Title:
METHODS AND APPARATUS FOR IMPROVED SUB-BAND ADAPTIVE FILTERING IN ECHO CANCELLATION SYSTEMS
Document Type and Number:
WIPO Patent Application WO2000076081
Kind Code:
A3
Abstract:
In methods and apparatus for echo cancellation using sub-band adaptive filtering, the bandwidth of each of a number of sub-band analysis filters, as well as the bandwidth of each of a number of synthesis filters, is increased as compared to a corresponding bandwidth in a conventional system. More specifically, the -3dB bandwidths of adjacent filters in an analysis or synthesis filter bank according to the invention are designed to overlap one another. For example, each of M (an integer) sub-band filters in an analysis or synthesis filter bank according to the invention can include a -3dB bandwidth somewhat greater than 1/M times a total bandwidth of interest. The increase in bandwidth tends to cancel aliasing effects resulting from sub-band down-sampling, and an echo cancelling device according to the invention can therefore provide superior output signal reconstruction as compared to conventional devices.
Inventors:
GRUNDSTROEM PATRIK
EHRENSTRAALE FREDRIK
EHRENSTRAALE FREDRIK
Application Number:
PCT/EP2000/004861
Publication Date:
August 09, 2001
Filing Date:
May 29, 2000
Export Citation:
Assignee:
ERICSSON TELEFON AB L M (SE)
International Classes:
H04M1/60; H04B3/23; H04M9/08; (IPC1-7): H04M9/08
Foreign References:
| EP0709958A1 | 1996-05-01 | |||
| US4956838A | 1990-09-11 | |||
| EP0443547A2 | 1991-08-28 |
Other References:
TAHERNEZHADI M ET AL: "AN IMPROVED SUBBAND ACOUSTIC ECHO CANCELLER FOR TELECONFERENCING APPLICATIONS", PROCEEDINGS OF THE MIDWEST SYMPOSIUM ON CIRCUITS AND SYSTEMS,US,NEW YORK, IEEE, vol. SYMP. 37, 1994, pages 1424 - 1427, XP000531911, ISBN: 0-7803-2429-3
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