Telecommunications terms starting with S

935 terms

spillover In an antenna, the part of the radiated energy from the feed that does not impinge on the reflectors.
spiral track A track with a spiral shape written on a diskette, as part of a method of copy protection. [2382-pt.8]
spiral wrap A molded, insulated plastic product in the form of a helix, used to contain or dress electrical wiring, e.g.
spiral-four cable A quadded cable with four conductors. Synonym star quadded cable.
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.
splice closure A usually weatherproof encasement, commonly made of tough plastic, that envelops the exposed area between spliced cables, i.e.
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…
splice organizer In optical communication, a device that facilitates the splicing or breaking out of fiber optic cables.
split 1. With respect to a signal, to divert a portion of it, or divide it, into usually predetermined or specified proportions. 2.
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.
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…
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…
splitter See directional coupler, T-coupler, tee coupler.
Sponsor An individual or business establishment that financially supports a race driver, team, race or series of races in return for advertising and marketing…
sponsor certificate A certificate that indicates the restrictions on those documents and transactions that an entity may authorize. [After X9.45]
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…
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.
spooling The use of auxiliary storage as buffer storage to reduce processing delays when transferring data between peripheral equipment and the processors of a…
Sporadic E In solar-terrestrial terms, a phenomenon occurring in the E region of the ionosphere, which significantly affects HF radiowave propagation.
sporadic E propagation Synonym sporadic E.
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…
spot jamming The jamming of a specific channel or frequency. [JP 1-02]
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…
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…
spot speed In facsimile systems, the speed of the scanning or recording spot along the available line.
spread spectrum Telecommunications techniques in which a signal is transmitted in a bandwidth considerably greater than the frequency content of the original information.
spur A secondary route having a junction to the primary route in a network.
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…
spurious noise Circuit noise or interference that is like a signal. [T1.401-1988]
spurious radiation Any unintentional emission.
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…
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…
SQL Structured Query Language (Computer term).
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.
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…
squatting See cybersquatting.
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…
SR AFSPC Regulation.
SS7 Abbreviation for Signaling System No. 7.
SSB Single Side Band.
SSB-SC Abbreviation for single-sideband suppressed carrier. See single-sideband suppressed carrier transmission.
stability Tendency of systems, especially ecosystems, to persist, relatively unchanged, through time; also, persistence of a component of a system.
Stagger The difference in size between the tires on the left and right side of a car. Because of a tire's makeup, slight variations in circumference result.
Standard a statement that describes an acceptable level of performance, excellence, or attainment in that particular activity.
standard frequency and time signal service A radiocommunication service for scientific, technical and other purposes, providing the transmission of specified frequencies, time signals, or both, of…
standard frequency and time signal station A station in the standard frequency and time signal service. [NTIA] [RR]
standard frequency and time signal-satellite service A radiocommunication service using space stations on Earth satellites for the same purpose as those of the standard frequency and time signal service.
Standard Generalized Mark-up Language See SGML.
standard operating conditions The set of conditions (e.g., voltage, temperature, humidity, and the like) over which the specified parameters maintain their stated performance rating.
standard optical source A reference optical source to which emitting and detecting devices are compared for calibration purposes.
standard telegraph level (STL) The power per individual telegraph channel required to yield the standard composite data level.
standard test signal A single-frequency signal with standardized level used for testing the peak power transmission capability and for measuring the total harmonic distortion…
standard test tone A single-frequency signal with a standardized level generally used for level alignment of single links and of links in tandem.
standard time and frequency signal (STFS) service In the United States, standard time and frequency signals, broadcast on very precise carrier frequencies by the U.S.
standardized profile 1. A profile that specifies one or more interoperable open systems interconnection stacks that are intended to cover one or more specific functional areas.
Standards Documents, established by consensus and approved by a recognized body that provides, for common and repeated use, rules, guidelines, or characteristics…
standards developer An organization that develops standards and is accredited by its National Body, as appropriate [POSIX.0]
standby In computer and communications systems operations, pertaining to a power-saving condition or status of operation of equipment that is ready for use but…
standing wave In a transmission line, a wave in which the distribution of current, voltage, or field strength is formed by the superposition of two waves propagating in…
standing wave ratio (SWR) The ratio of the amplitude of a standing wave at an anti-node (minimum) to the amplitude at an adjacent node (maximum).
star (*) property 1. [The] Bell-La Padula security model rule allowing a subject write access to an object only if the security level of the object dominates the security…
star coupler A passive optical coupler having a number of input and output ports, used in network applications.
star network See network topology.
star quadded cable Synonym spiral-four cable.
star topology See network topology.
start message Synonym go-ahead notice.
start notice Synonym go-ahead notice.
start pulse See A-condition, start signal.
start signal A signal that prepares a device to receive data or to perform a function. 2. In start-stop transmission, a signal at the beginning of a character that…
start-dial signal An on-hook signal indicating customer installation (CI) readiness to receive network outpulsing that is used in conjunction with controlled outpulsing.
start-of-heading character (SOH) A transmission control character used as the first character of a message heading.
start-of-text character (STX) A transmission control character that precedes a text and may be used to terminate the message heading.
start-record signal In facsimile systems, a signal used for starting the process of converting the electrical signal to an image on the record medium.
start-stop character A character that includes one start signal at the beginning and one or two stop signals at the end.
start-stop distortion In start-stop modulation, the ratio of (a) the maximum absolute difference between the actual and the theoretical intervals that separate any significant…
start-stop margin In start-stop modulation, the maximum amount of overall start-stop distortion that is compatible with correct translation by the start-stop equipment of…
start-stop modulation A method of modulation in which the time of occurrence of the bits within each character, or block of characters, relates to a fixed time frame, but the…
start-stop system Synonym asynchronous communications system.
start-stop transmission Asynchronous transmission in which a start pulse and a stop pulse are used for each symbol. 2.
start-stop TTY distortion Synonym teletypewriter signal distortion.
start-up KEK Key-encryption-key held in common by a group of potential communicating entities and used to establish ad hoc tactical networks. [INFOSEC-99]
starting frame delimiter A specified bit pattern that indicates the start of a transmission frame.
Statement A summary of all transactions that occurred over the preceding month and could be associated with a deposit account or a credit card account.
static data Data that are relatively long-lived in comparison to ephemeral data, and which have a longer period of validity.
staticizer See serial-to-parallel conversion.
Station Any one of a series of stakes or points indicating distance from a point of beginning or reference.
station battery Within a facility, a separate battery power source that satisfies all significant requirements for dc input power associated with the facility.
station clock In a station, the principal clock, or alternate clock, that provides the timing reference at the station.
station equipment See customer premises equipment.
station load The total power requirements of the integrated station facilities.
station message-detail recording (SMDR) A record of all calls originated or received by a switching system. Note: SMDRs are usually generated by a computer.
station-to-station basis The term applied to the basis of toll rate making which contemplates that the message toll service charge (telephone or TWX) covers the use made of all…
stationary satellite See geostationary orbit.
stationary wave Synonym standing wave.
statistical multiplexing Multiplexing in which channels are established on a statistical basis; i.e., connections are made according to probability of need.
statistical time-division multiplexing Time-division multiplexing in which connections to communication circuits are made on a statistical basis.
statistically unique A characteristic of a quantity such that, for an n-bit quantity, the probability of two values' repeating is less likely than or equal to the probability…
status field (SF) The bits of a link status signal unit that indicate one of the major signaling link states. [T1.226-1992]
statute mile A unit of distance equal to 1.609 km (0.869 nmi, 5280 ft.).
STDM Abbreviation for statistical time-division multiplexing.