SE8205839D0 - echo canceller - Google Patents

echo canceller

Info

Publication number
SE8205839D0
SE8205839D0 SE8205839A SE8205839A SE8205839D0 SE 8205839 D0 SE8205839 D0 SE 8205839D0 SE 8205839 A SE8205839 A SE 8205839A SE 8205839 A SE8205839 A SE 8205839A SE 8205839 D0 SE8205839 D0 SE 8205839D0
Authority
SE
Sweden
Prior art keywords
echo
signal
echo canceller
canceller
stage
Prior art date
Application number
SE8205839A
Other languages
Swedish (sv)
Other versions
SE8205839L (en
Inventor
D A Alsberg
R P Coulter
T H Curtis
G-S Fang
Original Assignee
Western Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Western Electric Co filed Critical Western Electric Co
Publication of SE8205839D0 publication Critical patent/SE8205839D0/en
Publication of SE8205839L publication Critical patent/SE8205839L/en

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/20—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/20—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other
    • H04B3/23—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a replica of transmitted signal in the time domain, e.g. echo cancellers
    • H04B3/237—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a replica of transmitted signal in the time domain, e.g. echo cancellers using two adaptive filters, e.g. for near end and for end echo cancelling
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/20—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other
    • H04B3/23—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a replica of transmitted signal in the time domain, e.g. echo cancellers
    • H04B3/234—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a replica of transmitted signal in the time domain, e.g. echo cancellers using double talk detection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/20—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other
    • H04B3/23—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a replica of transmitted signal in the time domain, e.g. echo cancellers
    • H04B3/238—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a replica of transmitted signal in the time domain, e.g. echo cancellers using initial training sequence

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Noise Elimination (AREA)

Abstract

The invention is a two-stage echo canceller arrangement including a first echo cancelling stage (20) and a second echo cancelling stage (18). The first a. echo canceller adapts an input signal (x(k)) to synthesize a first estimate of an echo replica signal (@1(k)). A combiner (28) subtracts this first echo replica signal from the actual echo signal to generate a first echo cancelled signal (e1(k)). A control unit (30) monitors the change in value of the echo cancelled signal, and locks the adaptation process of the first echo canceller when the first echo cancelled signal is sufficiently less than the input signal, usually 6 dB of the input signal, to allow a near-end speech detector (23) included in the second stage to function correctly, ie to reduce the echo to a level below that at which it might be wrongly identified as near end speech. The second echo canceller, which is disposed after the first echo canceller, functions in a similar manner as the first echo canceller, and, unless inhibited by the detection of near end speech, continues to operate after the first echo canceller is locked until the echo cancelled signal produced by the second echo canceller is approximately equal to zero. <IMAGE>
SE8205839A 1981-10-23 1982-10-14 echo canceller SE8205839L (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US31449081A 1981-10-23 1981-10-23

Publications (2)

Publication Number Publication Date
SE8205839D0 true SE8205839D0 (en) 1982-10-14
SE8205839L SE8205839L (en) 1983-04-24

Family

ID=23220171

Family Applications (1)

Application Number Title Priority Date Filing Date
SE8205839A SE8205839L (en) 1981-10-23 1982-10-14 echo canceller

Country Status (8)

Country Link
JP (1) JPS5881346A (en)
KR (1) KR840002179A (en)
AU (1) AU8965682A (en)
DE (1) DE3238564A1 (en)
FR (1) FR2515454A1 (en)
GB (1) GB2109207A (en)
NL (1) NL8204096A (en)
SE (1) SE8205839L (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1238381A (en) * 1985-03-14 1988-06-21 Ephraim Arnon Multi-stage echo canceller
US4868874A (en) * 1986-04-18 1989-09-19 Hitachi, Ltd. Echo canceller
CA2004379C (en) * 1988-12-01 1993-07-06 Tetsu Taguchi Echo canceller with means for determining filter coefficients from autocorrelation and cross-correlation coefficients
US5471527A (en) 1993-12-02 1995-11-28 Dsc Communications Corporation Voice enhancement system and method
US5631899A (en) * 1995-05-31 1997-05-20 Lucent Technologies Inc. Acoustic echo canceler
GB2308283A (en) * 1995-12-16 1997-06-18 Ibm System and method for echo cancellation

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1816153B2 (en) * 1968-12-20 1971-04-15 CIRCUIT ARRANGEMENT FOR ECHO SUPPRESSION IN A TALK CIRCUIT ON A FOUR WIRE TRANSMISSION SYSTEM IN THE CASE OF A TRANSITION TO A TWO WIRE TRANSMISSION PATH
US4282411A (en) * 1979-06-04 1981-08-04 Tellabs, Inc. Residual echo suppressor for echo canceller
JPS56153850A (en) * 1980-04-28 1981-11-28 Kokusai Denshin Denwa Co Ltd <Kdd> Echo control system
FR2487144B1 (en) * 1980-07-21 1986-10-24 Trt Telecom Radio Electr DEVICE FOR CANCELING A COMPOSITE ECHO SIGNAL

Also Published As

Publication number Publication date
NL8204096A (en) 1983-05-16
JPS5881346A (en) 1983-05-16
DE3238564A1 (en) 1983-05-05
AU8965682A (en) 1983-04-28
KR840002179A (en) 1984-06-11
GB2109207A (en) 1983-05-25
FR2515454A1 (en) 1983-04-29
SE8205839L (en) 1983-04-24

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