Echo control device with quick response to sudden echo-path chan

Details Echo control device with quick response to sudden echo-path chan Echo control device with quick response to sudden echo-path chan

1995-12-13

2000-09-26

Zele, Krista

Telephonic communications

Substation or terminal circuitry

For loudspeaking terminal

379400, 379406, 379410, H04M 100, H04M 900

Patent

active

061251798

ABSTRACT:
An Acoustic Echo Control (AEC) device operates to reduce acoustic echo feedback in a speakerphone. An adaptive echo canceller responds to a far-end speech signal to generate an estimated echo which is subtracted from a near-end speech signal, to generate a compensated near-end speech signal. An Echo Return Loss (ERL) estimator provides an accurate but gradually adjusted estimate of the ERL of the echo canceller. A non-linear processor responds to the ERL estimation and provides additional attenuation to maintain the overall system ERL. The AEC device also incorporates dual talking mode detectors, one for the adaptive filter and one for the non-linear processor, to detect a plurality of talking modes, which are used to control the adaptation of the adaptive filter and the attenuation provided by the non-linear processor. A convergence indicator responds to the sudden echo path changes, and quickly corrects the ERL estimation; thereby adjusting the talking mode detector and the non-linear processor accordingly to maintain the overall system ERL and stability.

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