JPS57109449A - Call detecting circuit - Google Patents

Call detecting circuit

Info

Publication number
JPS57109449A
JPS57109449A JP18377180A JP18377180A JPS57109449A JP S57109449 A JPS57109449 A JP S57109449A JP 18377180 A JP18377180 A JP 18377180A JP 18377180 A JP18377180 A JP 18377180A JP S57109449 A JPS57109449 A JP S57109449A
Authority
JP
Japan
Prior art keywords
line
contact
voltage
call
capacitor
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
JP18377180A
Other languages
Japanese (ja)
Other versions
JPS6159582B2 (en
Inventor
Masao Uchiumi
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Priority to JP18377180A priority Critical patent/JPS57109449A/en
Publication of JPS57109449A publication Critical patent/JPS57109449A/en
Publication of JPS6159582B2 publication Critical patent/JPS6159582B2/ja
Granted legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/82—Line monitoring circuits for call progress or status discrimination

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Monitoring And Testing Of Exchanges (AREA)

Abstract

PURPOSE:To detect a channel stably and surely, by storing a momentary value of the AC signal under the connection state of the line between a calling subscriber and a called subscriber and by comparing the stored value with the succeeding state. CONSTITUTION:An oscillator 8 is connected to a line. For a call, the polarity of the line is inverted. When detecting the inversion, a relay 1 controls a contact 21 so that the contact 21 is opened after closing for a constant time. When the contact 21 is closed, the output voltage of an amplifier 12 rectified by a rectifier 13 is stored in a capacitor 17. Since the capacitor 17 is connected to the gate of an FET 16 operated as a source follower, the capacitor 17 holds the voltage even if the contact 21 is opened. Consequently, the source voltage is equal to the voltage supplied from the oscillator under the connection state of the line. If the calling subscriber stops the call, the impedance of the line becomes high, and as the result, the voltage in one terminal of a comparator 14 is lowered to generate an output from the comparator 14, thus detecting the stop of the call.
JP18377180A 1980-12-26 1980-12-26 Call detecting circuit Granted JPS57109449A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP18377180A JPS57109449A (en) 1980-12-26 1980-12-26 Call detecting circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP18377180A JPS57109449A (en) 1980-12-26 1980-12-26 Call detecting circuit

Publications (2)

Publication Number Publication Date
JPS57109449A true JPS57109449A (en) 1982-07-07
JPS6159582B2 JPS6159582B2 (en) 1986-12-17

Family

ID=16141665

Family Applications (1)

Application Number Title Priority Date Filing Date
JP18377180A Granted JPS57109449A (en) 1980-12-26 1980-12-26 Call detecting circuit

Country Status (1)

Country Link
JP (1) JPS57109449A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63198250U (en) * 1987-06-09 1988-12-20

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55100776A (en) * 1979-01-26 1980-07-31 Nippon Telegr & Teleph Corp <Ntt> Answer supervisory system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55100776A (en) * 1979-01-26 1980-07-31 Nippon Telegr & Teleph Corp <Ntt> Answer supervisory system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63198250U (en) * 1987-06-09 1988-12-20
JPH054362Y2 (en) * 1987-06-09 1993-02-03

Also Published As

Publication number Publication date
JPS6159582B2 (en) 1986-12-17

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