US3774207A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nadir seeker orientation of a space vehicle in relation to the planet being orbited
Assignee: United States Department of the Navy
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Filing: 1972-04-25
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Granted: 1973-11-20
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Expires: 1992-04-25
Abstract
Abstract A space vehicle orientation system, for sensing the space vehicles orientation relative to the Z axis or vertical axis in the nadir direction, which uses a pulsed doppler radar to trace the nadir. The antenna of the radar is directed at the plantes surface. Operating in the beam limited condition, a coherent pulse is transmitted and when the center of the beam is pointed exactly at nadir the illuminated patch on the earth is essentially circular or symmetrically illuminated and the returned signal is symmetrical in doppler frequency shift and in pulse shape. Any deviation from the nadir will result in a change in either or both the doppler shift or the pulse width. By sensing these changes the radar beam may be redirected toward the spot directly below the space vehicle, the nadir.
Inventors
- 👤 B Yaplee
- 👤 A Shapiro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 11:33
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S13/58; G01S13/60
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
154 words
A system for use in space vehicle orientation which comprises: a radar system which is installed in an orbiting satellite, said radar system comprising: transmitter means for transmitting coherent signal pulses; antenna means for directing said coherent signal pulses in a signal transmitted beam and gathering return coherent signal pulses from a reflected single beam; means to control said antenna means to track a point on the surface of a celestial body; receiver means coupled to said antenna means for receiving said return; said receiver having at least a first and second output; said first output being indicative of the antenna error in the direction of travel of said satellite; said second output being indicative of the antenna error in the cross travel direction perpendicular to the direction of travel of said satellite; whereby said antenna means employs said first and second outputs to track said point on the surface of said celestial body.
Claim 2
Independent Claim
154 words
A system for use in space vehicle orientation which comprises: a radar system which is installed in an orbiting satellite, said radar system comprising: transmitter means for transmitting coherent signal pulses; antenna means for directing said coherent signal pulses in a signal transmitted beam and gathering return coherent signal pulses from a reflected single beam; means to control said antenna means to track a point on the surface of a celestial body; receiver means coupled to said antenna means for receiving said return; said receiver having at least a first and second output; said first output being indicative of the antenna error in the direction of travel of said satellite; said second output being indicative of the antenna error in the cross travel direction perpendicular to the direction of travel of said satellite; whereby said antenna means employs said first and second outputs to track said point on the surface of said celestial body.
Claim 3
Dependent Claim
19 words
The system described in claim 1 wherein said point on said surface is the nadir of the space vehicle.
Claim 4
Dependent Claim
122 words
The system described in claim 1 wherein said first output is represented by the doppler shift in said coherent signal pulses; detecting means coupled to said first output for detecting said doppler shift and for controlling said antenna in said direction of travel; and said second output is represented by the reflected pulse width of said coherent signal pulses; pulse width detector means coupled to said second output for detecting the size of said pulse width; said antanna means being controlled in said cross travel direction by the detected pulse width from said pulse width detector; thereby said antenna means is controlled by said doppler shift and said detected pulse width to track said point on the surface of said celestial body.
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) | 1976-11-19 | 1977-05-21 | 1977-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-19 | 1981-05-21 | 1981-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-19 | 1985-05-21 | 1985-11-20 | $7700.00 | Window Closed / Lapsed |