Patent ID: 7555116
Filing Date: 2009-06-30
Classification: H04M

Abstract:
1. A real time processing and management method for echo cancellation between a loudspeaker and a microphone of a computer terminal managed by an operating system that executes a plurality of variable-priority tasks including an audio acquisition thread and a playback thread, the echo being caused by parasitic physical coupling between the loudspeaker delivering a loudspeaker signal and the microphone receiving a microphone signal and corrected by subtracting from the microphone signal a correction signal formed by a fraction of the loudspeaker signal delayed and filtered, wherein it comprises the steps of: choosing a reference signal from two signals: a) the loudspeaker signal, and b) the microphone signal, the other of the two signals being a non-reference signal; synchronizing the non-reference signal with respect to the reference signal; synchronizing the audio acquisition and playback threads; periodically measuring the existing delay between the non-reference signal and the reference signal, so as to obtain a measured value of existing delay; validating the measurement of existing delay so as to obtain a value of current delay and controlling the delay applied to said reference signal on the basis of this current delay, thereby making it possible to cancel said echo signal.