Abstract: A coupling network at the junction of several multichannel TDM/PCM links comprises a pair of switching networks each including a set of input group units receiving incoming messages from respective PCM links, a set of output group units transmitting outgoing messages to respective PCM links, and a switching matrix interconnecting the two sets of group units. The bits of a code word representing an incoming message sample, arriving at a line unit individually associated with the respective PCM channel, are delivered to the corresponding input group unit during a receiving period, are read out during a transfer interval via the switching matrix to the output group unit for which they are intended, and are thence fed to the proper line unit during a transmitting period.

Abstract: An incoming bit stream of a first bit frequency, divided into a succession of n-bit words, is converted into an outgoing bit stream of a second bit frequency with the aid of two n-stage buffer registers alternately loaded by two sets of interleaved writing pulses, on every n.sup.th cycle of the first bit frequency, with incoming words which are alternately read out on every n.sup.th cycle of the second bit frequency by two sets of interleaved reading pulses. A logic network detects the coincidence of a reading pulse from one set with either of two guard pulses immediately preceding and succeeding, respectively, each writing pulse of the corresponding set; upon such coincidence, a switching network transposes the two sets of writing pulses to restore an original relative pulse position in which the reading pulses of each set occur substantially midway between writing pulses of the same set.