K to suit European frequency allo- Association Suisse de Normalisation. (Swiss stand- cations.) ards making body.) Time Assignment Speech Interpolation. (Method SOGITS Senior Officals Group on Information Technology used in analogue speech transmission where the Standards. (Part of the European Community.) channel is activated only when speech is present. Senior Officials Group on Telecommunications. This allows several users to share a common chan- (Part of European Community, composed of Minis- nel.) ters of Telecommunications and Industry from Transport Class. (E.g. TC TC 4, etc.) member states.) Technical Co-operation Department. Section Overhead. (Information used in SDH trans- Time Compression Multiplexing. (Technique which mission structure.) separates the two directions of transmission in time.) SONET Synchronous Optical Network. (Synchronous opti- TCM/DPSK Trellis Coded Modulation/Differential Phase Shift cal transmission system developed in North Keying. America, and which has been developed by CCITT TCP/IP Transmission Control Protocol/ Internet Protocol. into SDH.) (Widely used transmission protocol, originating SPADE Single channel per carrier Pulse code modulation from the US ARPA defence project.) multiple Access Demand assignment Equipment. (A Time Division Duplex transmission. SCPC technique.) Time Division Multiplexing. (Technique for com- Standards Promotion and Application Group. (Euro- bining, by interleaving, several channels of data onto pean group involved in preparation of functional a common channel. The equipment which does this standards and inter-operability testing.) is called a Time Division Multiplexer.) Stored Program Controller. (Usually referes to a Time Division Multiple Access. (A multiplexing digital exchange.) technique where users gain access to a common Speech Predictive Encoding Communications. channel on a time allocation basis. Commonly used Acronyms 62/17 in satellite systems, where several earth stations Television Receive Only. (Domestic equipment for have total use 