Patent ID: 6574337
Filing Date: 2003-06-03
Classification: H04M

Abstract:
An echo canceler that removes an echo of a received signal from a local input signal by subtracting an echo replica from the local input signal to generate a residual signal, comprising:an adaptive filter using a plurality of recent samples of the received signal and estimated transfer characteristics of a path of the echo to calculate the echo replica, and using the recent samples of the received signal and a recent sample of the residual signal to modify the estimated transfer characteristics; a double-talk detector detecting a double-talk condition in the local input signal; a memory storing samples of the received signal previous to the samples used by the adaptive filter, and samples of the residual signal previous to the sample used by the adaptive filter; and a control unit coupled to the adaptive filter, the double-talk detector, and the memory, using the samples stored in the memory to undo recent modifications of the estimated transfer characteristics when the double-talk condition is detected, thereby restoring the adaptive filter to the estimated transfer characteristics that were in use before the double-talk condition occurred.