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Vehicle location system accuracy enhancement for airborne vehicles

  • US 5,099,245 A
  • Filed: 05/08/1989
  • Issued: 03/24/1992
  • Est. Priority Date: 10/23/1987
  • Status: Expired due to Term
First Claim
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1. A vehicle location system for locating the position of an airborne user vehicle, comprising:

  • a transmitter located aboard the user, said transmitter being capable of periodic transmission of a first signal unique to said user;

    a plurality of ground enhancement stations, said ground enhancement stations being capable of receipt of said first signal from said user and retransmission thereof as a second signal after a predetermined time delay;

    at least one satellite, said satellite being capable of receipt of said first signal transmitted from said user and said second signal retransmitted by said ground enhancement stations, said satellite further capable of retransmission of a single composite signal incorporating said first and second received signals; and

    a ground base station, said ground base station being capable of receipt of said composite signal from said at least one satellite, said ground base station incorporating computer means for calculating the position of said user from the known locations of said ground enhancement stations and said at least one satellite and from the time difference of arrival of said first signals transmitted directly from the user to the satellite and then to the ground base station and the second signals transmitted from the user and relayed by the ground enhancement stations to the satellite and then to the ground base station, said ground enhancement stations and said at least one satellite providing a ground reference combined with an aerial reference for reducing geometric dilution of precision errors and for improving accuracy in locating said airborne user vehicle.

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