Synchronisation system for PCM TDM telephone network - compares local signals with control signals describing position and duration of received blocks

摘要

The synchronisation system establishes synchronisation between a PCM telephone exchange and its PCM subscriber stations using signal blocks comprising coded voice signal word preceded by signalling and sync. bits. Both states of the bits in the signals are represented by signal variables that differ from the signal state prevailing during breaks in transmission. Control signals are derived from received blocks and describe their position and duration. A receiver register is enabled to receive signal blocks serially when these control signals coincide with signals generated locally by a counter. The contents of the register's output stages are evaluated to established synchronisation.