Importance

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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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First Claim