GB1380944A – Echo canceller having two echo path models
– Google Patents
GB1380944A – Echo canceller having two echo path models
– Google Patents
Echo canceller having two echo path models
Info
Publication number
GB1380944A
GB1380944A
GB2350272A
GB2350272A
GB1380944A
GB 1380944 A
GB1380944 A
GB 1380944A
GB 2350272 A
GB2350272 A
GB 2350272A
GB 2350272 A
GB2350272 A
GB 2350272A
GB 1380944 A
GB1380944 A
GB 1380944A
Authority
GB
United Kingdom
Prior art keywords
signal
echo
echo path
outgoing
path model
Prior art date
1971-05-19
Legal status (The legal status 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 status listed.)
Expired
Application number
GB2350272A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
Nippon Electric Co Ltd
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.)
1971-05-19
Filing date
1972-05-18
Publication date
1975-01-22
1971-05-19
Priority claimed from JP3385871A
external-priority
patent/JPS5635052B1/ja
1971-08-13
Priority claimed from JP6173671A
external-priority
patent/JPS5429847B2/ja
1972-05-18
Application filed by Nippon Electric Co Ltd
filed
Critical
Nippon Electric Co Ltd
1975-01-22
Publication of GB1380944A
publication
Critical
patent/GB1380944A/en
Status
Expired
legal-status
Critical
Current
Links
Espacenet
Global Dossier
Discuss
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
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
Abstract
1380944 Echo suppressors NIPPON ELECTRIC CO Ltd 18 May 1972 [19 May 1971 13 Aug 1971] 23502/72 Heading H4R An echo suppressor for cancelling the echo signal appearing from the actual echo path comprises self-adaptive means provided with a first echo path model approximating the characteristics of said echo path and further comprises a second echo path model approximating said characteristics, means for comparing the models, and means responsive to the results of comparison for substituting one of said echo path models for the other. The second echo path model is included to overcome problems that arise in known echo suppressors employing self adaptive echo path models when both parties on a telephone connection are talking simultaneously. Fig. 1 shows the general arrangement of one embodiment in which the echo suppressor bridges an incoming one way path 11 and an outgoing one way path 12 of a four-wire line 13 connected to a two-wire line 14 through a hybrid circuit 15, which delivers in practice a fraction of the incoming signal to the outgoing path 12 as an echo signal. The echo suppressor comprises a first echo path model unit 21 connected to the incoming path 11 for modifying or processing the incoming received signal x in conformity with a first echo path model or a first set of parameters h1 contained therein to # produce a first synthesized echo signal y 1 ; a first combining circuit 22 for combining the first synthesized signal with the outgoing received signal y to produce a first combined signal e 1 ; and means symbolically depicted by a connection 23 for adjusting the first set of parameters h 1 in compliance with the outgoing received signal y and the first combined signal e 1 . A second echo path model unit 26 is connected to the incoming one-way path 11 for modifying the incoming received signal x in conformity with a second set of parameters h 2 contained therein to produce a second syn- # thesized echo signal y 2 ; a second combining circuit 27 interposed in the outgoing one-way path 12 for combining the second synthesized signal with the outgoing received signal y to produce a second combined signal e 2 which is delivered through the outgoing path 12 to the remote end as the outgoing transmitted signal; an echo path model comparing circuit 28 supplied with the first and second combined signals for producing a command signal when the short-time average of the former is smaller by a predetermined threshold than that of the latter; and a switching circuit or gate 29 responsive to the command signal for substituting the contents of the first echo path model unit 21 for the contents of the second echo path model unit 26. In this arrangement the signal e 2 supplied to the outgoing path is that produced by the second echo path model which is not self adaptive and has its characteristics h 2 altered to those, h 1 of the first echo path model where the latter results in a first combined signal e 1 which is freer of echo, and therefore on average lower in amplitude, than the second combined signal, or outgoing signal, e 2 . Hence when the parameters h 1 of the first echo path model are distorted due to a non-echo signal in the outgoing signal e 2 , the second echo path model previously derived from the first echo path model continues to be used until the first echo path model again yields a signal e 1 which is freer of echo than the signal e 2 . In a second embodiment (Fig. 5, not shown) the parameters of the second echo path model can be written into the first echo path model and vice versa according to which model is giving the better results. Either the first or second combined signals e 1 or e 2 can then be used as the outgoing signal. It is to be noted that the purpose of having the first echo path model self adaptive is to allow for changes in the transmission properties of the hybrid 15. When there is no speech to be transmitted from the hybrid 15, the first echo path model should self adapt to yield a zero outgoing signal e 2 (e 1 ). Two detailed arrangements for use as the echo path model arrangements of Fig. 1 are described. The first (Fig. 3, not shown) is based on sampling the incoming signal x on line 11 and the outgoing-received signal y on line 12 in successive time intervals, and involves converting all speech to digital form before performing the various steps necessary for producing the signals e 1 , e 2 which are then time samples in digital form, a final digital-analogue converter yielding the outgoing signal. Shift registers are then used for storing the echo path model characteristics h 1 , h 2 in digital form. The second arrangement (Fig. 4, not shown) is based on the frequency content of the signals and involves fourier transforming successive samples of the signals. The characteristics h 1 , h 2 are then a non-linear conversion of the fourier transformers of the first combined signal e 1 . A full description of the arrangement of Figs. 3 and 4 is given in the Specification; examples of a suitable comparing circuit 28 are also described. U.S. Specifications 3,465,106, 3,499,999 and 3,500,000 are referred to.
GB2350272A
1971-05-19
1972-05-18
Echo canceller having two echo path models
Expired
GB1380944A
(en)
Applications Claiming Priority (2)
Application Number
Priority Date
Filing Date
Title
JP3385871A
JPS5635052B1
(en)
1971-05-19
1971-05-19
JP6173671A
JPS5429847B2
(en)
1971-08-13
1971-08-13
Publications (1)
Publication Number
Publication Date
GB1380944A
true
GB1380944A
(en)
1975-01-22
Family
ID=26372630
Family Applications (1)
Application Number
Title
Priority Date
Filing Date
GB2350272A
Expired
GB1380944A
(en)
1971-05-19
1972-05-18
Echo canceller having two echo path models
Country Status (5)
Country
Link
US
(1)
US3787645A
(en)
CA
(1)
CA949247A
(en)
DE
(1)
DE2224403C3
(en)
GB
(1)
GB1380944A
(en)
IT
(1)
IT955642B
(en)
Cited By (1)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
GB2164529A
(en)
*
1984-09-12
1986-03-19
Plessey Co Plc
Echo canceller
Families Citing this family (41)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
DE2334546C2
(en)
*
1973-07-06
1982-05-27
Siemens AG, 1000 Berlin und 8000 München
Echo canceller
GB1434239A
(en)
*
1972-08-10
1976-05-05
Siemens Ag
Echo cancellers
JPS51144111A
(en)
*
1975-06-05
1976-12-10
Kokusai Denshin Denwa Co Ltd
Echo cancelling method
JPS5737937A
(en)
*
1980-08-15
1982-03-02
Hitachi Ltd
Automatic hybrid circuit
US4669115A
(en)
*
1981-12-07
1987-05-26
Regents Of The University Of California
Hybrid circuit and method
US4621172A
(en)
*
1982-12-22
1986-11-04
Nec Corporation
Fast convergence method and system for echo canceller
US4628156A
(en)
*
1982-12-27
1986-12-09
International Business Machines Corporation
Canceller trained echo suppressor
US4574166A
(en)
*
1983-02-04
1986-03-04
At&T Bell Laboratories
Tandem adaptive filter arrangement
US4554417A
(en)
*
1983-02-04
1985-11-19
At&T Bell Laboratories
Tandem adaptive echo canceler arrangement
JPS59151546A
(en)
*
1983-02-18
1984-08-30
Nec Corp
Adaptive type echo cancellor
FR2556530B1
(en)
*
1983-10-28
1986-04-04
Telediffusion Fse
ECHO CORRECTION DEVICE, ESPECIALLY FOR A DATA BROADCASTING SYSTEM
US4707824A
(en)
*
1983-12-15
1987-11-17
Nec Corporation
Method and apparatus for cancelling echo
AU4695485A
(en)
*
1984-09-21
1986-03-27
Alcatel N.V.
Digital hybrid
US4805215A
(en)
*
1986-10-01
1989-02-14
Racal Data Communications Inc.
Adaptive echo canceller with sparse dynamically positioned taps
NL8701633A
(en)
*
1987-07-10
1989-02-01
Philips Nv
DIGITAL ECHO COMPENSATOR.
GB2237483A
(en)
*
1989-10-11
1991-05-01
Plessey Co Plc
An adaptive fir filter having restricted coefficient ranges
US5809463A
(en)
*
1995-09-15
1998-09-15
Hughes Electronics
Method of detecting double talk in an echo canceller
SE505150C3
(en)
1995-10-18
1997-08-04
Ericsson Telefon Ab L M
Adaptive dual filter echo leakage procedure
JP3199155B2
(en)
*
1995-10-18
2001-08-13
日本電信電話株式会社
Echo canceller
SE517602C2
(en)
*
1995-10-20
2002-06-25
Ericsson Telefon Ab L M
Locked loop
US5978473A
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*
1995-12-27
1999-11-02
Ericsson Inc.
Gauging convergence of adaptive filters
KR100233463B1
(en)
*
1997-03-07
1999-12-01
윤종용
Apparatus and method for noise cancellation
US6256383B1
(en)
*
1997-11-07
2001-07-03
Legerity, Inc.
IIR filter of adaptive balance circuit for long tail echo cancellation
US6031908A
(en)
*
1997-11-14
2000-02-29
Tellabs Operations, Inc.
Echo canceller employing dual-H architecture having variable adaptive gain settings
US6240180B1
(en)
1997-11-14
2001-05-29
Tellabs Operations, Inc.
Echo canceller employing dual-H architecture having split adaptive gain settings
US6181793B1
(en)
1997-11-14
2001-01-30
Tellabs Operations, Inc.
Echo canceller employing dual-H architecture having improved coefficient transfer
US6028929A
(en)
*
1997-11-14
2000-02-22
Tellabs Operations, Inc.
Echo canceller employing dual-H architecture having improved non-linear echo path detection
US6266409B1
(en)
*
1997-11-14
2001-07-24
Tellabs Operations, Inc.
Echo canceller employing dual-H architecture having improved double-talk detection
US6198819B1
(en)
*
1997-11-14
2001-03-06
Tellabs Operations, Inc.
Echo canceller having improved non-linear processor
JP3566158B2
(en)
*
1999-12-07
2004-09-15
三菱電機株式会社
Echo canceller device
US7164659B2
(en)
*
1999-12-09
2007-01-16
Broadcom Corporation
Adaptive gain control based on echo canceller performance information
US7085245B2
(en)
*
2001-11-05
2006-08-01
3Dsp Corporation
Coefficient domain history storage of voice processing systems
US7817797B2
(en)
*
2006-06-07
2010-10-19
Mitel Networks Corporation
Method and apparatus for detecting echo path changes in an acoustic echo canceller
US20080080702A1
(en)
*
2006-10-03
2008-04-03
Santera Systems, Inc.
Method, System, and Computer-Readable Medium for Calculating an Echo Path Delay
US8411871B2
(en)
*
2007-08-22
2013-04-02
Lantiq Deutschland Gmbh
Echo cancellation
US9076426B2
(en)
2011-12-20
2015-07-07
Avago Technologies General Ip (Singapore) Pte. Ltd.
Training an echo canceller in severe noise
GB201309779D0
(en)
2013-05-31
2013-07-17
Microsoft Corp
Echo removal
GB201309771D0
(en)
*
2013-05-31
2013-07-17
Microsoft Corp
Echo removal
GB201309777D0
(en)
2013-05-31
2013-07-17
Microsoft Corp
Echo suppression
GB201309773D0
(en)
2013-05-31
2013-07-17
Microsoft Corp
Echo removal
CN109309764B
(en)
*
2017-07-28
2021-09-03
北京搜狗科技发展有限公司
Audio data processing method and device, electronic equipment and storage medium
Family Cites Families (3)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
US3499999A
(en)
*
1966-10-31
1970-03-10
Bell Telephone Labor Inc
Closed loop adaptive echo canceller using generalized filter networks
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
US3732410A
(en)
*
1969-12-22
1973-05-08
Postmaster Department Res Labo
Self adaptive filter and control circuit therefor
1972
1972-05-17
US
US00254071A
patent/US3787645A/en
not_active
Expired – Lifetime
1972-05-18
CA
CA142,520A
patent/CA949247A/en
not_active
Expired
1972-05-18
GB
GB2350272A
patent/GB1380944A/en
not_active
Expired
1972-05-18
DE
DE2224403A
patent/DE2224403C3/en
not_active
Expired
1972-05-18
IT
IT24542/72A
patent/IT955642B/en
active
Cited By (1)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
GB2164529A
(en)
*
1984-09-12
1986-03-19
Plessey Co Plc
Echo canceller
Also Published As
Publication number
Publication date
CA949247A
(en)
1974-06-11
DE2224403C3
(en)
1983-12-22
US3787645A
(en)
1974-01-22
DE2224403B2
(en)
1975-01-30
IT955642B
(en)
1973-09-29
DE2224403A1
(en)
1973-03-22
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Legal Events
Date
Code
Title
Description
1975-06-04
PS
Patent sealed [section 19, patents act 1949]
1992-06-17
PE20
Patent expired after termination of 20 years
