US4049919A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Communication system trunk circuit
Assignee: AG Communication Systems Corp
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Filing: 1976-11-03
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Granted: 1977-09-20
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Expires: 1996-11-03
Abstract
Abstract A trunk circuit for interconnecting an electronic and a step-by-step electromechanical switching exchange including a sensing circuit that is transparent to the transmission and supervisory signals. The sensing circuit consists of a pair of voltage dividers composed of at least four resistors each with the midpoint of each voltage divider connected to a voltage differential detecting means. The midpoints of the voltage dividers have substantially equal voltage levels in one state of the transmission path and have a measurable voltage differential in another state of the transmission path. Under conditions where a subscriber flash signal is not to be propagated through, the voltage dividers are arranged to have their resistance decreased, simulating an off-hook condition.
Inventors
- 👤 John S. Young
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 21:14
CPC Classifications
H; H04; H04M; H04M7/00; H04M7/0096
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
301 words
An electronic sensing circuit for use with a telephone communication circuit of two-wire configuration and including off-hook and on-hook conditions, comprising: a first voltage divider network including a first and a second pair of series connected resistor elements having a mid-point connection between said pairs of series connected resistors and having one circuit end thereof connected to a first wire of said two-wire communication circuit and the other circuit end thereof connected to a voltage supply source, a second voltage divider network including another two pairs of series connected resistor elements having a mid-point connection between said pairs of series connected resistors and having one circuit end thereof connected to a second wire of said two-wire communication circuit and the other circuit end thereof connected to ground potential, and further including a first and a second connection respectively to the junction of each of said resistors of each said pair of resistors of said first voltage divider network to a first shunting means and a third and fourth connection respectively to the junction of each of said resistors of each said pair of resistors of said second voltage divider network to a second shunting means, said mid-point connections being at the same voltage potential with said communication circuit in said on-hook condition and having a difference of voltage potential there-between with said communication circuit in said off-hook condition, and differential voltage detecting means connected between said mid-point connections for providing a first output signal during said on-hook condition and for detecting said voltage difference occurring with said off-hook condition of said communication circuit to provide a second output signal, and means responsive to said detecting means for operating said shunting means upon the detection of an on-hook condition after an off-hook condition to present a lower impedance to said communication circuit.
Claim 2
Dependent Claim
301 words
An electronic sensing circuit for use with a telephone communication circuit of two-wire configuration and including off-hook and on-hook conditions, comprising: a first voltage divider network including a first and a second pair of series connected resistor elements having a mid-point connection between said pairs of series connected resistors and having one circuit end thereof connected to a first wire of said two-wire communication circuit and the other circuit end thereof connected to a voltage supply source, a second voltage divider network including another two pairs of series connected resistor elements having a mid-point connection between said pairs of series connected resistors and having one circuit end thereof connected to a second wire of said two-wire communication circuit and the other circuit end thereof connected to ground potential, and further including a first and a second connection respectively to the junction of each of said resistors of each said pair of resistors of said first voltage divider network to a first shunting means and a third and fourth connection respectively to the junction of each of said resistors of each said pair of resistors of said second voltage divider network to a second shunting means, said mid-point connections being at the same voltage potential with said communication circuit in said on-hook condition and having a difference of voltage potential there-between with said communication circuit in said off-hook condition, and differential voltage detecting means connected between said mid-point connections for providing a first output signal during said on-hook condition and for detecting said voltage difference occurring with said off-hook condition of said communication circuit to provide a second output signal, and means responsive to said detecting means for operating said shunting means upon the detection of an on-hook condition after an off-hook condition to present a lower impedance to said communication circuit.
Claim 3
Dependent Claim
26 words
An electronic sensing circuit as claimed in claim 1 wherein the two-wire communication circuit presents a balanced impedance to said first and second voltage divider networks.
Claim 4
Dependent Claim
20 words
An electronic sensing circuit as claimed in claim 1 wherein said differential voltage detecting means comprises a differential amplifier circuit.
Claim 5
Dependent Claim
34 words
An electronic sensing circuit as claimed in claim 1 further including: a bridge rectifier circuit having four diode legs and connected between said two-wire communication circuit and said first and second voltage divider networks.
Claim 6
Dependent Claim
20 words
An electronic sensing circuit as claimed in claim 2 wherein said differential voltage detecting means comprises a differential amplifier circuit.
Claim 7
Dependent Claim
34 words
An electronic sensing circuit as claimed in claim 3 further including: a bridge rectifier circuit having four diode legs and connected between said two-wire communication circuit and said first and second voltage divider networks.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-09-19 | 1981-03-21 | 1981-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-19 | 1985-03-21 | 1985-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-19 | 1989-03-21 | 1989-09-20 | $7700.00 | Window Closed / Lapsed |