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ES8704057A1 - A method of reducing echo in a digital switching system and a digital hybrid therefor - Google Patents

A method of reducing echo in a digital switching system and a digital hybrid therefor

Info

Publication number
ES8704057A1
ES8704057A1 ES547190A ES547190A ES8704057A1 ES 8704057 A1 ES8704057 A1 ES 8704057A1 ES 547190 A ES547190 A ES 547190A ES 547190 A ES547190 A ES 547190A ES 8704057 A1 ES8704057 A1 ES 8704057A1
Authority
ES
Spain
Prior art keywords
digital
signal
end subscriber
far end
input
Prior art date
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
ES547190A
Other languages
Spanish (es)
Other versions
ES547190A0 (en
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.)
Nokia Spain SA
Original Assignee
Alcatel Espana SA
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 Alcatel Espana SA filed Critical Alcatel Espana SA
Publication of ES547190A0 publication Critical patent/ES547190A0/en
Publication of ES8704057A1 publication Critical patent/ES8704057A1/en
Expired legal-status Critical Current

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
    • 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
    • H04B3/231—Echo cancellers using readout of a memory to provide the echo replica

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Interface Circuits In Exchanges (AREA)

Abstract

A method and digital hybrid circuit apparatus is disclosed for connecting a near end subscriber to a far end subscriber with the near end subscriber providing a digital input signal Vs which undesirably contains an interfering echo signal e(T). This signal is transmitted to a connected far end subscriber which far end subscriber provides a far end digital input signal VRX for reception by the near end subscriber. In order to eliminate the echo signal, first HA(f) and second HB(f) programmable coefficient digital filters have an input to receive the far end digital signal with the outputs of the filters coupled to an input of an adder 12, 16 with one input of each adder to receive the near end input signal, means 20 is provided for programming each of the filters with a different set of coefficients and logic means 25 are coupled to the output of the adders for comparing the average power output of each of the adders and means for selecting that filter and adder which provides the lowest value of average power and to employ those coefficients in filter HA(f) to thereby provide an output signal to be transmitted to the far end subscriber which contains a minimum level of the interfering echo signal.
ES547190A 1984-09-21 1985-09-20 A method of reducing echo in a digital switching system and a digital hybrid therefor Expired ES8704057A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US65374384A 1984-09-21 1984-09-21

Publications (2)

Publication Number Publication Date
ES547190A0 ES547190A0 (en) 1987-02-16
ES8704057A1 true ES8704057A1 (en) 1987-02-16

Family

ID=24622141

Family Applications (1)

Application Number Title Priority Date Filing Date
ES547190A Expired ES8704057A1 (en) 1984-09-21 1985-09-20 A method of reducing echo in a digital switching system and a digital hybrid therefor

Country Status (3)

Country Link
AU (1) AU4695485A (en)
ES (1) ES8704057A1 (en)
GB (1) GB2164828A (en)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ATE62365T1 (en) * 1986-01-30 1991-04-15 Siemens Ag ECHO COMPENSATOR.
NL8701633A (en) * 1987-07-10 1989-02-01 Philips Nv DIGITAL ECHO COMPENSATOR.
ATE235763T1 (en) * 1994-05-06 2003-04-15 Nippon Telegraph & Telephone METHOD FOR ECHO COMPENSATION AND ECHO PATH ESTIMATION
SE505150C3 (en) * 1995-10-18 1997-08-04 Ericsson Telefon Ab L M Adaptive dual filter echo leakage procedure
FI104524B (en) * 1997-04-18 2000-02-15 Nokia Mobile Phones Ltd An echo cancellation system and method and a mobile station
US6965640B2 (en) 2001-08-08 2005-11-15 Octasic Inc. Method and apparatus for generating a set of filter coefficients providing adaptive noise reduction
US6957240B2 (en) 2001-08-08 2005-10-18 Octasic Inc. Method and apparatus for providing an error characterization estimate of an impulse response derived using least squares
US6999509B2 (en) 2001-08-08 2006-02-14 Octasic Inc. Method and apparatus for generating a set of filter coefficients for a time updated adaptive filter
US6970896B2 (en) 2001-08-08 2005-11-29 Octasic Inc. Method and apparatus for generating a set of filter coefficients

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3787645A (en) * 1971-05-19 1974-01-22 Nippon Electric Co Echo canceller having two echo path models

Also Published As

Publication number Publication date
GB2164828A (en) 1986-03-26
AU4695485A (en) 1986-03-27
ES547190A0 (en) 1987-02-16
GB8523031D0 (en) 1985-10-23

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Legal Events

Date Code Title Description
FD1A Patent lapsed

Effective date: 20031001