US2491540A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Frequency variation system for echo ranging
Assignee: Individual
•
Filing: 1940-12-31
•
Granted: 1949-12-20
•
Expires: 1960-12-31
Abstract
No abstract record available.
Inventors
- 👤 William W Wiseman
- 👤 Russell B Wright
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:53
CPC Classifications
G; G01; G01S; G01S1/00; G01S1/02; Y; Y10; Y10S; Y10S367/00; Y10S367/903
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
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) | 1952-12-19 | 1953-06-20 | 1953-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1956-12-19 | 1957-06-20 | 1957-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1960-12-19 | 1961-06-20 | 1961-12-20 | $7700.00 | Window Closed / Lapsed |