Signal transmission system

摘要

A transmission signal train-forming circuit is supplied with a differential pulse mode modulated signal train (a DPCM signal train) and a predictive signal train, both signal trains being coded from an input signal by an input signal coding circuit; a transmission signal train-forming circuit judges whether a series of words constituting a specified number of consecutive DPCM signals have the prescribed contents; and where it is detected that the words have the prescribed contents, then a transmission signal train is formed by inserting a specified pattern signal never used as a DPCM signal and a predictive signal into the positions of said words. A reproduction circuit detects the specified pattern signal from the received transmission signal train and reproduces the predictive signal train from the transmission signal train by inserting the transmitted predictive signal into the positions of the respective words previously replaced by the specified pattern signal and predictive signal.