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JPS56156087A - Loop detecting circuit - Google Patents

Loop detecting circuit

Info

Publication number
JPS56156087A
JPS56156087A JP5973880A JP5973880A JPS56156087A JP S56156087 A JPS56156087 A JP S56156087A JP 5973880 A JP5973880 A JP 5973880A JP 5973880 A JP5973880 A JP 5973880A JP S56156087 A JPS56156087 A JP S56156087A
Authority
JP
Japan
Prior art keywords
line
case
phase
rrb
rra
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.)
Pending
Application number
JP5973880A
Other languages
Japanese (ja)
Inventor
Tadashi Nakanishi
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
NEC Corp
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.)
Filing date
Publication date
Application filed by NEC Corp, Nippon Electric Co Ltd filed Critical NEC Corp
Priority to JP5973880A priority Critical patent/JPS56156087A/en
Publication of JPS56156087A publication Critical patent/JPS56156087A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M3/00—Automatic or semi-automatic exchanges
    • H04M3/22—Arrangements for supervision, monitoring or testing
    • H04M3/2272—Subscriber line supervision circuits, e.g. call detection circuits

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Interface Circuits In Exchanges (AREA)

Abstract

PURPOSE:To obtain an accurate loop monitor information, by giving no operation in case the same phase is secured between the current flowing through a chip line and the current flowing through a link line and delivering information on a loop detection in the case of an opposite phase. CONSTITUTION:The directions of voltages across each of resistances Rra and Rrb are in an opposite phase to each other when the normal current flows and thus added to each other. Then a differential amplifier 20 is inverted to give information on a loop detection to an output 7. In case the in-phase current flows to a chip line and a ring line due to an induction of a power line or the like, the direction is equal between the voltage produced across the resistance Rra and the voltage caused across the resistance Rrb. These directions of voltages are offset to each other to cause no difference of potential between the input terminals of the amplifier 20.
JP5973880A 1980-05-06 1980-05-06 Loop detecting circuit Pending JPS56156087A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP5973880A JPS56156087A (en) 1980-05-06 1980-05-06 Loop detecting circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP5973880A JPS56156087A (en) 1980-05-06 1980-05-06 Loop detecting circuit

Publications (1)

Publication Number Publication Date
JPS56156087A true JPS56156087A (en) 1981-12-02

Family

ID=13121851

Family Applications (1)

Application Number Title Priority Date Filing Date
JP5973880A Pending JPS56156087A (en) 1980-05-06 1980-05-06 Loop detecting circuit

Country Status (1)

Country Link
JP (1) JPS56156087A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01314093A (en) * 1988-06-13 1989-12-19 Fujitsu Ltd Loop detection circuit

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52122015A (en) * 1976-04-06 1977-10-13 Nec Corp Line signal supervisor
JPS5439510A (en) * 1977-09-05 1979-03-27 Hitachi Ltd Detection circuit for outgoing call

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52122015A (en) * 1976-04-06 1977-10-13 Nec Corp Line signal supervisor
JPS5439510A (en) * 1977-09-05 1979-03-27 Hitachi Ltd Detection circuit for outgoing call

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01314093A (en) * 1988-06-13 1989-12-19 Fujitsu Ltd Loop detection circuit

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