Abstract: A method and apparatus for adapting dual filters is disclosed. In one aspect, a method may include transforming a signal, adapting a first adaptive filter based on the transformed signal, estimating a delay of an impulse response based on the adaptation of the first filter, delaying a signal based on the estimated delay, and adapting a second adaptive filter based on the delayed signal. In one aspect, an echo or other unwanted signal may be reduced or cancelled based on the adaptation of the second filter.

Abstract: A first adaptive filter having a first filter length estimates a channel weight vector of an echo channel using an affine projection (AP) update. The echo channel receives a send input sequence and a receive input sequence. The echo channel has a plurality of sparse multi-path channels. A delay estimator determines a plurality of delays in the echo channel using the estimated channel weight vector. A second adaptive filter estimates a plurality of short weight vectors using the AP update and the plurality of delays. The short weight vectors correspond to the sparse multi-path channels. Each of the short weight vectors has a short filter length.

Abstract: An adaptive filter estimates a channel weight vector of an echo channel using an affine projection (AP) update. The echo channel receives a send input sequence and a receive input sequence. The channel weight vector has first and second lengths when the adaptive filter operates in a first adaptation mode and a second adaptation mode, respectively. A delay estimator determines a delay in the echo channel using the adaptive filter in the first adaptation mode.

Abstract: A first adaptive filter having a first filter length estimates a channel weight vector of an echo channel using an affine projection (AP) update. The echo channel receives a send input sequence and a receive input sequence. The echo channel has a plurality of sparse multi-path channels. A delay estimator determines a plurality of delays in the echo channel using the estimated channel weight vector. A second adaptive filter estimates a plurality of short weight vectors using the AP update and the plurality of delays. The short weight vectors correspond to the sparse multi-path channels. Each of the short weight vectors has a short filter length.

Abstract: An adaptive filter estimates a channel weight vector of an echo channel using an affine projection (AP) update. The echo channel receives a send input sequence and a receive input sequence. The channel weight vector has first and second lengths when the adaptive filter operates in a first adaptation mode and a second adaptation mode, respectively. A delay estimator determines a delay in the echo channel using the adaptive filter in the first adaptation mode.