GB1489143A - Subscriber line interface circuit - Google Patents

Subscriber line interface circuit

Info

Publication number
GB1489143A
GB1489143A GB4527475A GB4527475A GB1489143A GB 1489143 A GB1489143 A GB 1489143A GB 4527475 A GB4527475 A GB 4527475A GB 4527475 A GB4527475 A GB 4527475A GB 1489143 A GB1489143 A GB 1489143A
Authority
GB
United Kingdom
Prior art keywords
line
circuits
circuit
feed
voltage
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.)
Expired
Application number
GB4527475A
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 Business Machines Corp
Original Assignee
International Business Machines 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 Business Machines Corp filed Critical International Business Machines Corp
Publication of GB1489143A publication Critical patent/GB1489143A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M19/00—Current supply arrangements for telephone systems
    • H04M19/001—Current supply source at the exchanger providing current to substations
    • H04M19/005—Feeding arrangements without the use of line transformers

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Signal Processing (AREA)
  • Devices For Supply Of Signal Current (AREA)
  • Interface Circuits In Exchanges (AREA)

Abstract

1489143 Automatic exchange systems INTERNATIONAL BUSINESS MACHINES CORP 31 Oct 1975 [23 Dec 1974] 45274/75 Heading H4K In a subscriber's line circuit one wire 15 of the subscriber's line is connected via a feed circuit 35 and a selection circuit 46 to two terminals, - 30 V., - 48 V. of a power supply, the selection circuits having control inputs A, Z, RC for governing to which of the two supply voltages the wire 15 is connected. The voltage of - 30 V. is applied if the handset 11 is on-hook (Z= 1), or if ringing current is applied (RC = 1) or if the line current is above an upper tolerance level VH (A>VH). The voltage of -48 V. is only applied if the handset is off-hook (Z = 0) and the line current is below a lower tolerance level VL (A<VL). Fig. 3B (not shown) illustrates a logic circuit realization of the selection circuit 46. The feed circuits 34, 35, Fig. 2, comprise socalled gyrator circuits, e.g. 34a, which for D.C. current approximates to resistances whereas for A.C. currents they each approximate to an inductance in series with a resistance, the inductance being given by L=R3.R2.C1. Where no varistor circuitry is included in the substation circuits components Z2, T3 and R5, Fig. 2, are omitted from each feed circuit and a changeover of supply voltage requires no modification of these circuits. However, if varistor circuitry is included it is necessary to maintain the line current constant on voltage changeover and transistor T3 is turned off by a signal B from the selection circuit when the voltage is switched to - 30 V. and the Zener diode Z2 acts to maintain the line current constant. Transistor T2 is switched on to inhibit the feed circuit during ringing, by using a signal RX derived from the selection circuit. A differential amplifier arrangement 44, 45 (Fig. 1) is used to eliminate echoes which may occur due to the signal 52 on line 18 being fed via the feed circuits 34, 35 to the line 26; the circuit 45 is therefore designed to simulate the feed circuits in this respect. Diode arrangements 36-38, 40-43 are used to limit signal amplitude levels. Components 19, 20 constitute the line terminating impedance.
GB4527475A 1974-12-23 1975-10-31 Subscriber line interface circuit Expired GB1489143A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH1721974A CH586983A5 (en) 1974-12-23 1974-12-23

Publications (1)

Publication Number Publication Date
GB1489143A true GB1489143A (en) 1977-10-19

Family

ID=4423686

Family Applications (1)

Application Number Title Priority Date Filing Date
GB4527475A Expired GB1489143A (en) 1974-12-23 1975-10-31 Subscriber line interface circuit

Country Status (5)

Country Link
JP (1) JPS5929985B2 (en)
CH (1) CH586983A5 (en)
DE (1) DE2551916C3 (en)
FR (1) FR2296325A1 (en)
GB (1) GB1489143A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4139608A1 (en) * 1991-11-30 1993-06-03 Siemens Nixdorf Inf Syst Supply voltage setting system for communications subscriber circuit - uses detected loop circuit resistance upon initial connection of subscriber circuit to 2=wire subscriber line
WO1993020645A1 (en) * 1992-04-03 1993-10-14 Northern Telecom Limited Telephone line interface circuit with voltage switching
US5323461A (en) * 1991-01-31 1994-06-21 Northern Telecom Limited Telephone line interface circuit with voltage switching
US5323453A (en) * 1990-03-15 1994-06-21 Telefonaktiebolaget L M Ericsson Power down feed
CN105812590A (en) * 2016-05-11 2016-07-27 福建星网智慧科技股份有限公司 Switching method for long line feed and short line feed of user line

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2655005C3 (en) * 1976-12-02 1980-04-17 Deutsche Telephonwerke Und Kabelindustrie Ag, 1000 Berlin Circuit arrangement for an electronic subscriber feed
NL7614118A (en) * 1976-12-20 1978-06-22 Philips Nv CIRCUIT FOR PROTECTING TELEPHONE LINES.
JPS54151307A (en) * 1978-05-19 1979-11-28 Nec Corp Supply circuit for communication current
US4254305A (en) * 1979-02-07 1981-03-03 International Telephone And Telegraph Corporation Current limited subscriber line feed circuit
NL7903663A (en) * 1979-05-10 1980-11-12 Philips Nv AMPLIFIER FOR APPLICATION IN A LINE CIRCUIT.
NL7903664A (en) * 1979-05-10 1980-11-12 Philips Nv LINE CIRCUIT.
NL7903662A (en) * 1979-05-10 1980-11-12 Philips Nv LINE CIRCUIT.
US4315106A (en) * 1979-11-28 1982-02-09 International Telephone And Telegraph Corporation Apparatus for regulating current supplied to a telephone line signal of the type employed in digital telephone systems
GB2065418B (en) * 1979-12-06 1984-02-15 Standard Telephones Cables Ltd Telephone line feed
DE3369445D1 (en) * 1982-02-25 1987-02-26 Siemens Ag Circuit arrangement for telecommunication installations, especially for telephone exchange installations, with direct voltage converters
JPS5983452A (en) * 1982-11-05 1984-05-14 Fujitsu Ltd Dc current supply system in exchange
IT1214603B (en) * 1985-04-30 1990-01-18 Ates Componenti Elettron TELEPHONE CIRCUIT, MONOLITHICALLY INTEGRABLE, FOR THE SUPPLY OF A USER TELEPHONE LINE.
DE4233682A1 (en) * 1992-10-02 1994-04-07 Deutsche Telephonwerk Kabel Circuit arrangement for the supply of digital devices

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5323453A (en) * 1990-03-15 1994-06-21 Telefonaktiebolaget L M Ericsson Power down feed
US5323461A (en) * 1991-01-31 1994-06-21 Northern Telecom Limited Telephone line interface circuit with voltage switching
DE4139608A1 (en) * 1991-11-30 1993-06-03 Siemens Nixdorf Inf Syst Supply voltage setting system for communications subscriber circuit - uses detected loop circuit resistance upon initial connection of subscriber circuit to 2=wire subscriber line
WO1993020645A1 (en) * 1992-04-03 1993-10-14 Northern Telecom Limited Telephone line interface circuit with voltage switching
CN105812590A (en) * 2016-05-11 2016-07-27 福建星网智慧科技股份有限公司 Switching method for long line feed and short line feed of user line

Also Published As

Publication number Publication date
CH586983A5 (en) 1977-04-15
DE2551916B2 (en) 1981-07-02
DE2551916A1 (en) 1976-11-04
JPS5186908A (en) 1976-07-30
FR2296325A1 (en) 1976-07-23
DE2551916C3 (en) 1982-02-25
JPS5929985B2 (en) 1984-07-24
FR2296325B1 (en) 1981-03-06

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Legal Events

Date Code Title Description
PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee