H - Electricity – 04 – B
Patent
H - Electricity
04
B
H04B 15/00 (2006.01) H04B 3/23 (2006.01)
Patent
CA 2062701
In an echo canceller used in a four-wire digital telephone circuit, a main echo estimator (21) and a sub echo estimator (22) are coupled with a receive path for measuring a receive signal, and subtracters (25, 26) are inserted in a transmit path for cancelling an echo component in a transmit signal. Filter coefficients in said estimators (21, 22) are adaptively controlled by a convergence control processor (24). The main echo estimator has a small step gain for updating filter coefficients so that the response to an echo is slow, while the sub echo estimator (22) has a large step gain and quick response for an echo. An register accumulator (23) is provided so that the filter coefficients by the sub echo estimator (22) are selectively accumulated on the related filter coefficients in the main echo estimator (21) according to operation modes, ordinary mode, accumulating mode, and reset mode. In an ordinary mode, said two echo estimators (21, 22) operate independently from each other, updating the filter coefficients. In an accumulating mode, when an echo output of the second subtracter (26) is lower than that of the first subtracter(25), and the filter coefficients in the sub echo estimator (22) converge, the filter coefficients in the sub echo estimator (22) are accumulated on the related ones in the main echo estimator (21), respectively, and after reset of the coefficients in the sub echo estimator (22), the mode is then switched to the ordinary mode. When the filter coefficients in the sub echo estimator (22) diverge, or echo output of the second subtracter (26) is larger than that of the first subtracter (25), the sub echo estimator (22) is reset, and then, the mode is switched to the ordinary mode.
Sugaya Fumiaki
Yatsuzuka Youtaro
Cassan Maclean
Kokusai Denshin Denwa Co. Ltd.
LandOfFree
Echo canceller does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Echo canceller, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Echo canceller will most certainly appreciate the feedback.
Profile ID: LFCA-PAI-O-1665571