Telecommunications terms starting with S

935 terms

Steady state condition When model input values are nearly constant for a defined period of time.
steady-state throughput The value to which a throughput measurement converges, as the duration of the observation period increases with statistically constant load on the virtual…
Steganography The hiding of information within a more obvious kind of communication. Although not widely used, digital steganography involves the hiding of data inside…
step-by-step (SXS) switching system An automatic dial telephone system in which calls are switched by a succession of switches that move a step at a time, from stage to stage, each step…
step-index fiber An optical fiber with a core having a uniform refractive index.
step-index profile For an optical fiber, a refractive index profile characterized by a uniform refractive index within the core and a sharp decrease in refractive index at…
steradian (sr) The metric unit of solid angle. See International System of Units.
stereophonic crosstalk An undesired signal occurring in the main channel from modulation of the stereophonic channel or that occurring in the stereophonic channel from…
stereophonic sound subcarrier A subcarrier within the FM broadcast baseband used for transmitting signals for stereophonic sound reception of the main broadcast program service. [47CFR]
STFS Abbreviation for standard time and frequency signal. See standard time and frequency signal service.
still image Nonmoving visual information, i.e., fixed images, such as graphs, drawings, and pictures.
still video Video imagery that is not intended to convey the appearance of movement.
Stimulated Emission Physical process by which an excited molecule is induced by incident radiation to emit radiation at an identical frequency and in phase with the incident…
STL Abbreviation for standard telegraph level, studio-to-transmitter link.
stop element See stop signal.
stop signal In start-stop transmission, a signal at the end of a character that prepares the receiving device for the reception of a subsequent character.
stop-record signal In facsimile systems, a signal used for stopping the process of converting the electrical signal to an image on the record medium.
stopband A band of frequencies, between specified limits, that a circuit, such as a filter or telephone circuit, does not transmit.
Storage The retention of water or delay of runoff either by planned operation, as in a reservoir, or by temporary filling of overflow areas, as in the progression…
storage cell An addressable storage unit. 2. The smallest subdivision of storage into which a unit of data can be entered, stored, and retrieved.
Storage Element A physical grid component that is a storage component, such as a disk or array. See also: Grid Component
storage object 1. An object supporting both read and write accesses to an information system (IS). [INFOSEC-99] 2.
storage register See register.
store-and-forward (S-F) Pertaining to communications systems in which messages are received at intermediate routing points and recorded i.e., stored, and then transmitted, i.e.
store-and-forward switching center A message switching center in which a message is accepted from the originating user, i.e.
stored-program computer A computer that (a) is controlled by internally stored instructions, (b) can synthesize and store instructions, and (c) can subsequently execute those…
STP (1) System Test Plan (2) Sensor Task Plan.
STRAP HATMD System Training Plan.
stratum The number of a clock (in a hierarchical synchronization distribution system) that defines the quality of the clock by specifying parameters such as…
stray current Electrical current through a path other than the intended path.
streamer Synonym streaming tape drive.
streaming Amazon EMR: A utility that comes with Hadoop that enables you to develop MapReduce executables in languages other than Java.
streaming media audio-visual content that is played as it is being downloaded. Thus, an Internet user could begin watching a video clip as the footage downloads rather…
streaming tape drive A magnetic tape unit capable of recording from, and dumping to, another storage medium without stopping at interblock gaps.
streaming tape recording A method of recording on magnetic tape, which method maintains continuous tape motion without the requirement to start and stop within the interrecord gap.
strength member Any component of a communication cable, metallic or optical, the function of which is to protect the transport medium, i.e.
strength of mechanism 1. A measure of the effectiveness of a security mechanism to prevent a breach of the System Security policy, assuming it has been correctly implemented…
stressed environment In radiocommunications, an environment that is under the influence of extrinsic factors that degrade communications integrity, such as when (a) the benign…
string A series of alphanumeric characters of any length enclosed by quotes.
stroke In medicine, a loss of blood flow to part of the brain, which damages brain tissue.
stroke edge In character recognition, the line of discontinuity between a side of a stroke and the background, obtained by averaging, over the length of the stroke…
stroke speed In facsimile systems, the rate at which a fixed line perpendicular to the direction of scanning is crossed in one direction by a scanning or recording…
stroke width In character recognition, the distance between the two edges of a stroke, measured perpendicular to the stroke centerline.
strong authentication Authentication by means of cryptographically derived credentials. [After X.509]
structured development Development of a system or part of a system where components at lower levels are traceable from those at the higher level [CESG].
structured programming A style of programming usually associated with languages such as C, Fortran, Pascal and so on.
structured text Text for which a well-defined, unambiguous internal structure is defined. Such text shall be human readable and interpreted identically by all conforming…
STU Secure Telephone Unit.
stub network A network that conveys data only among local hosts. Note: Even if the local hosts are connected to more than one other network, these hosts do not carry…
studio-to-transmitter link (STL) A communications link used for the transmission of broadcast material from a studio to the transmitter.
stuffing See bit stuffing, de-stuffing.
stunt box A device that controls the nonprinting functions of a printer at a terminal.
STX Abbreviation for start-of-text character.
SUB Under or subordinate to.
sub-band adaptive differential pulse code modulation (SB-ADPCM) Modulation in which (a) an audio frequency band is split into two sub-bands, i.e.
sub-registration authority (SRA) [An] Individual with primary responsibility for managing the distinguished name process. [INFOSEC-99]
Subassembly Two or more parts joined together to form a unit, capable of disassembly, which is only a part of a complete machine, structure, or other article.
subcarrier A carrier used to modulate another carrier. Note: The modulated carrier can be used to modulate another carrier, and so on, so that there can be several…
subclass Each asset class - stock, bonds, and cash equivalents, for example - is made up of a number of different groups of investments called subclasses.
Subject The Subject of an email message should be a short summary of its contents. Email clients usually display it in a mailbox display together with the sender.
subject authority An authority recognized in a Security Domain as a trusted source of security information concerning security subjects (human beings and Applications)…
Subject Security Level A subject's security level is equal to the security level of the objects to which it has both read and write access.
sublayer In a layered open communications system, a specified subset of the services, functions, and protocols included in a given layer. 2.
Subnet Address In computer networks, a subnetwork or subnet is a range of logical addresses within the address space that is assigned to an organization.
subnet mask A number that is used to identify a subnetwork so that IP addresses can be shared on a local area network.
subnetwork 1. A collection of equipment and physical transmission media that forms an autonomous whole and that can be used to interconnect systems for purposes of…
subordinate station Synonym slave station.
subroutine A named or otherwise accessible piece of program that can be invoked from elsewhere in the program in order to accomplish some sub-goal of the program.
subscribe In computer conferencing, to add one's address to a distribution list, or to join a forum. [2382-pt.35]
Subscriber A party who receives a credential or token from a CSP and becomes a claimant in an authentication protocol.
subscriber data key See subscriber key.
subscriber key A key encrypting key or data key transported in a multiple center CSM for eventual distribution to a pair of subscribers. [After X9.28]
subscriber line Synonym loop. 2. A communication channel between a telephone station, PBX or TWX station and the central office which serves it. Synonym exchange line.
Subscriber Line Charge (SLC) A monthly fee paid by telephone subscribers that is used to compensate the local telephone company for part of the cost of installation and maintenance of…
substitute character (SUB) A control character that is used in the place of a character that is recognized to be invalid or in error or that cannot be represented on a given device.
substitution method In optical fiber technology, a method of measuring the transmission loss by (a) using a stable optical source, at the wavelength of interest, to drive a…
subtributary office A class of tributary office which does not have direct access to its toll center, but which is connected to its toll center office by means of circuits…
subvoice-grade channel A channel with a bandwidth narrower than that of a voice-grade channel. Note: A subvoice-grade channel is usually a subchannel of a voice-grade line.
successful block delivery The transfer of a nonduplicate user information block between the source user and intended destination user.
successful block transfer The transfer of a correct, nonduplicate, user information block between the source user and intended destination user.
successful disengagement The termination of user information transfer between a source user and a destination user in response to a disengagement request.
Sudden Ionospheric Disturbance (SID) In solar-terrestrial terms, HF propagation anomalies due to ionospheric changes resulting from solar flares, proton events and geomagnetic storms.
suitability of function An aspect of the assessment of the effectiveness of a Target of Evaluation, namely the suitability of its security enforcing functions and mechanisms to…
sum check Synonym summation check.
summation check 1. A check based on the formation of the sum of the digits of a numeral. Note: The sum of the individual digits is usually compared with a previously…
Sunspot Dark areas on the Sun created by strong magnetic fields beneath the Sun’s surface.
super high frequency (SHF) See electromagnetic spectrum.
superclass A class from which a particular class is derived, perhaps with one or more classes in between. See also subclass, subtype.
superencryption [The] process of encrypting encrypted information. Note: [This process] occurs when a message, encrypted off-line, is transmitted over a secured, on-line…
superframe (SF) In T-carrier, a synchronization frame that delineates 12 DS1 frames. [J. Beaty, FAA] 2.
supergroup See group, multiplex hierarchy.
supergroup distribution frame (SGDF) In frequency-division multiplexing (FDM), the distribution frame that provides terminating and interconnecting facilities for group modulator output…
superhighway See National Information Infrastructure.
superluminescent LED A light-emitting diode in which there is stimulated emission with amplification but insufficient feedback for oscillations to build up to achieve lasing…
Superradiance The process used by a superradiant laser to generate or amplify a laser beam in a single pass through a lasant material, or, in the case of a free…
supersector An oversized sector written on a diskette, as part of a method of copy protection. [2382-pt.8]
supersession [In security,] scheduled or unscheduled replacement of a COMSEC aid with a different edition. [INFOSEC-99]
superuser The person whom the "operating system" will let do almost anything. Typically your system administrator or someone pretending to be your system…
supervisor Synonym supervisory program.
supervisor state Synonym executive state.