Subband echo canceler

Details Subband echo canceler Subband echo canceler

1995-01-04

1996-10-15

Olms, Douglas W.

Multiplex communications

Wide area network

Packet switching

379411, 379410, H04B 321

Patent

active

055661670

ABSTRACT:
Failure to cancel echos at frequencies in which the frequency characteristics of sub-band filters in the X and Y analysis filter banks overlag in subband echo cancelers is overcome by employing an X-analysis filter bank in which the pass-band of the subband filters is wider than the pass-band of the corresponding subband filters in the Y-analysis filter bank. This insures that there is sufficient energy in the tap delay lines of the adaptive filters in the subband echo cancelers at all frequencies where echos are to be synthesized. More specifically, the keeping of sufficient energy in the tap delay lines of the adaptive filters in the subband echo cancelers avoids exciting eigenmodes associated with the small eigenvalues of the correlation matrix.

REFERENCES:
patent: 3500000 (1970-03-01), Kelly, Jr. et al.
patent: 5136577 (1992-08-01), Amano et al.
patent: 5272695 (1993-12-01), Makino et al.
patent: 5351291 (1994-09-01), Menez et al.
patent: 5428605 (1995-06-01), Andre
"A Twelve-Channel Digita Echo Canceler", Duttweiler, 1978, pp 647-653.
"A New Technique for the Design of Non-Recursive Digital Filter", Hofstetter et al. pp 64-72.
"Adaptive Filtering in Subbands with Centical Sampling: Analysis, Experiments, and Application to Acoustic Echo Cancellation", Gilloire et al., 1992, pp 1862-1875.
"Numerical Recipes in C", Press et al. 1988, pp 394-420.

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