Frame synchronising circuit for PCM receiver in TDM telephone network - compares signals in frame synchronising time slot with those of corresponding time slot one frame period later

摘要

The frame synchronising circuit, for a PCM receiver in a TDM telephone network, stores the contents of the time slot within which the frame sync. signals can occur for the duration of one frame. These stored contents are compared with the contents in the time slot immediately following. If the two are different during the synchronisation time the receive counter is set to a given initial count. The advantage lies in speeding-up synchronisation by avoiding long synchronising times caused by voice signals simulating frame identification words.