Frequency domain adaptive echo canceller for full-duplex data tr

Details Frequency domain adaptive echo canceller for full-duplex data tr Frequency domain adaptive echo canceller for full-duplex data tr

1990-11-09

1992-05-26

Olms, Douglas W.

Multiplex communications

Wide area network

Packet switching

379411, 379406, H04M 908, H04L 514

Patent

active

051174189

ABSTRACT:
A system and method for reducing echoes on a duplex communication channel having both transmitted and received signals carried thereon, particularly a telephone channel having digital data transmitted thereon by way of a modem. The transmitted signal is converted from a time domain signal to a frequency domain transmitted signal by a fast fourier transform process. The frequency domain transmitted signal is multiplied by a set of filter coefficients to generate estimated echo coefficients. The estimated echo coefficients are converted from the frequency domain to the time domain by an inverse fast fourier transform process and then subtracted from the received signal to generate a residual echo signal. The residual echo signal is converted to a frequency domain residual echo signal by a fast fourier transform process and then multiplied by the complex conjugate of the frequency domain transmitted signal to generate correlation frequency components. The correlation frequency components are then used to update the filter coefficients so as to minimize the residual echo and at least partially cancel the echo present on the communication channel.

REFERENCES:
patent: 4593161 (1986-06-01), Desblache et al.
patent: 4813073 (1989-03-01), Ling
patent: 4853765 (1989-05-01), Bergmans et al.
patent: 4896318 (1990-01-01), Kokubo et al.
patent: 4951269 (1990-08-01), Amano et al.
patent: 5008923 (1991-04-01), Kitamura et al.

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