An adaptive echo canceller using digital signal processor LSI chips

This paper discusses a compact adaptive echo canceller with digital signal processor (SP) chips on the basis of a cascadable structure. By using this cascadable structure, tap number expansibility and program modification for satisfying various requirements can be easily obtained. Two kinds of echo cancellers were implemented. One for teleconference use, which has 600 taps with 12 SPs, has accomplished more than 20 dB echo cancellation in a conference room. It provides subjective high performance. The other, for telephone line use, with up to 300 taps, attains more than 30 dB echo return loss enhancement (ERLE). Each of these echo cancellers was implemented on a single board.