Echo canceller with dynamically positioned adaptive filter taps

Details Echo canceller with dynamically positioned adaptive filter taps Echo canceller with dynamically positioned adaptive filter taps

1986-10-01

1989-04-18

Ng, Jin F.

Telephonic communications

Subscriber line or transmission line interface

Network interface device

370 321, H04B 323

Patent

active

048233820

ABSTRACT:
An echo canceller according to the present invention includes means for storing an impulse response in a memory, the impulse response being indicative of the characteristics of a transmission line. It also includes a detector for detecting ranges of samples within the impulse response having relatively large distribution of echo energy, these ranges of samples of relatively large distribution of echo energy being indicative of echoes on the transmission line. An echo canceller includes a digital filter having a plurality of weighted taps, each of the weighted taps having an associated tap weight value. A tap allocation circuit establishes the tap weight values in response to said detecting means so that only taps within the regions of relatively large distributions of echo energy are turned on. The ranges of echo energy are detected coarsely by detecting ranges of samples having relatively high estimated average echo power. The echo is more finely located by computing the terms analogous to the mechanical computation of the center of gravity type calculation referred to as a `center of echo` and radius of gyration type calculation referred to as `radius of echo` of the echo energy within the coarsely located ranges of samples.

REFERENCES:
patent: 3465106 (1969-09-01), Nagata et al.
patent: 3535473 (1970-10-01), Flanagan et al.
patent: 3578544 (1986-03-01), Colin de Verdiere et al.
patent: 3721777 (1973-03-01), Thomas
patent: 3723911 (1973-03-01), Forney, Jr.
patent: 3732410 (1973-05-01), Mackechnie
patent: 3735055 (1973-05-01), Thomas
patent: 4024357 (1977-05-01), Sourgens et al.
patent: 4087654 (1978-05-01), Mueller
patent: 4464545 (1984-08-01), Werner
patent: 4582963 (1986-04-01), Danstrom
patent: 4593161 (1986-06-01), Desblache et al.
patent: 4602133 (1986-07-01), O'Neill
patent: 4677668 (1987-06-01), Ardalan et al.
Translation Japanese Patent Publication 57-42242, United States Patent and Trademark Office, 9-87.
Digital Signal Processing, 1975 Prentice-Hall, pp. 239-250.
Digital Processing of Signals, Gold and Rader, Lincon Laboratory Publication, 217-232.
Digital Filter Design Handbook, Marcel Dekker, Inc., 1983, pp. 135-151.
IBM Technical Disclosure Bulletin, vol. 21, No. 5, Oct. 1978, (New York, U.S.), "Centering Transversal Equalizer Tap Coefficients".
IEEE Global Telecommunications Conference, Houston, Tex., 1-4 Dec. 1986, "A DSP-Based Echo-Canceller with Two Adaptive Filters".
Signal Analysis, by Athanasios Papoulis, 1977. .
Shin-ichi Kawamura and Mitsutoshi Hatori, "A Tap Selection Algorithm for Adaptive Filters", Proceediongs of ICASSP, pp. 2979-2982, 1986.
Makoto Itami, Takashi Mochizuki and Mitsutoshi Hatori, "Hardware Implementation of FM Mutlipath Distortion Canceller", Proc. of ICASSP, pp. 1301-1304, 1986.
Bede Lie, "Effect of Finite Word Length on the Accuracy of Digital Filters-A Review", IEE Trans. Circuit Theory, pp. 361-369, Nov. 1971.
Oscar Agazzi, David G. Messerschmitt and David A. Hodges, "Nonlinear Echo Cancellation of Data Signals", IEE Transactions on Communications, pp. 2421-2433, Nov. 1982.
Stephen B. Weinsten, "Echo Cancellation in the Telephone Network" IEE Communications Society Magazine, pp. 9-15, Jan. 1977.
M. M. Sondhi, "An Adaptive Echo Canceller", The Bell System Technical Journal , pp. 497-511, Mar. 1967.

Affiliated with

Also associated with

Rating

Echo canceller with dynamically positioned adaptive filter taps does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Echo canceller with dynamically positioned adaptive filter taps, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Echo canceller with dynamically positioned adaptive filter taps will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2400978