GB1447522A - Pcm time division mutliplex exchange systems - Google Patents

Abstract

1447522 Automatic exchange systems SIEMENS AG 26 Sept 1973 [28 Sept 1972] 44983/73 Heading H4K In a p.c.m., t.d.m. exchange system four wire incoming/outgoing highway pairs are formed into groups, each group Gn including a switch through units and having its own decentral control unit ESn as described in Specification 1,351,408. The groups are interconnected by Go and Return (relative to an originating group) intermediate highways and during the setting up or disestablishment of a connection the Return intermediate highway is used to signal the address of the called group and the address relative to the called group of the Return intermediate highway from the called group to the decentral control unit of the calling group. For a call originating in group G1 to a destination reached by group 15, a central control first determines a free path in known manner and then signals to the decentral control unit ES1 of group G1 via an operating field control over wire LZ1 all the information needed to set up the connection with the exception of the above mentioned addresses. The information includes the address of the Go intermediate highway to be used relative to group G1, the time slots to be used on this highway, the addresses of the pairs of highways of groups G1 and G15 to be interconnected together with the time slots thereon which are to be interconnected. The control unit ES1 can then establish a connection to the relevant time slot on the intermediate highway Za, interconnecting groups G1 and G15. An intermediate highway address register in group 15 is thereby activated to transmit the two missing addresses to the central unit ES1 over highway Zb during a special signalling time slot. Control unit ES1, now having the address of group G15, transmits all the information necessary to complete and hold the connection to control unit ES15 over a special order wire LV. A similar signalling operation takes place on disestablishment. The intermediate highways use a super multiplex cycle comprising 64 time slots, the 64th slot being used for signalling.