JPS55100778A - Answer supervisory system - Google Patents

Answer supervisory system

Info

Publication number
JPS55100778A
JPS55100778A JP777679A JP777679A JPS55100778A JP S55100778 A JPS55100778 A JP S55100778A JP 777679 A JP777679 A JP 777679A JP 777679 A JP777679 A JP 777679A JP S55100778 A JPS55100778 A JP S55100778A
Authority
JP
Japan
Prior art keywords
variation
subscriber
current
answer
comparator com
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
JP777679A
Other languages
Japanese (ja)
Inventor
Nobuyoshi Akiyama
Shogo Usuda
Yoshinori Oikawa
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.)
NTT Inc
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 JP777679A priority Critical patent/JPS55100778A/en
Publication of JPS55100778A publication Critical patent/JPS55100778A/en
Pending legal-status Critical Current

Links

Landscapes

  • Devices For Supply Of Signal Current (AREA)
  • Interface Circuits In Exchanges (AREA)

Abstract

PURPOSE: To realize an easily-IC-implemented answer supervisory system which detects the answer of a called subscriber, by comparing the variation of a calling current when the called subscriber is called with a preset value.
CONSTITUTION: A calling signal from calling signal source IR is applied to a called subscriber not shown in the figure by way of switches S0 and S1. Denoting a signal current at the time of a subscriber's on-hook by Il, input VIN of comparator COM is expressed by VIN=-E0+R2Il. Once the subscriber answers, variation in impedance in a telephone set causes variation in signal current Il. Reference voltage Vref applied to comparator COM is so fixed adequately that its current variation can be detected by comparator COM.
COPYRIGHT: (C)1980,JPO&Japio
JP777679A 1979-01-26 1979-01-26 Answer supervisory system Pending JPS55100778A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP777679A JPS55100778A (en) 1979-01-26 1979-01-26 Answer supervisory system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP777679A JPS55100778A (en) 1979-01-26 1979-01-26 Answer supervisory system

Publications (1)

Publication Number Publication Date
JPS55100778A true JPS55100778A (en) 1980-07-31

Family

ID=11675069

Family Applications (1)

Application Number Title Priority Date Filing Date
JP777679A Pending JPS55100778A (en) 1979-01-26 1979-01-26 Answer supervisory system

Country Status (1)

Country Link
JP (1) JPS55100778A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5637793A (en) * 1979-09-05 1981-04-11 Hitachi Ltd Loop detecting circuit
JPS5888953A (en) * 1981-11-20 1983-05-27 Fujitsu Ltd Ring trip circuit
JPS60253358A (en) * 1984-05-30 1985-12-14 Fujitsu Ltd Ring trip circuit

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5637793A (en) * 1979-09-05 1981-04-11 Hitachi Ltd Loop detecting circuit
JPS5888953A (en) * 1981-11-20 1983-05-27 Fujitsu Ltd Ring trip circuit
JPS60253358A (en) * 1984-05-30 1985-12-14 Fujitsu Ltd Ring trip circuit

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