Echo canceler and echo canceling program

Details Echo canceler and echo canceling program Echo canceler and echo canceling program

2008-11-06

2011-12-06

Briney, III, Walter F (Department: 2614)

Telephonic communications

Echo cancellation or suppression

C370S286000, C455S570000

Reexamination Certificate

active

08073132

ABSTRACT:
An echo canceller uses an adaptive filter to remove an echo of an incoming far-end signal from an outgoing near-end signal. Filter coefficients are calculated and updated while the far-end signal is active so as to minimize the residual echo. In addition, the far-end signal and near-end signal are sampled to generate simulated far-end and near-end signals, from which substitute filter coefficients are similarly calculated while the far-end signal is silent. When the far-end signal changes from silent to active, the substitute filter coefficients are swapped in as initial values for the filter coefficients, thereby speeding up subsequent convergence of the filter coefficients without significant added computational cost.

REFERENCES:
patent: 5559881 (1996-09-01), Sih
patent: 5740242 (1998-04-01), Hayashi
patent: 1152547 (2001-11-01), None
patent: 08-237174 (1996-09-01), None
Haykin,Tekio firuta nyumon(Japanese translation ofIntroduction to Adaptive Filters), Gendaikogakusha, Sep. 1987.
Denwa sabisu no intafesu(Telephone service interface), 5th edition, Nippon Telegraph and Telephone Corporation, 1998, p. 19.

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