Patent ID: 6771772
Filing Date: 2004-08-03
Classification: H04B

Abstract:
In a telephone line, an echo cancellation apparatus for canceling telephone line transmission echo signals, the echoes comprising an impulse response bulk delay, peak delay, echo span, and echo tail, the telephone lines having a proximal end and a distal end and carrying a proximal signal and an echo signal, the apparatus comprising:a subband adaptive echo canceller for generating a set of subband adaptive coefficients; a full-band adaptive echo canceller coupled to the subband adaptive echo canceller for receiving the set of subband adaptive coefficients and initializing a set of full-band coefficients therefrom, said full-band adaptive echo canceller reducing the telephone line transmission signal echoes through use of the full-band adaptive coefficients; and an estimator coupled between the subband echo canceller and full-band echo canceller, the estimator receiving the subband adaptive coefficients and calculating the echo signal bulk delay therefrom, said full-band adaptive echo canceller receiving the calculated echo signal bulk delay and echo span, and in turn refining the set of full-band adaptive coefficients.