Echo canceller having improved non-linear processor

Details Echo canceller having improved non-linear processor Echo canceller having improved non-linear processor

2006-01-19

2008-11-11

Singh, Ramnandan (Department: 2614)

Telephonic communications

Echo cancellation or suppression

Residual echo cancellation

C379S406020

Reexamination Certificate

active

07450714

ABSTRACT:
A non-linear processor for use in an echo canceller is set forth. The non-linear processor includes a center clipping digital filter receiving an echo compensated signal. The non-linear processor provides a center clipped output signal having non-linear thresholds at values of +TNLPand −TNLP. The value of TNLPis dynamically dependent, at least in part, on echo return loss measurements. To limit the processor's susceptibility to corruption from double-talk conditions, the non-linear processor inhibits the dynamic setting of the TNLPvalue when a double-talk condition is present. Additionally, or in the alternative, the non-linear processor locks the value of the echo return loss measurement after a predetermined number of consecutive echo return loss measurements have values falling within a predetermined range of one another. Such locking further reduces the susceptibility of the non-linear processor to corruption from double-talk conditions.

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