Telecommunications — page 21 of 85

Telecommunications terms

2001. dBm0p Noise power in dBm0, measured by a psophometer or noise measuring set having psophometric weighting.
2002. DBMS Database Management System.
2003. dBmV Abbreviation. dB referenced to one millivolt across 75 ohms. Note: This reference is not equivalent to dBm; it is, in fact, 1.33 × 10-5 milliwatts.
2004. dBr Abbreviation. The power ratio, expressed in dB, between any point and a reference point selected as the zero relative transmission level point.
2005. dBrn Abbreviation. dB above reference noise. Note 1: Weighted noise power in dB is referred to 1.0 picowatt. Thus, 0dBrn = -90 dBm.
2006. dBrn adjusted Synonym dBa.
2007. dBrn(144-line) Weighted noise power in dBrn, measured by a noise measuring set with 144-line weighting.
2008. dBrn(f1-f2) Flat noise power in dBrn, measured over the frequency band between frequencies f1 and f2.
2009. dBrnC Weighted noise power in dBrn, measured by a noise measuring set with C-message weighting.
2010. dBrnC0 Noise power in dBrnC referred to or measured at a zero transmission level point (0TLP).
2011. DBS Direct Broadcast Satellite. 73
2012. dBu Abbreviation. dB in reference to 1 mW at 600 ohms, equal to 0.775 V, mainly used in audio systems (e.g.
2013. dBv Abbreviation. dB relative to 1 volt peak-to-peak. Note: The dBv is usually used for television video signal level measurements. [From Weik '89]
2014. dBW Abbreviation. dB referenced to one watt.
2015. dBx Abbreviation. dB above reference coupling. Note: dBx is used to express the amount of crosstalk coupling in telephone circuits.
2016. DC See Direct current
2017. dc patch bay A patch bay in which dc circuits are grouped.
2018. DCA (1) Defensive Counter Air. (2) OBSOLETE. Defense Communications Agency. (Now known as Defense Information Systems Agency (DISA)).
2019. DCE (1) Data Communications Equipment ( TelComm /Computer term). (2) Distributed Computer Environment.
2020. DCE clear signal A call control signal transmitted by data circuit-terminating equipment (DCE) to indicate that it is clearing the associated circuit after a call is…
2021. DCE waiting signal A call control signal at the data-circuit-terminating-equipment/data-terminal-equipment (DCE/DTE) interface that indicates that the DCE is ready for…
2022. DCOM Abbreviation for distributed component object model. A model for developing objects in a language-independent format so that those objects can be…
2023. DCS Deputy Chief of Staff.
2024. DDD Abbreviation for direct distance dialing.
2025. DDL Disclosure authority letter.
2026. DDN Defense Data Network.
2027. de-stuffing The controlled deletion of stuffing bits from a stuffed digital signal, to recover the original signal.
2028. DEA key A 64-bit parameter consisting of 56 independent bits and 8 parity bits operating in concert as a data encryption algorithm key. [After X9.52]
2029. Dead Link An internet link which doesn't lead to a page or site, probably because the server is down or the page has moved or no longer exists.
2030. dead sector In facsimile, the interval between (a) the end of scanning of one object line and (b) the start of scanning of the following line.
2031. dead space The area, zone, or volume of space that is within the expected range of a radio, radar, or other transmitted signal but in which the signal is not…
2032. deadlock A situation that arises when two threads each acquires the lock to one of a set of resources that they both need.
2033. Dealer Numbering Pools Numbers allocated by a service provider to a retail dealer for use in the sale and establishment of service on behalf of that service provider.
2034. debug To detect, trace, and eliminate mistakes.
2035. deception See electronic deception.
2036. deception repeater A device that can (a) receive a signal, (b) amplify, delay, or otherwise manipulate the signal, and (c) retransmit it solely for creating deception.
2037. decertification [In security, the] Revocation of the certification of an information-system (IS) item or equipment for cause. [INFOSEC-99]
2038. Decibel A unit for expressing the relative intensity of sounds on a scale from zero for the average least perceptible sound to about 130 for the average level at…
2039. decipher [To] convert enciphered text to the equivalent plain text by means of a cryptographic system.
2040. Decipherment The reversal of a corresponding reversible encipherment [7498-2]
2041. decision circuit A circuit that measures the probable value of a signal element and makes an output signal decision based on the value of the input signal and a…
2042. decision instant In the reception of a digital signal, the instant at which a decision is made by a receiving device as to the probable value of a signal condition.
2043. decode To convert data by reversing the effect of previous encoding. 2. To interpret a code. 3. [To] convert encoded text into plain text by means of a code.
2044. decollimation In a beam with the minimum possible ray divergence or convergence, any mechanism by which rays are caused to diverge or converge from parallelism.
2045. decompression The reversal of the procedure conducted by the compression algorithm, which reversal returns [expands] the data to its original size and condition.
2046. decrypt To convert encrypted content back into its original form.
2047. Decryption Transformation of encrypted (or scrambled) data back to original form.
2048. dedicated circuit A circuit designated for exclusive use by specified users. Note: DOD normally considers a dedicated circuit to be between two users only.
2049. dedicated mode An information-system (IS) security mode of operation wherein each user with direct or indirect access to the system, its peripherals, remote terminals…
2050. dedicated security mode A system operating in this mode is one whose users are all cleared for, need to know about and have access to all the data stored on and/or processed by…
2051. dedicated service In a communications system, a specified set of functions provided to designated users.
2052. dedicated service link connection A link connection that is for the exclusive use of a single service customer. [T1.263-1998]
2053. deemphasis In FM transmission, the process of restoring (after detection) the amplitude-vs.-frequency characteristics of the signal.
2054. deep linking In hypertext systems, such as the World Wide Web, bypassing the main (home) page and linking directly to a subordinate page.
2055. deep space Space at distances from the Earth equal to or greater than 2 × 106 kilometers. [NTIA] [RR]
2056. deeply depressed cladding fiber An optical fiber construction, usually a single-mode fiber, that has an outer cladding of approximately the same refractive index as the core, and an…
2057. Default Default occurs when a debtor is unable to meet the legal obligation of debt repayment, one form of which is the failure to promptly pay interest or…
2058. default ACL An ACL which is used in determining the initial discretionary access control information for objects created within a directory [POSIX.6].
2059. Defense Communications System (DCS) Department of Defense long-haul voice, data, and record traffic system which includes the Defense Data Network, Defense Satellite Communications Systems…
2060. Defense Data Network (DDN) A component of the Defense Communications System used for switching Department of Defense automated data processing systems. [JP 1-02]
2061. Defense Switched Network (DSN) A component of the Defense Communications System that handles Department of Defense voice, data, and video communications.
2062. definition A declaration that reserves storage (for data) or provides implementation (for methods). See also declaration.
2063. Deflection Upstream or downstream movement of a dam or dike.
2064. degauss To remove a residual magnetic field from a magnetized object, usually by introducing much stronger and gradually diminishing magnetic fields of…
2065. degaussing [A] procedure that reduces the magnetic flux to virtual zero by applying a reverse magnetizing field. Synonym demagnetizing. [INFOSEC-99]
2066. Degradation Process wherein the elevation of streambeds, sandbars, and flood plains is lowered by erosion. The opposite of aggradation.
2067. degraded minute (DM) A 1-minute interval with a BER (bit error ratio) worse than 10:6. The 1-minute intervals are derived by removing severely errored seconds from the total…
2068. degraded service state The condition that exists when one or more of the required service performance parameters fall outside predetermined limits, resulting in a lower quality…
2069. degraded unit of time A specified period of time during which bits are transferred from a source to a destination, where a bit error ratio worse than a specified threshold…
2070. degree of coherence A dimensionless unit, expressed as a ratio, used to indicate the extent of coherence of an electromagnetic wave such as a lightwave.
2071. degree of isochronous distortion In data transmission, the ratio of (a) the absolute value of the maximum measured difference between the actual and the theoretical intervals separating…
2072. degree of start-stop distortion In asynchronous data transmission, the ratio of (a) the absolute value of the maximum measured difference between the actual and theoretical intervals…
2073. dehop To modify a frequency-hopping signal so that it has a constant center frequency.
2074. dejitterizer A device that reduces jitter in a digital signal. Note 1: A dejitterizer usually consists of an elastic buffer in which the signal is temporarily stored…
2075. Delay A device used to obtain detonation of charges at separate times. An electric blasting cap which explodes at a set interval after current is passed through…
2076. delay distortion In a waveform consisting of two or more wave components at different frequencies, distortion caused by the difference in arrival times of the frequency…
2077. delay encoding The encoding of binary data to form a two-level signal such that (a) a "0" causes no change of signal level unless it is followed by another "0" in which…
2078. delay equalizer A corrective network designed to make the phase delay or envelope delay of a circuit or system substantially constant over a desired frequency range.
2079. delay line A transmission line, or equivalent device, used to delay a signal. 2. A single-input-channel device, such as a single-input sequential logic element, in…
2080. delay modulation See delay encoding.
2081. delay time Synonym delay.
2082. delay working In telephone switchboard operations, operation intended to ensure fair distribution of the time of one or more lines among groups of call originators.
2083. delayed-delivery facility In a communications network, a facility that stores data, destined for delivery to one or more addresses, for delivery at a later time.
2084. delegated accrediting authority Synonym designated approving authority.
2085. deleted bit A bit not delivered to the intended destination.
2086. deleted block A block not delivered to the intended destination.
2087. delimiter A "character" or "string" that sets bounds to an arbitrarily-sized textual object, not to be confused with a "separator" or "terminator".
2088. Deliverable An item produced or used during development of a system that is required to be made available to the evaluators for evaluation purposes.
2089. delivered block A successfully transferred block.
2090. delivered duplicated frame A frame D received by a particular destination user when both of the following conditions are true: D was not generated by the source user; D is exactly…
2091. delivered errored frame A delivered frame when the value of one or more bits in the frame is in error, or when some, but not all, bits in the frame are lost bits or extra bits (i.
2092. delivered out-of-sequence frame A delivered frame, Fi, that arrives at the destination user after any of the frames F(i+1), F(i+2), . . .
2093. delivered overhead bit A bit that (a) is successfully transferred to a destination user, (b) performs its primary function within the telecommunications system, and (c) does not…
2094. delivered overhead block A block that (a) is successfully transferred to a destination user, (b) performs its primary function within the telecommunications system, and (c) does…
2095. Delivery The amount of water delivered to the point of use. The difference between delivery and release is usually the same as consumptive use.
2096. delivery confirmation Information returned to the originator indicating that a given unit of information has been delivered to the intended addressee(s).
2097. Dellinger effect An effect--lasting from several minutes to several hours--that causes electromagnetic sky wave signals to disappear rapidly as a result of greatly…
2098. Dellinger fadeout Synonym Dellinger effect.
2099. Dellinger fading Synonym Dellinger effect.
2100. delta frame In digital television technology, a video frame created from the preceding key frame by modifying only those pixels that have changed.