DIGITAL FREQUENCY DETECTING DEVICE

摘要

The present invention relates to a digital frequency recognition device for a receiver of multifrequency PCM signals, and consists essentially in forming characteristic values V(fi) for each frequency fi, in forming characteristic values V(fi+/-l) for adjacent frequencies of the code in question, in comparing the value V(fi) with the values V(fi+/-l), the result of said comparison making it possible to deduce whether said frequency fi is effectively recognized. The invention is applicable to the signalling between automatic telephone exchanges or between subscribers and telephone exchanges.