Interconnection Units of P.C.M.

Summary form only given, as follows. There are two types of interconnectionunits (SCU, for the subscribers) and the inter-exchange or transit interconnectionunits. For the latter, three different circuits having one of the following functions have been realized. First function: Construction of the PCM. trains using the octets supplied by the connection network and vice-versa. A specialized processor realizes this function ; the speed of output signa : 2.048 Mbits/second. Second function: Since every exchange has its own "clock", a special processor is used to set all incident plesiosynchronous signals (plesio : slightly different from ...), in strict synchronization with the exchange clock, thus making it an isosynchronous signal (iso: equal). Third function: To assure the possible links between 24 channels PCM. (USA) and 32 channels PCM. (Europe).