Telecommunications — page 72 of 85

Telecommunications terms

7101. spacecraft A man-made vehicle which is intended to go beyond the major portion of the Earth's atmosphere. [NTIA] [RR] [47CFR]
7102. spacing bias The uniform lengthening of all spacing signal pulses at the expense of the pulse width of all marking signal pulses.
7103. spacing end distortion See end distortion.
7104. spacing pulse Synonym yyspace.
7105. spacing signal Synonym yyspace.
7106. Spam Unelicited emails in large quantities; rapidly repeated scrolling text.
7107. Spamming See spamdexing. Spamming is also used more generally to refer to the sending of unsolicited bulk electronic mail, and the search engine use is derived…
7108. spare An individual part, subassembly, or assembly supplied for the maintenance or repair of systems or equipment.
7109. spatial application An application requiring high spatial resolution, possibly at the expense of reduced temporal positioning accuracy, i.e., increased jerkiness.
7110. spatial coherence See coherent.
7111. spatial edge noise In a video display, that form of edge busyness that is characterized by spatially varying distortion that occurs in close proximity to the edges of…
7112. spatially coherent radiation See coherent.
7113. special grade access line In the Defense Switched Network, an access line specially conditioned, usually by providing amplitude and delay equalization, to give it characteristics…
7114. special grade of service In the Defense Switched Network, a network-provided service in which specially conditioned interswitch trunks and access lines are used to provide secure…
7115. special information tone (SIT) A tone that comprises three precise sequential frequencies used to identify recorded announcements. [After T1.207-1998]
7116. special interest group See community of interest, interest group, forum, SIG.
7117. special purpose computer A computer that is designed to operate on a restricted class of problems.
7118. special service A radiocommunication service, not otherwise defined in this Section [of the Radio Regulations], carried on exclusively for specific needs of general…
7119. special services All services other than message telephones, e.g., teletypewriter exchange service (TWX), private line services. [47 CFR Pt.36-A]
7120. specialized common carrier (SCC) A common carrier offering a limited type of service or serving a limited market.
7121. specific detectivity For a photodetector, a figure of merit used to characterize performance, equal to the reciprocal of noise equivalent power (NEP), normalized to unit area…
7122. specification a written description of the invention and the manner and process of making and using the same -- see MPEP 608.01 for more
7123. specification point An industry agreed-upon location where a set of specifications would apply, for example, the node in the originating network where specification occurs.
7124. speckle noise Synonym modal noise.
7125. speckle pattern In optical systems, a field-intensity pattern produced by the mutual interference of partially coherent beams that are subject to minute temporal and…
7126. spectral bandwidth See spectral width.
7127. Spectral Density A radar term for the distribution of power by frequency.
7128. Spectral Irradiance The monochromatic irradiance of a surface per unit bandwidth at a particular wavelength, usually expressed in Watts per square meter-nanometer bandwidth.
7129. Spectral Line An emission (bright) or absorption (dark) of light at a specific frequency or wavelength.
7130. spectral loss curve Of an optical fiber, a plot of attenuation as a function of wavelength. Note: Spectral loss curves must be normalized with respect to distance before…
7131. spectral purity The degree to which a signal is monochromatic.
7132. spectral radiance Radiance per unit wavelength interval at a given wavelength, expressed in watts per steradian per unit area per wavelength interval.
7133. spectral responsivity The ratio of an optical detector's electrical output to its optical input, as a function of optical wavelength.
7134. spectral width A measure of the spread of the Doppler spectrum and consequently is sensitive to the spread in the particle size spectra.
7135. spectral window See window.
7136. Spectrum Electromagnetic radiation arranged in order of wavelength from Ion wavelength radio waves to short wavelength gamma rays.
7137. spectrum designation of frequency See electromagnetic spectrum.
7138. spectrum signature The pattern of radio signal frequencies, amplitudes, and phases, which pattern characterizes the output of a particular device and tends to distinguish it…
7139. Specular reflection Also known as direct reflection, regular reflection, or mirror reflection. The reflection of electromagnetic rays without scattering or diffusion.
7140. speech digit signaling Synonym bit robbing.
7141. speech level The power in dBm of a speech signal measured using a technique equivalent to Method B of ITU-T Recommendation P.56. [T1.255-1997]
7142. speech power See volume unit.
7143. speech privacy Techniques using fixed sequence permutations or voice/speech inversion to render speech unintelligible to the casual listener. [INFOSEC-99]
7144. speech synthesizer A device that is capable of accepting digital or analog data and developing intelligible speech sounds that correspond to the input data, without…
7145. speech-plus Pertaining to a circuit that was designed and used for speech transmission, but to which other uses, such as digital data transmission, facsimile…
7146. speech-plus-duplex operation Operation in which speech and telegraphy (duplex or simplex) are transmitted simultaneously over the same circuit, and mutual interference is eliminated…
7147. speech-plus-signaling Pertaining to equipment that permits the use of part of a voice-frequency band for signaling.
7148. speech-to-speech-correlated-noise ratio (Q) The ratio of the speech power to the power of speech-correlated noise in a digital transmission system. [T1.501-1988]
7149. speed calling A service feature that enables a switch or station to store certain telephone numbers and dial them automatically when a short (1-, 2-, or 3-digit) code…
7150. speed dialing 1. Synonym abbreviated dialing. 2. Dialing at a speed greater than the normal ten pulses per second.
7151. speed of light (c) The speed of an electromagnetic wave in free space, precisely 299,792,458 m/s. Note 1: The preceding figure is precise because by international agreement…
7152. speed of service The time between release of a message by the originator to receipt of the message by the addressee, as perceived by the end user.
7153. speed-up tone Synonym camp-on busy signal.
7154. Spider Search engine crawlers which search or "spider" the web for pages to include in the index.
7155. spike 1. An inflorescence in which the main axis is elongated and the flowers are sessile. 2.
7156. spike file See last-in first-out.
7157. spill forward In automatic switching, the transfer of full control on a call to the succeeding office by sending forward the complete telephone address of the called…
7158. spill-forward feature A service feature, in the operation of an intermediate office, that, acting on incoming trunk service treatment indications, assumes routing control of…
7159. spillover In an antenna, the part of the radiated energy from the feed that does not impinge on the reflectors.
7160. spiral track A track with a spiral shape written on a diskette, as part of a method of copy protection. [2382-pt.8]
7161. spiral wrap A molded, insulated plastic product in the form of a helix, used to contain or dress electrical wiring, e.g.
7162. spiral-four cable A quadded cable with four conductors. Synonym star quadded cable.
7163. splice To join, permanently, physical media that conduct or transmit power or a communication signal. 2. A device that so joins conducting or transmitting media.
7164. splice closure A usually weatherproof encasement, commonly made of tough plastic, that envelops the exposed area between spliced cables, i.e.
7165. splice loss In fiber optic systems, any loss of optical power at a splice. Note: A practical splice, of physically realizable fibers, has losses attributable to a…
7166. splice organizer In optical communication, a device that facilitates the splicing or breaking out of fiber optic cables.
7167. split 1. With respect to a signal, to divert a portion of it, or divide it, into usually predetermined or specified proportions. 2.
7168. split homing The connection of a terminal facility to more than one switching center by separate access lines, each of which has a separate directory number.
7169. Split Knowledge A procedure whereby a cryptographic key is handled as multiple key components from the time that the key or the separate key components are generated…
7170. split screen On a display device, display space that has been divided into two or more areas, so that each area can display different portions of the same file or…
7171. splitter See directional coupler, T-coupler, tee coupler.
7172. Sponsor An individual or business establishment that financially supports a race driver, team, race or series of races in return for advertising and marketing…
7173. sponsor certificate A certificate that indicates the restrictions on those documents and transactions that an entity may authorize. [After X9.45]
7174. spontaneous emission Radiation emitted when the internal energy of a quantum mechanical system drops from an excited level to a lower level without regard to the simultaneous…
7175. Spoofing Some market analysts maintain that the increased volatility in stock markets may be the result of an illegal practice known as spoofing, or phantom bids.
7176. spooling The use of auxiliary storage as buffer storage to reduce processing delays when transferring data between peripheral equipment and the processors of a…
7177. Sporadic E In solar-terrestrial terms, a phenomenon occurring in the E region of the ionosphere, which significantly affects HF radiowave propagation.
7178. sporadic E propagation Synonym sporadic E.
7179. spot beam In satellite communications systems, a narrow beam from a satellite station antenna that illuminates, with high irradiance, a limited area of the Earth by…
7180. spot jamming The jamming of a specific channel or frequency. [JP 1-02]
7181. spot projection In facsimile systems, optical scanning in which a scanning spot is moved across the object and the scanning spot size is determined by the illuminated…
7182. spot size The size of the electron spot on the face of a cathode ray tube. Note: The spot size is larger than the diameter of the electron beam because of the…
7183. spot speed In facsimile systems, the speed of the scanning or recording spot along the available line.
7184. spread spectrum Telecommunications techniques in which a signal is transmitted in a bandwidth considerably greater than the frequency content of the original information.
7185. spur A secondary route having a junction to the primary route in a network.
7186. spurious emission Emission on a frequency or frequencies which are outside the necessary bandwidth and the level of which may be reduced without affecting the corresponding…
7187. spurious noise Circuit noise or interference that is like a signal. [T1.401-1988]
7188. spurious radiation Any unintentional emission.
7189. spurious response In radio reception, a response in the receiver intermediate frequency (IF) stage produced by an undesired emission in which the fundamental frequency (or…
7190. spurious tones Any tone that (a) is other than a fundamental tone or its harmonics, and (b) is generated within the back-to-back connected transmit and receive terminal…
7191. SQL Structured Query Language (Computer term).
7192. square pixel A pixel of equal width and height; i.e., having an aspect ratio of 1:1 Note: Pixels created by computer graphics usually have an aspect ratio of 1:1.
7193. square wave A wave that has two significant conditions, i.e., two levels of amplitude, that change from one condition to the other in a relatively short time compared…
7194. squatting See cybersquatting.
7195. squelch A circuit function that acts to suppress the audio output of a receiver. [NTIA] Note: The squelch function is activated in the absence of a sufficiently…
7196. SR AFSPC Regulation.
7197. SS7 Abbreviation for Signaling System No. 7.
7198. SSB Single Side Band.
7199. SSB-SC Abbreviation for single-sideband suppressed carrier. See single-sideband suppressed carrier transmission.
7200. stability Tendency of systems, especially ecosystems, to persist, relatively unchanged, through time; also, persistence of a component of a system.