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 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]
significant conditionIn the modulation of a carrier, one of the values of the signal parameter chosen to represent information.
significant digitIn a representation of a number, a digit that is needed for a given purpose; in particular, a digit that must be kept to preserve a given accuracy or a…
significant instantIn a signal, any instant at which a significant condition of a signal begins or ends.
significant intervalThe time interval between two consecutive significant instants.
silence codeIn digital telephony, a code composed of a reserved binary number that is sent instead of an actual sound sample value from the CODEC when the incoming…
silent intervalAny portion of a ringing cycle during which the ringing signal is not being applied. [T1.401-1998]
silicon photodiodeA silicon-based PN- or PIN-junction photodiode. Note 1: Such photodiodes are useful for direct detection of optical wavelengths shorter than approximately…
simple authenticationAuthentication by means of simple password arrangements. [After X.509]
simple bufferingThe assigning of buffer storage for the duration of the execution of a computer program.
Simple Network Management Protocol (SNMP)A standard Internet protocol that facilitates communications between a system being managed and the management console or framework.
simple scanningIn facsimile transmission, scanning using only one spot at a time.
Simple Security ConditionA Bell- LaPadula security model rule allowing a subject read access to an object only if the security level of the subject dominates the security level of…
simple security property[The] Bell-La Padula security model rule allowing a subject read access to an object, only if the security level of the subject dominates the security…
simplex (SX) signalingSignaling in which two conductors are used for a single channel, and a center-tapped coil, or its equivalent, is used to split the signaling current…
simplex circuitA circuit that provides transmission in one direction only. 2. Deprecated definition: A circuit using ground return and affording communication in either…
simplex operationOperation in which transmission occurs in one and only one preassigned direction. Synonym one-way operation.
simplex protocolA communications protocol that is purely one-way, and where acknowledgments are not part of any application protocol.
simulateTo represent certain features of the behavior of a physical or abstract system by the behavior of another system.
SINADAbbreviation for signal-plus-noise-plus-distortion to noise-plus-distortion ratio. 1. The ratio of (a) total received power, i.e.
singingAn undesired self-sustained audio oscillation in a circuit. Note: Singing is usually caused by positive feedback, excessive gain, or unbalance of a hybrid…
singing marginThe difference in power levels between the singing point and the operating gain of a system or component.
singing pointThe threshold point at which additional gain in the system will cause self-oscillation.
Singing Return Loss (High & Low)The term "Singing Return Loss" denotes the frequency weighted measure of return loss at the edges of the voice band, where singing (instability) problems…
single classComprising or containing only one security class [CESG].
single class deviceA device which can only be used to process information of a single security class at a time [CESG]
single point keying[A] means of distributing key to multiple, local crypto-equipment or devices from a single fill point. [INFOSEC-99]
single point of controlA control relationship where the same phase or aspect of a call/service attempt is influenced by one and only one service control function. [T1.667-1999]
single-ended service featureA feature, e.g., call/service attempt manipulation, that applies to only one of the parties that may be involved on a call/service attempt. [T1.667-1999]
single-ended synchronizationSynchronization between two locations, in which phase error signals used to control the clock at one location are derived by comparing the phase of the…
single-frequency (SF) signalingIn telephony, signaling in which dial pulses or supervisory signals are conveyed by a single voice-frequency tone in each direction.
single-frequency interferenceInterference caused by a single-frequency source. Note 1: An example of single-frequency interference is interference in a transmission channel induced by…