Telecommunications — page 22 of 85

Telecommunications terms

2101. delta modulation (DM) Analog-to-digital signal conversion in which (a) the analog signal is approximated with a series of segments, (b) each segment of the approximated signal…
2102. delta-sigma modulation Delta modulation in which the integral of the input signal is encoded rather than the signal itself.
2103. demagnetizing Synonym degaussing.
2104. demand assignment An operation in which several users share access to a communications channel on a real-time basis, i.e.
2105. demand assignment multiple access (DAMA) In a communications system, a technique for allocating use of bandwidth among multiple users, based on demand.
2106. demand factor The ratio of (a) the maximum real power consumed by a system to (b) the maximum real power that would be consumed if the entire load connected to the…
2107. demand load In general, the total power required by a facility. Note: The demand load is the sum of the operational load (including any tactical load) and…
2108. demand service In ISDN applications, a telecommunications service that establishes an immediate communication path in response to a user request made through…
2109. demarc Acronym for demarcation point.
2110. demarcation point (demarc) That point at which operational control or ownership of communications facilities changes from one organizational entity to another.
2111. democratically synchronized network A mutually synchronized network in which all clocks in the network are of equal status and exert equal amounts of control on the others, the network…
2112. demodulation The recovery, from a modulated carrier, of a signal having substantially the same characteristics as the original modulating signal.
2113. demon See daemon.
2114. demultiplex (DEMUX) See demultiplexing.
2115. demultiplexing The separation of two or more channels previously multiplexed; i.e., the reverse of multiplexing.
2116. deMUX Acronym for demultiplex and demultiplexer.
2117. denial of service 1. The prevention of authorized access to resources or the delaying of time-critical operations. [2382-pt.8] 2.
2118. dense binary code A binary code in which all possible bit patterns that can be made from a fixed number of bits are used to encode user information but no overhead…
2119. dense wavelength division multiplexing (DWDM) Multiplexing using close spectral spacing of individual optical carriers (wavelengths) to take advantage of desirable transmission characteristics (e.g.
2120. Density The average number of people, families, or housing units on one unit of land. Density is also expressed as dwelling units per acre.
2121. Department of Defense (DOD) master clock See DOD master clock.
2122. departmental security officer The person responsible to the Permanent Head of a Government Department for establishing and enforcing Departmental Security policy; this includes the…
2123. departure angle The angle between the axis of the main lobe of an antenna pattern and the horizontal plane at the transmitting antenna. Synonym takeoff angle.
2124. dependency In security, a relationship between requirements such that one requirement must be satisfied before others can meet their own objectives.
2125. depolarization Reducing or randomizing the polarization of an electromagnetic wave. Note: Depolarization may be caused by transmission through a nonhomogeneous medium or…
2126. depressed-cladding fiber Synonym doubly clad fiber.
2127. depressed-inner-cladding fiber Synonym doubly clad fiber.
2128. dequeue To remove items from a queue.
2129. Deregulation The process of changing regulatory policies and laws to increase competition among suppliers of commodities and services.
2130. derivation key A double-length key used to compute another key cryptographically. Note: The derivation key is normally used (in receiving a transaction) to derive or…
2131. derived unique key per transaction (DUKPT) In cryptography, a key-management technique that uses a unique key for each separate transaction to prevent the disclosure of any past key used by the…
2132. DES A synthetic form of the hormone estrogen that was prescribed to pregnant women between about 1940 and 1971 because it was thought to prevent miscarriages.
2133. descrambler The inverse of a scrambler. Note: The descrambler output is a signal restored to the state that it had when it entered the associated scrambler, provided…
2134. descriptive top-level specification (DTLS) A top-level specification that is written in a natural language (e.g., English), an informal program design notation, or a combination of the two [TCSEC].
2135. Descriptor See "file descriptor".
2136. desensitation The reduction of desired signal gain as a result of receiver reaction to an undesired signal.
2137. design margin The additional performance capability above required standard basic system parameters that may be specified by a system designer to compensate for…
2138. design objective (DO) In communications systems, a desired performance characteristic for communications circuits and equipment that is based on engineering analyses, but (a)…
2139. Design, Verify and Assign (DVA) Describes a given point in the order completion process in which the circuit design is checked for accuracy and all assignments are verified/available.
2140. designated accrediting authority Synonym designated approving authority.
2141. designated approving authority (DAA) [The] official with the authority to formally assume responsibility for operating a system at an acceptable level of risk.
2142. desktop publishing The use of computers and associated application software to compose, lay out, model, and develop prototypes of documents that are usually intended to be…
2143. desktop video The application of nondedicated personal computers to the performance of video auditioning (viewing) or editing.
2144. desktop video teleconferencing See video teleconference.
2145. despotically synchronized network A synchronized network in which a unique master clock controls all other clocks in the network. [From Weik '89]
2146. despun antenna In a rotating communications satellite, an antenna with a main beam that is continuously redirected with respect to the satellite so that the antenna…
2147. destination node A node having the network address, as determined by the release node, to be where an existing call should be routed.
2148. destination routing In communications system operations, the routing of messages based on the name of the destination office, the destination user, or the address on the…
2149. destination routing address A list of called party numbers (primary and alternative). [T1.667-1999]
2150. destination user In an information transfer transaction, the user that receives information from the source, i.e., from the originating user.
2151. desynchronizer That portion of a network element (NE) that attempts to recreate a signal's original clock and attenuates the high-frequency phase variations that result…
2152. detailed design left
2153. Detection The first of five Early Warning System components consisting of the processes and equipment necessary to collect information about the threatening event…
2154. detectivity The reciprocal of noise equivalent power.
2155. Detector A passive IR, visible, UV detector turns photons into an electrical signal. The IFOV of the detector is its solid angular sub-tense.
2156. deterministic routing In a switched network, switching in which the routes between given pairs of nodes are pre-programmed, i.e., are determined, in advance of transmission.
2157. deterministic transfer mode An asynchronous transfer mode in which the maximum information transfer capacity of a telecommunication service is provided throughout a call.
2158. Deutsches Institut für Normung (DIN) Germany's standards-setting organization, equivalent to the American National Standards Institute (ANSI).
2159. Developer The person or organization that manufacturers a Target of Evaluation [ITSEC].
2160. developer security left
2161. development environment 1. The set of procedures, methods, tools and standards used during system development. See also: Operational Environment [CESG]. 2.
2162. development process The set of phases and tasks whereby a Target of Evaluation is constructed, translating requirements into actual hardware and software [ITSEC].
2163. deviation ratio In a frequency modulation system, the ratio of the maximum frequency deviation of the carrier to the maximum modulating frequency of the system under…
2164. device certificate In cryptography, a public key certificate or an attribute certificate, issued by a device manufacturer, tying the identity of the device to its attributes.
2165. device driver Software that enables hardware or devices (such as a printer, mouse, or keyboard) to work with your computer.
2166. DFSK Abbreviation for double-frequency shift keying.
2167. dHTML Abbreviation for dynamic Hypertext Markup Language. A form of HTML used to create Web-page content that, as perceived by the viewer, appears to change…
2168. Di Group A basic group of Pulse Code Modulation (PCM) channels assembled by Time Division Multiplex. In the United States it usually consists of 24 channels at 1.
2169. diad Synonym dibit.
2170. diagnostic program A program used to investigate the cause or the nature of conditions or problems within specified elements of a system. 2.
2171. dial around Pertaining to long-distance services that require consumers to dial a long-distance provider's access code (or a "10-10" number) before dialing a…
2172. dial back Synonym call back.
2173. dial mode Operation of data circuit-terminating equipment (DCE) so that circuitry, such as data terminal equipment (DTE), associated with call origination is…
2174. 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…
2175. 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…
2176. dial service assistance (DSA) A network-provided service feature, associated with the switching center equipment, in which services, such as directory assistance, call interception…
2177. dial signaling Signaling in which dual tone multifrequency (DTMF) signals or pulse trains are transmitted to a switching center.
2178. dial switching equipment Switching equipment actuated by electrical impulses generated by a dial or key pulsing arrangement. [47 CFR Pt.36-A]
2179. 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…
2180. 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.
2181. dial-pulse period One complete cycle of a dial pulse, consisting of fall time, break interval, rise time, and make interval. [T1.409-1996]
2182. 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…
2183. dial-tone delay The time between the instant of going off-hook and the instant of receiving a dial tone.
2184. 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…
2185. dialed digits Untranslated address information collected/received from the originating line/trunk. [T1.667-1999]
2186. dialing In a communications system, using a device that generates signals for selecting and establishing connections.
2187. diametral index of cooperation Synonym index of cooperation.
2188. dibit A group of two bits. Note: The four possible states for a dibit are 00, 01, 10, and 11. Synonym diad.
2189. 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…
2190. dichroic mirror A mirror used to reflect light selectively according to its wavelength.
2191. DID defense in depth - multiple layers of security to provide added protection to IT resources
2192. 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.
2193. dielectric filter See interference filter.
2194. 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.
2195. dielectric strength Of an insulating material, the maximum electric field strength that it can withstand intrinsically without breaking down, i.e.
2196. 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…
2197. difference frame Synonym delta frame.
2198. 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…
2199. 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.
2200. differential mode attenuation In an optical fiber, the variation in attenuation among the propagating modes.