differential mode delayIn an optical fiber, the variation in propagation delay that occurs because of the different group velocities of different modes.
differential mode interferenceInterference that causes a change in potential of one side of a signal transmission path relative to the other side. 2.
differential modulationModulation in which the choice of the significant condition for any signal element is dependent on the significant condition for the previous signal…
differential phase-shift keying (DPSK)Phase-shift keying that is used for digital transmission in which the phase of the carrier is discretely varied (a) in relation to the phase of the…
differential pulse-code modulation (DPCM)Pulse-code modulation in which an analog signal is sampled and the difference between the actual value of each sample and its predicted value, derived…
differential quantum efficiencyIn an optical source or detector, the slope of the curve relating output quanta to input quanta.
differentiating networkA network, or circuit, that produces an output waveform that is the time derivative of the input waveform.
DiffractionThe spreading out of electromagnetic radiation as it leaves an aperture. The angle of spread, which cannot be eliminated by focusing, is proportional to…
diffraction gratingAn array of fine, parallel, equally spaced grooves ("rulings") on a reflecting or transparent substrate, which grooves result in diffractive and mutual…
diffraction limitedIn optics, pertaining to a light beam in which the far-field beam divergence is equal to that predicted by diffraction theory. 2.
diffraction regionIn radio propagation, a region that is in the geometric shadow of an electromagnetic source, but into which propagation nonetheless takes place by virtue…
diffuse reflectionReflection from a rough or irregular surface which does not maintain the integrity of the incident wavefront.
digeratiKnowledgeable individuals at the forefront of Internet development and implementation. [Bahorsky] Note: Derived from the word "literati."
digestTo cut DNA molecules with one or more restriction endonucleases.
digicashAbbreviation for digital cash. [After ANSDIT] Synonyms digital cash, e-cash, electronic cash.
digitA symbol, numeral, or graphic character that represents an integer. Note 1: Examples of digits include any one of the decimal characters "0" through "9"…
digit time slotIn a digital data stream, a time interval that is allocated to a single digit and that can be uniquely recognized and defined.
DigitalInformation stored as a string of ones and zeros. Opposite of analog.
digital access and cross-connect system (DACS)In communications systems, a digital system in which (a) access is performed by T-1 hardware architecture in private and public networks with centralized…
digital access lineAn access line composed of digital facilities, containing no analog sections, and having a digital interface at the local digital exchange office (DEO)…
digital alphabetA coded character set in which the characters of an alphabet have a one-to-one relationship with their digitally coded representations.
digital cash (digicash)A bank-issued number that can be used in place of cash for Internet transactions.
digital certificateElectronic records that contain keys used to decrypt information, especially information sent over a public network like the Internet.
digital channelA means for conveying information from one point to another in digital form. A digital channel may be implemented on a network composed of digital…
digital circuitA combination of two digital transmission channels permitting bidirectional digital transmission in both directions between two points, to support a…
digital circuit patch bayA patch bay in which low-level digital data circuits can be patched, monitored, and tested.
digital combiningA method of interfacing digital data signals, in either synchronous or asynchronous mode, without converting the data into a quasi-analog signal.
digital computerA computer that consists of one or more central processing units (CPUs), that is controlled by internally stored programs, and that stores and processes…
digital crossconnect system (DCS)A network element that is used to arrange lower level digital signals among higher level digital bit streams.
digital dataData represented by discrete values or conditions, as opposed to analog data. 2. Discrete representations of quantized values of variables, e.g.
digital data service (DDS)A generic description for synchronous digital transmission operating up to 64 kb/s. [T1.Rpt39-1995]
digital data system (DDS)A synchronous system providing for full-duplex, end-to-end transmission of digital data at the subrate data channel rates of 2.4, 4.8, 9.6, 19.
digital end office (DEO) complexA complex that includes the DEO and all connected remote switching units (RSUs), remote digital terminals (RDTS) and optical network units (ONUs). [T1.
digital envelopeIn cryptosystems, data appended to a message, that allow the intended recipient to verify the integrity of the content of the message. [2382-pt.8]
digital errorAn inconsistency between the digital signal actually received and the digital signal that should have been received.
digital exchangeAn exchange that switches digital signals by means of digital switching. [T1.206-1988]
digital facsimile equipmentFacsimile equipment that digitally encodes the picture signal, i.e., encodes the baseband signal resulting from scanning the object.
digital filterA filter (usually linear), in discrete time, that is normally implemented through digital electronic computation.
Digital FingerprintA fixed-length hash code that uniquely represents the binary content of a file.
digital frequency modulationThe transmission of digital data by frequency modulation of a carrier, as in binary frequency-shift keying.
digital linkA means of digital transmission with specified characteristics between two points. [T1.206-1988]
digital loop carrier (DLC)The equipment, including lines, that is used for digital multiplexing of telephone circuits, and that is provided by the network as part of the subscriber…
digital loopbackA mechanism incorporated into a terminal or into equipment in the network whereby a duplex communication path may be connected back upon itself so that…
digital milliwattIn digital telephony, a test signal consisting of eight 8-bit words corresponding to one cycle of a sinusoidal signal approximately 1 kHz in frequency and…
digital modulationThe process of varying one or more parameters of a carrier wave as a function of two or more finite and discrete states of a signal. 2.
digital multiplex hierarchyA hierarchy consisting of an ordered repetition of tandem digital multiplexers that produce signals of successively higher data rates at each level of the…
digital multiplexerA device for combining several digital signals into an aggregate bit stream. Note: Digital multiplexing may be implemented by interleaving bits, in…
digital pathThe whole of the means of transmitting and receiving a digital signal of specified rate between the two digital distribution frames (or equivalent) at…
digital phase modulationModulation in which the instantaneous phase of the modulated wave is shifted between a set of predetermined discrete values in accordance with the…
digital phase-locked loopA phase-locked loop in which the reference signal, the controlled signal, or the controlling signal, or any combination of these, is in digital form.
digital primary patch bayA patch bay that provides (a) the first access of most local user digital circuits in a technical control facility and (b) patching, monitoring, and…
digital reference signal (DRS)A digital representation of a 0-dBmO 1004-Hz analog sinusoid, such that it will be decoded into an analog signal equal in level to the analog signal…
digital selective calling (DSC)A synchronous system developed by the International Radio Consultative Committee (CCIR), used to establish contact with a station or group of stations…
digital service unit (DSU)A replacement for the modem in synchronous connections to the Internet, and which formats data for transmission.
digital signal (DS)A signal in which discrete steps are used to represent information. Note 1: In a digital signal, the discrete steps may be further characterized by signal…
digital signal 0 (DS0)In T-carrier, a basic digital signaling rate of 64 kb/s, corresponding to the capacity of one voice-frequency-equivalent channel.
digital signal 1 (DS1)A digital signaling rate of 1.544 Mb/s, corresponding to the North American and Japanese T1 designator.
digital signal 1C (DS1C)A digital signaling rate of 3.152 Mb/s, corresponding to the North American T1C designator.
digital signal 2 (DS2)A digital signaling rate of 6.312 Mb/s, corresponding to the North American and Japanese T2 designator.
digital signal 3 (DS3)1. A digital signal rate of 44.736 Mb/s, corresponding to the North American T3 designator. 2. A digital signaling rate of 32.
digital signal 4 (DS4)1. A digital signal rate of 274.176 Mb/s, corresponding to the North American T4 designator. 2. A digital signaling rate of 97.
digital signatureThe electronic equivalent of a handwritten signature, a digital signature is a unique block of text that verifies a user's identity and is appended to a…
Digital Signature Standard (DSS)A 1994-approved specification (FIPS-186-1) ruling the use of a single technique for generating signatures using the Digital Signature Algorithm.
digital slipIn the reception of a digital data stream, the loss of a bit, or the insertion by the receiver of a bit that was not transmitted, because of a difference…
digital speech interpolation (DSI)In digital speech transmission, the use of periods of inactivity or constant signal level to increase the transmission efficiency by insertion of…
digital subscriber line (DSL)In Integrated Services Digital Networks (ISDN), equipment that provides full-duplex service on a single twisted metallic pair at a rate sufficient to…
digital switchA switch that performs time-division-multiplexed switching of digitized signals.
digital switchingSwitching in which digitized signals are switched without converting them to or from analog signals.
digital synchronizationSynchronization based on the start of a transmitted digital data unit, such as a bit, character, block, or frame.
Digital Television (DTV)Any technology, using any of several digital encoding schemes, used in connection with the transmission and reception of television signals.
digital test access unit (DTAU)A generic term for the functions associated with accessing one or more channels within a digital signal for the purpose of testing.
digital transmission groupA group of digitized voice or data channels or both with bit streams that are combined into a single digital bit stream for transmission over…
digital transmission systemA transmission system in which (a) all circuits carry digital signals and (b) the signals are combined into one or more serial bit streams that include…
digital videoA video (television) signal represented by computer-readable binary numbers that describe luminance levels as well as a finite set of colors.
digital voice transmissionTransmission of analog voice signals that have been converted into digital signals.
digital watermarkAn identification code or bit pattern integrated into multimedia data that aids copyright owners in identifying illegally distributed audio, video, or…
digital-to-analog (D-A) converterA device that converts a digital input signal to an analog output signal carrying equivalent information.
digitizeThe process of converting an analog value into a digital (numeric) representation.
digitizerDevice that converts analog information into a digital format; for flat graphic material, such as maps, a digitizer can either be flatbed or scanning.
digitizer tabletA graphics drawing tablet used with a puck or stylus.
digroupAbbreviation for digital group. In telephony, a basic digital multiplexing group.
DINAbbreviation for Deutsches Institut für Normung.
DipThe angle that a planar geologic surface, for example, a fault, is inclined from the horizontal.
DIP switchA group of subminiature switches mounted in a package compatible with standard integrated-circuit sockets.
diplex operationThe sharing of one common element, such as a single antenna or channel, for transmission or reception of two simultaneous, independent signals on two…
diplexerA three-port frequency-dependent device that may be used as a separator or a combiner of signals.
dipole antennaUsually a straight, center-fed, one-half wavelength antenna.
dipulse codingThe coding of "1's" and "0's" in a message in which one full cycle of a square wave, i.e.