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N, and the index of refraction, n, in the ionosphere when collisions are neglected. . Using the default values for electron charge , permittivity of free space and electron mass , and changing angular velocity with respect to frequency this yields to and solving for the refraction index n, Critical Frequency and F laye... | per m3 and fc is in Hz. Critical Frequency as a Function of Maximum Usable Frequency Formula Critical frequency can be computed by: where MUF is maximum usable frequency and is the angle of incidence Relationship with Plasma Frequency The dependence of critical frequency with respect with electron density can be relate... |
performance by double acts Xiangsheng, also translated as "crosstalk", a traditional Chinese comedic monologue or dialogue Crosstalk (novel), a 2016 novel by American science fiction author Connie Willis Crosstalk (film), a 1982 science fiction thriller film Cross Talk, a 1980 album by the Pretty Things Crosstalk: Amer... | refers to any signal or circuit unintentionally affecting another signal or circuit. Crosstalk may also refer to: Science and computing Crosstalk (biology) Crosstalk Mk.4, a communications application for PCs. Arts and entertainment Cross talk, a style of comedy used in performance by double acts Xiangsheng, also trans... |
as to distribution, usage, etc. A cryptochannel is analogous to a radio circuit. See also Cryptosystem Secure channel References Cryptography | which provided; and (f) pertinent notes as to distribution, usage, etc. A cryptochannel is analogous to a radio circuit. See also Cryptosystem Secure channel References Cryptography Military communications |
oscillator circuit. A fundamental crystal oscillator circuit is simpler and more efficient and has more pullability than a third overtone circuit. Depending on the manufacturer, the highest available fundamental frequency may be 25 MHz to 66 MHz. A major reason for the wide use of crystal oscillators is their high Q fa... | in electronics were synthetic. In 1968, Juergen Staudte invented a photolithographic process for manufacturing quartz crystal oscillators while working at North American Aviation (now Rockwell) that allowed them to be made small enough for portable products like watches. Although crystal oscillators still most commonly... |
data compaction accomplished by replacing data to be stored or transmitted with an analytical expression. Examples of curve-fitting compaction consisting of discretization and then interpolation are: Breaking of | series of straight line segments and specifying the slope, intercept, and range for each segment Using a mathematical expression, such as a polynomial or a trigonometric function, and a single |
the customer premises. 2. The digital loop carrier (DLC) multiplexing function that is near the exchange termination (ET) when provided by a stand-alone multiplexer. Note: This function | customer office terminal is a stand-alone multiplexer located on the customer premises. 2. The digital loop carrier (DLC) multiplexing function that is near the exchange termination (ET) when provided by a stand-alone multiplexer. Note: This |
premises, hence, customer-premises equipment. In the U.S. Federal Communications Commission (FCC) proceeding the Second Computer Inquiry, the FCC ruled that telecommunications carriers could no longer bundle CPE with telecommunications service, uncoupling the market power of the telecommunications service monopoly from... | or cable modem, a network switch, a consumer-grade router, and a wireless access point. In the past, such functions were provided by separate devices, but in recent years technological convergence has enabled multiple functions to be merged into a single device. One of the first home gateway devices to be launched was ... |
unit (CSU) is a device that provides an accessing arrangement at a user location to either switched | that provides an accessing arrangement at a user location to either switched or point-to-point, data-conditioned circuits at a specifically established data signaling rate. A CSU |
the initial and the cutback measurements. Several characteristics may be determined using the same test fiber. Attenuation measurement Since the attenuation is defined as proportional to the logarithm of the ratio between and , where is the power at point and respectively. Using the cutback technique, the power transmi... | the fiber under test at a point near the launching end, repeating the measurements on the short length of fiber, and subtracting the results obtained on the short length to determine the results for the residual long length. The cut should be made to retain 1 meter or more of the fiber, in order to establish equilibriu... |
case of the Chebyshev filter it is usual to define the cutoff frequency as the point after the last peak in the frequency response at which the level has fallen to the design value of the passband ripple. The amount of ripple in this class of filter can be set by the designer to any desired value, hence the ratio used ... | proportion is one half the passband power, also referred to as the 3 dB point since a fall of 3 dB corresponds approximately to half power. As a voltage ratio this is a fall to of the passband voltage. Other ratios besides the 3 dB point may also be relevant, for example see Chebyshev Filters below. Single-pole transfe... |
mandated by the Bell System, connected between the telephone line and non-Bell equipment, typically a modem. Following the Carterfone decision, which required Bell to allow customers to attach any non-harmful equipment to their network, Bell mandated that subscribers use DAAs - purchased exclusively from Western Electr... | affect the characteristics of the interface. A data circuit-terminating equipment (DCE) supplied or approved by a common carrier that permits a DCE or data terminal equipment (DTE) to be attached to the common carrier network. Data access arrangements are an integral part of all modems built for the public telephone ne... |
time. A data bank may also refer to an organization primarily concerned with the construction and maintenance of such a database. A data bank may be either centralized or decentralized, though most usage of this term refers to centralized storage and retrieval of information, by way of analogy to a monetary bank. The d... | and information architecture, a data bank or databank is a repository of information on one or more subjects – a database – that is organized in a way that facilitates local or remote information retrieval and is able to process many continual queries over a long period of time. A data bank may also refer to an organiz... |
and probability analysis. Simply squeezing noncompacted data into a smaller space, for example by increasing packing density by transferring images from newsprint to microfilm or by transferring data on punched cards onto magnetic tape, is not data compaction. Everyday examples The use of acronyms in texting is | frequency analysis, and probability analysis. Simply squeezing noncompacted data into a smaller space, for example by increasing packing density by transferring images from newsprint to microfilm or by transferring data on punched cards onto magnetic tape, is not data compaction. Everyday examples The use of acronyms i... |
contexts may consist of data items. A named identifier of each of the entities and their attributes that are represented in a database. A basic unit of information built on standard structures having a unique meaning and distinct units or values. In electronic record-keeping, a combination of characters or bytes referr... | through a process of manual or automated Application Discovery and Understanding. Once data elements are discovered they can be registered in a metadata registry. In telecommunication, the term data element has the following components: A named unit of data that, in some contexts, is considered indivisible and in other... |
receives data from one data link and retransmits data representing the same information, using proper format and link protocols, to another data link. and (b) may forward data between (a) links | and retransmits data representing the same information, using proper format and link protocols, to another data link. and (b) may forward data between (a) links that are identical, i.e., TADIL B to TADIL B, |
network core performed datagram switching as in Baran's and Davies' model, but provision was added within the network, at its periphery, to deal with datagram losses and permutations. A reliable message transfer service was thus offered to user computers, thus greatly simplifying their own work, and keeping it less dep... | network service known to possibly produce non negligible datagram losses and permutations. Although Pouzin's concern "in a first stage is not to make breakthrough in packet switching technology, but to build a reliable communications tool for Cyclades", two members of his team, Hubert Zimmerman and Gérard Le Lann, made... |
could be re-derived. Types of integrity constraints Data integrity is normally enforced in a database system by a series of integrity constraints or rules. Three types of integrity constraints are an inherent part of the relational data model: entity integrity, referential integrity and domain integrity. Entity integri... | often detected through the use of simpler checks and algorithms, such as the Damm algorithm or Luhn algorithm. These are used to maintain data integrity after manual transcription from one computer system to another by a human intermediary (e.g. credit card or bank routing numbers). Computer-induced transcription error... |
data sink. Types There are at least three types of basic data-link configurations that can be conceived of and used: Simplex communications, most commonly meaning all communications in one direction only. Half-duplex communications, meaning communications in both directions, but not both ways simultaneously. Duplex com... | location to another for the purpose of transmitting and receiving digital information (data communication). It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver (two pieces of data terminal equipment) and the interconnecting data telecommunication circuit. These are governed ... |
on the WAN side. On the WAN side, the DSU, via a CSU, interfaces with a digital carrier such as DS1 or DS3 or a low speed Digital Data Service. On the DTE side, the DSU provides control lines, timing lines and appropriate physical and electrical interface. To maintain the synchronous relationship between the ports, the... | telecommunications service a DSU supports can be a point-to-point or multipoint operation in a digital data network. Form and purpose A DSU is a two or more port device; one port is called the WAN (wide area network) port and the other is called a DTE port. The purpose of the DSU is to transfer serial data synchronousl... |
single channel, the signaling rate is given by , where SCSR is the single-channel signaling rate in bits per second, T is the minimum time interval in seconds for which each level must be maintained, and n is the number of significant conditions of modulation of the channel. In the case where an individual end-to-end t... | the DSR is (m/T)log2n; in the case of a two-condition modulation, this reduces to m/T. The DSR may be expressed in bauds, in which case, the factor log2ni in the above summation formula should be deleted when calculating bauds. In synchronous binary signaling, the DSR in bits per second may be numerically the same as t... |
(DTEs). A data transmission circuit includes any required signal conversion equipment. A data transmission circuit may transfer information in (a) one direction only, (b) either direction but | used for the data transfer between data terminal equipment (DTEs). A data transmission circuit includes any required signal conversion equipment. A data |
a user or originator for dispatch. The DTG may be used as a message identifier if it is unique for each message. Military Date Time Group A form of DTG is used in the US Military's message traffic (a form of Automated Message Handling System). In US military messages and communications (e.g., on maps showing troop move... | it was handed into a transmission facility by a user or originator for dispatch. The DTG may be used as a message identifier if it is unique for each message. Military Date Time Group A form of DTG is used in the US Military's message traffic (a form of Automated Message Handling System). In US military messages and co... |
race in France, in Paris in 1945, being the only post-war cars entered. An open-wheeled DB7 appeared in 1947 (preceded by the heavy and large DB6 which saw very little action), after which the Automobiles Deutsch & Bonnet was officially formed. Neither single-seater DB was at all successful, but they did show Deutsch -... | racing. Nearly all DBs, even the road cars, were designed with competition foremost in mind. In 1952, a DB Speedster was entered in the 12 Hours of Sebring and won its class handsomely, beginning its career in the United States market. Steve Lansing and Ward Morehouse were the drivers. At the 1954 Le Mans DB entered fi... |
in assessing loud aircraft noise (IEC 537). B curves filter out more medium loudness levels when compared to an A curves. This curve is rarely ever used in the assessment or monitoring of noise levels anymore. C curves differ from both A and B in the fact that they filter less of the lower and higher frequencies. The f... | the phon (1 kHz equivalent level). Sound Sound has three basic components, the wavelength, frequency, and speed. In sound measurement, we measure the loudness of the sound in decibels (dB). Decibels are logarithmic with 0 dB as the reference. There are also a range of frequencies that sounds can have. Frequency is the ... |
the 'm' suffix, is permitted for relative quantities, but not accepted for use directly alongside SI units. 10 dBm may be written 10 dB (1 mW) in SI. In audio and telephony, dBm is typically referenced relative to a 600-ohm impedance, while in radio-frequency work dBm is typically referenced relative to a 50-ohm impeda... | to dBm0p, which is preferred. In audio, 0 dBm often corresponds to approximately 0.775 volts, since 0.775 V dissipates 1 mW in a 600 Ω load. The corresponding voltage level is 0 dBu, without the 600 Ω restriction. Conversely, for RF situations with a 50 Ω load, 0 dBm corresponds to approximately 0.224 volts, since 0.22... |
the frequency weighting. With 144 weightings, a one milliwatt, 1000 Hz white noise tone will also read +90 dBrn, but the same 3 kHz power will only read +82 dBrn, because of the different frequency weighting. Note: In telecommunications, dBrn adjusted also called dBa denotes "decibels adjusted", i.e. weighted absolute ... | distributed over a 3 kHz band will read approximately +88.5 dBrn, because of the frequency weighting. With 144 weightings, a one milliwatt, 1000 Hz white noise tone will also read +90 dBrn, but the same 3 kHz power will only read +82 dBrn, because of the different frequency weighting. Note: In telecommunications, dBrn ... |
equipment (DCE) is a device that sits between the data terminal equipment (DTE) and a data transmission circuit. It is also called data communication(s) equipment and data carrier equipment. Usually, the DTE device is the terminal (or computer), and the DCE is a modem. In a data station, the DCE performs functions such... | nomenclature include: Federal Standard 1037C, MIL-STD-188 RS-232 Certain ITU-T standards in the V series (notably V.224 and V.35) Certain ITU-T standards in the X series (notably X.21 and X.25) A general rule is that DCE devices provide the clock signal (internal clocking) and the DTE device synchronizes on the provide... |
in rank, whereby a military officer is reduced to a lower rank for misconduct Degradation, the former ceremony of defrocking a disgraced priest Degradation, a song by the Violent Femmes, from Add It Up (1981–1993) See also | human-induced processes acting upon the land Polymer degradation, as plastics age Other Elegant degradation, gradual rather than sudden Graceful degradation, in a fault-tolerant system Degradation (knighthood), revocation of knighthood Cashiering, whereby a military officer |
instants are not necessarily consecutive. This value is usually expressed as a percentage. The result of the measurement should be qualified by an indication if the period, usually limited, of the observation. For a prolonged modulation (or demodulation), | a percentage. The result of the measurement should be qualified by an indication if the period, usually limited, of the observation. For a prolonged modulation (or demodulation), it will be appropriate to consider the probability that an assigned value of the degree of distortion will |
immediately preceding it to (b) the unit interval. The highest absolute value of individual distortion affecting the significant instants of a start-stop modulation. The degree of distortion of a start-stop | actual and theoretical intervals separating any significant instant of modulation (or demodulation) from the significant instant of the start element immediately preceding it to (b) the unit interval. The highest absolute value of individual distortion affecting the significant instants of a start-stop modulation. The ... |
envelopes of the various sinusoidal components of a signal Network delay, the delay of an IP packet within an IP network Propagation delay, a measurement of the time for a signal to reach its destination Queuing delay, or queueing delay, the time a job waits in a queue until it can be executed Satellite delay, the noti... | time-delay system in terms of its values at previous times Delay encoding, a radio transmission technique Delay line (disambiguation) Delay-line memory, a type of random-access memory Delay-line oscillator, a form of electronic oscillator that uses a delay line as its principal timing element Delay slot, a computer ins... |
destination Analog delay line, used to delay a signal Bi-directional delay line, a numerical analysis technique used in computer simulation for solving ordinary | length of time taken for something to reach its destination Analog delay line, used to delay a signal Bi-directional delay line, a numerical analysis technique used in computer simulation for |
amplitude of the input signal can be , where fs is the sampling frequency and ω is the frequency of the input signal and σ is step size in quantization. So Amax is the maximum amplitude that DM can transmit without causing the slope overload and the power of transmitted signal depends on the maximum amplitude. Bit-rate... | N times the sampling frequency. Adaptive delta modulation Adaptive delta modulation (ADM) was first published by Dr. John E. Abate (AT&T Bell Laboratories Fellow) in his doctoral thesis at NJ Institute Of Technology in 1968. ADM was later selected as the standard for all NASA communications between mission control and ... |
to conventional telephone switching, in which common trunks are provided for many users, on a demand basis, through a limited-size trunk group. See also Time-assignment | basis, i.e., a user needing to communicate with another user on the same network requests the required circuit, uses it, and when the call is finished, the circuit is released, making the circuit available |
understood by the context. Electrical engineering In electrical engineering the demand factor is taken as a time independent quantity where the numerator is taken as the maximum demand in the specified time period instead of the averaged or instantaneous demand. This is the peak in the load profile divided by the full ... | electrical power industry, the term demand factor is used to refer to the fractional amount of some quantity being used relative to the maximum amount that could be used by the same system. The demand factor is always less than or equal to one. As the amount of demand is a time dependent quantity so is the demand facto... |
each of the connected loads and a diversity factor to the sum total. At a communications center, the power required by all automatic switching, synchronous, and terminal equipment (operated simultaneously on-line or in standby), control and keying equipment, plus lighting, | applying the proper demand factor to each of the connected loads and a diversity factor to the sum total. At a communications center, the power required by all automatic switching, synchronous, and terminal equipment (operated simultaneously on-line |
undesired signal. The gain reduction is generally due to overload of some portion of the receiver (e.g., the automatic gain control circuitry) resulting in suppression | signal. The gain reduction is generally due to overload of some portion of the receiver (e.g., the automatic gain control circuitry) resulting in |
not have been demonstrated that the requirement can be met considering other constraints, such as cost and size. A DO is sometimes established in a standard for developmental consideration. A DO may also specify a performance characteristic used in the preparation of specifications for development or procurement of new... | in the state of the art, (b) the requirement may not have been fully confirmed by measurement or experience with operating circuits, and (c) it may not have been demonstrated that the requirement can be met considering other constraints, such as cost and size. A DO is sometimes established in a standard for development... |
wave Detector (film), a 2000 Norwegian film USS Detector, two United States Navy ships , was a coastal minesweeper launched 29 | (radio), a device that recovers information from a modulated wave Detector (film), a 2000 Norwegian film USS Detector, two United States Navy ships , was a coastal minesweeper |
routes between given pairs of nodes. Examples: In a network where routing is controlled by a telephone switch or network switch, switching in which the routes between given pairs of nodes are pre-programmed, i.e., are determined, in advance of transmission. The routes used to complete a | in advance of transmission. The routes used to complete a given call through a network are identified, in advance of transmission, in routing tables maintained in each switch database. The tables assign the trunks that are to be used |
or by accumulation in digit registers. Pulse rate and coding In the first electromechanical switching systems the current pulses generated by the rotary dial on the local loop directly operated electrical stepping switches at the central office. The mechanical nature of these relays generally limited the speed of opera... | operate reliably. Most telephone systems used the nominal rate of ten pulses per second, but operator dialing within and between central offices often used pulse rates up to twenty per second. Early automatic exchanges Automatic telephone exchange systems were developed in the late 19th and early 20th century. For iden... |
be induced in any molecule in which the asymmetric distortion of the nuclei is possible (distortion polarisation). Orientation polarisation results from a permanent dipole, e.g., that arising from the 104.45° angle between the asymmetric bonds between oxygen and hydrogen atoms in the water molecule, which retains polar... | the presence of an electric field, the charge cloud is distorted, as shown in the top right of the figure. This can be reduced to a simple dipole using the superposition principle. A dipole is characterised by its dipole moment, a vector quantity shown in the figure as the blue arrow labeled M. It is the relationship b... |
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 materi... | 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 ex... |
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. The... | 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. 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 redu... |
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. 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. Assu... | 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, ... |
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 a... | (IIR) behaviour, but if the denominator is made equal to unity, i.e. no feedback, then this becomes a finite impulse response (FIR) filter. Analysis techniques 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 i... |
PCM decoder produces a sinusoidal signal with a frequency of with one milliwatt in power (). 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 | 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, |
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. Some currently available digital multiplexers have been designated as Dl-, DS-, or M-series, all of which operate at T-carr... | hierarchies, care must be exercised to ensure interoperability of the multiplexers used in the hierarchy. Digroup Digroup is an abbreviation for digital group. In telephony, a basic group in the digital multiplex hierarchy. In the North American and Japanese T-carrier digital hierarchies, each digroup supports 12 PCM v... |
modern synchronous systems such as SDH/SONET. 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/... | of the samples. This results in a data rate of 64 kbit/s. 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 exch... |
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. Unlike traditional dial-up modems, which modulate bits into signals in the 300–3400 Hz audio baseband, DSL modems modulate frequencies f... | sharing, also contributed to the popularity of ADSL technology. 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 kn... |
stream for transmission over communications media. Digital transmission groups usually are categorized by their maximum capacity, not by a specific number of channels. However, the maximum digital transmission | transmission over communications media. 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 |
Server 2012 Direct access (computing), a concept in computer science Direct Access Archive, a proprietary file format Direct access storage device, | Archive, a proprietary file format Direct access storage device, a secondary computer storage device Direct Access Test Unit, special numbers used to test telephone exchanges Direct |
Connect, a brand name used by Sprint Corporation for its digital push-to-talk service, | Instant Messenger Sprint Direct Connect, a brand name used by Sprint Corporation for its digital push-to-talk service, |
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. San Francisco required the special area code 318 due to temporary routing requirements. San Francisco and Oakland each had their own separate toll-switch... | 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. San Francisco required the special area co... |
bandwidth is restored, while the unintentional and intentional interference is substantially reduced. 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-sequ... | 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 re... |
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, | In telecommunication, a disengagement originator is the user or execution unit that initiates a disengagement |
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 | at the input will be different from the waveform at the output of the link. 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 |
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. Frequency response distortion Non-flat frequency response is a form of distortion that occurs when different frequencies are amplified by differen... | 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 dete... |
is reached when the system distorts the shape of the waveform beyond specified limits. For linear systems, distortion-limited operation is equivalent | operation is reached when the system distorts the shape of the waveform beyond specified limits. For linear |
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 b... | 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... |
repairs may take longer than in a LAN and Wi-Fi because the damage may be inaccessible. 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 essent... | 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 whic... |
often called host-remote switching. 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 peo... | though it is often called host-remote switching. 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 don... |
disturbance voltage is a voltage that produces (a) false signals in a telephone, (b) Noise (radio) in a radio receiver, or (c) distortion in | 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 |
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. See also Terminator (solar) - "grey line" References Radio frequency propagation | tidal range. In cable systems, significant phase shifts can be occasioned by diurnal temperature variance. See also Terminator (solar) - "grey line" References Radio |
are referenced. 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. Govern... | 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. 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 |
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 incoming digital signal and the phase of the internal clocks at both exchanges. |
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. See also Double-sideband | is provided to the modulator. 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. |
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. DSB-SC transmission is a special case of double-sideband reduced carrier transmission. It is used for ra... | 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. The equation above shows that by multiplying the modulated signal by the carrier signal, the resu... |
change in an attribute of a system or equipment Film and television Drift (film series), 2006–2008 film series by Futoshi Jinno Drift, 2006 TV crime drama film directed by Paul W.S. Anderson Drift, fictional technology system that links the minds of two Jaeger pilots in the 2013 sci-fi film Pacific Rim and its sequel D... | starring Sam Worthington Drift (2013 Belgian film), art house film Drift (2015 film), Swiss film Drift (2017 film), German film Drift, 2007 experimental short film by Max Hattler Books Drift (novel), a 2002 Doctor Who novel Drift: The Unmooring of American Military Power, a book by Rachel Maddow Plot drift, when a stor... |
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 where d is the tube diameter. The mass m of the drop hanging from the end of the tube can be found by equatin... | 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. Viscosity and pitch drop experiments Some substances that appear to be solid, can be shown to instead be extremely viscous liquids, ... |
an intermediate point, and introduces (insert) a different signal for subsequent transmission in the same position. 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... | introduces (insert) a different signal for subsequent transmission in the same position. Drop and insert is practiced, for example, in time-division multiplexing (TDM) when a time slot or frequency band is replaced from another source. |
Out with The Barracudas, by The Barracudas, 1981 Science and technology Dropout (astronomy), a radiation source whose radiation intensity falls off sharply Dropout (bicycle part), a type of fork end Dropout (communications), a momentary loss of signal Dropout (neural networks), a regularization technique for reducing o... | Out with The Barracudas, by The Barracudas, 1981 Science and technology Dropout (astronomy), a radiation source whose radiation intensity falls off sharply Dropout (bicycle part), a type of fork end Dropout (communications), a momentary loss of signal Dropout (neural networks), a regularization technique for reducing o... |
and data transmission Distance to empty, a feature in an automobile electronic instrument cluster Dithioerythritol, a chemical DTE (direct to edit), a digital video recording method DTE80, the Microsoft Development Environment 8.0 | a chemical DTE (direct to edit), a digital video recording method DTE80, the Microsoft Development Environment 8.0 Extensibility namespace DTE Energy, a Detroit, Michigan-based utility Dora the Explorer, |
access lines using a single message routing indicator or telephone number. In satellite communications, the transmission of two carriers simultaneously through a single communication | The connection of a user to two switching centers by separate access lines using a single message routing indicator or telephone number. In satellite communications, the transmission of two carriers simultaneously through a single communication satellite repeater. Also, |
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.... | 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 t... |
adhesive tape Ducted fan, motor for aircraft Electrical bus duct, a metal enclosure for busbars 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 contamina... | signals to travel unusually long distances Earth–ionosphere waveguide, a type of atmospheric duct Surface duct, a sound propagation phenomenon at sea Duct bank, a set of electrical conduits or telecommunications conduits, entering a building underground Duct Publishing, an imprint of the German group VDM Publishing dev... |
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. On shared-antenna sites, the bandpass duplexer variety is greatly preferred because this virtually eliminates interference between transm... | 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). Types Transmit-receive switch... |
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.... | could be a fraction of a second, a day, or even a week, depending on the length of the period. 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. The... |
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... | 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: However, the usable dynamic range may be greater, as a properly dithered recording device can record signals well below the noise floor. The 16-bit compact disc has a theoretical undithere... |
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. Dap... | 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. Daphnis’ rendition differs radically fro... |
data, such as bits, characters, blocks, or frames, transferred per unit time from a source and accepted as valid by a sink. Note: The effective data transfer rate is usually | 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 |
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 | 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 |
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 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 |
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 | 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 |
power A measurement of horsepower "effective power" bug, an iPhone | horsepower "effective power" bug, an iPhone bug |
facility. 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. The | a significant measurement time interval divided by (b) the measurement time interval. The effective transmission rate is usually expressed as a number of units of data per unit time, such as |
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 pra... | 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 condition... |
bottom of a short monopole (a vertical, or whip antenna) to "electrically lengthen" it and achieve electrical resonance as seen through the loading coil. Phase length 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. ... | 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. For example, a typical velocity factor for coax... |
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. Electrostatics In the special case of a steady state (stationary charges and currents), the Maxwell-Faraday inductive effect disappears. The resulting two equations (Gau... | 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. Electrostatic fields Electrostatic fields are electric fields that do not change with time. Such fields are pr... |
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". Audio frequency, from very low frequencies up to around 20 kHz. Frequencies up to 100 kHz may sometimes be classified a... | by the way it appears on different conductors: Common-mode coupling: noise appears in phase (in the same direction) on two conductors. Differential-mode coupling: noise appears out of phase (in opposite directions) on two conductors. Inductive coupling Inductive coupling occurs where the source and victim are separated... |
the term electromagnetic environment (EME) has the following meanings: 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 me... | 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). The resulting product of the power and time distribution, in various frequency ranges, of the radi... |
emissions that are unnecessary for system, subsystem, or equipment operation are reduced, minimized, or eliminated. Note: Electromagnetic radiated and conducted emissions are controlled regardless of | electromagnetic interference control (EMI) is the control of radiated and conducted energy such that emissions that are unnecessary for system, subsystem, or equipment |
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." E3 The E3 component is different from E1 and E2. E3 is a much slower pulse, lasting tens to hundreds of seconds... | 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. Soviet Test 184 In 1962, the Soviet Union also performed three EMP-producing nuclear tests in space... |
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. Low-level exposure The World Health Organization began a research effort in 1996 to study the health ef... | 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." Since 1962, the microwave auditory effect or tinnitus has been shown from radio frequency exposure at levels ... |
environment. 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 | or equipment to resume functioning without evidence of degradation following temporary exposure to an adverse electromagnetic environment. The system, subsystem, or equipment performance may be degraded during exposure to the adverse electromagnetic environment, but |
of electronic deception are: Manipulative electronic deception – Actions to eliminate revealing or convey misleading, telltale indicators that may be used by hostile forces Simulative electronic deception – Actions to represent friendly notional or actual capabilities to mislead hostile forces Imitative electronic dece... | to enemy electronics-dependent weapons. Among the types of electronic deception are: Manipulative electronic deception – Actions to eliminate revealing or convey misleading, telltale indicators that may be used by hostile forces Simulative electronic deception |
relay-operated metallic paths or crossbar switches operated by stored program control (SPC) systems. 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 w... | 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 mult... |
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 t... | tactical employment of forces. Electronic support data can be used to produce signals intelligence (SIGINT), communications intelligence (COMINT) and electronics intelligence (ELINT). Electronic support measures gather intelligence through passive "listening" to electromagnetic radiations of military interest. Electron... |
effect on refractive index for wavelengths near the absorption edge, due to the Kramers–Kronig relation. 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... | 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 e... |
the electric field in the crystal. 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... | 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 Now suppose we apply a sinusoidally varying potential voltage to the EOM with frequency and small amplitude . This adds a time dependent pha... |
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