Patent US3525816A successfully refreshed from Google Patents.
US3525816A
Expired / Lapsed
US
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Loop supervision circuitry
Assignee: International Standard Electric Corp
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Filing: 1966-06-07
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Granted: 1970-08-25
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Expires: 1986-06-07
Abstract
Abstract A resistor network is connected to a two wire line and used to detect and overcome changes of direct current levels without disturbing any alternating current signals superimposed thereon. Direct connections between the d.c. source and the network eliminate the effects of any fluctuations in the source voltage. The invention has general utility wherever changes in d.c. levels must be detected; however, a particular use of the invention is to compensate for longitudinal voltages induced on a telephone line.
Inventors
- 👤 Eberhard Herter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:14
CPC Classifications
H; H04; H04Q; H04Q3/00; H04Q3/42; H04M; H04M1/00; H04M1/26; H04M1/515; H04M3/00; H04M3/22; H04M3/2272; H04Q1/00; H04Q1/18; H04Q1/30; H04Q1/38
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2823263A
Cited
US2835740A
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US2895012A
Cited
US3129289A
Cited
US3156778A
Cited
DE1112755B
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-08-24 | 1974-02-23 | 1974-08-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-08-24 | 1978-02-23 | 1978-08-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-08-24 | 1982-02-23 | 1982-08-25 | $7700.00 | Window Closed / Lapsed |