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Small RFID

  1. Sep 20, 2007 #1

    i need help.... i am planing to design a small location detection system within a room using RFID tags or some resonace technique. Each object must have a unique identification code. I intend to place 4 detectors like Satellites to determine the exact position of the object.... I need suggestions and ideas.... please help me.

  2. jcsd
  3. Sep 20, 2007 #2


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    RFID tags have a very short reading range ( typically a few cm)
    You can read them at longer distances with more power and a more directional antenae.
    You would also need more than just a simple RFID detector to give a good direction of the signal you would have to either scan the detectors to locate the maximum signal direction or have some sort of phased array receiver.
    The timing of the rfid reply isn't repeatable enough to do a time-of-flight position fix.
  4. Sep 27, 2007 #3
    I'm doing a little research into RFID tags myself and many of them have ranges greater than 10 feet. If you make any progress on determining accurate location, please post it. Here are some here are some RFID tags that I found.
  5. Sep 27, 2007 #4


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    That is a very non-trivial problem, especially when you factor in multipath effects. Are there any other options like video location and triangulation, etc.? What other constraints are there in this project? Do the tags have to be passive (or at least not self-powered)? What frequency bands were you considering using? What interfering sources are you going to have to contend with?
  6. Sep 27, 2007 #5


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    Hey benzun, check out the end of my post #5 in this thread that cnichols is referring to:


    At first I didn't think there was a way to do this effectively, but the end of my post has an interesting possibility that pretty much gets around multipath issues, at least to a first order. It's not simple or cheap, though.
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