Satellite orientation detection system
First Claim
1. A system for detecting the pointing and roll orientation of a geosynchronous satellite relative to a reference location on the earth, said satellite having a pointing direction and a longitudinal axis, comprising:
- a ground station for transmitting first and second reference beams of electromagnetic energy, said first beam being linearly polarized along a first axis and said second beam being circularly polarized;
a receive antenna, coupled to said satellite, for receiving said first and second reference beams and for generating an antenna-beam pattern which rotates about a reference axis;
rotating polarizer means, aligned with said receive antenna, for periodically varying the portion of said linearly polarized energy within said first reference beam transmitted thereby and for transmitting said circularly polarized second reference beam;
first means for detecting the intensity of said received portion of said first reference beam and for generating a roll error signal indicative of the angle between said longitudinal axis and said first axis in response thereto; and
second means for generating pitch and yaw error signals indicative of the orientation of said reference axis relative to said reference location in response to time variation in the intensity of said received portion of said second reference beam.
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Accused Products
Abstract
A satellite orientation detection system disposed to detect the pointing orientation of a geosynchronous satellite (10) relative to a reference location on the earth. The present invention is also capable of ascertaining the angular orientation of a longitudinal axis of the satellite (10) relative to a defined axis on the surface of the earth. A ground station (20) is included for transmitting a first linearly polarized and a second circularly polarized electromagnetic reference beam. The present system also includes a receive antenna (28) coupled to the satellite (10) for receiving the first and second reference beams and for generating an antenna-beam pattern P1 and P2 disposed to rotate about a reference axis A. A rotating polarizer arrangement (44), aligned with the receive antenna (28), periodically varies the portion of the linearly polarized energy within the first reference beam transmitted thereby. The present invention further includes a first network (54) for detecting the intensity of the received portion of said first reference beam and for generating a roll error signal indicative of the angle between the longitudinal axis and the first polarization direction in response thereto. A second network (80) generates pitch and yaw pointing error signals in response to time variation in the intensity of the received portion of the second reference beam.
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Citations
14 Claims
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1. A system for detecting the pointing and roll orientation of a geosynchronous satellite relative to a reference location on the earth, said satellite having a pointing direction and a longitudinal axis, comprising:
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a ground station for transmitting first and second reference beams of electromagnetic energy, said first beam being linearly polarized along a first axis and said second beam being circularly polarized; a receive antenna, coupled to said satellite, for receiving said first and second reference beams and for generating an antenna-beam pattern which rotates about a reference axis; rotating polarizer means, aligned with said receive antenna, for periodically varying the portion of said linearly polarized energy within said first reference beam transmitted thereby and for transmitting said circularly polarized second reference beam; first means for detecting the intensity of said received portion of said first reference beam and for generating a roll error signal indicative of the angle between said longitudinal axis and said first axis in response thereto; and second means for generating pitch and yaw error signals indicative of the orientation of said reference axis relative to said reference location in response to time variation in the intensity of said received portion of said second reference beam. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for detecting the pointing and roll orientation of a geosynchronous satellite relative to a reference location on the earth, said satellite having a pointing direction and longitudinal axis, comprising the steps of:
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a) transmitting first and second reference beams of electromagnetic energy, said first beam being linearly polarized along a first axis and said second beam being circularly polarized; b) projecting an antenna-beam pattern from said satellite; c) rotating said antenna-beam pattern about said reference axis; d) positioning a rotating polarizer coupled to said satellite in alignment with said first and second reference beams; e) varying the portion of said first reference beam transmitted by said rotating polarizer; f) receiving said transmitted portions of said first and second reference beams; g) detecting the intensity of said received portion of said first reference beam and generating a roll error signal indicative of the angle between said longitudinal axis and said first axis in response thereto; and h) generating pitch and yaw error signals in response to the intensity of said received portion of said second reference beam.
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Specification