GB2021358A - Line state detection circuit - Google Patents

Line state detection circuit

Info

Publication number
GB2021358A
GB2021358A GB7916180A GB7916180A GB2021358A GB 2021358 A GB2021358 A GB 2021358A GB 7916180 A GB7916180 A GB 7916180A GB 7916180 A GB7916180 A GB 7916180A GB 2021358 A GB2021358 A GB 2021358A
Authority
GB
United Kingdom
Prior art keywords
circuit
outputs
input
telephone line
line
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
GB7916180A
Other versions
GB2021358B (en
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.)
International Standard Electric Corp
Original Assignee
International Standard Electric 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 International Standard Electric Corp filed Critical International Standard Electric Corp
Publication of GB2021358A publication Critical patent/GB2021358A/en
Application granted granted Critical
Publication of GB2021358B publication Critical patent/GB2021358B/en
Expired 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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M19/00—Current supply arrangements for telephone systems
    • H04M19/02—Current supply arrangements for telephone systems providing ringing current or supervisory tones, e.g. dialling tone or busy tone
    • H04M19/026—Arrangements for interrupting the ringing current
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q1/00—Details of selecting apparatus or arrangements
    • H04Q1/18—Electrical details
    • H04Q1/30—Signalling arrangements; Manipulation of signalling currents
    • H04Q1/32—Signalling arrangements; Manipulation of signalling currents using trains of dc pulses

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Monitoring And Testing Of Exchanges (AREA)
  • Monitoring And Testing Of Transmission In General (AREA)

Abstract

To detect the condition-made or broken-of a telephone line (1g1, 1g2) a smoothing circuit (FC) is connected to one wire of that line, the smoothing circuit including a biassed diode (D) with resistors (R1, R2, R3) and a capacitor (C) to get rid of noise and other short- term line voltage fluctuations. The output of the smoothing circuit is connected to the input of a comparison circuit CC, which latter includes two voltage comparators AC1 and AC2. The comparison circuit input is connected to the non- inverting inputs of the comparators each of whose inverting input is connected to a reference voltage. For each comparator the two inputs are inter-connected via a diode. The comparator outputs are connected via respective NAND gates (ps1, ps2) to outputs (ss1, ss2) of the comparison circuit. The logic conditions of the two outputs, i.e. 00, 01, 10, 11, are inductive of the condition of the telephone line to which the circuit is connected. Its high input impedance means that it has little or no detrimental affect on the operation of the telephone line. <IMAGE>
GB7916180A 1978-05-17 1979-05-10 Line state detection circuit Expired GB2021358B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7814536A FR2426370A1 (en) 1978-05-17 1978-05-17 TRANSMISSION LINE STATUS DETECTION CIRCUIT

Publications (2)

Publication Number Publication Date
GB2021358A true GB2021358A (en) 1979-11-28
GB2021358B GB2021358B (en) 1982-04-21

Family

ID=9208313

Family Applications (1)

Application Number Title Priority Date Filing Date
GB7916180A Expired GB2021358B (en) 1978-05-17 1979-05-10 Line state detection circuit

Country Status (2)

Country Link
FR (1) FR2426370A1 (en)
GB (1) GB2021358B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4456791A (en) * 1981-03-11 1984-06-26 Telecommunications Radioelectriques Et Telephoniques T.R.T. Off-hook detector with reduced sensitivity to common mode
GB2173373A (en) * 1985-03-29 1986-10-08 Bhg Hiradastech Vallalat Hook state sensing circuit particularly for processor-controlled digital subexchanges
CN102346478A (en) * 2011-09-08 2012-02-08 重庆长安汽车股份有限公司 Circuit and method for detecting failures in data acquisition of overall controller of automobile

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4456791A (en) * 1981-03-11 1984-06-26 Telecommunications Radioelectriques Et Telephoniques T.R.T. Off-hook detector with reduced sensitivity to common mode
GB2173373A (en) * 1985-03-29 1986-10-08 Bhg Hiradastech Vallalat Hook state sensing circuit particularly for processor-controlled digital subexchanges
CN102346478A (en) * 2011-09-08 2012-02-08 重庆长安汽车股份有限公司 Circuit and method for detecting failures in data acquisition of overall controller of automobile
CN102346478B (en) * 2011-09-08 2013-04-03 重庆长安汽车股份有限公司 Circuit and method for detecting failures in data acquisition of overall controller of automobile

Also Published As

Publication number Publication date
FR2426370A1 (en) 1979-12-14
FR2426370B3 (en) 1980-12-19
GB2021358B (en) 1982-04-21

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Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee