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: Abbreviation for bit.
- Browse Related Terms: AC, AMI, app, ATM, B, b/s, basecom, BCI, Bd, BOC, BW, C.O., CAD, CATV, CCS, COG, EO, EOW, ESD, ESF, FC, FEP, FIFO, FILO, FO, MFD, MFJ, MHz, MTA, mw, NA, nmi, Np, NPA, NVIS, OD, OPX, OTAR, PLA, PLS, POT, PPP, RAD, RI, RJ, RO, RQ, RSL, RX, s, sr, STP, SX, THD, TLM, TLP, TRANSEC, TX, uv, VNL, XO, XT
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A communications channel used for the transmission of an aggregate signal generated by multichannel transmitting equipment. 2. The CCITT (now, ITU-T) designation for a clear channel, 64-kb/s service capability provided to a subscriber under the Integrated Services Digital Network offering. Note: The B channel, also called the bearer channel, is intended for transport of user information, as opposed to signaling information.
- Browse Related Terms: aggregator, automatic ringdown circuit, B channel, Block Holder, compatibility testing, exchange access, facility, maintenance, MJU, network administration, number portability, open video systems, pair-gain system, point code (PC), positioned interface structure, second dialtone, service bit, service integrity, service signals, service-provider portability, system services API, terminal service profile (TSP), Toll Free Service End-User Subscriber, verified off-hook
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An MPEG video frame type that provides bidirectional interframe compression. Note: A b frame derives its content from the closest 1 or P frame, one in the past and one in the future. Generating b frames requires greater computing power than does generating 1 or P frames. The use of b frames enables compression ratios of 200:1. Robust MPEG encoders employ a combination of b, 1, and P frame encoding. [After Silicon]
- Browse Related Terms: active video frame identification, b frame, camcorder, frame grabber, frame matching, motion compensation, motion response degradation, normal resolution still image, object persistence, object retention, scene cut, video imagery, videoconference
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Abbreviation for bits per second.
- Browse Related Terms: AC, AMI, app, ATM, B, b/s, basecom, BCI, Bd, BOC, BW, C.O., CAD, CATV, CCS, COG, EO, EOW, ESD, ESF, FC, FEP, FIFO, FILO, FO, MFD, MFJ, MHz, MTA, mw, NA, nmi, Np, NPA, NVIS, OD, OPX, OTAR, PLA, PLS, POT, PPP, RAD, RI, RJ, RO, RQ, RSL, RX, s, sr, STP, SX, THD, TLM, TLP, TRANSEC, TX, uv, VNL, XO, XT
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Abbreviation for bipolar with three-zero substitution. A T-carrier line code in which bipolar violations are deliberately inserted if user data contain a string of 3 or more consecutive zeros. Note 1: B3ZS is used to ensure a sufficient number of transitions to maintain system synchronization when the user data stream contains an insufficient number of "ones" to do so. Note 2: B3ZS is used in the North American hierarchy at the T3 rate.
- Browse Related Terms: B3ZS, B6ZS, B8ZS, content hierarchy levels, fractional T1, Manchester code, multistreaming technology, presentation unit, time-division multiplexing (TDM), trunk group multiplexer (TGM)
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Abbreviation for bipolar with six-zero substitution. A T-carrier line code in which bipolar violations are deliberately inserted if user data contain a string of 6 or more consecutive zeros. Note 1: B6ZS is used to ensure a sufficient number of transitions to maintain system synchronization when the user data stream contains an insufficient number of "ones" to do so. Note 2: B6ZS is used in the North American hierarchy at the T2 rate.
- Browse Related Terms: B3ZS, B6ZS, B8ZS, content hierarchy levels, fractional T1, Manchester code, multistreaming technology, presentation unit, time-division multiplexing (TDM), trunk group multiplexer (TGM)
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Abbreviation for bipolar with eight-zero substitution. A T-carrier line code in which bipolar violations are deliberately inserted if user data contains a string of 8 or more consecutive zeros. Note 1: B8ZS is used to ensure a sufficient number of transitions to maintain system synchronization when the user data stream contains an insufficient number of "ones" to do so. Note 2: B8ZS is used in the European hierarchy at the T1 rate.
- Browse Related Terms: B3ZS, B6ZS, B8ZS, content hierarchy levels, fractional T1, Manchester code, multistreaming technology, presentation unit, time-division multiplexing (TDM), trunk group multiplexer (TGM)
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A code in which eight consecutive zeros are replaced with the sequence 000+-0-+ if the preceding pulse was + and with the sequence 000-+0+- of the preceding pulse was -, where + represents a positive pulse, - represents a negative pulse, and 0 represents no pulse.
- Browse Related Terms: B8ZS (Bipolar with 8-Zero Substitution), BCH code, binary code, Bose-Chaudhuri-Hochquenghem code, CELP, most significant bit, multilevel modulation, non-return-to-zero change-on-ones (NRZ1), paired disparity code, Parity, redundant code, unit-distance code
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In transmission systems, the aggregate of crosstalk induced in a given line by all other lines.
- Browse Related Terms: anisochronous transmission, babble, nonsynchronous system, nonsynchronous transmission, radio telegraphy, vocoder, voice coder
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Synonym trapdoor.
- Browse Related Terms: back door, coherent bundle, flow diagram, flywheeling, magic cookie, news client, passive element, plunger, radiant exitance, Scene, scream, set-top box, sexadecimal, spacing pulse, spacing signal, switchpoint, telephone sidetone, WRU signal
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A direct connection between the output of a transmitting device and the input of an associated receiving device. Note: When used for equipment measurements or testing purposes, such a back-to-back connection eliminates the effects of the transmission channel or medium. 2. A direct connection between the output of a receiving device and the input to a transmitting device. Note: The term "direct," as used in both definitions, may be construed as permitting a passive device such as a pad (attenuator) to accommodate power level constraints.
- Browse Related Terms: back-to-back connection, branching repeater, combinational logic element, common-mode rejection ratio (CMRR), equal-level patch bay, noise suppression, output rating, protection ratio, rated output power, receive-after-transmit time delay, receiver attack-time delay, sequential logic element, squelch, through-group equipment, vogad, zero-level decoder
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The high-traffic-density connectivity portion of any communications network. 2. In packet-switched networks, a primary forward-direction path traced sequentially through two or more major relay or switching stations. Note: In packet-switched networks, a backbone consists primarily of switches and interswitch trunks.
- Browse Related Terms: ARPANET, Backbone, burst switching, connection-oriented mode transmission, end-to-end communication, first-route traffic, Martian, multicast, multilink operation, network utility, packet filtering, packet mode, packet switching, packet transfer mode, packet-switched data transmission service, packet-switching network, packet-switching node, PAD, screening router, switched network, trace packet, transmission control protocol, virtual circuit capability
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In Web pages, an image or color, usually defined in HTML, that serves as the underlying color or imagery for a Web page. Note: Browsers may also be configured to dictate backgrounds. 2. In computer display systems, the underlying color or imagery for the main screen or for the fundamental window of a computer's operating system.
- Browse Related Terms: background, checkbox, Common Gateway Interface, content, cookie, external viewer, file name extension, form, network browser, online shopping, SIG, wallpaper, Web ring, Webmaster, white space
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The total system noise in the absence of information transmission.
- Browse Related Terms: articulation index, articulation score (AS), atmospheric noise, background noise, burst, C-Message Noise, C-Notched Noise, common-mode interference, equivalent pulse code modulation (PCM) noise, path intermodulation noise, picowatt, psophometrically weighted, pink noise, presence noise, random noise, sidetone, spurious noise, total channel noise, transmitter power output rating, uniform-spectrum random noise, weighting network, worst hour of the year
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The execution of lower priority computer programs when higher priority programs are not using the system resources. Note: Priorities may be assigned by system software, application software, or the operator.
- Browse Related Terms: access type, assembly time, asynchronous operation, audit review file, background processing, base address, Batch Processing, Buffer Overflow, computer system, emulate, file privilege flag, machine-independent, malicious applets, multiprogramming, Object, overlay, Parallel Processing, process, restart, Run, simple buffering, Software Engineering, supervisory program, time-sharing
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1. The practice of routing telecommunications traffic beyond its intended destination, and then back to the intended destination, usually for the purpose of taking advantage of tariffs or prices that are lower than those afforded by direct routing. 2. In security, to bring a call that has been routed along a particular path (usually via satellite) to some earlier position in the switching sequence (also using satellites). Note: The technique supports CALEA, the Communications Assistance to Law Enforcement Act and LAES, Lawfully Authorized Electronic Surveillance. 3. In commercial telephone networks, referring to a trunk or line between two central offices that may not share the same facilities or geographic location, and which trunk is used to support special services, e.g., orderwires, off-premises extensions, common exchange number routing, or least-cost routing of customer centrex services. 4. In mission programs requiring contingency networking, referring to a link that provides feedback to the mission control center to verify that the transmission via a primary communications has been successful. Note: In cases where the primary path fails to deliver the transmission, the communications may occur over the backhaul connection or an alternative network connection. 5. In contingency networking, an alternative connection that is routed via a diversified path, e.g., an alternative frequency, satellite facility, cable, trunk, or time slot.
- Browse Related Terms: alarm center, backhaul, circuit switching center, common user network, message center, message switching, multiple homing, noncritical technical load, operational load, proration, signal center, split homing, switching system, telecommunications center
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Radio wave propagation in which the direction of the incident and scattered waves, resolved along a reference direction (usually horizontal) are oppositely directed. A signal received by backscattering is often referred to as "backscatter." [JP 1-02] 2. In optics, the scattering of light into a direction generally opposite to the original one.
- Browse Related Terms: absorption peak, anomalous propagation (AP), backscattering, Brillouin diagram, Brillouin scattering, forward scatter, material scattering, Mie Scattering, Rayleigh scattering, Scatter, Scattering, scattering center
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[A] copy of files and programs made to facilitate recovery, if necessary. [INFOSEC-99] 2. See backup file.
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A copy of a file made for purposes of later reconstruction of the file, if necessary. Note: A backup file may be used for preserving the integrity of the original file and may be recorded on any suitable medium. Synonym job-recovery control file.
- Browse Related Terms: automated data medium, backup file, brick, clockwise polarized wave, media converter, record sheet, streamer, streaming tape drive