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Out of plane antenna vector system and method

  • US 5,561,432 A
  • Filed: 05/12/1995
  • Issued: 10/01/1996
  • Est. Priority Date: 05/12/1995
  • Status: Expired due to Term
First Claim
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1. An attitude determination system, comprising:

  • first, second, and third GPS antennas, said second and third GPS antennas separated from said first GPS antenna by respective first and second baseline distances, said respective first and second baseline distances being greater than the length of a radio carder signal wavelength from satellites providing GPS signals to said first through third GPS antennas;

    first and second pairs of first and second phase coherent GPS correlators connected respectively to said first and second antennas and said first and third antennas, and having respective first, second, third, and fourth correlator outputs derived from said GPS satellite radio carrier signal as independently received by each of said first and second and said first and third GPS antennas wherein said first, second, third, and fourth correlator outputs respectively include first and second phase differences;

    at least a single computer connected to said respective first and second and first and third phase coherent GPS correlators for determining first through fourth pluralities of possible attitudes to first through fourth respective GPS satellites based upon respective first and second phase differences between said first and second and said third and fourth correlator outputs for a first radio carrier signal from said respective first through fourth GPS satellites, wherein said first through fourth pluralities of possible attitudes includes more than one possible attitude due to whole cycle carrier phase ambiguities; and

    at least a single attitude solution computer connected to said at least a single computer for comparing said first through fourth pluralities of possible attitudes and for identifying at least one geometry for said first, second, and third antennas by establishing first baseline integer position candidates given constraints on limited pitch of said first, second, and third antennas, based upon minimum and maximum projections of the first baseline for each satellite direction, and establishing second baseline integer position candidates, by pointing the first baseline into a candidate vector, swinging said first, second, and third antennas around the first baseline, determining an arc subject to tilt limitations and determining minimum and maximum projections of the second baseline onto each satellite vector, that satisfies at least three of said first through fourth plurality of possible attitudes and eliminating any additional geometries for said first, second and third antennas, that satisfies at least three of said first through fourth plurality of possible attitudes that have a less perfect fit to said respective geometries for the pair of antennas that satisfies four of the first through fourth plurality of possible attitudes.

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