摘要:
A zero-delay structure to be used in sub-band echo cancellation systems. In telecommunications, a delay is usually introduced in sub-band decomposition and/or sub-band reconstruction. This invention will help remove this. This structure not only removes the delay but does not sacrifice the performance of the echo canceller. It is to be used in combination with any sub-band-based echo canceller or wavelet echo canceller.
摘要:
An echo canceller comprising a first wavelet decomposition block for decomposing a reference signal into a plurality of reference wavelet packets; a second wavelet decomposition block for decomposing an echo signal into a plurality of echo signal packets; an adaptive filter bank for receiving and filtering the reference wavelet packets and in response generating a plurality of filtered output packets replicating the echo signal packets; a plurality of subtracters for receiving and subtracting respective ones of the filtered output packets from the echo signal packets and in response generating and applying a plurality of error signals to the adaptive filter bank for modifying the transfer function of the adaptive filter bank; and a wavelet reconstruction block for receiving and reconstructing the error signals to form a residual signal from which the echo signal has been cancelled. Optimum wavelet filters for the best echo cancellation are provided, as are two wavelet echo cancellation structures.