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Method and apparatus for determining a geographical location of a mobile communication unit

  • US 6,246,361 B1
  • Filed: 06/28/1999
  • Issued: 06/12/2001
  • Est. Priority Date: 06/28/1999
  • Status: Expired due to Fees
First Claim
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1. A method of determining a geographical location of a mobile unit, the method comprising the steps of:

  • determining a first instantaneous distance between an apparatus traveling above a surface of Earth and the mobile unit based on a first signal travel time of a first signal;

    determining a second instantaneous distance between the apparatus and the mobile unit based on second signal travel time of a second signal;

    calculating two possible location regions of the mobile unit based on an intersection of the first instantaneous distance and the second instantaneous distance; and

    identifying one of the two possible location regions as the location region including the location of the mobile unit by observing a movement of the mobile unit due to a rotation of Earth.

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