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Discussion Groups | Echo Cancellation | Re:Re: Does anybody know where I can get C source code fo r the AEC?
Re:Re: Does anybody know where I can get C source code fo r the AEC? - Author Unknown - Jul 23 22:15:00 2002
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Hello Maximus, There are algorithms that do not rely on level differences to determine if double-talk is present. These algorithms do not suffer from input level differences. I would suggest you do a patent search on echo canceller double-talk detectors. One detector I know of implements a form of the Optimal Bounding Ellipsoid by preventing the update of the adaptive filter if no innovation is detected from the last samle to the present. To answer specifically your question, the echo contains the double-talk signal as well as the echo. By applying the ALC to this signal, you are amplyfing the echo as well as the double-talk signal. The ALC my not help since the ratio of the 2 will not be changed. In the worst case, the echo can be 6 dB down from a nominal input level, and the double-talk signal can be 8 dB down from a nomimal input level. Under these conditions, you need more than level detection to determine if double-talk is present. Maurice Givens |
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