Echo cancelling method and apparatus using fast projection schem

Details Echo cancelling method and apparatus using fast projection schem Echo cancelling method and apparatus using fast projection schem

1995-02-09

1996-07-23

Olms, Douglas W.

Multiplex communications

Wide area network

Packet switching

379410, H04M 908

Patent

active

055397310

ABSTRACT:
In an echo cancelling method of a p-order fast projection algorithm which subtracts an estimated echo signal y(k) from a microphone output signal u(k) to obtain an error signal e(k), adaptively calculates a pre-filter coefficient .beta.(k) from the auto-correlation of a received speech signal x(k) and the error signal, generating an intermediate variable z(k) updated by a coefficient s(k) obtained by smoothing the pre-filter coefficient, convolutes the received speech signal x(k) and the intermediate variable z(k), calculates the inner product of the auto-correlation of the received speech signal and the smoothed pre-filter coefficient s(k) and adding the inner product and the convoluted output to obtain the estimated echo signal, the magnitudes of the received speech signal x(k) and the error signal e(k) are compared and when the result of comparison satisfies a predetermined condition, a reset signal is generated to set the pre-filter coefficient .beta.(k) to zero for at least a period of time p, thereby preventing the accuracy of estimated echo characteristics from lowering during double-talk or send single-talk.

REFERENCES:
patent: 5351291 (1994-09-01), Menez et al.

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