Telephonic communications – Echo cancellation or suppression – Using digital signal processing
Reexamination Certificate
2006-06-07
2010-10-19
Tsang, Fan (Department: 2614)
Telephonic communications
Echo cancellation or suppression
Using digital signal processing
C379S003000, C379S406010, C381S071100
Reexamination Certificate
active
07817797
ABSTRACT:
An echo canceller comprising a first adaptive filter having N_long coefficients for converging to an echo path, a non-adaptive filter representing a direct echo path portion captured by the first adaptive filter and having N_short default coefficients, where N_long>N_short, for quick convergence of the echo canceller at start-up, wherein the default coefficients are replaced by the first N_short coefficients from the first adaptive filter responsive to an improvement in echo return loss enhancement (ERLE) of the first adaptive filter, a second adaptive filter having N_short default coefficients for modeling the direct echo path and providing an indication of double-talk and echo path changes, decision logic for receiving error signal outputs from the first and second adaptive filters and the non-adaptive filter and in response distinguishing between echo path changes and double-talk, and a non-linear processor for attenuating signals responsive to input from the decision logic.
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Popovic Mirjana
Schulz Dieter
Swan Dean
Wu Andrew
Mitel Networks Corporation
Sharifzada Ibraham
Tsang Fan
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