Method and apparatus for soft-response echo suppression
AssigneeAvaya Inc.
InventorsEric John Diethorn, Richard Szajdecki
Life of this patent
Estimating the term…
Abstract
Methods and apparatus are provided for reducing echo from a received signal. A suppression gain is applied to an output of an echo canceler that has processed the received signal. The suppression gain includes a region of sloping attenuation about a decision point. The echo canceler optionally estimates an echo path and subtracts then estimate from the received signal. The suppression gain includes a non-zero lower bound, gmin, on a maximum attenuation applied by a suppressor, that is based on operating conditions of the echo canceler. The region of sloping attenuation applies a variable amount of attenuation that depends on the size of an output error ē(n) of the echo canceler relative to the received signal, x(n).
Claims18
A method comprising:
- receiving a signal processed by an echo canceler and computing a suppression gain, gdB(n), based on (max[gmin,dB, min[0, ē(n)< x(n)+T]]), where:
- i. T is a threshold that is computed based on (ERL+ERLE−Guard), where:
- (a) ERL is an echo return loss,
- (b) ERLE is an echo return loss enhancement, and
- (c) GUARD is a value that compensates for variances in one or both of the ERL and ERLE, wherein GUARD>=0 decibels,
- ii. gmin,dB is a value that is computed to satisfy an echo reduction of Y decibels, wherein gmin,dB is computed based on (−Y dB+ERL+ERLE),
- iii. ē(n) is an output error of the signal processed by the echo canceler, and
- iv. x(n) is a measurement of one or more control paths;
- and
- applying the suppression gain, gdB(n), to the signal processed by the echo canceler.
An apparatus comprising:
- an echo canceler;
- and
- a suppressor, wherein the suppressor computes a suppression gain, gdB(n), based on, (max[gmin,dB, min[0, ē(n)− x(n)+T]]), where:
- i. T is a threshold that is computed based on (ERL+ERLE−Guard), where:
- (a) ERL is an echo return loss,
- (b) ERLE is an echo return loss enhancement, and
- (c) GUARD is a value that compensates for variances in one or both of the ERL and ERLE, wherein GUARD>=0 decibels,
- ii. gmin,dB is a value that is computed to satisfy an echo reduction of Y decibels, wherein gmin,dB is computed based on (−Y dB+ERL+ERLE),
- iii. ē(n) is an output error of the signal processed by the echo canceler, and
- iv. x(n) is a measurement of one or more control paths;
- wherein the suppressor applies the suppression gain, gdB(n), to the signal processed by the echo canceler.
Dependencies are inferred from the claim text.