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Passive position fix system

  • US 6,185,502 B1
  • Filed: 12/23/1998
  • Issued: 02/06/2001
  • Est. Priority Date: 12/23/1998
  • Status: Expired due to Fees
First Claim
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1. A passive position fix system on a vehicle, the vehicle having a geographic position over the earth, comprising:

  • (a) gyro means for providing a first gyro position of the vehicle;

    (b) map storage means for receiving the first gyro position and in response providing map-sets associated with geographic positions in the vicinity of the first gyro position provided by the gyro means, each map-set comprising a stored set of gravity gradients and a gravity anomaly at an associated geographic position on the earth;

    (c) gravity sensor means for providing a GSS-set, the GSS-set comprising a sensed set of gravity gradients values and a gravity anomaly value at the geographic position of the vehicle;

    (d) comparator means for receiving the GSS-set and for sequencially receiving the map-sets and for determining when there is a match between the GSS-set and a map-set and for providing a displacement vector based on which map-set matches the GSS-set; and

    (e) processor means for placing a second gyro position in the gyro means based on the first gyro position and on the displacement vector.

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