US3622707A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiple channel subscriber loop
Assignee: AT&T Inc
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Filing: 1969-09-03
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Granted: 1971-11-23
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Expires: 1989-09-03
Abstract
Abstract A time division multiplex system for use with subscriber stations utilizes a pilot tone to control switches which connect subscribers to the common line during designated portions of each cycle. The pilot tone taken from the line is changed in frequency before being used to control subscriber connection time to eliminate problems of feedback and crosstalk. Further, each subscriber station set is powered by the subscriber''s power during normal operation to further improve crosstalk performance. Service is maintained, however, if any subscriber''s power fails by reverting to line power and party line operation for the duration of the power failure. Private line service is automatically returned when subscriber power reappears.
Inventors
- 👤 John J Golembeski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:16
CPC Classifications
H; H04; H04Q; H04Q11/00; H04Q11/04
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
152 words
A time division multiplex system comprising, in combination: first and second telephone stations utilizing a common telephone line; first and second switches for connecting said first and second stations, respectively, to said line; means for receiving a control signal from said line, said control signal having a frequency outside the frequency band utilized for transmitting voice signals on said line; and means for utilizing said control signal to control said first and second switches for connecting said first and second stations, respectively, across said line in first and second time intervals, respectively, of a repetitive cycle, said utilizing means including a frequency multiplier circuit for changing the frequency of said control signal to form a second signal so that said first and second switches operate at a frequency different than said frequency of said control signal thereby to reduce feedback and crosstalk caused by the operation of said first and second switches.
Claim 2
Dependent Claim
152 words
A time division multiplex system comprising, in combination: first and second telephone stations utilizing a common telephone line; first and second switches for connecting said first and second stations, respectively, to said line; means for receiving a control signal from said line, said control signal having a frequency outside the frequency band utilized for transmitting voice signals on said line; and means for utilizing said control signal to control said first and second switches for connecting said first and second stations, respectively, across said line in first and second time intervals, respectively, of a repetitive cycle, said utilizing means including a frequency multiplier circuit for changing the frequency of said control signal to form a second signal so that said first and second switches operate at a frequency different than said frequency of said control signal thereby to reduce feedback and crosstalk caused by the operation of said first and second switches.
Claim 3
Dependent Claim
76 words
Apparatus in accordance with claim 1 wherein said utilizing means further includes a threshold crossing detector circuit and a differentiator circuit for converting said second signal into first and second pulse trains having pulses in said first and second time intervals, respectively; and first and second circuit means for imparting a desired configuration to said pulses in said first and second pulse, respectively, and applying said pulse trains to operate said first and second switches, respectively.
Claim 4
Dependent Claim
52 words
Apparatus in accordance with claim 1 wherein said first and second telephone stations are energized from a source of power isolated from said line, and including an emergency circuit for connecting said first and second stations directly to said line when said source of power malfunctions so that said stations remain operable.
References Cited (Backward Citations)
US2451347A
Cited
US3496301A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-22 | 1975-05-24 | 1975-11-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-22 | 1979-05-24 | 1979-11-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-22 | 1983-05-24 | 1983-11-23 | $7700.00 | Window Closed / Lapsed |