GB1514189A - Exchange for pcm words - Google Patents

Abstract

1514189 Automatic exchange systems TELEFON AKTIE BOLAGET L M ERICSSON 15 Oct 1975 [17 Oct 1974] 42338/75 Heading H4K In a PCM TDM inter-highway switching system; all connections pass over a common bus or superhighway; the time frame used on the bus is divided into a plurality of phases at least equal in number to the number of time channels used on any incoming or outgoing highway; each incoming and each outgoing highway has individual speech and holding stores, said holding stores are arranged during each phase to address on location of its speech store, which location corresponds to one channel on its highway, and to identify the time channel used on the bus for that connection. The system shown uses a common bus 1HW to provide interconnections between incoming and outgoing highways such as La and Lb. Each highway has an associated speech store Wa, Wb into or from the locations of which are cyclically written or read speech samples from or to corresponding channels on the incoming or outgoing highways. During each phase of a time frame on the bus one location of each speech store (e.g. the location corresponding to channel 6 on highway La in phase II) is addressed by its holding store such as 1a and a PCM speech sample is transferred to or from a buffer register Ra, Rb in a timing adjustment stage Sa, Sb which is also supplied during that phase from its holding store 1a, 1b with the identity within that phase of the bus time slot used for that connection (e.g. bus time slot 125 of phase II). The number of phases exceeds the number of channels used on a highway to reduce blocking and to allow each storage location to be read at different times. (For figure see next page)