Telephonic communications – Echo cancellation or suppression
Patent
1994-07-07
1995-06-27
Dwyer, James L.
Telephonic communications
Echo cancellation or suppression
379410, 379411, 370 321, H04B 323
Patent
active
054286816
ABSTRACT:
Apparatus for reducing the risk of undesirable drifting of the parameters, so-called bursting, of an adaptive echo filter which is coupled between a receiving branch and a transmitting branch included in a four-wire loop. A difference signal (E) which contains no echo from the receiving branch is generated in the transmitting branch in a known manner. The apparatus includes an adaptive predictor filter which is coupled between the transmitting branch and the receiving branch and which functions to generate a compensation signal from the difference signal (E) when transmitting narrowband signals from a near-end. The compensating signal is subtracted from a signal which appears in the receiving branch and the predictor filter is updated in a manner to minimize the correlation between the difference signal (E) and the input signal (X') of the echo filter. A relatively small predictor filter is sufficient to essentially eliminate this correlation when transmitting signals which, at maximum, consist of some few single sinusoidal tones.
REFERENCES:
patent: 4712235 (1987-12-01), Jones, Jr.
patent: 4782525 (1988-11-01), Sylvain et al.
patent: 4845746 (1989-07-01), Li
Patent Abstract of Japan, vol. 10, No. 192 (E-417) abstract of JP 61-035630, publ. Feb. 20, 1986. Matsushita Electric Ind. Co. Ltd.
Ding, Z. et al. Frequency-Dependent Bursting in Adaptive Echo Cancellation and Its Prevention Using Double-Talk Detectors. International Journal of Adaptive Control and Signal Processing, vol. 4, 219-236, 1990.
Sethares, W. et al. Bursting in Adaptive Hybrids. IEEE Transactions on Communications, vol. 37, No. 8, 791-799, 1989.
Dwyer James L.
Shehata M.
Telefonaktiebolaget L M Ericsson
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