TDM PCM communications system - synchronises quickly by adding channel switch outputs to bit-shifted copies of sync code

摘要

The tdm PCM communications system has a local code generator in the system's receiver's synchronising unit that produces m copies of the synchronising code at m outputs. These copies are shifted by a given number of bits with respect to one another. Each of these m outputs is connected to one of m modulo-2 adders whose other inputs are coupled to the combined outputs of a channel switch and whose outputs feed m groups of n counters. The count of the synchronising code and the groups of each of 12 transmission channels are so chosen that the time intervals of completed channels are used.