Combination TASI and ADPCM apparatus

摘要

A digital circuit multiplication system for interconnecting a transmission trunk link having a plurality of bearer channels to a second plurality of telephone communication trunks, with the second plurality exceeding the first. The system comprises transmission apparatus at a first end of the transmission link within which there is apparatus for detecting signals on the second plurality of telephone communication trunks and apparatus for assigning each trunk on which signals are present to an available one of the first plurality of bearer channels and for providing assignment messages indicating such assignments. The speech signals are transmitted in bit reduced form by adaptive differential pulse code modulation (ADPCM) transmitting apparatus which is operative to be coupled to the first plurality of bearer channels. The output of the ADPCM transmitting apparatus is combined with the assignment messages along the first plurality of bearer channels, and the assignment messages are stripped from the speech signals at the other end of the transmission link by a signal receiving and message detection apparatus. A receiving apparatus operates to assign each of the first plurality of bearer channels carrying signals to a corresponding one of the second plurality of trunks in accordance with the assignment information received from the transmission apparatus. The signal receiving and detection apparatus contains delay circuitry for temporarily storing the received signals and detecting whether there are assignment messages contained in them, whereupon if these are detected, a message extractor apparatus replaces them with output signals constituting a predetermined signal pattern.