Howling canceller

Details Howling canceller Howling canceller

1985-04-03

1988-05-24

Ng, Jin F.

Telephonic communications

Substation or terminal circuitry

For loudspeaking terminal

379410, H04B 323

Patent

active

047471328

ABSTRACT:
A howling canceller includes a group of filters for dividing an output of a microphone into a plurality of frequency bands, a transfer characteristic estimation unit for estimating a transfer characteristic (i.e.-impulse response) of a low frequency range in an echo path extending from a loudspeaker to the microphone, an echo signal estimation unit for producing an approximate echo signal of the low frequency range proceeding from the loudspeaker to the microphone, a subtracter for subtracting an output of the echo signal estimation unit from an output of a low-pass filter of the filters, and an adder for adding an output of the subtracter to outputs of the filters other than the low-pass filter.

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patent: 4591670 (1986-05-01), Itoh
patent: 4609787 (1986-09-01), Horna
"Electronic Detection of Acoustic Feedback and Automatic Sound System Gain Control", E. T. Patronis, Jr., Journal of the Audio Engineering Society, Alanta, Ga., vol. 26, No. 5, May 1978, pp. 323-326.
"Proceedings of the International Teleconference Symposium", Apr. 3-5, 1984, Communications Satellite Corporation (Comsat) USA Marriott Hotel, Philadelphia, Overseas Telecommunication Commission Australia (OTC) The Conference Center, OTC House, Sydney.
"Cancellation of Acoustic Feedback in Teleconference Rooms", Horna, O.A., Comsat Labs., Clarksburg, Md., U.S.A., IEEE Sourtheastcon '83 Conference Proceedings pp. 284-289 1983, Apr. 11-14, 1983 Orlando, Fla., U.S.A.
"An adaptive Echo Canceller Using Digital Signal Processor LSI Chips", Ozawa, K. et al., Canoc Systems Res. Labs., Nec Corp., Kawasaki, Japan, IEEE Proceedings of ICASSP 83. IEEE International Converence on Acoustics, Speech and Signal Processing pp. 466-469 vol. 1, Apr. 14-16, 1983.
"A Microprocessor Echo Canceller", Araseki, T.; Itoh, Y.; Ochiai, K. Nippon Electric Co., Ltd. Kawasaki, Japan, IEEE; Telglobe Canada et al. Fourth International Conference on Digital Satellite Communications pp. 219-224, 1978, Oct. 23-25, 1978, Montreal, Canada.
"Cancellation of Acoustic Feedback", Horna, O., pp. 319-333, Index: Echo Control, Telephone Transmission, Integrated Circuits, Filters.

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