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Ship position and velocity using satellite ephemerides and radar range measurement of satellite

  • US 9,459,344 B1
  • Filed: 01/14/2011
  • Issued: 10/04/2016
  • Est. Priority Date: 01/14/2011
  • Status: Active Grant
First Claim
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1. A method for geolocation of a movable platform, said method comprising the steps of:

  • operating a radar system mounted on said movable platform;

    measuring, with said radar system, a range from the movable platform to each of N satellites in Earth orbit, where N is greater than 2, and where N is the total number of range measurements made using the radar system;

    providing a memory having ephemerides data for each of said N satellites;

    obtaining from said memory on said movable platform, said ephemerides data for said satellites;

    establishing an initial estimated position of said movable platform;

    iteratively performing in a computer coupled to said memory and to said radar system, and using as input the N range measurements from the movable platform to the corresponding satellite, the steps of;

    estimating a range to each of the N satellites based on the estimated position;

    comparing the estimated ranges to the N range measurements obtained from the radar system;

    setting up range equations which express the geolocation relative to said satellites; and

    updating the estimated position of the movable platform by applying a least-squares solution based on the range equations, the N range measurements and the estimated ranges; and

    determining the geolocation of the movable platform based on the estimated position in response to a determination that an iteration threshold has been reached.

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