Method and apparatus for integrated echo cancellation and noise reduction for fixed subscriber terminals

摘要

A method and apparatus for echo cancellation and noise reduction are provided that use synergy among system components. Double-talk detection is performed using either the voice activity detector of a codec or a secondary double-talk detector, depending on the signal-to-noise ratio (SNR) obtained from the encoder. The echo canceller is implemented via an adaptive filter and operates in a dual-mode. Under low SNR conditions, variable step-size methods, VAD-based double-talk detection and emergency coefficients are used. Under high SNR conditions, a secondary double-talk detector employing an echo loss return estimator and comparator for near-end and far-end levels is used, as well as a non-linear gain function and masking noise.