WO1997024853A3 - Echo reduction for telephone communication system - Google Patents

Echo reduction for telephone communication system Download PDF

Info

Publication number
WO1997024853A3
WO1997024853A3 PCT/US1996/020149 US9620149W WO9724853A3 WO 1997024853 A3 WO1997024853 A3 WO 1997024853A3 US 9620149 W US9620149 W US 9620149W WO 9724853 A3 WO9724853 A3 WO 9724853A3
Authority
WO
WIPO (PCT)
Prior art keywords
telephone communication
band filter
stop band
transmission path
multiple stop
Prior art date
Application number
PCT/US1996/020149
Other languages
French (fr)
Other versions
WO1997024853A2 (en
Inventor
William Christopher Hardy
Original Assignee
Mci Communications Corp
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 Mci Communications Corp filed Critical Mci Communications Corp
Publication of WO1997024853A2 publication Critical patent/WO1997024853A2/en
Publication of WO1997024853A3 publication Critical patent/WO1997024853A3/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
    • H04B3/21—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a set of bandfilters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M9/00—Arrangements for interconnection not involving centralised switching
    • H04M9/08—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic
    • H04M9/087—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic using different frequency bands for transmitting and receiving paths ; using phase shifting arrangements

Landscapes

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

Abstract

An efficient and cost effective method and apparatus to control echo in long distance telephone communication systems are provided. A first multiple stop band filter is connected to a first transmission path. The first multiple stop band filter is used to remove a first set of frequency components from the transmission signals within the first transmission path. A second multiple stop band filter is connected to a second transmission path. The second multiple stop band filter is used to remove a second set of complementary frequency components from the transmission signals within the second transmission path.
PCT/US1996/020149 1995-12-29 1996-12-30 Echo reduction for telephone communication system WO1997024853A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US58071495A 1995-12-29 1995-12-29
US08/580,714 1995-12-29

Publications (2)

Publication Number Publication Date
WO1997024853A2 WO1997024853A2 (en) 1997-07-10
WO1997024853A3 true WO1997024853A3 (en) 1997-09-12

Family

ID=24322233

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1996/020149 WO1997024853A2 (en) 1995-12-29 1996-12-30 Echo reduction for telephone communication system

Country Status (1)

Country Link
WO (1) WO1997024853A2 (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3622714A (en) * 1969-09-02 1971-11-23 Bell Telephone Labor Inc Telephonic transmission using complementary comb filters
DE3706540A1 (en) * 1986-03-03 1987-09-10 Head Stereo Gmbh Device for improving the return loss or loop gain in intercom devices

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3622714A (en) * 1969-09-02 1971-11-23 Bell Telephone Labor Inc Telephonic transmission using complementary comb filters
DE3706540A1 (en) * 1986-03-03 1987-09-10 Head Stereo Gmbh Device for improving the return loss or loop gain in intercom devices

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
WALKER M: "HANDSFREE SPEAKING - A STEP TOWARDS NATURAL COMMUNICATION", ELECTRICAL COMMUNICATION, 1 January 1993 (1993-01-01), pages 181 - 187, XP000368137 *

Also Published As

Publication number Publication date
WO1997024853A2 (en) 1997-07-10

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