Method for controlling echo canceling in an echo canceller

Details Method for controlling echo canceling in an echo canceller Method for controlling echo canceling in an echo canceller

1996-02-23

1997-11-11

Zele, Krista M.

Telephonic communications

Subscriber line or transmission line interface

Network interface device

379390, 379406, 370286, 370289, 370290, H04B 320

Patent

active

056872291

ABSTRACT:
A method for controlling echo canceling in an echo cancellation system using a state machine controller. A far-end speech signal transmitted through a communications channel may be passed through an echo channel to produce an echo signal. The echo signal is summed with a near-end speech signal and transmitted back to the far-end. An echo canceller rejects the echo signal by forming an estimate of the echo signal and subtracting the estimate from the sum of the near-end speech signal and the echo signal. The echo canceller includes a state machine which is configured into a predetermined state of a plurality of states depending on the presence near-end speech signal, far-end speech signal, or both near-end and far-end speech signals. Based on the predetermined state of the state machine, the controller in the state machine controls the update of coefficients of a plurality of adaptive filters. The adaptive filters filter the far-end signal to form the estimate of the echo signal, which is canceled from an output signal provided to an output speech channel at the far-end.

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