Patent US4234971A successfully refreshed from Google Patents.
US4234971A
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Precise RF timing signal distribution to remote stations
Assignee: National Aeronautics and Space Administration
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Filing: 1979-09-24
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Granted: 1980-11-18
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Expires: 1999-09-24
Abstract
Abstract This invention relates to a method and apparatus for distributing a stable reference frequency from a hydrogen maser frequency standard, or similar RF source, to remote stations over great distances with very good phase stability, and with constant amplitude, at each distribution point, using a light beam carrier, and more particularly to a technique for providing automatic gain control at an optical receiver with phase stability in the RF reference.
Inventors
- 👤 with respect to an invention of Frosch Robert A. Administrator of the National Aeronautics and Space Administration
- 👤 Georg F. Lutes, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 02:31
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/25; H04B10/2589; H04B10/25891
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
152 words
A method of distributing a precise RF frequeny signal from a source to a plurality of remotely located stations for use at said stations in processing of data comprising, generating a light beam, modulating the amplitude of said light beam with said RF timing signal from said source, dividing said modulated beam into a plurality of split beams, transmitting each split beam to a different station over an optical fiber, and at each station detecting the amplitude modulation of the split beam with an optical detector to produce an RF electrical signal that conforms in frequency with said RF reference signal from said source for use at the station, detecting the average amplitude of said RF electrical signal to produce an automatic gain control signal, and controlling an optical attenuator at the input of said optical detector for automatic gain control of said RF electrical signal without introducing any appreciable phase shift.
Claim 2
Independent Claim
152 words
A method of distributing a precise RF frequeny signal from a source to a plurality of remotely located stations for use at said stations in processing of data comprising, generating a light beam, modulating the amplitude of said light beam with said RF timing signal from said source, dividing said modulated beam into a plurality of split beams, transmitting each split beam to a different station over an optical fiber, and at each station detecting the amplitude modulation of the split beam with an optical detector to produce an RF electrical signal that conforms in frequency with said RF reference signal from said source for use at the station, detecting the average amplitude of said RF electrical signal to produce an automatic gain control signal, and controlling an optical attenuator at the input of said optical detector for automatic gain control of said RF electrical signal without introducing any appreciable phase shift.
Claim 3
Dependent Claim
13 words
The method of claim 1 wherein said beam is a coherent light beam.
Claim 4
Dependent Claim
16 words
The method of claim 1 wherein said beam is of the infrared or visible red wavelength.
Claim 5
Dependent Claim
99 words
In a system for transmitting an RF signal amplitude modulated on a light beam to a remote station, an optical receiver comprising means for detecting said light beam and producing an RF electrical signal proportional to the amplitude thereof, means responsive to said RF electrical signal for producing an automatic gain control signal proportional to the average amplitude of said electrical signal, and voltage variable means for attenuating said light received for detection by said detecting means in response to said automatic gain control signal, whereby automatic gain control is achieved for said RF electrical signal with phase stability.
Claim 6
Dependent Claim
99 words
In a system for transmitting an RF signal amplitude modulated on a light beam to a remote station, an optical receiver comprising means for detecting said light beam and producing an RF electrical signal proportional to the amplitude thereof, means responsive to said RF electrical signal for producing an automatic gain control signal proportional to the average amplitude of said electrical signal, and voltage variable means for attenuating said light received for detection by said detecting means in response to said automatic gain control signal, whereby automatic gain control is achieved for said RF electrical signal with phase stability.
Claim 7
Dependent Claim
42 words
In a system as defined in claim 4, a plurality of identical receivers for receiving a portion of the same modulated light beam, whereby a plurality of remote stations are provided an RF reference signal from the same source with phase stability.
Claim 8
Dependent Claim
52 words
In a system as defined in claim 5, a plurality of optical fibers, one for each remote station, for conducting a portion of said optical beam to each remote station, means at said central station for splitting said modulated beam into portions, and means for distributing said portions into said optical fibers.
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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) | 1983-11-18 | 1984-05-19 | 1984-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-11-18 | 1988-05-19 | 1988-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-11-18 | 1992-05-19 | 1992-11-18 | $7700.00 | Window Closed / Lapsed |