Telecommunications terms starting with S

935 terms

ship Earth station A mobile Earth station in the maritime mobile-satellite service located on board ship. [NTIA] [RR]
ship station A mobile station in the maritime mobile service located on board a vessel which is not permanently moored, other than a survival craft station. [NTIA] [RR]
ship's emergency transmitter A ship's transmitter to be used exclusively on a distress frequency for distress, urgency or safety purposes. [NTIA] [RR]
shock excitation Synonym impulse excitation.
shock spectrum Synonym response spectrum.
shopping basket In electronic commerce (also called "e-commerce"), an application allowing users of a commercial Web site to select products from the screen display as…
Short Circuit Test Line The term "Short Circuit Test Line" denotes an arrangement in an end office which provides for an ac short circuit termination of a trunk or line by means…
short haul toll traffic A general term applied to message toll traffic between nearby points. In common usage, this term is ordinarily applied to message toll traffic between…
short interruption event (SIE) An event beginning with the occurrence of a bit error ratio (BER) of 10-2 or worse, continuously for each of three or more consecutive seconds, which can…
short message service (SMS) A service in GSM mobile telephony systems that allows the user to send and receive short (maximum 160-character) messages independently of voice calls; a…
short wavelength In optical communication, optical radiation having a wavelength less than approximately 1 m.
Shortwave Also known as Shortwave Trough; a disturbance in the mid or upper part of the atmosphere which induces upward motion ahead of it.
shot noise The noise caused by random fluctuations in the motion of charge carriers in a conductor.
SI Special Intelligence.
SID See definition for: security ID (SID)
side circuit Either of the two circuits used to derive a phantom circuit.
side effect An effect of a drug, chemical, or other medicine that is in addition to its intended effect, especially an effect that is harmful or unpleasant.
side lobe In a directional antenna radiation pattern, a lobe in any direction other than that of the main lobe.
sideband In amplitude modulation (AM), a band of frequencies higher than or lower than the carrier frequency, containing energy as a result of the modulation…
sideband transmission See single-sideband transmission.
sidetone The sound of the speaker's own voice (and background noise) as heard in the speaker's telephone receiver.
SIG Abbreviation for special interest group. 1. Within a given technical discipline or area of knowledge, a circle of individuals or organizations having an…
SIGINT Signal Intelligence.
signal A bolt out of the blue; that is, an event triggered by the "operating system", probably when you're least expecting it.
signal center A combination of signal communication facilities operated by the Army in the field and consisting of a communications center, telephone switching central…
signal compression In analog (usually audio) systems, reduction of the dynamic range of a signal by controlling it as a function of the inverse relationship of its…
signal contrast In facsimile, the ratio of the level of the white signal to the level of the black signal. Note: Signal contrast is usually expressed in dB.
signal conversion equipment Synonym modem.
signal distance A measure of the difference between a given signal and a reference signal. Note: For analog signals, the signal distance is the root mean square…
signal distortion See distortion.
signal droop In an otherwise essentially flat-topped rectangular pulse, distortion characterized by a decline of the pulse top.
signal duration A multifrequency (MF) or dual-tone multifrequency (DTMF) signal timing interval during which the signal is being transmitted.
signal element A part of a signal, distinguished by its nature, magnitude, duration, transition, or relative position.
signal expansion Restoration of the dynamic range of a compressed signal.
signal frequency shift See frequency shift.
signal intelligence See signals intelligence.
signal level In a communications system, the signal power or intensity at a specified point and with respect to a specified reference level, e.g., 1 mW.
signal message In communications systems, a message, i.e., an assembly of signaling information, that (a) includes associated message alignment and service indications…
signal processing The processing--such as detection, shaping, converting, coding, and time positioning--of signals, that results in their transformation into other forms…
signal processing gain The ratio of (a) the signal-to-noise ratio of a processed signal to (b) the signal-to-noise ratio of the unprocessed signal.
signal reference subsystem The portion of a facility grounding system that (a) provides reference planes, such as ground-return circuits, for all of the signal paths in the facility…
signal regeneration Signal processing that restores a signal so that it conforms to its original characteristics.
signal sample The value of a particular characteristic of a signal at a chosen instant.
signal sampling The process of obtaining a sequence of instantaneous values of a particular signal characteristic, usually at regular time intervals.
signal security A generic term that includes both communications security and electronics security. [JP 1-02]
signal transfer point (STP) In a common-channel signaling network, a switch that provides for the transfer from one signaling link to another.
signal transition In the modulation of a carrier, a change from one significant condition to another.
signal unit (SU) A group of bits forming a separately transferable entity used to convey information on a signaling link. [T1.226-1992]
signal unit alignment The alignment that exists when flags are received at intervals that correspond to integral numbers of octets and that fall within certain upper and lower…
signal unit error rate monitoring A procedure by which the error rate of an active signaling link is measured on the basis of a count of correctly checking and erroneous signal units. [T1.
signal unit sequence control Procedures used at Level 2 to ensure that message signal units are transported in sequence, without loss or duplication, over a particular signaling link.
signal-plus-noise-plus-distortion to noise-plus-distortion ratio See SINAD.
signal-plus-noise-to-noise ratio ((S+N)/N) At a given point in a communications system, the ratio of (a) the power of the desired signal plus the noise to (b) the power of the noise.
signal-return circuit A current-carrying return path from a load back to the signal source, i.e., the low side of the closed loop energy transfer circuit between a source-load…
Signal-to-C-Notched Noise Ratio The term "Signal-to-C-Notched Noise Ratio" denotes the ratio in dB of a test signal to the corresponding C-Notched Noise.
signal-to-crosstalk ratio At a specified point in a circuit, the ratio of the power of the wanted signal to the power of the unwanted signal from another channel.
signal-to-noise ratio (SNR) The ratio of the amplitude of the desired signal to the amplitude of noise signals at a given point in time.
signal-to-noise ratio per bit The ratio given by Eb/N0, where Eb is the signal energy per bit and N0 is the noise energy per hertz of noise bandwidth.
signaling The use of signals for controlling communications. 2. In a telecommunications network, the information exchange concerning the establishment and control…
signaling channel A data channel in combination with its associated signaling terminal equipment. [T1.226-1992]
signaling connection control part (SCCP) 1. A component part of SS7 protocol that provides additional functions to the message transfer part (MTP) to provide for Connectionless and Connection…
signaling data link A combination of two data channels operating together in a single signaling system. [T1.226-1992]
signaling destination point A signaling point to which a message is destined. [T1.226-1992]
signaling end point A signaling point that can send or receive SS7 messages, and has no message transfer function. [T1.235-1993] 2.
signaling information field The bits of a message signal unit that carry information particular to a certain user transaction and always contain a label. [T1.110-1987] [T1.226-1992]
signaling link A transmission facility that consists of a signaling data link and its transfer control functions, used for reliable transfer of a signaling message.
signaling link activation The process of making a signaling link ready to carry signaling traffic.
signaling link blocking An event that causes the unavailability of a signaling link, typically consisting in a "processor outage" condition at one end of that signaling link. [T1.
signaling link code 1. A field with certain signaling network management messages, which indicates the particular signaling link to which the message refers among those…
signaling link deactivation The procedure by which a signaling link is taken out of service. [T1.110-1987]
signaling link failure An event that causes the unavailability of a signaling link, typically consisting of a failure in signaling terminal equipment or in the signaling data…
signaling link group A set of signaling links directly connecting two signaling points and having the same physical characteristic (bit rate, propagation delay, and the like).
signaling link management function One of a group of functions that control and take actions when required to preserve integrity of locally connected signaling link sets.[T1.226-1992]
signaling link restoration An event characterizing the completion of the initial alignment procedure on a signaling link following the removal of the previous causes of failure; in…
signaling link selection (SLS) A field of the routing label that is typically used by the message routing function to perform load sharing among different signaling links n, or link…
signaling link selection field A field of the routing label that is typically used by the message routing function to perform load sharing among different signaling links or link sets.
signaling link set A set of signaling link(s) directly connecting two signaling points. [T1.110-1987]
signaling message 1. An assembly of signaling information pertaining to a call that includes, but is not limited to, management transactions, that is transferred (between…
signaling message discrimination At a given signaling point, the process that decides, for each incoming message, whether the signaling point is destination point or if it should act as…
signaling message distribution The process of determining upon receipt of a signaling message at its destination point, to which user part the signaling message is to be delivered. [T1.
signaling message handling functions Functions that, at the actual transfer of a message, direct the message to the proper signaling link or user part. [T1.
signaling message route The signaling link or consecutive links connected in tandem that are used to convey a signaling message from an originating point to its destination point.
signaling message routing The process for selecting, for each signaling message to be sent, the signaling link to be used. [T1.110-1987]
signaling network A network used for signaling by one or more users and consisting of signaling points and connecting signaling links. [T1.110-1987] [T1.226-1992]
signaling network functions The functions that are performed by the message transfer part at level 3 and are common to, and independent of, the operation of individual signaling…
signaling network management (SNM) functions Functions that control the current message routing and configuration of signaling network facilities based on predetermined data and current information…
signaling originating point A signaling point that is the source of a message. [T1.226-1992]
signaling path In a transmission system, a path used for system control, synchronization, checking, signaling, and service signals used in system management and…
signaling point A node in a signaling network that either originates and receives signaling messages, or transfers signaling messages from one signaling link to another…
signaling point code A binary code uniquely identifying a signaling point in a signaling network. This code is used, according to its position in the label either as…
signaling rate See data signaling rate.
signaling route A predetermined path described by a succession of signaling points that may be traversed by signaling messages directly by a signaling point towards a…
Signaling System No. 7 (SS7) A common-channel signaling system defined by the CCITT in the 1988 Blue Book, in Recommendations Q.771 through Q.774.
signaling time slot In TDM carrier systems, a time slot starting at a particular phase or instant in each frame and allocated to the transmission of signaling (supervisory…
signaling traffic flow control Actions and procedures intended to limit signaling traffic at its source in the case when the signaling network is not capable of transferring all…
signaling traffic management functions Functions that control, and when necessary, modify, routing information used by message routing information to control the transfer of signaling traffic…
signaling transfer point (STP) See signal transfer point.
signaling transition See signal transition.
signals intelligence (SIGINT) 1. A category of intelligence comprising, either individually or in combination, all communications intelligence, electronics intelligence, and foreign…
signals security [A] generic term encompassing communications security and electronic security. [NIS]