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Apparatus and method for locating missing persons, animals, and objects

  • US 6,317,049 B1
  • Filed: 01/08/1999
  • Issued: 11/13/2001
  • Est. Priority Date: 02/17/1998
  • Status: Expired due to Fees
First Claim
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1. A method for locating a missing person, animal, or object, said method comprising the steps of:

  • (a) providing a transponder having an access code that identifies said transponder, said transponder configured to receive an interrogation radio signal and transmit a response radio signal, said transponder transmitting said response radio signal in response to receiving said interrogation radio signal if said interrogation radio signal includes a code matching said access code;

    (b) determining said access code corresponding to said transponder;

    (c) transmitting said interrogation radio signal including said access code from a transmitter located aboard an Earth-orbiting satellite;

    (d) receiving said response radio signal;

    (e) measuring a Doppler shift in frequency of said response radio signal; and

    (f) calculating a position of said transponder based on said Doppler shift.

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