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Systems and methods to determine motion parameters using RFID tags

  • US 8,242,888 B2
  • Filed: 06/05/2008
  • Issued: 08/14/2012
  • Est. Priority Date: 06/05/2008
  • Status: Active Grant
First Claim
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1. A method implemented in a radio frequency identification (RFID) system, the method comprising:

  • interrogating an RFID device by an RFID reader using radio frequency electromagnetic waves;

    receiving at least one radio frequency signal from the RFID device, comprising receiving a first signal at a first antenna and a second signal at a second antenna;

    determining a frequency difference between the first signal received at the first antenna and the second signal received at the second antenna;

    detecting a Doppler frequency shift based on the frequency difference; and

    calculating a motion parameter of the RFID device, based on the Doppler frequency shift.

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