Full duplex echo cancelling circuit

Details Full duplex echo cancelling circuit Full duplex echo cancelling circuit

2005-06-07

2005-06-07

Kuntz, Curtis (Department: 2643)

Telephonic communications

Echo cancellation or suppression

C379S390020, C379S406040, C379S406160

Reexamination Certificate

active

06904146

ABSTRACT:
Sub-band filtering, adaptive echo cancellation, and residual echo suppression are selectively and separately applied in hierarchical order under the control of a circuit that monitors four separate signals to determine n machine states. The number of machine states is further divided among m levels of noise in determining which, and how much of, sub-band filtering, adaptive echo cancellation, and residual echo suppression to use at any given time. A voice activity detector (VAD) is used to monitor each signal and provides statistical information in addition to whether or not a voice signal is detected. Sub-band filter, echo cancelling, and non-linear processing are not permitted to provide maximum reduction simultaneously. Even so, the invention provides at least 15 dB more echo suppression than systems without a sub-band filter bank series coupled with a non-linear processor in each channel.

REFERENCES:
patent: 5646990 (1997-07-01), Li
patent: 5721730 (1998-02-01), Genter
patent: 5982755 (1999-11-01), Forrester et al.
patent: 6272106 (2001-08-01), Kawahara et al.
patent: 6385176 (2002-05-01), Iyengar et al.
patent: 6434110 (2002-08-01), Hemkumar
patent: 6574336 (2003-06-01), Kirla
Digital Signal Processing in Telecommunicationsby Kishan Shenoi, Prentice-Hall, 1995, Chapter 6 (pp. 334-385).
Analysis of Subband Impulse Responses in Subband Echo Cancelers, Eneroth & Gänsler, Signal Processing Report SPR-46, Jul. 1999; available at url: www.es.lth.se/ sig/publ/spr/SPR/SPR-46.pdf.
A Frequency Domain Adaptive Echo Canceller with Post-Processing Residual Echo Suppression by Decorrelation, Eneroth & Gänsler, Signal Processing Report SPR-40, Nov. 1997; available at url: www.es.lth.se/sig/publ/ spr/SPR/SPR-40.pdf.
Data sheet CS6420 Full-Duplex Speaker Phone Chip, Jun. 1997, Cirrus Logic, Inc.
ICs for Communications,Acoustic Echo Canceller, PSB2170, Version 1.1, Data Sheet Jan. 1998 Siemens AG.
ICs for Communications,Acoustic Echo Canceller, PSB2170, Version 2.1, Preliminary Data Sheet Oct. 1999 infineon technologies.

Affiliated with

Also associated with

Rating

Full duplex echo cancelling circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Full duplex echo cancelling circuit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Full duplex echo cancelling circuit will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3478789