An adaptive technique for multiple echo cancelation in telephone networks

To cancel multiple echos, the number of tap coefficients of a conventional echo canceler must be large. The length of the echo canceler will directly affect both the degree of accuracy and the convergence speed of the adaptation process. We present a new adaptive structure which cancels multiple echos in telephone networks with a much smaller number of coefficients. The core of this new structure is a multiple delay estimator which estimates and distributes delays to each individual fixed length short echo canceler. With the delays given, this new structure can update the echo path accurately. Since the number of tap coefficients has been dramatically reduced, the convergence speed and the degree of accuracy of estimation in the adaptation process can be improved.