SIF(1) System Integration Facility. (2) Selective Identification Feature
SIGAbbreviation for special interest group. 1. Within a given technical discipline or area of knowledge, a circle of individuals or organizations having an…
SignA fixture or area containing lettering or logos used to advertise a store, goods, or services.
sign bitIn twos-complement notation, the most significant bit in an integer value is used to determine the sign of the value.
sign extensionWhen an integer value from a type with a particular range is stored in a variable with a bigger range, Java uses sign extension to determine the resulting…
signalA bolt out of the blue; that is, an event triggered by the "operating system", probably when you're least expecting it.
signal centerA combination of signal communication facilities operated by the Army in the field and consisting of a communications center, telephone switching central…
signal compressionIn 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 contrastIn 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 distanceA 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 handlerA "subroutine" that, instead of being content to be called in the normal fashion, sits around waiting for a bolt out of the blue before it will deign to…
signal levelIn 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 messageIn communications systems, a message, i.e., an assembly of signaling information, that (a) includes associated message alignment and service indications…
signal processingThe processing--such as detection, shaping, converting, coding, and time positioning--of signals, that results in their transformation into other forms…
signal processing gainThe 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 subsystemThe 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 regenerationSignal processing that restores a signal so that it conforms to its original characteristics.
signal sampleThe value of a particular characteristic of a signal at a chosen instant.
signal samplingThe process of obtaining a sequence of instantaneous values of a particular signal characteristic, usually at regular time intervals.
signal securityA 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 transitionIn 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 alignmentThe 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 monitoringA 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 controlProcedures 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-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 circuitA 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 RatioThe 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 ratioAt 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 RatioA specifically produced response (signal) compared to the response level (noise) when no specific stimulus (activity) is present.
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 bitThe ratio given by Eb/N0, where Eb is the signal energy per bit and N0 is the noise energy per hertz of noise bandwidth.
signalingThe use of signals for controlling communications. 2. In a telecommunications network, the information exchange concerning the establishment and control…
signaling channelA 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 linkA combination of two data channels operating together in a single signaling system. [T1.226-1992]
signaling end pointA signaling point that can send or receive SS7 messages, and has no message transfer function. [T1.235-1993] 2.
signaling information fieldThe 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 linkA transmission facility that consists of a signaling data link and its transfer control functions, used for reliable transfer of a signaling message.
signaling link blockingAn 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 code1. A field with certain signaling network management messages, which indicates the particular signaling link to which the message refers among those…
signaling link failureAn 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 groupA 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 functionOne 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 restorationAn 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 fieldA 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 setA set of signaling link(s) directly connecting two signaling points. [T1.110-1987]
signaling message1. An assembly of signaling information pertaining to a call that includes, but is not limited to, management transactions, that is transferred (between…
signaling message discriminationAt 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 distributionThe 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 functionsFunctions that, at the actual transfer of a message, direct the message to the proper signaling link or user part. [T1.
signaling message routeThe 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 routingThe process for selecting, for each signaling message to be sent, the signaling link to be used. [T1.110-1987]
signaling networkA 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 functionsThe 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) functionsFunctions that control the current message routing and configuration of signaling network facilities based on predetermined data and current information…
signaling pathIn a transmission system, a path used for system control, synchronization, checking, signaling, and service signals used in system management and…
signaling pointA node in a signaling network that either originates and receives signaling messages, or transfers signaling messages from one signaling link to another…
signaling point codeA 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 routeA 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 slotIn 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 controlActions 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 functionsFunctions that control, and when necessary, modify, routing information used by message routing information to control the transfer of signaling traffic…
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]
signatoryThe entity that generates a digital signature on data. [After X9.31]
signatory authorityIn secure communications, an agreed entity (usually a third party) that issues signatory certificates to organizations participating in this authorization…
signatory certificateIn encryption, a certificate, issued by a signatory authority, that identifies the authorized signatories of an organization. [After X9.45]
Signature CertificateA public key certificate that contains a public key intended for verifying digital signatures rather than encrypting data or performing any other…
Signature DynamicsA behavioral biometric modality that analyzes dynamic characteristics of an individual's signature, such as shape of signature, speed of signing, pen…
SIGNATURE fileA file you copy to the root directory of your storage device. The file contains a job ID, manifest file, and a signature.
Signature GenerationUses a digital signature algorithm and a private key to generate a digital signature on data.