Echo canceler and echo canceling method

Details Echo canceler and echo canceling method Echo canceler and echo canceling method

2007-10-23

2011-12-06

Tsang, Fan (Department: 2614)

Telephonic communications

Echo cancellation or suppression

Using digital signal processing

C370S290000

Reexamination Certificate

active

08073133

ABSTRACT:
An echo canceler has an adaptive filter that generates an echo replica signal from a far-end signal. The filter coefficients of the adaptive filter are updated according to a residual error signal, which is obtained by subtracting the echo replica signal from a near-end signal to cancel echo. A background noise estimator estimates the near-end background noise power level from the residual error signal. A step size calculator uses the estimated near-end background noise power in determining the step size of the adaptive updating of the filter coefficients. When the estimated near-end background noise level is high, a small step size is used, which improves echo cancellation under these conditions. When the estimated near-end background noise level is low, a larger step size is used to permit rapid convergence of the filter coefficients.

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