US2833857A
Expired / Lapsed
US
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Frequency shift signalling system
Assignee: National Research Development Corp UK
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Filing: 1956-02-06
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Granted: 1958-05-06
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Expires: 1976-02-06
Abstract
No abstract record available.
Inventors
- 👤 Robin Harold Kilner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:40
CPC Classifications
H; H04; H04L; H04L5/00; H04L5/22; H04L5/26; H04L27/00; H04L27/10
Claims Analysis
Total Claims: 0
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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) | 1961-05-05 | 1961-11-04 | 1962-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-05-05 | 1965-11-04 | 1966-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-05-05 | 1969-11-04 | 1970-05-06 | $7700.00 | Window Closed / Lapsed |