Telephonic communications – Subscriber line or transmission line interface – Network interface device
Patent
1995-02-09
1997-01-28
Matar, Ahmad F.
Telephonic communications
Subscriber line or transmission line interface
Network interface device
379406, 379390, 370290, H04M 908
Patent
active
055984681
ABSTRACT:
A signal processor for, e.g., a telephonic communication system interconnecting a near location and at least one far location includes an echo canceller for suppressing the re-transmission of received signals. The operation of the echo canceller is controlled according to whether the near location is transmitting or receiving, and whether the far location is transmitting or receiving. The signal processor includes means for detecting doubletalk, and for controlling the echo canceller in response to the detection of doubletalk, such that doubletalk is permitted. In one method of operation, a delay is applied to the inputs to the echo canceller from the near and far ends, such that each of these signals is used for determining the operating state of the echo canceller before being used to operate an adaptive filter of the echo canceller. In another method of operation, doubletalk detection is carried out, in part, by evaluating the performance of an auxiliary adaptive filter. In another method of operation, the doubletalk detection is carried out, in part, by evaluating a pair of statistics that respectively indicate whether the near-end input to the echo canceller contains more energy than an expected echo generated from the far-end input, and whether an echo is being effectively removed. According to such method, a doubletalk state is declared only is these statistics satisfy predetermined conditions.
REFERENCES:
patent: 4029912 (1977-06-01), Geigel et al.
patent: 4782525 (1988-11-01), Sylvain et al.
patent: 4845746 (1989-07-01), Li
patent: 4864608 (1989-09-01), Miyamoto et al.
patent: 4894820 (1990-01-01), Miyamoto et al.
patent: 4897832 (1990-01-01), Suzuki et al.
patent: 4918727 (1990-04-01), Rohrs et al.
patent: 4951269 (1990-08-01), Amano et al.
patent: 4979163 (1990-12-01), Erving et al.
patent: 4984265 (1991-01-01), Connan et al.
patent: 5007046 (1991-04-01), Erving et al.
patent: 5016271 (1991-05-01), Ford
patent: 5099472 (1992-03-01), Townsend et al.
patent: 5136577 (1992-08-01), Amano et al.
patent: 5193112 (1993-03-01), Sano
patent: 5272695 (1993-12-01), Makino et al.
patent: 5305307 (1994-04-01), Chu
patent: 5307405 (1994-04-01), Sih
patent: 5343521 (1994-08-01), Jullien et al.
patent: 5353348 (1994-10-01), Sendyk et al.
patent: 5390250 (1995-02-01), Janse et al.
patent: 5418848 (1995-05-01), Armbruster
Ammicht Egbert
Thi James C. H.
Finston Martin I.
Kumar T. Devendra
Lucent Technologies - Inc.
Matar Ahmad F.
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