Digital filtering in PCM telephone systems
Albert Kündig · IEEE Transactions on Audio and Electroacoustics · 1970
The advent of cheap and fast digital integrated circuits permits, at least in principle, the application of digital processing directly to PCM coded telephone signals. At present, the following applications look most promising: channel filters; digital conference circuits; receivers for MFC or touch-tone signals; and sampling rate conversion. Following a review of these fields, an account is given of the problems which exist specifically in a PCM telephone system.