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Range Extension and Multiple Access in Modulated Backscatter Systems

  • US 20100060424A1
  • Filed: 03/18/2009
  • Published: 03/11/2010
  • Est. Priority Date: 03/19/2008
  • Status: Abandoned Application
First Claim
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1. An RFID communication system comprising an RFID reader in communication with a plurality of RFID tags having an integrated circuit and a memory unit, the memory unit storing tag data representing the RFID tag identification, each RFID tag having a spreading sequence associated with the tag, the RFID tags responding to an RF signal from the RFID reader with a spread spectrum modulated backscatter signal including the tag data mixed with the spreading sequence, the RFID tag providing the spread spectrum modulated backscatter signal having a signal to noise ratio higher that a corresponding backscatter signal without the spreading sequence, the RFID reader receiving and correlating the spread spectrum modulated backscatter signal against expected spreading sequences to identify the corresponding RFID tag at a distance greater than for an RFID tag sending the corresponding backscatter signal without the spreading sequence.

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