Telecommunications terms starting with D

656 terms

dial pulse A dc pulse produced by an end instrument that interrupts a steady current at a sequence and rate determined by the selected digit and the operating…
dial pulsing Pulsing in which a direct-current pulse train is produced by interrupting a steady signal according to a fixed or formatted code for each digit and at a…
dial service assistance (DSA) A network-provided service feature, associated with the switching center equipment, in which services, such as directory assistance, call interception…
dial signaling Signaling in which dual tone multifrequency (DTMF) signals or pulse trains are transmitted to a switching center.
dial switching equipment Switching equipment actuated by electrical impulses generated by a dial or key pulsing arrangement. [47 CFR Pt.36-A]
dial through A technique, applicable to access circuits, that permits an outgoing routine call to be dialed by the PBX user after the PBX attendant has established the…
dial tone A tone employed in a dial telephone system to indicate to the calling party that the equipment is ready to receive dial or tone pulses.
dial-pulse period One complete cycle of a dial pulse, consisting of fall time, break interval, rise time, and make interval. [T1.409-1996]
dial-pulse signaling A method of transmitting a telephone address over a direct-current path. The dc current is interrupted at the transmitting end in a defined pattern…
dial-tone delay The time between the instant of going off-hook and the instant of receiving a dial tone.
dial-up A service feature in which a user initiates service on a previously arranged trunk or transfers, without human intervention, from an active trunk to a…
dialed digits Untranslated address information collected/received from the originating line/trunk. [T1.667-1999]
dialing In a communications system, using a device that generates signals for selecting and establishing connections.
diametral index of cooperation Synonym index of cooperation.
dibit A group of two bits. Note: The four possible states for a dibit are 00, 01, 10, and 11. Synonym diad.
dichroic filter An optical filter that reflects one or more optical bands or wavelengths and transmits others, while maintaining a nearly zero coefficient of absorption…
dichroic mirror A mirror used to reflect light selectively according to its wavelength.
DID defense in depth - multiple layers of security to provide added protection to IT resources
dielectric A substance in which an electric field may be maintained with zero or near-zero power dissipation, i.e., the electrical conductivity is zero or near zero.
dielectric filter See interference filter.
dielectric lens In the radio regime, a lens made of dielectric material that refracts radio waves in the same manner that an optical lens refracts light waves.
dielectric strength Of an insulating material, the maximum electric field strength that it can withstand intrinsically without breaking down, i.e.
dielectric waveguide A waveguide that consists of a dielectric material surrounded by another dielectric material, such as air, glass, or plastic, with a lower refractive…
difference frame Synonym delta frame.
differential encoding Encoding in which signal significant conditions represent binary data, such as "0" and "1", and are represented as changes to succeeding values rather…
differential Manchester encoding Encoding in which (a) data and clock signals are combined to form a single self-synchronizing data stream, (b) one of the two bits, i.e.
differential mode attenuation In an optical fiber, the variation in attenuation among the propagating modes.
differential mode delay In an optical fiber, the variation in propagation delay that occurs because of the different group velocities of different modes.
differential mode interference Interference that causes a change in potential of one side of a signal transmission path relative to the other side. 2.
differential modulation Modulation 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 efficiency In an optical source or detector, the slope of the curve relating output quanta to input quanta.
differentially coherent phase-shift keying See coherent differential phase-shift keying.
differentially encoded baseband Synonym non-return-to-zero mark.
differentiating network A network, or circuit, that produces an output waveform that is the time derivative of the input waveform.
Diffraction The spreading out of electromagnetic radiation as it leaves an aperture. The angle of spread, which cannot be eliminated by focusing, is proportional to…
diffraction grating An array of fine, parallel, equally spaced grooves ("rulings") on a reflecting or transparent substrate, which grooves result in diffractive and mutual…
diffraction limited In optics, pertaining to a light beam in which the far-field beam divergence is equal to that predicted by diffraction theory. 2.
diffraction region In radio propagation, a region that is in the geometric shadow of an electromagnetic source, but into which propagation nonetheless takes place by virtue…
diffuse reflection Reflection from a rough or irregular surface which does not maintain the integrity of the incident wavefront.
digerati Knowledgeable individuals at the forefront of Internet development and implementation. [Bahorsky] Note: Derived from the word "literati."
digest To cut DNA molecules with one or more restriction endonucleases.
digicash Abbreviation for digital cash. [After ANSDIT] Synonyms digital cash, e-cash, electronic cash.
digit A 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 slot In a digital data stream, a time interval that is allocated to a single digit and that can be uniquely recognized and defined.
Digital Information 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 line An access line composed of digital facilities, containing no analog sections, and having a digital interface at the local digital exchange office (DEO)…
digital alphabet A coded character set in which the characters of an alphabet have a one-to-one relationship with their digitally coded representations.
digital audio tape (DAT) See DAT.
digital cash (digicash) A bank-issued number that can be used in place of cash for Internet transactions.
digital certificate Electronic records that contain keys used to decrypt information, especially information sent over a public network like the Internet.
digital channel A 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 circuit A combination of two digital transmission channels permitting bidirectional digital transmission in both directions between two points, to support a…
digital circuit patch bay A patch bay in which low-level digital data circuits can be patched, monitored, and tested.
digital combining A method of interfacing digital data signals, in either synchronous or asynchronous mode, without converting the data into a quasi-analog signal.
digital computer A 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 data Data 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) complex A complex that includes the DEO and all connected remote switching units (RSUs), remote digital terminals (RDTS) and optical network units (ONUs). [T1.
digital envelope In 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 error An inconsistency between the digital signal actually received and the digital signal that should have been received.
digital exchange An exchange that switches digital signals by means of digital switching. [T1.206-1988]
digital facsimile equipment Facsimile equipment that digitally encodes the picture signal, i.e., encodes the baseband signal resulting from scanning the object.
digital filter A filter (usually linear), in discrete time, that is normally implemented through digital electronic computation.
Digital Fingerprint A fixed-length hash code that uniquely represents the binary content of a file.
digital frequency modulation The transmission of digital data by frequency modulation of a carrier, as in binary frequency-shift keying.
digital group See digroup.
digital link A 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 loopback A 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 milliwatt In 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 modulation The 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 hierarchy A hierarchy consisting of an ordered repetition of tandem digital multiplexers that produce signals of successively higher data rates at each level of the…
digital multiplexer A device for combining several digital signals into an aggregate bit stream. Note: Digital multiplexing may be implemented by interleaving bits, in…
digital network See integrated digital network.
digital path The 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 modulation Modulation 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 loop A 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 bay A 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 radio See software defined radio.
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 signal level 1 (DS1) See digital signal 1.
digital signature The 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 Algorithm Asymmetric algorithms used for digitally signing data.
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 slip In 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…