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Vehicle position determination system and method

  • US 5,438,517 A
  • Filed: 02/18/1993
  • Issued: 08/01/1995
  • Est. Priority Date: 02/05/1990
  • Status: Expired due to Fees
First Claim
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1. A method for improving the accuracy of terrestrial position estimates of a user antenna located on a vehicle based on pseudoranges derived from satellites of a global position system, the method comprising the steps of:

  • (1) obtaining a known position of a reference antenna;

    (2) receiving electromagnetic signals at said reference antenna from a constellation of satellites and responsively determining respective reference antenna pseudoranges;

    (3) determining an estimated position of said reference antenna using said reference antenna pseudoranges;

    (4) comparing said estimated position of said reference antenna with said known position of said reference antenna to derive a spatial bias;

    (5) transmitting said reference antenna pseudoranges and said spatial bias to the vehicle;

    (6) receiving electromagnetic signals at the user antenna on the vehicle, receiving said reference antenna pseudoranges and said spatial bias at the vehicle and responsively determining a position estimate of the vehicle as a function of said spatial bias and said electromagnetic signals;

    (7) at the vehicle, determining another estimate of the position of the reference antenna as a function of said reference antenna pseudoranges;

    (8) determining an offset as a function of said another estimate of the position of said reference antenna and said known position of said reference antenna; and

    (9) updating said position estimate of the vehicle as a function of said offset; and

    (10) repeating steps (7)-(9) until said offset is less than a predetermined threshold.

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