Patent ID: 8073497
Filing Date: 2011-12-06
Classification: H04M

Abstract:
1. A communications system comprising: a near-end transceiver configured for sending a signal and receiving a signal in communications with one or more far-end transceivers, wherein the near-end transceiver is subject to coupling between a downlink received signal and an uplink signal, forming an echo path; each far-end transceiver comprising: (i) a speech analysis coder operable to compress a far-end audio signal to provide the received signal at the near-end transceiver in a compressed format comprising linear prediction coefficients and variance values, and (ii) a speech reproduction decoder for receiving linear prediction coefficients and variance values for a received signal from the near-end transceiver and reproducing the received signal; the near-end transceiver comprising: (i) a speech analysis coder operable to compress a near-end audio signal to provide the received signal at each far-end transceiver in a compressed format comprising linear prediction coefficients and variance values, and (ii) a speech reproduction decoder for receiving linear prediction coefficients and variance values for the received signal from the far-end transceivers and reproducing the received signal; and, an echo canceller associated with each transceiver, the echo canceller comprising an adaptive finite impulse response filter configured to correlate at least a component of the received signal with at least a component of the send signal, and to converge on a set of coefficients that characterize the echo path; wherein the echo canceller further comprises a filter for applying the received signal to the set of coefficients to generate a predicted echo signal and a summing node at which the predicted echo signal is subtracted from the send signal, thereby removing echo from the send signal, wherein the variance values from the speech analysis coder are adopted by the echo canceller as a pre-whitened component of the received signal.