1978-02-23
1978-11-21
Claffy, Kathleen H.
1791708, H04B 320
Patent
active
041267702
ABSTRACT:
An echo canceller in a telephone circuit for minimizing a residual echo obtained by subtracting a pseudo-echo reproduced from an impulse response of an echo path from a true echo, in which the inpulse response is corrected by the use of the product of the residual echo and received input. A variable coefficient circuit is provided between a multiplier for obtaining the product and a circuit for correcting the impulse response. A control circuit is provided for reducing the coefficient of the variable coefficient circuit in accordance with the lapse of time of the duration of the received input exceeding a predetermined threshold level after receiving a circuit connection completion signal of the telephone circuit.
REFERENCES:
patent: 3588385 (1971-06-01), Moye
patent: 3732410 (1973-05-01), Mackechnie
patent: 3903377 (1975-09-01), Sato
patent: 4007341 (1977-02-01), Sourgens et al.
Kitayama Seishi
Sato Akira
Tamura Junzo
Adams Bruce L.
Burns Robert E.
Claffy Kathleen H.
Kokusai Denshin Denwa Kabushiki Kaisha
Lobato Emmanuel J.
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