Patent US2769787A successfully refreshed from Google Patents.
Patent US4935959A successfully refreshed from Google Patents.
US4935959A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Two-wire telecommunications line detection arrangements
Assignee: Nortel Networks Ltd
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Filing: 1989-04-28
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Granted: 1990-06-19
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Expires: 2009-04-28
Abstract
Abstract A loop closure detector for a two-wire telephone line comprises a four-arm resistive bridge, in which the four arms are constituted respectively by a first battery feed resistor, the two-wire line in series with a second battery feed resistor, and two resistors forming a potential divider across the battery voltage which is coupled across one diagonal of the bridge. A voltage sensing circuit, constituted by a comparator or a light emitting diode, is connected across the other diagonal of the bridge to provide an output representing a loop closure state of the line. A ring-ground detector is also described using a similar bridge and voltage sensing arrangements.
Inventors
- 👤 Milan Markovic
- 👤 Alexander Shtulman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:21
CPC Classifications
H; H04; H04B; H04B3/00; H04M; H04M3/00; H04M3/22; H04M3/2272
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
94 words
A loop closure detector for a two-wire telecommunications line, comprising: two battery feed resistors for coupling respective wires of the line to a supply voltage and ground, a junction between one of the battery feed resistors and the respective wire of the line defining a first junction point; a potential divider coupled between the supply voltage and ground and defining a second junction point; and voltage comparison means connected to the first and second junction points and responsive to differential voltage therebetween for providing an output representing a loop closure state of the line.
Claim 2
Dependent Claim
94 words
A loop closure detector for a two-wire telecommunications line, comprising: two battery feed resistors for coupling respective wires of the line to a supply voltage and ground, a junction between one of the battery feed resistors and the respective wire of the line defining a first junction point; a potential divider coupled between the supply voltage and ground and defining a second junction point; and voltage comparison means connected to the first and second junction points and responsive to differential voltage therebetween for providing an output representing a loop closure state of the line.
Claim 3
Dependent Claim
17 words
A detector as claimed in claim 1 wherein the voltage comparison means comprises a light emitting diode.
Claim 4
Dependent Claim
95 words
A ring-ground detector for a two-wire telecommunications line, comprising: first and second resistors, coupled in series and defining a first junction point therebetween, for coupling a ring wire of the line to a supply voltage; a potential divider coupled between the supply voltage and ground and defining a second junction point; and voltage comparison means connected to the first and second junction points and responsive to differential voltage therebetween for providing an output representative of whether or not the ring wire is connected to ground at an end of the line remote from the detector.
Claim 5
Dependent Claim
95 words
A ring-ground detector for a two-wire telecommunications line, comprising: first and second resistors, coupled in series and defining a first junction point therebetween, for coupling a ring wire of the line to a supply voltage; a potential divider coupled between the supply voltage and ground and defining a second junction point; and voltage comparison means connected to the first and second junction points and responsive to differential voltage therebetween for providing an output representative of whether or not the ring wire is connected to ground at an end of the line remote from the detector.
Claim 6
Dependent Claim
17 words
A detector as claimed in claim 9 wherein the voltage comparison means comprises a light emitting diode.
References Cited (Backward Citations)
GB1201093A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-18 | 1993-12-18 | 1994-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-18 | 1997-12-18 | 1998-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-18 | 2001-12-18 | 2002-06-19 | $7700.00 | Window Closed / Lapsed |