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US4551580A
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Time-frequency scrambler
Assignee: Nokia Bell Labs
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Filing: 1982-11-22
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Granted: 1985-11-05
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Expires: 2002-11-22
Abstract
Abstract Subband signals are formed each corresponding to a portion of an input signal frequency spectrum. The subband signals are partitioned into subband time segments. The subband time segment signals are permuted. The permuted signals are combined to form a scrambled signal.
Inventors
- 👤 Richard V. Cox
- 👤 Nuggehally S. Jayant
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:17
CPC Classifications
H; H04; H04K; H04K1/00
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
46 words
prescribed signal. 20. The method of claim 16 wherein the subband sample signal forming step comprises applying the digital sample signals to a quadrature mirror filter and the inverse permuted block combining step comprises applying the inverse permuted digital signal blocks to a quadrature mirror filter.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-11-04 | 1989-05-06 | 1989-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-11-04 | 1993-05-06 | 1993-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-11-04 | 1997-05-06 | 1997-11-05 | $7700.00 | Window Closed / Lapsed |