Telephonic communications – Echo cancellation or suppression – Using digital signal processing
Reexamination Certificate
2007-07-10
2007-07-10
Singh, Ramnandan (Department: 2614)
Telephonic communications
Echo cancellation or suppression
Using digital signal processing
C379S406070, C379S406110
Reexamination Certificate
active
10178427
ABSTRACT:
A communication system having an echo canceller is disclosed. One embodiment of the echo canceller includes an adaptive filter used to provide an estimate of reflected echo which is removed from the send signal. The echo canceller may also include a near-end talker signal detector which may be used to prevent the adaptive filter from adapting when a near-end talker signal is present. The echo canceller may also include a nonlinear processor used to further reduce any residual echo and to preserve background noise. The echo canceller may also include a monitor and control unit which may be used to monitor the filter coefficients and gain of the adaptive filter to maintain stability of the echo canceller, estimate pure delay, detect a tone, and inject a training signal. The echo canceller may also include a nonadaptive filter used to reduce the length of the adaptive filter.
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Dyba Roman A.
He Perry P.
Pessoa Lucio F. C.
Smith Roger A.
Chiu Joanna G.
Hill Susan C.
Singh Ramnandan
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