Spacecraft methods and structures with beacon-receiving field-of-view matched to beacon station window
First Claim
1. A method of enhancing the accuracy of the service attitude of a spacecraft that orbits the earth each solar day wherein an earth-based beacon station transmits a beacon signal and, relative to said spacecraft, moves along a path that defines a beacon-station window, the method comprising the steps of:
- configuring a beacon-receiving antenna to have a beacon-receiving field-of-view that substantially matches said beacon-station window wherein said beacon-receiving antenna has a beacon-receiving boresight and generates a difference signal that corresponds to a difference angle between said beacon-receiving boresight and a line-of-sight from said spacecraft to said beacon station;
fixing said beacon-receiving boresight in an attitude relative to said spacecraft that maintains said beacon station within said beacon-receiving field-of-view over said solar day;
receiving said beacon signal with said beacon-receiving antenna; and
controlling said service attitude in response to said difference signal;
said accuracy enhanced because said beacon-receiving field-of-view substantially matches said beacon-station window.
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Accused Products
Abstract
Methods and structures are provided that enhance the accuracy of the service attitude of an inclined-orbit spacecraft and, thereby, facilitate reduction of service error between a communication service area and the spacecraft'"'"'s payload beam. The enhancement is realized by configuring a beacon-receiving antenna to have a beacon-receiving field-of-view that substantially matches a beacon-station window. Preferably, the beacon-receiving field-of-view is elongated and tilted to enhance its match with the beacon-station window in both size and orientation. The goals are also realized by configuring the beacon-receiving antenna to have a beacon-receiving field-of-view that is substantially smaller than the beacon-station window and successively steering a beacon-receiving boresight to successive beacon-receiving attitudes that maintain the beacon station within the beacon-receiving field-of-view over each solar day. In an embodiment of the invention, successive positions of the beacon-receiving field-of-view are arranged in a tiled arrangement. Spacecraft structures are also provided to practice the methods of the invention.
6 Citations
28 Claims
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1. A method of enhancing the accuracy of the service attitude of a spacecraft that orbits the earth each solar day wherein an earth-based beacon station transmits a beacon signal and, relative to said spacecraft, moves along a path that defines a beacon-station window, the method comprising the steps of:
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configuring a beacon-receiving antenna to have a beacon-receiving field-of-view that substantially matches said beacon-station window wherein said beacon-receiving antenna has a beacon-receiving boresight and generates a difference signal that corresponds to a difference angle between said beacon-receiving boresight and a line-of-sight from said spacecraft to said beacon station;
fixing said beacon-receiving boresight in an attitude relative to said spacecraft that maintains said beacon station within said beacon-receiving field-of-view over said solar day;
receiving said beacon signal with said beacon-receiving antenna; and
controlling said service attitude in response to said difference signal;
said accuracy enhanced because said beacon-receiving field-of-view substantially matches said beacon-station window. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of enhancing the accuracy of the service attitude of a spacecraft that orbits the earth each solar day wherein an earth-based beacon station radiates a beacon signal and, relative to said spacecraft, moves along a path that defines a beacon-station window, the method comprising the steps of:
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configuring a beacon-receiving antenna to have a beacon-receiving field-of-view that is substantially smaller than said beacon-station window wherein said beacon-receiving antenna has a beacon-receiving boresight and generates a difference signal that corresponds to a difference angle between said beacon-receiving boresight and a line-of-sight from said spacecraft to said beacon station;
successively steering said beacon-receiving boresight to beacon-receiving attitudes, relative to said service attitude, that maintain said beacon station within said beacon-receiving field-of-view over said solar day;
receiving said beacon signal with said beacon-receiving antenna; and
controlling said service attitude in response to said difference signal;
said accuracy enhanced because said beacon-receiving field-of-view is substantially smaller than said beacon-station window. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A spacecraft that enhances the accuracy of the spacecraft'"'"'s service attitude as it orbits the earth each solar day wherein an earth-based beacon station radiates a beacon signal and, relative to said spacecraft, moves along a path that defines a beacon-station window, the spacecraft comprising:
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a spacecraft body;
an attitude-control system carried by said body to maintain a service attitude of said body;
at least one solar panel coupled to said body to provide electrical power to said attitude-control system;
an antenna system that forms a beacon-receiving antenna which has a beacon-receiving boresight and a beacon-receiving field-of-view that is elongated and tilted to substantially match said beacon-station window wherein said beacon-receiving antenna generates a difference signal that corresponds to a difference angle between said beacon-receiving boresight and a line-of-sight from said spacecraft to said beacon station; and
a data processor in said attitude-control system that is programmed to instruct;
a) said antenna system to receive said beacon signal with said beacon-receiving antenna; and
b) said attitude-control system to control said service attitude in response to said difference signal;
said accuracy enhanced because said beacon-receiving field-of-view is substantially matches said beacon-station window in size and orientation. - View Dependent Claims (19, 20, 21, 22)
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23. A spacecraft that enhances the accuracy of the spacecraft'"'"'s service attitude as it orbits the earth each solar day wherein an earth-based beacon station radiates a beacon signal and, relative to said spacecraft, moves along a path that defines a beacon-station window, the spacecraft comprising:
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a spacecraft body;
an attitude-control system carried by said body to maintain a service attitude of said body;
at least one solar panel coupled to said body to provide electrical power to said attitude-control system;
an antenna system that forms a beacon-receiving antenna which has a beacon-receiving boresight and a beacon-receiving field-of-view that is substantially smaller than said beacon-station window wherein said beacon-receiving antenna generates a difference signal that corresponds to a difference angle between said beacon-receiving boresight and a line-of-sight from said spacecraft to said beacon station; and
a data processor in said attitude-control system that is programmed to instruct;
a) said antenna system to successively steer said beacon-receiving boresight to successive beacon-receiving attitudes, relative to said service attitude, that maintain said beacon station within said beacon-receiving field-of-view over said solar day;
b) said antenna system to receive said beacon signal with said beacon-receiving antenna; and
c) said attitude-control system to control said service attitude in response to said difference signal;
said accuracy enhanced because said beacon-receiving field-of-view is substantially matches said beacon-station window in size and orientation. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification