Speakerphone with adaptive cancellation of room echoes

Details Speakerphone with adaptive cancellation of room echoes Speakerphone with adaptive cancellation of room echoes

1985-09-20

1987-01-13

Rubinson, Gene Z.

Telephonic communications

Substation or terminal circuitry

For loudspeaking terminal

379411, 381 71, 381 94, H04B 1500

Patent

active

046365869

ABSTRACT:
An arrangement for generating an electrical audio signal in response to a sound signal applied to a microphone in a reverberating room removes the reverberations with an adaptive filter. The filter learns or adapts so as to cancel the room echoes by receiving both the audio signal affected by reverberation and a clean audio signal from a highly directional local-acting microphone placed near the source of the sound. The signal to be filtered is applied to a transversal filter including a tapped delay line having variable taps or multipliers to produce incrementally delayed multiplied samples. The multiplied samples are summed, and the sum signal is subtracted from the clean signal to produce a difference signal. A .mu.P is programmed to iteratively calculate the effects of changes to the tap values and to select tap values which tend to reduce the magnitude of the difference signal. When the filter is converged, the difference signal is near zero. At this time, the filtered signal and the clean signal are similar, and therefore the filter characteristic removes the effect of reverberation. The tap values are then fixed, and the signal with room reverberations can be made clean by the adapted filter.

REFERENCES:
patent: 4087654 (1978-05-01), Mueller
patent: 4118601 (1978-10-01), Yeap
patent: 4225754 (1980-09-01), Bernard et al.
patent: 4480333 (1984-10-01), Ross
patent: 4497980 (1985-02-01), Gorman et al.
patent: 4594695 (1986-06-01), Garconnat et al.
Article-"Echo Cancellation in Speech and Data Transmission" by: D. G. Messerschmitt, published at pp. 293-297, to the IEEE Journal of Selected Areas in Communications, vol. SAC-2, No. 2, Mar. 1984.

Affiliated with

Also associated with

Rating

Speakerphone with adaptive cancellation of room echoes does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Speakerphone with adaptive cancellation of room echoes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Speakerphone with adaptive cancellation of room echoes will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2356665