Delay insertion for echo cancellation, with echo supression,...

Details Delay insertion for echo cancellation, with echo supression,... Delay insertion for echo cancellation, with echo supression,...

2005-09-13

2005-09-13

Tran, Sinh (Department: 2644)

Telephonic communications

Echo cancellation or suppression

C379S406040, C379S406050, C379S406060, C379S406080, C379S406090, C379S406120

Reexamination Certificate

active

06944289

ABSTRACT:
The invention provides an apparatus and method for bulk delay insertion prior to echo cancellation, with echo suppression. The exemplary apparatus embodiment (100) bandpass filters (120) and down samples (130), by a down sampling factor, a reference signal and a combined signal that includes an echo of the reference signal. An adaptive echo delay filter (140) determines a plurality of filter coefficients, using the down sampled reference signal, and using an error signal formed as a difference between the down sampled combined signal and the adaptive echo delay filter output. When the filter coefficients have converged, an echo delay time period is determined as a product of the tap location of the maximum filter coefficient and the down sampling factor. When the echo delay time period is greater than the capacity of an associated echo canceller, an adaptive delay inserter (110) inserts the echo delay time period prior to echo cancellation. Following insertion of the delay, echo suppression (170) is implemented while the echo canceller retrains with the new, inserted delay.

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patent: 2003/0118177 (2003-06-01), Kakakas et al.

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