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Differential ranging for a frequency-hopped remote position determination system

  • US 5,596,330 A
  • Filed: 02/16/1995
  • Issued: 01/21/1997
  • Est. Priority Date: 10/15/1992
  • Status: Expired due to Fees
First Claim
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1. A differential ranging mobile transmitter location system, comprising:

  • a mobile transmitter having a unique identifier, and having a transmitter for simultaneously sending a first frequency-hopped spread spectrum carrier signal and a second frequency-hopped spread spectrum carrier signal, at least one of which containing the unique identifier, the first frequency-hopped spread spectrum carrier having a different frequency than the second frequency-hopped spread spectrum carrier signal;

    a first base station having an antenna operable for receiving the first and second frequency-hopped spread spectrum carrier signals and capable of determining a first time of arrival of the frequency-hopped spread spectrum carrier signals;

    a second base station also having an antenna operable for receiving the first and second frequency-hopped spread spectrum carrier signals and capable of determining a second time of arrival of the frequency-hopped spread spectrum carrier signals; and

    a central station connected to the first base station and the second base station, and operable for;

    1.) receiving the first time of arrival of the first and second frequency-hopped spread spectrum carrier signals from the first base station;

    2.) receiving the second time of arrival of the first and second frequency-hopped spread spectrum carrier signals from the second base station;

    3.) generating a first hyperbolic plot based on the differential time of arrival of the first and second frequency-hopped spread spectrum carrier signals at the first and second base stations; and

    4.) using a third information source to determine the location of the transmitter along the first hyperboplic plot.

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