Telecommunications — page 26 of 85

Telecommunications terms

2501. dual-homed Host A general-purpose computer system that has at least two network interfaces.
2502. dual-precedence message A message that contains two precedence designations. Note: Usually the higher precedence message is for all action addressees and the lower for all…
2503. dual-tone multifrequency (DTMF) signaling In telephone systems, multifrequency signaling in which standard set combinations of two specific voice band frequencies, one from a group of four low…
2504. dual-use access line A user access line normally used for analog voice communication, but which has special conditioning for use as a digital transmission circuit.
2505. dub 1. A duplicate copy made in the same format from one recording medium to another. 2. See audio dubbing.
2506. duct 1. In interfacility cabling, a conduit, which may be direct-earth buried or encased in concrete, used to enclose communications or power cables.
2507. ducting The propagation of radio waves within an atmospheric duct.
2508. dumb terminal An asynchronous terminal that (a) does not use a transmission control protocol and (b) sends or receives data sequentially one character at a time.
2509. dummy load A dissipative impedance-matched network, usually used at the end of a transmission line to absorb all incident energy.
2510. duobinary signal A pseudobinary-coded signal in which a "0" ("zero") bit is represented by a zero-level electric current or voltage; a "1" ("one") bit is represented by a…
2511. duplex cable A fiber-optic cable that contains two optical fibers. [After FAA]
2512. duplex circuit A circuit that permits transmission in both directions. Note: For simultaneous two-way transmission, see full-duplex circuit.
2513. duplex operation Operating method in which transmission is possible simultaneously, in both directions of a telecommunication channel.
2514. duplexer In radar systems, a device that isolates the receiver from the transmitter while permitting them to share a common antenna.
2515. Duty Cycle The duration and periodicity of the operation of a device.
2516. DVD See digital versatile disc (DVD).
2517. dvi Abbreviation for digital video interface. A standard for computer-generated multimedia text and graphics merged in video production.
2518. DWDM Abbreviation for dense wavelength division multiplexing.
2519. dwell time The period during which a dynamic process remains halted in order that another process may occur.
2520. DX signaling Abbreviation for direct current signaling.
2521. DX signaling unit A duplex signaling unit that repeats "E" and "M" lead signals into a cable pair(s) via "A" and "B" leads.
2522. dynamic arming/disarming Enabling/disabling of a detection point by a service control function in the course of service control execution for a particular call/service attempt.
2523. dynamic HTML See dHTML.
2524. dynamic range In a system or device, the ratio of (a) a specified maximum level of a parameter, such as power, current, voltage, or frequency to (b) the minimum…
2525. dynamic variation A short-term variation (as opposed to long-term drift) in the characteristics of power delivered to electrical equipment.
2526. dynamic window control A procedure to modify the transmitter's transmit window in response to the user's perception of congestion conditions in the network. [T1.615-1992]
2527. dynamically adaptive routing In route determination for packet-switched networks, adaptive routing in which an algorithm is used that (a) automatically routes traffic around…
2528. dynamically created Web page A Web page designed to deliver content to users based on information obtained from users, from cookies, or from choices made by users as they access and…
2529. dynamicizer See parallel-to-serial conversion.
2530. E East
2531. E & M signaling In telephony, an arrangement that uses separate leads, called the "E" lead and "M" lead, for signaling and supervisory purposes.
2532. E layer See E region, ionosphere.
2533. E REGION In solar-terrestrial terms, a daytime layer of the earth's ionosphere roughly between the altitudes of 85 and 140 km.
2534. E-bend A smooth change in the direction of the axis of a waveguide, throughout which the axis remains in a plane parallel to the direction of electric E-field…
2535. e-cash Abbreviation for electronic cash. Data representing money, which data can be transferred by means of a computer network and can be traded as a token…
2536. e-Commerce electronic commerce
2537. e-mail Electronic mail or computer-based mail
2538. E-mail Address The address used to reach someone via email. The format of an email address is user@domain. For example, my email address is email.guide@about.
2539. e-mail exploder Synonym mail exploder.
2540. E-plane bend Synonym E-bend.
2541. e-trade Synonym e-commerce.
2542. e-zine Abbreviation for electronic magazine. A periodical publication that is stored on a file server and that may be distributed or accessed via a computer…
2543. e.m.r.p. Abbreviation for effective monopole radiated power.
2544. e.r.p. [or ERP] Abbreviation for effective radiated power.
2545. earth See ground.
2546. Earth coverage (EC) In satellite communications, the coverage that occurs when the satellite-to-Earth beam is sufficiently wide to cover all of the surface of the Earth…
2547. earth electrode subsystem A network of electrically interconnected rods, plates, mats, or grids, installed and connected, for the purpose of establishing a low-resistance contact…
2548. Earth exploration-satellite service A radiocommunication service between Earth stations and one or more space stations, which may include links between space stations, in which: information…
2549. earth ground See ground.
2550. Earth station A station located either on the Earth's surface or within the major portion of the Earth's atmosphere and intended for communication: with one or more…
2551. Earth terminal In a satellite link, one of the non-orbiting communications stations that receives, processes, and transmits signals between itself and a satellite.
2552. Earth terminal complex In satellite communications systems, the assembly of equipment and facilities necessary to integrate an Earth terminal into a communications network.
2553. EAS Abbreviation for extended area service.
2554. ease of use An aspect of the assessment of the effectiveness of a Target of Evaluation, namely that it cannot be configured or used in a manner which is insecure but…
2555. Eavesdropping Surreptitiously obtaining data from an unknowing end user who is performing a legitimate function.
2556. EBCDIC Extended Binary Code Decimal Interchange Code.
2557. EbN0 See signal-to-noise ratio per bit.
2558. EBS Emergency Broadcast System
2559. EC See: Enzyme Commission number.
2560. ECCM Electronic Counter-Countermeasures.
2561. Echo Energy back scattered from a target (precipitation, clouds, etc.) and received by and displayed on a radar screen.
2562. echo area See scattering cross section.
2563. echo attenuation In a communication circuit (4- or 2-wire) in which the two directions of transmission can be separated from each other, the attenuation of echo signals…
2564. echo canceler See echo suppressor.
2565. echo cancellation In a system, the reduction of the power level of an echo or the elimination of an echo.
2566. echo check A check to determine the integrity of transmission of data, whereby the received data are returned to the source for comparison with the originally…
2567. echo command A programming language command that causes an echo response from a computer to be displayed on a monitor or printer for analysis or monitoring of the…
2568. echo effect See ghost.
2569. echo line In computer systems, on a hard-output or display device, a line of information that verifies (reflects) data entered into the computer.
2570. echo loss The ratio in dB of the power of a transmitted signal that is echo loss weighted (as specified in ITU-T Recommendation G.
2571. echo path capacity The maximum echo path delay for which an echo canceler is designed to operate. [T1.508-1998]
2572. echo path delay (EPD) The time in milliseconds (ms) between the incidence of a signal and the incidence of that signal's echo at a measurement point. [T1.255-1997]
2573. echo return loss See return loss.
2574. echo sounding The measurement of the depth of a body of water or the distance to an object in a body of water by measuring the time it takes sound or electromagnetic…
2575. echo suppression The procedure by which characters entered into a system are not physically revealed [CESG].
2576. echo suppressor A device for connection to a two-way telephone circuit to attenuate echo signals in one direction caused by signals in the other direction.
2577. echoplex An echo check used in public switched networks operating in the full-duplex transmission mode, i.e., the two-way-simultaneous mode.
2578. ECM Enterprise content management.
2579. edge busyness In a video display, distortion that is concentrated at or near the edge of objects, and that is categorized further by its temporal and spatial…
2580. edge-emitting LED An LED that has a physical structure superficially resembling that of an injection laser diode, operated below the lasing threshold and emitting…
2581. EDI See electronic data interchange (EDI).
2582. EDTV Abbreviation for extended-definition television.
2583. edu In a URL, a domain-name suffix indicating an education institution.
2584. Effective 2-Wire The term "Effective 2-Wire" denotes a condition which permits the simultaneous transmission in both directions over a channel, but it is not possible to…
2585. Effective 4-Wire The term "Effective 4-Wire" denotes a condition which permits the simultaneous independent transmission of information in both directions over a channel.
2586. effective antenna gain contour (of a steerable satellite beam) An envelope of antenna gain contours resulting from moving the boresight of a steerable satellite beam along the limits of the effective boresight area.
2587. effective boresight area (of a steerable satellite beam) An area on the surface of the Earth within which the boresight of a steerable satellite beam is pointed.
2588. effective data transfer rate 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.
2589. Effective Date The date on which an insurance policy becomes effective.
2590. effective Earth radius The radius of a hypothetical Earth for which the distance to the radio horizon, assuming rectilinear propagation, is the same as that for the actual Earth…
2591. effective height The height of the center of radiation of an antenna above the effective ground level. 2.
2592. effective input noise temperature 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…
2593. effective isotropically radiated power (e.i.r.p.) The arithmetic product of (a) the power supplied to an antenna and (b) its gain.
2594. effective mode volume For an optical fiber, 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.
2595. effective monopole radiated power (e.m.r.p.) The product of the power supplied to the antenna and its gain relative to a short vertical antenna in a given direction. [RR]
2596. effective power In alternating-current power transmission and distribution, the product of the rms voltage and amperage, i.e.
2597. effective radiated power (e.r.p.) (in a given direction) The power supplied to an antenna multiplied by the antenna gain in a given direction.
2598. effective speed of transmission Synonym effective transmission rate.
2599. effective transmission rate The rate at which information is processed by a transmission facility. Note 1: The effective transmission rate is calculated as (a) the measured number of…
2600. Effectiveness A property of a Target of Evaluation representing how well it provides security in the context of its actual or proposed operational use [ITSEC].