Method for controlling echo canceling in an echo canceller

• Main Author: SIH; GILBERT C
• Format: Patent
• Language: English
• Published: 11.11.1997
• Edition: 6
• Subjects: ACOUSTICS; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; MUSICAL INSTRUMENTS; PHYSICS; SPEECH ANALYSIS OR SYNTHESIS; SPEECH OR AUDIO CODING OR DECODING; SPEECH OR VOICE PROCESSING; SPEECH RECOGNITION; TELEPHONIC COMMUNICATION; TRANSMISSION

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.