 ], "anchor_spans": [ [ 399, 405 ] ] }, { "plaintext": "The amplification window of an optical amplifier is the range of optical wavelengths for which the amplifier yields a usable gain. The amplification window is determined by the spectroscopic properties of the dopant ions, the glass structure of the optical fiber, and the wavelength and power of the pump laser.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Although the electronic transitions of an isolated ion are very well defined, broadening of the energy levels occurs when the ions are incorporated into the glass of the optical fiber and thus the amplification window is also broadened. This broadening is both homogeneous (all ions exhibit the same broadened spectrum) and inhomogeneous (different ions in different glass locations exhibit different spectra). Homogeneous broadening arises from the interactions with phonons of the glass, while inhomogeneous broadening is caused by differences in the glass sites where different ions are hosted. Different sites expose ions to different local electric fields, which shifts the energy levels via the Stark effect. In addition, the Stark effect also removes the degeneracy of energy states having the same total angular momentum (specified by the quantum number J). Thus, for example, the trivalent erbium ion (Er3+) has a ground state with J = 15/2, and in the presence of an electric field splits into J + 1/2 = 8 sublevels with slightly different energies. The first excited state has J = 13/2 and therefore a Stark manifold with 7 sublevels. Transitions from the J = 13/2 excited state to the J= 15/2 ground state are responsible for the gain at 1500nm wavelength. The gain spectrum of the EDFA has several peaks that are smeared by the above broadening mechanisms. The net result is a very broad spectrum (30nm in silica, typically). The broad gain-bandwidth of fiber amplifiers make them particularly useful in wavelength-division multiplexed communications systems as a single amplifier can be utilized to amplify all signals being carried on a fiber and whose wavelengths fall within the gain window.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 3061815, 3061815, 85754, 614763, 80464 ], "anchor_spans": [ [ 261, 272 ], [ 324, 337 ], [ 468, 474 ], [ 701, 713 ], [ 1517, 1548 ] ] }, { "plaintext": "An erbium-doped waveguide amplifier (EDWA) is an optical amplifier that uses a waveguide to boost an optical signal.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 53742121, 41863 ], "anchor_spans": [ [ 3, 35 ], [ 79, 88 ] ] }, { "plaintext": "A relatively high-powered beam of light is mixed with the input signal using a wavelength selective coupler (WSC). The input signal and the excitation light must be at significantly different wavelengths. The mixed light is guided into a section of fiber with erbium ions included in the core. This high-powered light beam excites the erbium ions to their higher-energy state. When the photons belonging to the signal at a different wavelength from the pump light meet the excited erbium ions, the erbium ions give up some of their energy to the signal and return to their lower-energy state.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A significant point is that the erbium gives up its energy in the form of additional photons which are exactly in the same phase and direction as the signal being amplified. So the signal is amplified along its direction of travel only. This is not unusual – when an atom \"lases\" it always gives up its energy in the same direction and phase as the incoming light. Thus all of the additional signal power is guided in the same fiber mode as the incoming signal. An optical isolator is usually placed at the output to prevent reflections returning from the attached fiber. Such reflections disrupt amplifier operation and in the extreme case can cause the amplifier to become a laser. ", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 41460 ], "anchor_spans": [ [ 465, 481 ] ] }, { "plaintext": "The erbium doped amplifier is a high gain amplifier.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The principal source of noise in DFAs is Amplified Spontaneous Emission (ASE), which has a spectrum approximately the same as the gain spectrum of the amplifier. Noise figure in an ideal DFA is 3dB, while practical amplifiers can have noise figure as large as 6–8dB.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 3519852, 41417 ], "anchor_spans": [ [ 41, 71 ], [ 162, 174 ] ] }, { "plaintext": "As well as decaying via stimulated emission, electrons in the upper energy level can also decay by spontaneous emission, which occurs at random, depending upon the glass structure and inversion level. Photons are emitted spontaneously in all directions, but a proportion of those will be emitted in a direction that falls within the numerical aperture of the fiber and are thus captured and guided by the fiber. Those photons captured may then interact with other dopant ions, and are thus amplified by stimulated emission. The initial spontaneous emission is therefore amplified in the same manner as the signals, hence the term Amplified Spontaneous Emission. ASE is emitted by the amplifier in both the forward and reverse directions, but only the forward ASE is a direct concern to system performance since that noise will co-propagate with the signal to the receiver where it degrades system performance. Counter-propagating ASE can, however, lead to degradation of the amplifier's performance since the ASE can deplete the inversion level and thereby reduce the gain of the amplifier and increase the noise produced relative to the desired signal gain.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 41432 ], "anchor_spans": [ [ 333, 351 ] ] }, { "plaintext": "Noise figure can be analyzed in both the optical domain and in the electrical domain. In the optical domain, measurement of the ASE, the optical signal gain, and signal wavelength using an optical spectrum analyzer permits calculation of the noise figure. For the electrical measurement method, the detected photocurrent noise is evaluated with a low-noise electrical spectrum analyzer, which along with measurement of the amplifier gain permits a noise figure measurement. Generally, the optical technique provides a more simple method, though it is not inclusive of excess noise effects captured by the electrical method such multi-path interference (MPI) noise generation. In both methods, attention to effects such as the spontaneous emission accompanying the input signal are critical to accurate measurement of noise figure.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Gain is achieved in a DFA due to population inversion of the dopant ions. The inversion level of a DFA is set, primarily, by the power of the pump wavelength and the power at the amplified wavelengths. As the signal power increases, or the pump power decreases, the inversion level will reduce and thereby the gain of the amplifier will be reduced. This effect is known as gain saturation – as the signal level increases, the amplifier saturates and cannot produce any more output power, and therefore the gain reduces. Saturation is also commonly known as gain compression.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 24065 ], "anchor_spans": [ [ 33, 53 ] ] }, { "plaintext": "To achieve optimum noise performance DFAs are operated under a significant amount of gain compression (10dB typically), since that reduces the rate of spontaneous emission, thereby reducing ASE. Another advantage of operating the DFA in the gain saturation region is that small fluctuations in the input signal power are reduced in the output amplified signal: smaller input signal powers experience larger (less saturated) gain, while larger input powers see less gain.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The leading edge of the pulse is amplified, until the saturation energy of the gain medium is reached. In some condition, the width (FWHM) of the pulse is reduced.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 41200 ], "anchor_spans": [ [ 133, 137 ] ] }, { "plaintext": "Due to the inhomogeneous portion of the linewidth broadening of the dopant ions, the gain spectrum has an inhomogeneous component and gain saturation occurs, to a small extent, in an inhomogeneous manner. This effect is known as spectral hole burning because a high power signal at one wavelength can 'burn' a hole in the gain for wavelengths close to that signal by saturation of the inhomogeneously broadened ions. Spectral holes vary in width depending on the characteristics of the optical fiber in question and the power of the burning signal, but are typically less than 1nm at the short wavelength end of the C-band, and a few nm at the long wavelength end of the C-band. The depth of the holes are very small, though, making it difficult to observe in practice.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 30285355 ], "anchor_spans": [ [ 229, 250 ] ] }, { "plaintext": "Although the DFA is essentially a polarization independent amplifier, a small proportion of the dopant ions interact preferentially with certain polarizations and a small dependence on the polarization of the input signal may occur (typically < 0.5dB). This is called Polarization Dependent Gain (PDG).", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The absorption and emission cross sections of the ions can be modeled as ellipsoids with the major axes aligned at random in all directions in different glass sites. The random distribution of the orientation of the ellipsoids in a glass produces a macroscopically isotropic medium, but a strong pump laser induces an anisotropic distribution by selectively exciting those ions that are more aligned with the optical field vector of the pump. Also, those excited ions aligned with the signal field produce more stimulated emission. The change in gain is thus dependent on the alignment of the polarizations of the pump and signal lasers – i.e. whether the two lasers are interacting with the same sub-set of dopant ions or not. ", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In an ideal doped fiber without birefringence, the PDG would be inconveniently large. Fortunately, in optical fibers small amounts of birefringence are always present and, furthermore, the fast and slow axes vary randomly along the fiber length. A typical DFA has several tens of meters, long enough to already show this randomness of the birefringence axes. These two combined effects (which in transmission fibers give rise to polarization mode dispersion) produce a misalignment of the relative polarizations of the signal and pump lasers along the fiber, thus tending to average out the PDG. The result is that PDG is very difficult to observe in a single amplifier (but is noticeable in links with several cascaded amplifiers).", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 174412, 749827 ], "anchor_spans": [ [ 32, 45 ], [ 429, 457 ] ] }, { "plaintext": "The erbium-doped fiber amplifier (EDFA) is the most deployed fiber amplifier as its amplification window coincides with the third transmission window of silica-based optical fiber. The core of a silica fiber is doped with trivalent erbium ions (Er3+) and can be efficiently pumped with a laser at or near wavelengths of 980nm and 1480nm, and gain is exhibited in the 1550nm region. The EDFA amplification region varies from application to application and can be anywhere from a few nm up to ~80nm. Typical use of EDFA in telecommunications calls for Conventional, or C-band amplifiers (from ~1525 nm to ~1565 nm) or Long, or L-band amplifiers (from ~1565 nm to ~1610 nm). Both of these bands can be amplified by EDFAs, but it is normal to use two different amplifiers, each optimized for one of the bands.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 9478, 21837 ], "anchor_spans": [ [ 232, 238 ], [ 323, 325 ] ] }, { "plaintext": "The principal difference between C- and L-band amplifiers is that a longer length of doped fiber is used in L-band amplifiers. The longer length of fiber allows a lower inversion level to be used, thereby giving emission at longer wavelengths (due to the band-structure of Erbium in silica) while still providing a useful amount of gain.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "EDFAs have two commonly used pumping bands – 980nm and 1480nm. The 980nm band has a higher absorption cross-section and is generally used where low-noise performance is required. The absorption band is relatively narrow and so wavelength stabilised laser sources are typically needed. The 1480nm band has a lower, but broader, absorption cross-section and is generally used for higher power amplifiers. A combination of 980nm and 1480nm pumping is generally utilised in amplifiers.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Gain and lasing in Erbium-doped fibers were first demonstrated in 1986–87 by two groups; one including David N. Payne, R. Mears, I.M Jauncey and L. Reekie, from the University of Southampton and one from AT&T Bell Laboratories, consisting of E. Desurvire, P. Becker, and J. Simpson. The dual-stage optical amplifier which enabled Dense Wave Division Multiplexing (DWDM) was invented by Stephen B. Alexander at Ciena Corporation.", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 3182592, 52435972, 98078 ], "anchor_spans": [ [ 103, 117 ], [ 119, 127 ], [ 165, 190 ] ] }, { "plaintext": "Thulium doped fiber amplifiers have been used in the S-band (1450–1490nm) and Praseodymium doped amplifiers in the 1300nm region. However, those regions have not seen any significant commercial use so far and so those amplifiers have not been the subject of as much development as the EDFA. However, Ytterbium doped fiber lasers and amplifiers, operating near 1 micrometre wavelength, have many applications in industrial processing of materials, as these devices can be made with extremely high output power (tens of kilowatts).", "section_idx": 2, "section_name": "Laser amplifiers", "target_page_ids": [ 30047, 553947, 251720, 34240 ], "anchor_spans": [ [ 0, 7 ], [ 53, 59 ], [ 78, 90 ], [ 300, 309 ] ] }, { "plaintext": "Semiconductor optical amplifiers (SOAs) are amplifiers which use a semiconductor to provide the gain medium. These amplifiers have a similar structure to Fabry–Pérot laser diodes but with anti-reflection design elements at the end faces. Recent designs include anti-reflective coatings and tilted wave guide and window regions which can reduce end face reflection to less than 0.001%. Since this creates a loss of power from the cavity which is greater than the gain, it prevents the amplifier from acting as a laser. Another type of SOA consists of two regions. One part has a structure of a Fabry-Pérot laser diode and the other has a tapered geometry in order to reduce the power density on the output facet.", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [ 196118, 142258, 41863 ], "anchor_spans": [ [ 154, 165 ], [ 166, 178 ], [ 297, 307 ] ] }, { "plaintext": "Semiconductor optical amplifiers are typically made from group III-V compound semiconductors such as GaAs/AlGaAs, InP/InGaAs, InP/InGaAsP and InP/InAlGaAs, though any direct band gap semiconductors such as II-VI could conceivably be used. Such amplifiers are often used in telecommunication systems in the form of fiber-pigtailed components, operating at signal wavelengths between 850nm and 1600nm and generating gains of up to 30dB.", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [ 144143, 522356, 2141015, 522356, 522356 ], "anchor_spans": [ [ 101, 105 ], [ 114, 117 ], [ 118, 124 ], [ 126, 129 ], [ 142, 145 ] ] }, { "plaintext": "The semiconductor optical amplifier is of small size and electrically pumped. It can be potentially less expensive than the EDFA and can be integrated with semiconductor lasers, modulators, etc. However, the performance is still not comparable with the EDFA. The SOA has higher noise, lower gain, moderate polarization dependence and high nonlinearity with fast transient time. The main advantage of SOA is that all four types of nonlinear operations (cross gain modulation, cross phase modulation, wavelength conversion and four wave mixing) can be conducted. Furthermore, SOA can be run with a low power laser.", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [ 21723, 1427967 ], "anchor_spans": [ [ 339, 348 ], [ 525, 541 ] ] }, { "plaintext": "This originates from the short nanosecond or less upper state lifetime, so that the gain reacts rapidly to changes of pump or signal power and the changes of gain also cause phase changes which can distort the signals.", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "This nonlinearity presents the most severe problem for optical communication applications. However it provides the possibility for gain in different wavelength regions from the EDFA. \"Linear optical amplifiers\" using gain-clamping techniques have been developed.", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "High optical nonlinearity makes semiconductor amplifiers attractive for all optical signal processing like all-optical switching and wavelength conversion. There has been much research on semiconductor optical amplifiers as elements for optical signal processing, wavelength conversion, clock recovery, signal demultiplexing, and pattern recognition.", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "A recent addition to the SOA family is the vertical-cavity SOA (VCSOA). These devices are similar in structure to, and share many features with, vertical-cavity surface-emitting lasers (VCSELs). The major difference when comparing VCSOAs and VCSELs is the reduced mirror reflectivity used in the amplifier cavity. With VCSOAs, reduced feedback is necessary to prevent the device from reaching lasing threshold. Due to the extremely short cavity length, and correspondingly thin gain medium, these devices exhibit very low single-pass gain (typically on the order of a few percent) and also a very large free spectral range (FSR). The small single-pass gain requires relatively high mirror reflectivity to boost the total signal gain. In addition to boosting the total signal gain, the use of the resonant cavity structure results in a very narrow gain bandwidth; coupled with the large FSR of the optical cavity, this effectively limits operation of the VCSOA to single-channel amplification. Thus, VCSOAs can be seen as amplifying filters.", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [ 436714, 16726586, 521510 ], "anchor_spans": [ [ 186, 191 ], [ 603, 622 ], [ 796, 811 ] ] }, { "plaintext": "Given their vertical-cavity geometry, VCSOAs are resonant cavity optical amplifiers that operate with the input/output signal entering/exiting normal to the wafer surface. In addition to their small size, the surface normal operation of VCSOAs leads to a number of advantages, including low power consumption, low noise figure, polarization insensitive gain, and the ability to fabricate high fill factor two-dimensional arrays on a single semiconductor chip. These devices are still in the early stages of research, though promising preamplifier results have been demonstrated. Further extensions to VCSOA technology are the demonstration of wavelength tunable devices. These MEMS-tunable vertical-cavity SOAs utilize a microelectromechanical systems (MEMS) based tuning mechanism for wide and continuous tuning of the peak gain wavelength of the amplifier. SOAs have a more rapid gain response, which is in the order of 1 to 100 ps.", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [ 19638 ], "anchor_spans": [ [ 753, 757 ] ] }, { "plaintext": "For high output power and broader wavelength range, tapered amplifiers are used. These amplifiers consist of a lateral single-mode section and a section with a tapered structure, where the laser light is amplified. The tapered structure leads to a reduction of the power density at the output facet.", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Typical parameters:", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " wavelength range: 633 to 1480nm", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " input power: 10 to 50mW", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " output power: up to 3 W", "section_idx": 3, "section_name": "Semiconductor optical amplifier", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "In a Raman amplifier, the signal is intensified by Raman amplification. Unlike the EDFA and SOA the amplification effect is achieved by a nonlinear interaction between the signal and a pump laser within an optical fiber. There are two types of Raman amplifier: distributed and lumped. A distributed Raman amplifier is one in which the transmission fiber is utilised as the gain medium by multiplexing a pump wavelength with signal wavelength, while a lumped Raman amplifier utilises a dedicated, shorter length of fiber to provide amplification. In the case of a lumped Raman amplifier, a highly nonlinear fiber with a small core is utilised to increase the interaction between signal and pump wavelengths, and thereby reduce the length of fiber required.", "section_idx": 4, "section_name": "Raman amplifier", "target_page_ids": [ 2851719 ], "anchor_spans": [ [ 51, 70 ] ] }, { "plaintext": "The pump light may be coupled into the transmission fiber in the same direction as the signal (co-directional pumping), in the opposite direction (contra-directional pumping) or both. Contra-directional pumping is more common as the transfer of noise from the pump to the signal is reduced.", "section_idx": 4, "section_name": "Raman amplifier", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The pump power required for Raman amplification is higher than that required by the EDFA, with in excess of 500mW being required to achieve useful levels of gain in a distributed amplifier. Lumped amplifiers, where the pump light can be safely contained to avoid safety implications of high optical powers, may use over 1 W of optical power.", "section_idx": 4, "section_name": "Raman amplifier", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The principal advantage of Raman amplification is its ability to provide distributed amplification within the transmission fiber, thereby increasing the length of spans between amplifier and regeneration sites. The amplification bandwidth of Raman amplifiers is defined by the pump wavelengths utilised and so amplification can be provided over wider, and different, regions than may be possible with other amplifier types which rely on dopants and device design to define the amplification 'window'.", "section_idx": 4, "section_name": "Raman amplifier", "target_page_ids": [ 19570111 ], "anchor_spans": [ [ 191, 203 ] ] }, { "plaintext": "Raman amplifiers have some fundamental advantages. First, Raman gain exists in every fiber, which provides a cost-effective means of upgrading from the terminal ends. Second, the gain is nonresonant, which means that gain is available over the entire transparency region of the fiber ranging from approximately 0.3 to 2µm. A third advantage of Raman amplifiers is that the gain spectrum can be tailored by adjusting the pump wavelengths. For instance, multiple pump lines can be used to increase the optical bandwidth, and the pump distribution determines the gain flatness. Another advantage of Raman amplification is that it is a relatively broad-band amplifier with a bandwidth > 5 THz, and the gain is reasonably flat over a wide wavelength range.", "section_idx": 4, "section_name": "Raman amplifier", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "However, a number of challenges for Raman amplifiers prevented their earlier adoption. First, compared to the EDFAs, Raman amplifiers have relatively poor pumping efficiency at lower signal powers. Although a disadvantage, this lack of pump efficiency also makes gain clamping easier in Raman amplifiers. Second, Raman amplifiers require a longer gain fiber. However, this disadvantage can be mitigated by combining gain and the dispersion compensation in a single fiber. A third disadvantage of Raman amplifiers is a fast response time, which gives rise to new sources of noise, as further discussed below. Finally, there are concerns of nonlinear penalty in the amplifier for the WDM signal channels.", "section_idx": 4, "section_name": "Raman amplifier", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Note: The text of an earlier version of this article was taken from the public domain Federal Standard 1037C.", "section_idx": 4, "section_name": "Raman amplifier", "target_page_ids": [ 37310 ], "anchor_spans": [ [ 86, 108 ] ] }, { "plaintext": "An optical parametric amplifier allows the amplification of a weak signal-impulse in a nonlinear medium such as a noncentrosymmetric nonlinear medium (e.g. Beta barium borate (BBO)) or even a standard fused silica optical fiber via the Kerr effect. In contrast to the previously mentioned amplifiers, which are mostly used in telecommunication environments, this type finds its main application in expanding the frequency tunability of ultrafast solid-state lasers (e.g. sapphire). By using a noncollinear interaction geometry optical parametric amplifiers are capable of extremely broad amplification bandwidths.", "section_idx": 5, "section_name": "Optical parametric amplifier", "target_page_ids": [ 1114367, 3510274, 20935882, 661039, 3184580, 495725, 3189581 ], "anchor_spans": [ [ 3, 31 ], [ 114, 132 ], [ 156, 174 ], [ 236, 247 ], [ 446, 463 ], [ 471, 479 ], [ 493, 505 ] ] }, { "plaintext": "The adoption of high power fiber lasers as an industrial material processing tool has been ongoing for several years and is now expanding into other markets including the medical and scientific markets. One key enhancement enabling penetration into the scientific market has been the improvements in high finesse fiber amplifiers, which are now capable of delivering single frequency linewidths (<5kHz) together with excellent beam quality and stable linearly polarized output. Systems meeting these specifications have steadily progressed in the last few years from a few watts of output power, initially to the tens of watts and now into the hundreds of watts power level. This power scaling has been achieved with developments in the fiber technology, such as the adoption of stimulated brillouin scattering (SBS) suppression/mitigation techniques within the fiber, along with improvements in the overall amplifier design including large mode area (LMA) fibers with a low-aperture core, micro-structured rod-type fiber helical core, or chirally-coupled core fibers, and tapered double-clad fibers (T-DCF). The latest generation of high finesse, high power and pulsed fiber amplifiers now deliver power levels exceeding what is available from commercial solid-state single frequency sources and are opening up new scientific applications as a result of the higher power levels and stable optimized performance.", "section_idx": 6, "section_name": "Recent achievements", "target_page_ids": [ 4555508, 622714, 44776375 ], "anchor_spans": [ [ 27, 38 ], [ 790, 810 ], [ 1164, 1170 ] ] }, { "plaintext": "There are several simulation tools that can be used to design optical amplifiers. Popular commercial tools have been developed by Optiwave Systems and VPI Systems.", "section_idx": 7, "section_name": "Implementations", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Regenerative amplification", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 7835939 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " Nonlinear theory of semiconductor lasers", "section_idx": 8, "section_name": "See also", "target_page_ids": [ 52207824 ], "anchor_spans": [ [ 1, 41 ] ] }, { "plaintext": " Overview of commercially available semiconductor tapered amplifiers", "section_idx": 10, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Overview of commercially available solid-state amplifiers", "section_idx": 10, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Encyclopedia of laser physics and technology on fiber amplifiers and Raman amplifiers", "section_idx": 10, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Current Trends in Unrepeatered Systems including ROPA Remote Optically-Pumped Amplifier", "section_idx": 10, "section_name": "External links", "target_page_ids": [], "anchor_spans": [] } ]

[ "Optical_devices", "Amplifiers", "Laser_science", "Fiber-optic_communications" ]

[]

[ { "plaintext": "Fiber Distributed Data Interface (FDDI) is a standard for data transmission in a local area network.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 42168, 17739 ], "anchor_spans": [ [ 58, 75 ], [ 81, 99 ] ] }, { "plaintext": "It uses optical fiber as its standard underlying physical medium, although it was also later specified to use copper cable, in which case it may be called CDDI (Copper Distributed Data Interface), standardized as TP-PMD (Twisted-Pair Physical Medium-Dependent), also referred to as TP-DDI (Twisted-Pair Distributed Data Interface).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3372377, 125293 ], "anchor_spans": [ [ 8, 21 ], [ 110, 116 ] ] }, { "plaintext": "FDDI was effectively made obsolete in local networks by Fast Ethernet which offered the same 100Mbit/s speeds, but at a much lower cost and, since 1998, by Gigabit Ethernet due to its speed, and even lower cost, and ubiquity.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 64506, 64636 ], "anchor_spans": [ [ 56, 69 ], [ 156, 172 ] ] }, { "plaintext": "FDDI provides a 100Mbit/s optical standard for data transmission in local area network that can extend in range up to . Although FDDI logical topology is a ring-based token network, it did not use the IEEE 802.5 Token Ring protocol as its basis; instead, its protocol was derived from the IEEE 802.4 token bus timed token protocol. In addition to covering large geographical areas, FDDI local area networks can support thousands of users. FDDI offers both a Dual-Attached Station (DAS), counter-rotating token ring topology and a Single-Attached Station (SAS), token bus passing ring topology.", "section_idx": 1, "section_name": "Description", "target_page_ids": [ 14832328, 42168, 17739, 7016168, 28030850, 147427 ], "anchor_spans": [ [ 19, 25 ], [ 47, 64 ], [ 68, 86 ], [ 212, 222 ], [ 223, 231 ], [ 300, 309 ] ] }, { "plaintext": "FDDI, as a product of American National Standards Institute X3T9.5 (now X3T12), conforms to the Open Systems Interconnection (OSI) model of functional layering using other protocols. The standards process started in the mid 1980s.", "section_idx": 1, "section_name": "Description", "target_page_ids": [ 659, 22747 ], "anchor_spans": [ [ 22, 59 ], [ 96, 124 ] ] }, { "plaintext": "FDDI-II, a version of FDDI described in 1989, added circuit-switched service capability to the network so that it could also handle voice and video signals. Work started to connect FDDI networks to synchronous optical networking (SONET) technology.", "section_idx": 1, "section_name": "Description", "target_page_ids": [ 40874, 32441, 38536 ], "anchor_spans": [ [ 52, 76 ], [ 142, 147 ], [ 198, 228 ] ] }, { "plaintext": "A FDDI network contains two rings, one as a secondary backup in case the primary ring fails. The primary ring offers up to 100Mbit/s capacity. When a network has no requirement for the secondary ring to do backup, it can also carry data, extending capacity to 200Mbit/s. The single ring can extend the maximum distance; a dual ring can extend . FDDI had a larger maximum frame size (4,352 bytes) than the standard Ethernet family, which only supports a maximum frame size of 1,500 bytes, allowing better effective data rates in some cases.", "section_idx": 1, "section_name": "Description", "target_page_ids": [ 9499 ], "anchor_spans": [ [ 414, 422 ] ] }, { "plaintext": "Designers normally constructed FDDI rings in a network topology such as a \"dual ring of trees\". A small number of devices, typically infrastructure devices such as routers and concentrators rather than host computers, were \"dual-attached\" to both rings. Host computers then connect as single-attached devices to the routers or concentrators. The dual ring in its most degenerate form simply collapses into a single device. Typically, a computer-room contained the whole dual ring, although some implementations deployed FDDI as a metropolitan area network.", "section_idx": 2, "section_name": "Topology", "target_page_ids": [ 41413, 25748, 43326 ], "anchor_spans": [ [ 47, 63 ], [ 164, 170 ], [ 530, 555 ] ] }, { "plaintext": "FDDI requires this network topology because the dual ring actually passes through each connected device and requires each such device to remain continuously operational.", "section_idx": 2, "section_name": "Topology", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "The standard actually allows for optical bypasses, but network engineers consider these unreliable and error-prone. Devices such as workstations and minicomputers that might not come under the control of the network managers are not suitable for connection to the dual ring.", "section_idx": 2, "section_name": "Topology", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "As an alternative to using a dual-attached connection, a workstation can obtain the same degree of resilience through a dual-homed connection made simultaneously to two separate devices in the same FDDI ring. One of the connections becomes active while the other one is automatically blocked. If the first connection fails, the backup link takes over with no perceptible delay.", "section_idx": 2, "section_name": "Topology", "target_page_ids": [ 16290509 ], "anchor_spans": [ [ 99, 109 ] ] }, { "plaintext": "The frame check sequence uses the same cyclic redundancy check as Token Ring and Ethernet.", "section_idx": 3, "section_name": "Frame format", "target_page_ids": [ 38838, 7016168, 9499 ], "anchor_spans": [ [ 39, 62 ], [ 66, 76 ], [ 81, 89 ] ] }, { "plaintext": "The Internet Engineering Task Force defined a standard for transmission of the Internet Protocol (which would be the protocol data unit in this case) over FDDI. It was first proposed in June 1989 and revised in 1990. Some aspects of the protocol were compatible with the IEEE 802.2 standard for logical link control. For example, the 48-bit MAC addresses that became popular with the Ethernet family. Thus other protocols such as the Address Resolution Protocol (ARP) could be common as well.", "section_idx": 3, "section_name": "Frame format", "target_page_ids": [ 15285, 15323, 15222, 145459, 20668, 47986 ], "anchor_spans": [ [ 4, 35 ], [ 79, 96 ], [ 271, 281 ], [ 295, 315 ], [ 341, 352 ], [ 434, 461 ] ] }, { "plaintext": "FDDI was considered an attractive campus backbone network technology in the early to mid 1990s since existing Ethernet networks only offered 10Mbit/s data rates and Token Ring networks only offered 4Mbit/s or 16Mbit/s rates. Thus it was a relatively high-speed choice of that era.", "section_idx": 4, "section_name": "Deployment", "target_page_ids": [ 2853516 ], "anchor_spans": [ [ 41, 57 ] ] }, { "plaintext": "By 1994, vendors included Cisco Systems, National Semiconductor, Network Peripherals, SysKonnect (acquired by Marvell Technology Group), and 3Com.", "section_idx": 4, "section_name": "Deployment", "target_page_ids": [ 51746, 100597, 5276522, 35503 ], "anchor_spans": [ [ 26, 39 ], [ 41, 63 ], [ 110, 134 ], [ 141, 145 ] ] }, { "plaintext": "FDDI installations have largely been replaced by Ethernet deployments.", "section_idx": 4, "section_name": "Deployment", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "FDDI standards included:", "section_idx": 5, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ANSI X3.139-1987, Media Access Control (MAC) — also ISO 9314-2", "section_idx": 5, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ANSI X3.148-1988, Physical Layer Protocol (PHY) — also ISO 9314-1", "section_idx": 5, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ANSI X3.166-1989, Physical Medium Dependent (PMD) — also ISO 9314-3", "section_idx": 5, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ANSI X3.184-1993, Single Mode Fiber Physical Medium Dependent (SMF-PMD) — also ISO 9314-4", "section_idx": 5, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " ANSI X3.229-1994, Station Management (SMT) — also ISO 9314-6", "section_idx": 5, "section_name": "Standards", "target_page_ids": [], "anchor_spans": [] } ]

[ "Local_area_networks", "Link_protocols", "ISO_standards" ]

[ "FDDI" ]

[ { "plaintext": "In physics, field strength means the magnitude of a vector-valued field (e.g., in volts per meter, V/m, for an electric field E). ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 22939, 577301, 32533, 26998617, 41092 ], "anchor_spans": [ [ 3, 10 ], [ 37, 46 ], [ 52, 58 ], [ 66, 71 ], [ 111, 125 ] ] }, { "plaintext": "For example, an electromagnetic field results in both electric field strength and magnetic field strength.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9735, 41092, 36563 ], "anchor_spans": [ [ 16, 37 ], [ 54, 77 ], [ 82, 105 ] ] }, { "plaintext": "As an application, in radio frequency telecommunications, the signal strength excites a receiving antenna and thereby induces a voltage at a specific frequency and polarization in order to provide an input signal to a radio receiver. Field strength meters are used for such applications as cellular, broadcasting, wi-fi and a wide variety of other radio-related applications.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 42852, 33094374, 690346, 31474404 ], "anchor_spans": [ [ 22, 37 ], [ 38, 56 ], [ 62, 77 ], [ 234, 254 ] ] }, { "plaintext": " Dipole field strength in free space", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 26064542 ], "anchor_spans": [ [ 1, 36 ] ] }, { "plaintext": " Field strength tensor", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 1912367 ], "anchor_spans": [ [ 1, 22 ] ] }, { "plaintext": " Signal strength in telecommunications", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 690346 ], "anchor_spans": [ [ 1, 38 ] ] } ]

[ "Electromagnetism", "Physical_quantities" ]

[]

[ { "plaintext": "In computing, a file server (or fileserver) is a computer attached to a network that provides a location for shared disk access, i.e. storage of computer files (such as text, image, sound, video) that can be accessed by the workstations that are able to reach the computer that shares the access through a computer network. The term server highlights the role of the machine in the traditional client–server scheme, where the clients are the workstations using the storage. A file server does not normally perform computational tasks or run programs on behalf of its client workstations.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 6513 ], "anchor_spans": [ [ 394, 407 ] ] }, { "plaintext": "File servers are commonly found in schools and offices, where users use a local area network to connect their client computers.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 17739 ], "anchor_spans": [ [ 74, 92 ] ] }, { "plaintext": "A file server may be dedicated or non-dedicated. A dedicated server is designed specifically for use as a file server, with workstations attached for reading and writing files and databases.", "section_idx": 1, "section_name": "Types of file servers", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "File servers may also be categorized by the method of access: Internet file servers are frequently accessed by File Transfer Protocol or by HTTP (but are different from, that often provide dynamic web content in addition to static files). Servers on a LAN are usually accessed by SMB/CIFS protocol (Windows and Unix-like) or NFS protocol (Unix-like systems).", "section_idx": 1, "section_name": "Types of file servers", "target_page_ids": [ 53289, 13443, 349873, 349873, 18890, 21347057, 51252 ], "anchor_spans": [ [ 111, 133 ], [ 140, 144 ], [ 281, 284 ], [ 285, 289 ], [ 301, 308 ], [ 313, 322 ], [ 327, 330 ] ] }, { "plaintext": "Database servers, that provide access to a shared database via a database device driver, are not regarded as file servers even when the database is stored in files, as they are not designed to provide those files to users and tend to have differing technical requirements.", "section_idx": 1, "section_name": "Types of file servers", "target_page_ids": [ 815760 ], "anchor_spans": [ [ 0, 15 ] ] }, { "plaintext": "In modern businesses, the design of file servers is complicated by competing demands for storage space, access speed, recoverability, ease of administration, security, and budget. This is further complicated by a constantly changing environment, where new hardware and technology rapidly obsolesces old equipment, and yet must seamlessly come online in a fashion compatible with the older machinery. To manage throughput, peak loads, and response time, vendors may utilize queuing theory to model how the combination of hardware and software will respond over various levels of demand. Servers may also employ dynamic load balancing scheme to distribute requests across various pieces of hardware.", "section_idx": 2, "section_name": "Design of file servers", "target_page_ids": [ 4367801, 41684, 12075392, 30932, 10356765, 14103070, 61118 ], "anchor_spans": [ [ 118, 132 ], [ 158, 166 ], [ 364, 374 ], [ 412, 422 ], [ 440, 453 ], [ 455, 461 ], [ 621, 635 ] ] }, { "plaintext": "The primary piece of hardware equipment for servers over the last couple of decades has proven to be the hard disk drive. Although other forms of storage are viable (such as magnetic tape and solid-state drives) disk drives have continued to offer the best fit for cost, performance, and capacity.", "section_idx": 2, "section_name": "Design of file servers", "target_page_ids": [ 13777, 20505, 7366298 ], "anchor_spans": [ [ 105, 120 ], [ 175, 188 ], [ 193, 211 ] ] }, { "plaintext": "Since the crucial function of a file server is storage, technology has been developed to operate multiple disk drives together as a team, forming a disk array. A disk array typically has cache (temporary memory storage that is faster than the magnetic disks), as well as advanced functions like RAID and storage virtualization. Typically disk arrays increase level of availability by using redundant components other than RAID, such as power supplies. Disk arrays may be consolidated or virtualized in a SAN.", "section_idx": 2, "section_name": "Design of file servers", "target_page_ids": [ 475485, 6829, 54695, 4148872, 40760, 219042, 20444608 ], "anchor_spans": [ [ 148, 158 ], [ 188, 193 ], [ 296, 300 ], [ 305, 327 ], [ 369, 381 ], [ 437, 451 ], [ 505, 508 ] ] }, { "plaintext": "Network-attached storage (NAS) is file-level computer data storage connected to a computer network providing data access to a heterogeneous group of clients. NAS devices specifically are distinguished from file servers generally in a NAS being a computer appliance – a specialized computer built from the ground up for serving files – rather than a general purpose computer being used for serving files (possibly with other functions). In discussions of NASs, the term \"file server\" generally stands for a contrasting term, referring to general purpose computers only.", "section_idx": 2, "section_name": "Design of file servers", "target_page_ids": [ 5300, 4122592, 42255358, 10429990 ], "anchor_spans": [ [ 45, 66 ], [ 82, 98 ], [ 126, 139 ], [ 246, 264 ] ] }, { "plaintext": " NAS devices are gaining popularity, offering a convenient method for sharing files between multiple computers. Potential benefits of network-attached storage, compared to non-dedicated file servers, include faster data access, easier administration, and simple configuration.", "section_idx": 2, "section_name": "Design of file servers", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "NAS systems are networked appliances containing one or more hard drives, often arranged into logical, redundant storage containers or RAID arrays. Network Attached Storage removes the responsibility of file serving from other servers on the network. They typically provide access to files using network file sharing protocols such as NFS, SMB/CIFS (Server Message Block/Common Internet File System), or AFP.", "section_idx": 2, "section_name": "Design of file servers", "target_page_ids": [ 10429990, 54695, 51252, 349873, 547707 ], "anchor_spans": [ [ 26, 36 ], [ 134, 138 ], [ 334, 337 ], [ 349, 397 ], [ 403, 406 ] ] }, { "plaintext": "File servers generally offer some form of system security to limit access to files to specific users or groups. In large organizations, this is a task usually delegated to directory services, such as openLDAP, Novell's eDirectory or Microsoft's Active Directory.", "section_idx": 2, "section_name": "Design of file servers", "target_page_ids": [ 334641, 256040, 2581364, 2807 ], "anchor_spans": [ [ 172, 190 ], [ 200, 208 ], [ 219, 229 ], [ 245, 261 ] ] }, { "plaintext": "These servers work within the hierarchical computing environment which treat users, computers, applications and files as distinct but related entities on the network and grant access based on user or group credentials. In many cases, the directory service spans many file servers, potentially hundreds for large organizations. In the past, and in smaller organizations, authentication could take place directly at the server itself.", "section_idx": 2, "section_name": "Design of file servers", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Backup", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 533867 ], "anchor_spans": [ [ 1, 7 ] ] }, { "plaintext": " File Transfer Protocol (FTP)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 53289 ], "anchor_spans": [ [ 1, 23 ] ] }, { "plaintext": " Server Message Block (SMB)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 349873 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " WebDav (WebDav)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 179849 ], "anchor_spans": [ [ 1, 7 ] ] }, { "plaintext": " Network-attached storage (NAS)", "section_idx": 3, "section_name": "See also", "target_page_ids": [ 451995 ], "anchor_spans": [ [ 1, 25 ] ] } ]

[ "Servers_(computing)", "Computer_storage_devices" ]

[]

[ { "plaintext": "In telecommunication, a filled cable is a cable that has a non-hygroscopic material, usually a gel called icky-pick, inside the jacket or sheath. The nonhygroscopic material fills the spaces between the interior parts of the cable, preventing moisture from entering minor leaks in the sheath and migrating inside the cable. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 33094374, 42418, 116790, 41207, 17596630 ], "anchor_spans": [ [ 3, 20 ], [ 42, 47 ], [ 59, 74 ], [ 95, 98 ], [ 106, 115 ] ] }, { "plaintext": "A metallic cable filled with a dielectric material, such as a coaxial cable or a metal waveguide, is not considered to be a \"filled cable\".", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41026, 46380, 41863 ], "anchor_spans": [ [ 31, 41 ], [ 62, 75 ], [ 87, 96 ] ] }, { "plaintext": "See Telcordia GR-421-CORE, Generic Requirements for Metallic Telecommunications Cables, for filled, polyolefin-insulated conductor (PIC) cable requirements.", "section_idx": 2, "section_name": "Further reading", "target_page_ids": [], "anchor_spans": [] } ]

[ "Signal_cables" ]

[]

[ { "plaintext": "In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide hardware abstraction services to higher-level software such as operating systems. For less complex devices, firmware may act as the device's complete operating system, performing all control, monitoring and data manipulation functions. Typical examples of devices containing firmware are embedded systems (running embedded software), home and personal-use appliances, computers, and computer peripherals.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 5213, 5309, 5734146, 21808348, 4473, 443015, 22194, 22194, 46630, 638447, 60644 ], "anchor_spans": [ [ 3, 12 ], [ 46, 63 ], [ 82, 99 ], [ 124, 132 ], [ 156, 160 ], [ 242, 262 ], [ 305, 321 ], [ 392, 408 ], [ 530, 546 ], [ 556, 573 ], [ 625, 644 ] ] }, { "plaintext": "Firmware is held in non-volatile memory devices such as ROM, EPROM, EEPROM, and Flash memory. Updating firmware requires ROM integrated circuits to be physically replaced, or EPROM or flash memory to be reprogrammed through a special procedure. Some firmware memory devices are permanently installed and cannot be changed after manufacture. Common reasons for updating firmware include fixing bugs or adding features to the device.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 780629, 18934934, 73333, 50597, 50595, 15150 ], "anchor_spans": [ [ 20, 39 ], [ 56, 59 ], [ 61, 66 ], [ 68, 74 ], [ 80, 92 ], [ 125, 143 ] ] }, { "plaintext": "Ascher Opler coined the term firmware in a 1967 Datamation article, as an intermediary term between \"hardware\" and \"software\".", "section_idx": 1, "section_name": "History and etymology", "target_page_ids": [ 658440 ], "anchor_spans": [ [ 48, 58 ] ] }, { "plaintext": "In this article, Opler was referring to a new kind of computer program that had a different practical and psychological purpose from traditional programs from the user's perspective. ", "section_idx": 1, "section_name": "History and etymology", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "As computers began to increase in complexity, it became clear that various programs needed to first be initiated and run to provide a consistent environment necessary for running more complex programs at the user's discretion. This required programming the computer to run those programs automatically. Furthermore, as companies, universities, and marketers wanted to sell computers to laypeople with little technical knowledge, greater automation became necessary to allow a lay-user to easily run programs for practical purposes. This gave rise to a kind of software that a user would not consciously run, and it led to software that a lay user wouldn't even know about.", "section_idx": 1, "section_name": "History and etymology", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Originally, it meant the contents of a writable control store (a small specialized high-speed memory), containing microcode that defined and implemented the computer's instruction set, and that could be reloaded to specialize or modify the instructions that the central processing unit (CPU) could execute. As originally used, firmware contrasted with hardware (the CPU itself) and software (normal instructions executing on a CPU). It was not composed of CPU machine instructions, but of lower-level microcode involved in the implementation of machine instructions. It existed on the boundary between hardware and software; thus the name firmware. Over time, popular usage extended the word firmware to denote any computer program that is tightly linked to hardware, including BIOS on PCs, boot firmware on smartphones, computer peripherals, or the control systems on simple consumer electronic devices such as microwave ovens, remote controls.", "section_idx": 1, "section_name": "History and etymology", "target_page_ids": [ 6559, 19999, 47772, 5218, 4473, 40909, 60644, 189768, 58017, 105803 ], "anchor_spans": [ [ 48, 61 ], [ 114, 123 ], [ 168, 183 ], [ 262, 285 ], [ 778, 782 ], [ 791, 804 ], [ 821, 840 ], [ 876, 903 ], [ 912, 926 ], [ 929, 943 ] ] }, { "plaintext": "In some respects, the various firmware components are as important as the operating system in a working computer. However, unlike most modern operating systems, firmware rarely has a well-evolved automatic mechanism of updating itself to fix any functionality issues detected after shipping the unit.", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 22194 ], "anchor_spans": [ [ 74, 90 ] ] }, { "plaintext": "The BIOS may be manually updated by a user via a small utility program. In contrast, firmware in mass storage devices (hard-disk drives, optical disc drives, flash memory storage e.g. solid state drive) is less frequently updated, even when flash memory (rather than ROM, EEPROM) storage is used for the firmware.", "section_idx": 2, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Most computer peripherals are themselves special-purpose computers. Devices such as printers, scanners, webcams, and USB flash drives have internally-stored firmware; some devices may also permit field upgrading of their firmware.", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 400414 ], "anchor_spans": [ [ 117, 132 ] ] }, { "plaintext": "Other instances of computer firmware include:", "section_idx": 2, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " The (U)EFI-compliant firmware used on Itanium systems, Intel-based Macs, and many newer PCs", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 866065, 15454, 19006979 ], "anchor_spans": [ [ 5, 11 ], [ 39, 46 ], [ 68, 71 ] ] }, { "plaintext": " Hard disk drive, solid-state drive or optical disc drive firmware", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 13777, 7366298, 299592 ], "anchor_spans": [ [ 1, 16 ], [ 18, 35 ], [ 39, 57 ] ] }, { "plaintext": " Video BIOS of a graphics card", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 2045850, 113624 ], "anchor_spans": [ [ 1, 11 ], [ 17, 30 ] ] }, { "plaintext": " Open Firmware, used in SPARC-based computers from Sun Microsystems and Oracle Corporation, PowerPC-based computers from Apple, and computers from Genesi", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 209452, 36954, 26980, 22591, 24281, 8564378 ], "anchor_spans": [ [ 1, 14 ], [ 24, 29 ], [ 51, 67 ], [ 72, 90 ], [ 92, 99 ], [ 147, 153 ] ] }, { "plaintext": " ARCS, used in computers from Silicon Graphics", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 1363270, 28013 ], "anchor_spans": [ [ 1, 5 ], [ 30, 46 ] ] }, { "plaintext": " Kickstart, used in the Amiga line of computers (POST, hardware init + Plug and Play auto-configuration of peripherals, kernel, etc.)", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 16994071, 1980, 1699425, 158859, 783036, 21346982 ], "anchor_spans": [ [ 1, 10 ], [ 24, 29 ], [ 49, 53 ], [ 71, 84 ], [ 85, 103 ], [ 120, 126 ] ] }, { "plaintext": " RTAS (Run-Time Abstraction Services), used in computers from IBM", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 2955185, 40379651 ], "anchor_spans": [ [ 1, 5 ], [ 62, 65 ] ] }, { "plaintext": " The Common Firmware Environment (CFE)", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 26862241 ], "anchor_spans": [ [ 5, 32 ] ] }, { "plaintext": ", most portable music players support firmware upgrades. Some companies use firmware updates to add new playable file formats (codecs). Other features that may change with firmware updates include the GUI or even the battery life. Most mobile phones have a firmware over the air firmware upgrade capability for much the same reasons; some may even be upgraded to enhance reception or sound quality.", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 1247491, 6660, 19644137, 811550 ], "anchor_spans": [ [ 7, 28 ], [ 127, 133 ], [ 236, 248 ], [ 257, 278 ] ] }, { "plaintext": "Since 1996, most automobiles have employed an on-board computer and various sensors to detect mechanical problems. , modern vehicles also employ computer-controlled anti-lock braking systems (ABS) and computer-operated transmission control units (TCUs). The driver can also get in-dash information while driving in this manner, such as real-time fuel economy and tire pressure readings. Local dealers can update most vehicle firmware.", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 13673345, 59587, 4135552 ], "anchor_spans": [ [ 17, 27 ], [ 165, 189 ], [ 219, 244 ] ] }, { "plaintext": "Other firmware applications include:", "section_idx": 2, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " In home and personal-use products:", "section_idx": 2, "section_name": "Applications", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Timing and control systems for washing machines", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 172111 ], "anchor_spans": [ [ 32, 47 ] ] }, { "plaintext": " Controlling sound and video attributes, as well as the channel list, in modern televisions", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 29831 ], "anchor_spans": [ [ 80, 90 ] ] }, { "plaintext": " In routers, switches, and firewalls:", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 25748, 40614, 26173989 ], "anchor_spans": [ [ 4, 11 ], [ 13, 21 ], [ 27, 36 ] ] }, { "plaintext": " LibreCMC a 100% free software router distribution based on the Linux-libre kernel", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 46494027, 10635, 24588622 ], "anchor_spans": [ [ 1, 9 ], [ 17, 30 ], [ 64, 75 ] ] }, { "plaintext": " IPFire an open-source firewall/router distribution based on the Linux kernel", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 57667966, 277663, 21347315 ], "anchor_spans": [ [ 1, 7 ], [ 11, 22 ], [ 65, 77 ] ] }, { "plaintext": " fli4l an open-source firewall/router distribution based on the Linux kernel", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 649047 ], "anchor_spans": [ [ 1, 6 ] ] }, { "plaintext": " OpenWrt an open-source firewall/router distribution based on the Linux kernel", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 30863145 ], "anchor_spans": [ [ 1, 8 ] ] }, { "plaintext": " m0n0wall an embedded firewall distribution of FreeBSD", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 881062, 7580554 ], "anchor_spans": [ [ 1, 9 ], [ 47, 54 ] ] }, { "plaintext": " Proprietary firmware", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 18761238 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " In NAS systems:", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 451995 ], "anchor_spans": [ [ 4, 7 ] ] }, { "plaintext": " NAS4Free an open-source NAS operating system based on FreeBSD", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 38430977 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Openfiler an open-source NAS operating system based on the Linux kernel", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 2824310 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Proprietary firmware", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 18761238 ], "anchor_spans": [ [ 1, 21 ] ] }, { "plaintext": " Field-Programmable Gate Array (FPGA) code may be referred to as firmware", "section_idx": 2, "section_name": "Applications", "target_page_ids": [ 10969 ], "anchor_spans": [ [ 1, 30 ] ] }, { "plaintext": "Flashing involves the overwriting of existing firmware or data, contained in EEPROM or flash memory module present in an electronic device, with new data. This can be done to upgrade a device or to change the provider of a service associated with the function of the device, such as changing from one mobile phone service provider to another or installing a new operating system. If firmware is upgradable, it is often done via a program from the provider, and will often allow the old firmware to be saved before upgrading so it can be reverted to if the process fails, or if the newer version performs worse. Free software replacements for vendor flashing tools have been developed, such as Flashrom.", "section_idx": 3, "section_name": "Flashing", "target_page_ids": [ 50597, 50595, 50595 ], "anchor_spans": [ [ 77, 83 ], [ 87, 99 ], [ 693, 701 ] ] }, { "plaintext": "Sometimes, third parties develop an unofficial new or modified (\"aftermarket\") version of firmware to provide new features or to unlock hidden functionality; this is referred to as custom firmware. An example is Rockbox as a firmware replacement for portable media players. There are many homebrew projects for various devices, which often unlock general-purpose computing functionality in previously limited devices (e.g., running Doom on iPods).", "section_idx": 4, "section_name": "Firmware hacking", "target_page_ids": [ 46887711, 1428783, 1560437, 1495667, 8521, 89847 ], "anchor_spans": [ [ 181, 196 ], [ 212, 219 ], [ 250, 272 ], [ 289, 297 ], [ 432, 436 ], [ 440, 444 ] ] }, { "plaintext": "Firmware hacks usually take advantage of the firmware update facility on many devices to install or run themselves. Some, however, must resort to exploits to run, because the manufacturer has attempted to lock the hardware to stop it from running unlicensed code.", "section_idx": 4, "section_name": "Firmware hacking", "target_page_ids": [ 9875, 3768009 ], "anchor_spans": [ [ 146, 153 ], [ 247, 262 ] ] }, { "plaintext": "Most firmware hacks are free software.", "section_idx": 4, "section_name": "Firmware hacking", "target_page_ids": [ 10635 ], "anchor_spans": [ [ 24, 37 ] ] }, { "plaintext": "The Moscow-based Kaspersky Lab discovered that a group of developers it refers to as the \"Equation Group\" has developed hard disk drive firmware modifications for various drive models, containing a trojan horse that allows data to be stored on the drive in locations that will not be erased even if the drive is formatted or wiped. Although the Kaspersky Lab report did not explicitly claim that this group is part of the United States National Security Agency (NSA), evidence obtained from the code of various Equation Group software suggests that they are part of the NSA.", "section_idx": 4, "section_name": "Firmware hacking", "target_page_ids": [ 22172878, 45420727, 13777, 30056, 21939 ], "anchor_spans": [ [ 17, 30 ], [ 90, 104 ], [ 120, 135 ], [ 198, 210 ], [ 437, 461 ] ] }, { "plaintext": "Researchers from the Kaspersky Lab categorized the undertakings by Equation Group as the most advanced hacking operation ever uncovered, also documenting around 500 infections caused by the Equation Group in at least 42 countries.", "section_idx": 4, "section_name": "Firmware hacking", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Mark Shuttleworth, the founder of the company Canonical, which maintains the Ubuntu Linux distribution, has described proprietary firmware as a security risk, saying that \"firmware on your device is the NSA's best friend\" and calling firmware \"a trojan horse of monumental proportions\". He has asserted that low-quality, closed source firmware is a major threat to system security: \"Your biggest mistake is to assume that the NSA is the only institution abusing this position of trust in fact, it's reasonable to assume that all firmware is a cesspool of insecurity, courtesy of incompetence of the highest degree from manufacturers, and competence of the highest degree from a very wide range of such agencies\". As a potential solution to this problem, he has called for declarative firmware, which would describe \"hardware linkage and dependencies\" and \"should not include executable code\". Firmware should be open-source so that the code can be checked and verified.", "section_idx": 5, "section_name": "Security risks", "target_page_ids": [ 604962, 1097414, 990298, 18934886, 21939, 18934886, 217392, 277663 ], "anchor_spans": [ [ 0, 17 ], [ 46, 55 ], [ 77, 89 ], [ 118, 129 ], [ 203, 206 ], [ 321, 334 ], [ 876, 891 ], [ 913, 924 ] ] }, { "plaintext": "Custom firmware hacks have also focused on injecting malware into devices such as smartphones or USB devices. One such smartphone injection was demonstrated on the Symbian OS at MalCon, a hacker convention. A USB device firmware hack called BadUSB was presented at the Black Hat USA 2014 conference, demonstrating how a USB flash drive microcontroller can be reprogrammed to spoof various other device types to take control of a computer, exfiltrate data, or spy on the user. Other security researchers have worked further on how to exploit the principles behind BadUSB, releasing at the same time the source code of hacking tools that can be used to modify the behavior of different USB devices.", "section_idx": 5, "section_name": "Security risks", "target_page_ids": [ 20901, 32073, 25686223, 30164499, 23777555, 43486434, 2398717, 400414 ], "anchor_spans": [ [ 53, 60 ], [ 97, 107 ], [ 164, 174 ], [ 178, 184 ], [ 188, 205 ], [ 241, 247 ], [ 269, 287 ], [ 320, 335 ] ] }, { "plaintext": " Bootloader", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 632068 ], "anchor_spans": [ [ 1, 11 ] ] }, { "plaintext": " Computer hardware", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 21808348 ], "anchor_spans": [ [ 1, 18 ] ] }, { "plaintext": " Coreboot", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 1556246 ], "anchor_spans": [ [ 1, 9 ] ] }, { "plaintext": " Custom firmware", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 46887711 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Microcode", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 19999 ], "anchor_spans": [ [ 1, 10 ] ] }, { "plaintext": " Proprietary device driver", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 5540467 ], "anchor_spans": [ [ 1, 26 ] ] }, { "plaintext": " Real-time operating system", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 26123 ], "anchor_spans": [ [ 1, 27 ] ] }, { "plaintext": " ROM image", "section_idx": 6, "section_name": "See also", "target_page_ids": [ 599647 ], "anchor_spans": [ [ 1, 10 ] ] } ]

[ "Firmware" ]

[ "Firmware" ]

[ { "plaintext": "Fixed access: In personal communications service (PCS), terminal access to a network in which there is a set relationship between a terminal and the access interface. A single \"identifier\" serves for both the access interface and the terminal. If the terminal moves to another access interface, that terminal assumes the identity of the new interface.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 24808, 249402, 4122592, 41409, 41250 ], "anchor_spans": [ [ 18, 49 ], [ 57, 65 ], [ 78, 85 ], [ 157, 166 ], [ 178, 188 ] ] } ]

[ "Network_access" ]

[]

[ { "plaintext": "Flag sequence: In data transmission or processing, a sequence of bits used to delimit, i.e. mark the beginning and end of a frame. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 42168, 27838, 41172 ], "anchor_spans": [ [ 19, 36 ], [ 54, 62 ], [ 125, 130 ] ] }, { "plaintext": "Note 1: An 8-bit sequence is usually used as the flag sequence; for example, the 8-bit flag sequence 01111110. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 3364, 2667276 ], "anchor_spans": [ [ 14, 17 ], [ 50, 54 ] ] }, { "plaintext": "Note 2: Flag sequences are used in bit-oriented protocols, such as Advanced Data Communication Control Procedures (ADCCP), Synchronous Data Link Control (SDLC), and High-Level Data Link Control (HDLC).", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 40700, 476943, 78261 ], "anchor_spans": [ [ 68, 114 ], [ 124, 153 ], [ 166, 194 ] ] } ]

[ "Data_transmission" ]

[]

[ { "plaintext": "In a noise-measuring set, flat weighting is a noise weighting based on an amplitude-frequency characteristic that is flat over a frequency range that must be stated. ", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 41415, 41421, 10779, 5167862 ], "anchor_spans": [ [ 5, 10 ], [ 46, 61 ], [ 84, 93 ], [ 129, 144 ] ] }, { "plaintext": " Note 1: Flat noise power is expressed in dBrn (f1 − f2) or in dBm (f1 − f2).", "section_idx": 1, "section_name": "Notes", "target_page_ids": [ 41419, 41004, 41003 ], "anchor_spans": [ [ 15, 26 ], [ 43, 47 ], [ 64, 67 ] ] }, { "plaintext": " Note 2: \"3 kHz flat weighting\" and \"15 kHz flat weighting\" are based on amplitude-frequency characteristics that are flat between 30Hz and the frequency indicated.", "section_idx": 1, "section_name": "Notes", "target_page_ids": [], "anchor_spans": [] } ]

[ "Noise" ]

[]

[ { "plaintext": "In a telephone network, flood search routing is non-deterministic routing in which a dialed number received at a switch is transmitted to all switches, i.e., flooded, in the area code directly connected to that switch; if the dialed number is not an affiliated subscriber at that switch, the number is then retransmitted to all directly connected switches, and then routed through the switch that has the dialed number corresponding to the particular user end instrument affiliated with it. All digits of the numbering plan are used to identify a particular subscriber. Flood search routing allows subscribers to have telephone numbers independent of switch codes. Flood search routing provides the highest probability that a telephone call will go through even though a number of switches and links fail.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 1966111, 25750, 28284, 627405, 259338, 2052479, 460792, 18790468, 406703 ], "anchor_spans": [ [ 5, 22 ], [ 66, 73 ], [ 113, 119 ], [ 174, 183 ], [ 261, 271 ], [ 451, 455 ], [ 456, 470 ], [ 618, 634 ], [ 726, 740 ] ] }, { "plaintext": "Flood search routing is used in military telecommunication systems, such as the mobile subscriber equipment (MSE) system.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": "Flooding (computer networking)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 3858596 ], "anchor_spans": [ [ 0, 30 ] ] } ]

[ "Telephone_exchanges", "Telecommunications_techniques", "Routing_algorithms" ]

[]

[ { "plaintext": "In electronics and communication, flutter is the rapid variation of signal parameters, such as amplitude, phase, and frequency. Examples of electronic flutter are:", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 9663, 5177, 41703, 37649, 24047, 10779 ], "anchor_spans": [ [ 3, 14 ], [ 19, 32 ], [ 68, 74 ], [ 95, 104 ], [ 106, 111 ], [ 117, 126 ] ] }, { "plaintext": "Rapid variations in received signal levels, such as variations that may be caused by atmospheric disturbances, antenna movements in a high wind, or interaction with other signals.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 202899, 187317 ], "anchor_spans": [ [ 85, 96 ], [ 111, 118 ] ] }, { "plaintext": "In radio propagation, a phenomenon in which nearly all radio signals that are usually reflected by ionospheric layers in or above the E-region experience partial or complete absorption.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 271195, 15097, 1384005 ], "anchor_spans": [ [ 3, 20 ], [ 99, 116 ], [ 174, 184 ] ] }, { "plaintext": "In radio transmission, rapidly changing signal levels, together with variable multipath time delays, caused by reflection and possible partial absorption of the signal by aircraft flying through the radio beam or common scatter volume.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 609152, 41385, 521267 ], "anchor_spans": [ [ 9, 21 ], [ 78, 87 ], [ 111, 121 ] ] }, { "plaintext": "The variation in the transmission characteristics of a loaded telephone line caused by the action of telegraph direct currents on the loading coils.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 946963, 3462904 ], "anchor_spans": [ [ 62, 76 ], [ 134, 141 ] ] }, { "plaintext": "In recording and reproducing equipment, the deviation of frequency caused by irregular mechanical motion, e.g., that of capstan angular velocity in a tape transport mechanism, during operation.", "section_idx": 0, "section_name": "Introduction", "target_page_ids": [ 10779, 16341729 ], "anchor_spans": [ [ 57, 66 ], [ 120, 127 ] ] }, { "plaintext": "Electronic Flutter", "section_idx": 1, "section_name": "See also", "target_page_ids": [], "anchor_spans": [] }, { "plaintext": " Wow (recording)", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 1642055 ], "anchor_spans": [ [ 1, 16 ] ] }, { "plaintext": " Wow and flutter measurement", "section_idx": 1, "section_name": "See also", "target_page_ids": [ 3970341 ], "anchor_spans": [ [ 1, 28 ] ] } ]

[ "Radio_frequency_propagation" ]

[]