公开(公告)号：WO1984000867A1

公开(公告)日：1984-03-01

申请号：PCT/US1983000434

申请日：1983-03-28

Applicant: WESTERN ELECTRIC COMPANY, INC.

Inventor： WESTERN ELECTRIC COMPANY, INC. ,  BATTISTA, Ralph, Nicholas ,  GROVES, Quentin, Durward ,  TOW, Jimmy

IPC: H04Q01/457

CPC classification number: H04Q1/457

Abstract: A tone receiver suitable for use in a telephone system and which adaptively narrows its amplitude sensitivity range defining valid tone signals on a per call basis in accordance with the amplitude of a first tone signal received on a call. The signal range adaptability improves signal echo rejection and spurius noise talkoff. A preferred embodiment is implemented by a programmed digital signal processor which increases the lower amplitude signal threshold in accordance with the amplitude of the first signal. An alternative embodiment adaptively attenuates the level of incoming signals before signal validation. A further improvement of both embodiments allows further amplitude range narrowing in response to any subsequent signal on a call which has an amplitude greater than that of any preceding signal in the call.