Patent US3883874A successfully refreshed from Google Patents.
US3883874A
Expired / Lapsed
US
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System for providing a reference frequency source
Assignee: Individual
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Filing: 1973-09-28
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Granted: 1975-05-13
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Expires: 1993-09-28
Abstract
Abstract A standard frequency package for radio communications and navigation and comprising VLF transmissions as a source of standard frequency. Commuted signals at the same frequency are utilized without regard to source details or phase, and a receiving antenna is multiplexed, thereby permitting the use of a poor oscillator in the system.
Inventors
- 👤 Eric R Swanson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 07:56
CPC Classifications
G; G01; G01S; G01S5/00; G01S5/02; G01S5/0205; G01S5/0221; G01S1/00; G01S1/02; G01S1/08; G01S1/20; G01S1/30; G01S1/308
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
211 words
Standard frequency apparatus comprising: antenna means for receiving VLF signals transmitted from a number of remote sources; clipper means connected to the output of said antenna means, filter means connected to the output of said clipper means and amplifier means connected to the output of said filter means, said serially connected clipper, filter and amplifier means being responsive to said VLF signals to produce a first signal at a frequency f1; oscillator means for producing a second signal at a frequency f2; phase detector means having a first input connected to the output of said amplifier means, a second input and an output; phase shifter means having a first input connected to the output of said oscillator means, a second input and an output, integrator and amplifier means connecting the output of said phase detector means to the second input of said phase shifter means, said phase shifter output (f2 + OR - Delta f) being connected to the second input of said phase detector means whereby when f1 f2 + OR - Delta f, the output of said phase detector is equal to zero; and, output terminal means connected to the output of said phase shifter means to produce said standard frequency when f2 + OR - Delta f f1.
Claim 2
Dependent Claim
211 words
Standard frequency apparatus comprising: antenna means for receiving VLF signals transmitted from a number of remote sources; clipper means connected to the output of said antenna means, filter means connected to the output of said clipper means and amplifier means connected to the output of said filter means, said serially connected clipper, filter and amplifier means being responsive to said VLF signals to produce a first signal at a frequency f1; oscillator means for producing a second signal at a frequency f2; phase detector means having a first input connected to the output of said amplifier means, a second input and an output; phase shifter means having a first input connected to the output of said oscillator means, a second input and an output, integrator and amplifier means connecting the output of said phase detector means to the second input of said phase shifter means, said phase shifter output (f2 + OR - Delta f) being connected to the second input of said phase detector means whereby when f1 f2 + OR - Delta f, the output of said phase detector is equal to zero; and, output terminal means connected to the output of said phase shifter means to produce said standard frequency when f2 + OR - Delta f f1.
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) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |