Telephonic communications – Audio message storage – retrieval – or synthesis – Multilingual system or operation
Patent
1994-06-23
1995-03-21
Brown, Thomas W.
Telephonic communications
Audio message storage, retrieval, or synthesis
Multilingual system or operation
370 321, 379410, H04J 1500, H04M 174
Patent
active
054003946
ABSTRACT:
An apparatus and method for echo cancellation in voice-messaging and voice-response systems, to enhance recognition of received DTMF and voice signals, comprising an efficient software echo canceller using adaptive digital filtering techniques. The voice messaging system includes analog telephone line interface modules which provide digitized voice data to a digital signal processor (DSP) chip. A transmit data line and a receive data line are each coupled to a cancel module with a cancel filter and an adapt/window module with an adaptive digital filter. The cancel filter causes echo cancellation on the receive data line; the adapt/window module monitors buffered transmit data in non-real time, without directly causing cancellation to occur, and selectively transfers an adjacent window of filter coefficients to the cancel filter under control of an adaptation control coupled to the adapt/window module. The control identifies a plurality of frames meeting a power criterion and passes the frames to the adaptive filter, which adapts on taps in frame segments during all available DSP real time, using a "cycle steal" approach for testing whether additional DSP processor cycles are available to use for echo cancellation. A masked white noise burst may be used to initialize adaptation. A windowing function identifies the best taps of an adapted frame, and corresponding coefficients are copied or loaded into the cancel filter. All control parameters are configurable, enabling site-specific performance optimization.
REFERENCES:
patent: 3499999 (1970-03-01), Sondhi
patent: 3500000 (1970-03-01), Kelly, Jr. et al.
patent: 3828147 (1974-08-01), Ochiai et al.
patent: 4057696 (1977-11-01), Gitlin et al.
patent: 4425483 (1984-01-01), Lee et al.
patent: 4479036 (1984-10-01), Yamamoto et al.
patent: 4554417 (1985-11-01), Boyer
patent: 4582963 (1986-04-01), Danstrom
patent: 4621172 (1986-11-01), Kanemasa et al.
patent: 4636586 (1987-01-01), Schiff
patent: 4712235 (1987-12-01), Jones, Jr.
patent: 4757527 (1988-07-01), Beniston et al.
patent: 4805215 (1989-01-01), Miller
patent: 4868874 (1989-09-01), Takatori et al.
patent: 4914692 (1990-04-01), Hartwell et al.
patent: 4935919 (1990-06-01), Hiraguchi
patent: 4947425 (1990-08-01), Grizmala et al.
patent: 4970715 (1990-11-01), McMahan
patent: 4984265 (1991-01-01), Connan et al.
patent: 5007007 (1991-04-01), van Zanten et al.
patent: 5029167 (1991-07-01), Arnon et al.
patent: 5125024 (1992-06-01), Gokcen et al.
Gitlin, et al., "On the Design of Gradient Algorithms for Digitally Implemented Adaptive Filters," IEEE Transactions on Circuit Theory, vol. CT-20, No. 2, Mar. 1973, pp. 125-136.
Duttweiler, et al., "A Single-Chip VLSI Echo Canceler," The Bell System Technical Journal, vol. 59, No. 2, Feb. 1980, pp. 149-161.
Mueller, "Combining Echo Cancellation and Decision Feedback Equalization," The Bell System Technical Journal, vol. 58, No. 2, Feb. 1979, (10 pages).
Sondhi, et al., "Silencing Echoes on the Telephone Network," Proceedings of the IEEE, vol. 68, No. 8, Aug. 1980, pp. 948-963.
Cioffi, "A Fast Echo Canceller Initialization Method for the CCITT V.32 Modem," IEEE Transactions on Communications, vol. 38, No. 5, May 1990, pp. 629-638.
Murano et al., "Echo Cancellation and Applications," IEEE Communications Magazine, Jan. 1990, pp. 49-55.
Benesty, et al., "A fast Exact Least Mean Square Adaptive Algorithm," IEEE, Publication No. CH2847-2/90/0000-1457, 1990, pp. 1457-1460.
Roulier, et al., "An Echo Cancellation Algorithm for Operation With a Digital Speech Coder in a Single Signal Processor," IEEE, Publication No. CH2561-9/88/0000-1628, 1988, pp. 1628-1631.
Proakis, "Echo Cancellation in Data Transmission over Telephone Channels," Digital Communications (Second Edition), McGraw-Hill, 1989, pp. 683-691.
Messerschmitt, et al., "Digital Voice Echo Canceller with a TMS32020," Digital Signal Processing Applications with the TMS320 Family, vol. 1, Texas Instruments, 1989, pp. 415-454.
Bogert et al., "The Quefrency Alanysis of Time Series for Echoes: Cepstrum, Pseudo-Autocovariance, Cross-Cepstrum and Saphe Cracking" Proceedings of the Symposium on Time Series Analysis, Rosenblatt, Murray, Editor, Brown University 1962, pp. 209-243.
Kuo, Sen, "An Implementation of Adaptive Filters with the TMS320C25 or the TMS320C30" Digital Signal Processing Applications with the TMS320 Family, Theory, Algorithms, and Implementation, vol. 3, Papamichals, Panos, Editor, Texas Instruments, 1990, pp. 191-243.
Widrow, et al., "Adaptive Signal Processing", Adaptive Signal Processing, Larson Publications, 1985, pp. 338-346.
Cromack Mark R.
Raman Vijay R.
Brown Thomas W.
Digital Sound Corporation
LandOfFree
Adaptive echo canceller for voice messaging system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Adaptive echo canceller for voice messaging system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adaptive echo canceller for voice messaging system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1155652