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JPS57133754A - Conference telephone set - Google Patents

Conference telephone set

Info

Publication number
JPS57133754A
JPS57133754A JP1953381A JP1953381A JPS57133754A JP S57133754 A JPS57133754 A JP S57133754A JP 1953381 A JP1953381 A JP 1953381A JP 1953381 A JP1953381 A JP 1953381A JP S57133754 A JPS57133754 A JP S57133754A
Authority
JP
Japan
Prior art keywords
circuit
amplitude
tau
compression
output
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.)
Granted
Application number
JP1953381A
Other languages
Japanese (ja)
Other versions
JPH028508B2 (en
Inventor
Kenzo Takahashi
Takashi Sakamoto
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.)
Nippon Telegraph and Telephone Corp
Original Assignee
Nippon Telegraph and Telephone 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 Nippon Telegraph and Telephone Corp filed Critical Nippon Telegraph and Telephone Corp
Priority to JP1953381A priority Critical patent/JPS57133754A/en
Publication of JPS57133754A publication Critical patent/JPS57133754A/en
Publication of JPH028508B2 publication Critical patent/JPH028508B2/ja
Granted legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M3/00—Automatic or semi-automatic exchanges
    • H04M3/42—Systems providing special services or facilities to subscribers
    • H04M3/56—Arrangements for connecting several subscribers to a common circuit, i.e. affording conference facilities
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M3/00—Automatic or semi-automatic exchanges
    • H04M3/002—Applications of echo suppressors or cancellers in telephonic connections

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)

Abstract

PURPOSE:To assure the quality of communication almost the same quality for communication between two parties, by providing an echo erase circuit, addition circuit and overload preventing circuit with a conference telephone device and determining the compression rate of added output at each sampling interval. CONSTITUTION:When a conference telephone device 1 enters operating state, a transmission signal via an A/D conversion circuit 2 and an echo erase circuit 3 is added with other trasmission signals at an addition circuit 4. The circuit 5 matches the added output with a reception signal. Taking the sampling of the Nyquist as an interval of tau/N, the value of the addition output Zi durin the time tau is stored in the circuit 5 and a compression signal Ri is outputted with a delay of tau. A compression function is selected so that the Zi is attenuated from the point of time exceeding the amplitude 17 and converged into an operating point 24 equal to the amplitude 17 at an amplitude 20 gradually. The compression rate is changed at each one sampling interval, and the compression is stopped after time tau from a time 26 to obtain Ri=Zi. Thus, the output Ri of the circuit 5 is within a maximum amplitude em, allowing to prevent the overload.
JP1953381A 1981-02-12 1981-02-12 Conference telephone set Granted JPS57133754A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP1953381A JPS57133754A (en) 1981-02-12 1981-02-12 Conference telephone set

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1953381A JPS57133754A (en) 1981-02-12 1981-02-12 Conference telephone set

Publications (2)

Publication Number Publication Date
JPS57133754A true JPS57133754A (en) 1982-08-18
JPH028508B2 JPH028508B2 (en) 1990-02-26

Family

ID=12001964

Family Applications (1)

Application Number Title Priority Date Filing Date
JP1953381A Granted JPS57133754A (en) 1981-02-12 1981-02-12 Conference telephone set

Country Status (1)

Country Link
JP (1) JPS57133754A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4741025A (en) * 1985-03-01 1988-04-26 Nec Corporation Speech additive distribution equipment for conferencing system

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54136208A (en) * 1978-04-14 1979-10-23 Toshiba Corp Telephone exchanger
JPS54139411A (en) * 1978-04-21 1979-10-29 Nec Corp Conference trunk circuit

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54136208A (en) * 1978-04-14 1979-10-23 Toshiba Corp Telephone exchanger
JPS54139411A (en) * 1978-04-21 1979-10-29 Nec Corp Conference trunk circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4741025A (en) * 1985-03-01 1988-04-26 Nec Corporation Speech additive distribution equipment for conferencing system

Also Published As

Publication number Publication date
JPH028508B2 (en) 1990-02-26

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