US4056688A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone range extender with gain
Assignee: AT&T Inc
•
Filing: 1976-11-11
•
Granted: 1977-11-01
•
Expires: 1996-11-11
Abstract
Abstract A telephone Range Extender with Gain (REG) is disclosed for extending the range of loop lengths over which telephone service can be provided. This is accomplished by providing voice frequency gain, a higher voltage talking battery, and supervisory and signaling circuitry for increasing the level of supervisory and signaling currents at the central office end. The range extender requires no adjustment for loops of different lengths. A π configuration negative impedance amplifier includes an adjustable gain circuit responsive to the resistance of the connected loop to automatically adjust the gain of the amplifier to the length of the loop. At the same time, an impedance matching circuit is transformer-coupled to the loop. The frequency shaping of the negative resistance amplifier and the impedance matching network, when reflected through the transformer, provides acceptable impedance matching for a wide range of loop lengths and wire gauges. For stability, the gain of the amplifier is forced to a low value when the central office termination becomes an open circuit.
Inventors
- 👤 Kenneth Erwin Stiefel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:36
CPC Classifications
H; H04; H04M; H04M19/00; H04M19/001; H04M19/006
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
88 words
A telephone range extender comprising means for connecting said range extender to a telephone central office; means for connecting said range extender to a telephone subscriber loop; a subscriber loop resistance detector connected to said subscriber loop connecting means; and a negative impedance bilateral amplifier connected in a π configuration, said amplifier comprising a central office side shunt negative impedance converter; a series negative impedance converter; and a subscriber side impedance transformer; each of said negative impedance converters being adjustable in response to said subscriber loop resistance detector.
Claim 2
Dependent Claim
88 words
A telephone range extender comprising means for connecting said range extender to a telephone central office; means for connecting said range extender to a telephone subscriber loop; a subscriber loop resistance detector connected to said subscriber loop connecting means; and a negative impedance bilateral amplifier connected in a π configuration, said amplifier comprising a central office side shunt negative impedance converter; a series negative impedance converter; and a subscriber side impedance transformer; each of said negative impedance converters being adjustable in response to said subscriber loop resistance detector.
Claim 3
Dependent Claim
41 words
The telephone range extender according to claim 1 wherein each said negative impedance converter includes a single normally open relay contact; and relay means for closing said normally open contacts in response to a preselected output level of said resistance detector.
Claim 4
Dependent Claim
56 words
The telephone range extender according to claim 1 wherein each of said negative impedance converters comprises a plurality of transistors connected in series with a positive impedance; a voltage divider coupled to said conductors for biasing said transistors from the direct current voltage on said conductors; and means for changing the value of said positive impedance.
Claim 5
Dependent Claim
21 words
The telephone range extender according to claim 1 further including a passive fixed impedance matching circuit coupled to said π configuration.
Claim 6
Dependent Claim
55 words
The telephone range extender according to claim 4 wherein the combination of the negative impedances of said converters and the positive impedances of said passive impedances is matched in the frequency domain to the impedance of said subscriber loop over a range of cable gauges and loop lengths without any adjustment of said passive impedances.
Claim 7
Dependent Claim
43 words
A bilateral amplifier in the form of a π network comprising a shunt negative impedance converter; a series negative impedance converter; a shunt impedance transformer; and a fixed impedance matching network connected between said shunt negative impedance converter and said shunt impedance transformer.
Claim 8
Dependent Claim
43 words
A bilateral amplifier in the form of a π network comprising a shunt negative impedance converter; a series negative impedance converter; a shunt impedance transformer; and a fixed impedance matching network connected between said shunt negative impedance converter and said shunt impedance transformer.
Claim 9
Dependent Claim
19 words
The bilateral amplifier according to claim 6 wherein said impedance transformer comprises a transformer coupled to a transmission line.
Claim 10
Dependent Claim
27 words
The bilateral amplifier according to claim 7 further including impedance detecting means responsive to the resistance of said transmission line for adjusting the gain of said amplifier.
Claim 11
Dependent Claim
18 words
The bilateral amplifier according to claim 8 wherein said means for adjusting gain comprises only normally open contacts.
Claim 12
Dependent Claim
31 words
The bilateral amplifier according to claim 6 wherein said shunt negative impedance converter further comprises means for reducing the negative admittance of said shunt negative impedance converter as frequency is increased.
Claim 13
Dependent Claim
31 words
The bilateral amplifier according to claim 6 wherein said series negative impedance converter further comprises means for increasing the negative impedance of said series negative impedance converter as frequency is reduced.
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) | 1980-10-31 | 1981-05-02 | 1981-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-31 | 1985-05-02 | 1985-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-31 | 1989-05-02 | 1989-11-01 | $7700.00 | Window Closed / Lapsed |