AWGNAbbreviation for additive white gaussian noise. See white noise.
axial propagation constantIn an optical fiber, the propagation constant evaluated along the optical axis of the fiber in the direction of transmission.
axial ratioOf an electromagnetic wave having elliptical polarization, the ratio of the magnitudes of the major axis and the minor axis of the ellipse described by…
axial rayA light ray that travels along the optical axis.
BAbbreviation used on long-term climate outlooks issued by CPC to indicate areas that are likely to be below normal for a given parameter (temperature…
B channelA communications channel used for the transmission of an aggregate signal generated by multichannel transmitting equipment. 2.
b frameAn 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…
B3ZSAbbreviation for bipolar with three-zero substitution. A T-carrier line code in which bipolar violations are deliberately inserted if user data contain a…
B6ZSAbbreviation for bipolar with six-zero substitution. A T-carrier line code in which bipolar violations are deliberately inserted if user data contain a…
B8ZSAbbreviation for bipolar with eight-zero substitution. A T-carrier line code in which bipolar violations are deliberately inserted if user data contains a…
B8ZS (Bipolar with 8-Zero Substitution)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…
babbleIn transmission systems, the aggregate of crosstalk induced in a given line by all other lines.
back-to-back connectionA direct connection between the output of a transmitting device and the input of an associated receiving device.
backboneThe bones, muscles, tendons, and other tissues that reach from the base of the skull to the tailbone.
backgroundIn Web pages, an image or color, usually defined in HTML, that serves as the underlying color or imagery for a Web page.
background noiseThe total system noise in the absence of information transmission.
background processingThe execution of lower priority computer programs when higher priority programs are not using the system resources.
backhaul1. The practice of routing telecommunications traffic beyond its intended destination, and then back to the intended destination, usually for the purpose…
backscatteringRadio wave propagation in which the direction of the incident and scattered waves, resolved along a reference direction (usually horizontal) are…
BackupTo create a copy of data as a precaution against the loss or damage of the original data.
backup fileA copy of a file made for purposes of later reconstruction of the file, if necessary.
backward channelIn data transmission, a secondary channel in which the direction of transmission is constrained to be opposite to that of the primary, i.e.
backward indicator bit (BIB)A signal unit (or sequence of bits) that (by changing its status) is used to request retransmission by the remote end whenever it receives a signal unit…
backward recoveryThe reconstruction of an earlier version of a file by using a newer version of data recorded in a journal.
backward sequence number (BSN)A field in a signal unit that contains the forward sequence number of a correctly received signal unit being acknowledged in the signal unit that is being…
backward signalA signal sent from the called to the calling station, i.e., from the original data sink to the original data source.
backward supervisionThe use of supervisory signal sequences from a secondary to a primary station.
bad sectoringA technique for copy protection in which bad sectors are intentionally written on a diskette. [2382-pt.8]
BalanceWe put each charge on your account, including interest or fees, into a balance category.
balance return lossA measure of the degree of balance between two impedances connected to two conjugate sides of a hybrid set, coil, network, or junction. 2.
balanced codeIn PCM systems, a code constructed so that the frequency spectrum resulting from the transmission of any code word has no dc component. 2.
balanced lineA transmission line consisting of two conductors in the presence of ground, capable of being operated in such a way that when the voltages of the two…
balanced modulatorA modulator constructed so that the carrier is suppressed and any associated carrier noise is balanced out.
balancing network1. In a hybrid set, hybrid coil, or resistance hybrid, a circuit used to match, i.e., to balance, the impedance of a uniform transmission line, i.e.
balunAbbreviation for balanced to unbalanced. In radio frequency usage, a device used to couple a balanced device or line to an unbalanced device or line.
bandOne layer of a multispectral image representing data values for a specific range of the electromagnetic spectrum of reflected light or heat (e.g.
band-stop filterA filter that attenuates, usually to very low levels, all frequencies between two non-zero, finite limits and passes all frequencies not within the limits.
BANDPASS FILTERA filter whose frequencies are between given upper and lower cutoff values, while substantially attenuating all frequencies outside these values (this…
bandpass limiterA device that imposes hard limiting on a signal and contains a filter that suppresses the unwanted products (harmonics) of the limiting process.
BandwidthThe amount of information or data that can be sent over a network connection in a given period of time.
bandwidth (BW)1. The difference between the limiting frequencies within which performance of a device, in respect to some characteristic, falls within specified limits.
bandwidth (of an optical fiber)The lowest modulation frequency at which the RMS peak-to-valley amplitude (optical power) difference of an intensity-modulated monochromatic signal…
bandwidth balancing mechanismIn a distributed-queue dual-bus network, a procedure in which a node occasionally skips the use of empty queued arbitrated slots, and which procedure…
bandwidth compressionThe reduction of the bandwidth needed to transmit a given amount of data in a given time. 2.
bandwidth•distance productOf an optical fiber, under specified launching and cabling conditions, at a specified wavelength, a figure of merit equal to the product of the fiber's…
bandwidth-limited operationThe condition prevailing when the system bandwidth limits performance. Note: Bandwidth-limited operation occurs when the system distorts the signal…
bangThe exclamation point character (!) used in early addressing schemes to separate the names of individual machines.
bannerAn HTML tag that creates scrolling text on a Web page. [Bahorsky] 2. Scrolling or fixed text used as an advertisement on a Web page, e.g.
bar codeA small pattern of vertical lines that can be read by a laser or an optical scanner.
Barrage JammingSimultaneous electronic jamming over a broad band of frequencies.
baseOne of the components of nucleosides, nucleotides and nucleic acids . Four different bases are found in naturally occurring DNA - the purines A (adenine )…
base address1. An address that is used as the origin in the calculation of addresses in the execution of a computer program. [From Weik '96] 2.
base communications (basecom)Communications services, such as the installation, operation, maintenance, augmentation, modification, and rehabilitation of communications networks…
base Earth stationAn Earth station in the fixed-satellite service or, in some cases, in the land mobile-satellite service, located at a specified fixed point or within a…
base keyA key used to derive (to compute cryptographically) or to decrypt transaction keys. [After X9.24]
base standardA standard or specification that is recognized as appropriate for normative reference in a profile by the body adopting that profile, but is not a profile…
Base StationA computer which accepts radio signals from ALERT gaging sites, decodes the data, places the data in a database, and makes the data available to other…
basebandThe original band of frequencies produced by a transducer, such as a microphone, telegraph key, or other signal-initiating device, prior to initial…
baseband local area networkA local area network in which information is encoded, multiplexed, and transmitted without modulation of carriers.
baseband modulationIntensity modulation of an optical source, e.g., LED or ILD, directly, without first modulating the signal of interest onto an electrical carrier wave.
baseband signalingTransmission of a digital or analog signal at its original frequencies; i.e., a signal in its original form, not changed by modulation.
basic accessA characterization of a simple standardized combination of access channels that constitute the access arrangements for the majority of ISDN users…
basic callA call between two users that does not include additional features (e.g., a plain telephone call).
basic call process (BCP)The sequence of activities used in processing a basic call attempt. [T1.667-1999]
basic componentA component that is identifiable at the lowest hierarchical level of specification produced during Detailed Design [ITSEC].
basic mode link controlControl of data links by use of the control characters of the 7-bit character set for information processing interchange as given in ISO Standard 646-1983…
basic rate interface (BRI)An ITU-T Integrated Services Digital Network (ISDN) multipurpose user interface standard that denotes the capability of simultaneous voice and data…
basic serviceA pure transmission capability over a communication path that is virtually transparent in terms of its interaction with customer-supplied information. 2.
basic service element (BSE)An optional unbundled feature, generally associated with the basic serving arrangement (BSA), that an enhanced-service provider (ESP) may require or find…
basic serving arrangement (BSA)The fundamental tariffed switching and transmission (and other) services that an operating company must provide to an enhanced service provider (ESP) to…
basic statusIn data transmission, the status of the capability of a secondary station to send or receive a frame containing an information field.
Bastion HostA bastion host is typically a firewall implemented on top of an operating system that has been specially configured and hardened to be resistant to attack.
batch processingThe processing of a large amount of data, or multiple records, in a single step.
batched transmissionThe transmission of two or more messages from one station to another without intervening responses from the receiving station.
baud (Bd)A unit of modulation rate. Note: One baud corresponds to a rate of one unit interval per second, where the modulation rate is expressed as the reciprocal…
Baudot codeA synchronous code in which five equal-length bits represent one character. Note 1: The Baudot code, which was developed circa 1880, has been replaced by…
BCCA Bcc (blind carbon copy) is a copy of an email message sent to a recipient whose email address does not appear in the message.
BCH codeAbbreviation for Bose-Chaudhuri-Hochquenghem code. A multilevel, cyclic, error-correcting, variable-length digital code used to correct errors up to…
BeaconA line of code placed in an ad or on a web page that helps track the visitor's actions, such as registrations or purchases.
beamThe main lobe of an antenna radiation pattern. 2. A column of light. Note: A beam may be parallel, divergent, or convergent. [After FAA]
beam diameterOf an electromagnetic beam, along any specified line that (a) intersects the beam axis and (b) lies in any specified plane normal to the beam axis, the…
beam divergenceOf an electromagnetic beam, in any plane that intersects the beam axis, the increase in beam diameter with distance from the aperture from which the beam…