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Systems and methods to determine kinematical parameters using RFID tags

  • US 8,461,966 B2
  • Filed: 06/05/2008
  • Issued: 06/11/2013
  • 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:

  • identifying, by an RFID reader, an RFID tag using an interrogating electromagnetic wave generated at an antenna of the RFID reader according to an interrogating signal from the RFID reader;

    receiving, in the RFID reader, a radio frequency signal from the RFID tag during interrogation of the RFID tag, wherein the received radio frequency signal is a reflection of the interrogating signal from the RFID tag, wherein the radio frequency signal is generated by the RFID tag by switching an antenna of the RFID tag between an absorptive mode and a reflective mode;

    generating a profile signal of a combination of the received radio frequency signal and the interrogating signal;

    determining magnitude of a portion of the profile signal corresponding to the antenna of the RFID tag being in the reflective mode; and

    determining a kinematical parameter of the RFID tag relative to the RFID reader based on the magnitude of the portion of the profile signal, wherein the determining of the kinematical parameter of the RFID tag comprises;

    identifying a plurality of characteristic points of the profile signal; and

    determining a time period of the plurality of characteristic points to compute a speed of the RFID tag.

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