Multiplex communications – Wide area network – Packet switching
Patent
1991-02-20
1992-08-04
Olms, Douglas W.
Multiplex communications
Wide area network
Packet switching
379410, 379411, H04B 321, H04M 908
Patent
active
051365774
ABSTRACT:
A sub-band acoustic echo canceller includes a first division and decimation process part for dividing a reception signal from a line into first band signals of N channels and for decimating each of the first band signals to output decimated first band signals in a form of complex signals, where N is an integer greater than or equal to two, a second division and decimation process part for dividing a transmission signal into second band signals of N channels and for decimating each of the second band signals to output decimated second band signals in a form of complex signals, an echo canceller group made up of a group of echo cancellers for generating a pseudo echo in each band based on a corresponding one of the decimated first band signals received from the first division and decimation process part by referring to a corresponding one of the decimated second band signals received from the second division and decimation process part and for outputting a residual signal in each band by subtracting the pseudo echo of one band from the decimated second band signal of the same band, and an interpolation and synthesis process part for subjecting the residual signals received from the echo canceller group to interpolation and synthesis to output a synthesized residual signal which is transmitted to a line as the transmission signal, where the echo canceller group carries out an echo cancelling operation for each band in a complex signal region.
REFERENCES:
patent: 4623980 (1986-11-01), Vary
patent: 4712235 (1987-12-01), Jones, Jr.
patent: 5001701 (1991-03-01), Gay
A. Gilloire, "Experiments With Sub-Band Acoustic Echo Cancellers for Teleconferencing", ICASSP '87, 1987.
W. Kellermann, "Analysis and Design of Multirate Systems for Cancellation of Acoustical Echoes", ICASSP '88, 1988.
Gay et al., "Fast Converging Subband Acoustic Echo Cancellation Using Rap on the WE DSP16A", ICASSP '90, 1990.
Perez et al., "A New Subband Echo Canceler Structure", The Transactions of the IEICE, vol. E73, No. 10, Oct. 1990.
Nakayama et al., "A Sub-Band Adaptive Filer Using Oversampling Filter Banks", Society of Applied Acoustics, Apr. 20, 1989.
International Conference on Acoustics, Speech, and Signal Processing, New York, Apr. 11-14, 1988, vol. 5, pp. 2574-2577, IEEE, New York, US; J. Chen et al.: "A New Structure for Sub-Band Acoustic Echo Canceler".
Amano Fumio
Meana Hector M. P.
Blum Russell W.
Fujitsu Limited
Olms Douglas W.
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