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need help in RFID circuit

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by gaurav707, Jun 15, 2006.

  1. gaurav707

    gaurav707 New Member

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    Hey,
    I have decided to use RFID technology to locate products or small items in home. I was wondering that can I able to build RFID reader and a transponder. If anyone knows about it..plz help me..I need the circuit for RFID receiver and transponder and any useful information regarding RFID. I thought i would use PIC controller to find out the distance b/w the product and the reader. U can email me to gaurav707@hotmail.com..thanx guys..
     
  2. philba

    philba New Member

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    what kind of distances are you talking about? inches? feet? meters? multiple meters? it makes a huge difference.
     
  3. gaurav707

    gaurav707 New Member

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    i m talking abt feet..ard 10-20 feet..For this purpose, is it better to use RF technology or RFID?
     
  4. dave

    Dave New Member

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  5. akg

    akg New Member

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    20feet ..so ur looking on to active rfid system, where both transmits.
    i don't think that an easy task .:rolleyes:
     
  6. Pommie

    Pommie Well-Known Member Most Helpful Member

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    Microchip have a few application notes showing how to design RFID circuits.

    Have a look at this RFID Application Note. It even has a schematic on page 107 (Adobe counting) using a 16C84 !!

    As AKG said, above a few inches distance will be tricky.

    Mike.
     
    Last edited: Jun 16, 2006
  7. gaurav707

    gaurav707 New Member

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    hey..i cant open the link...can u try to email it to me if possible..gaurav707@hotmail.com...or any other way to access that website..
     
  8. philba

    philba New Member

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  9. Pommie

    Pommie Well-Known Member Most Helpful Member

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    Link should work now.

    Mike.
     
  10. evandude

    evandude New Member

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    this doesn't sound like a task for RFID, which, as the name implies, is for identification, not for measuring distances or location...

    do you actually need to identify the objects with unique ID's, or are you only concerned with the distance measurement?

    Either way, if you want 10+ feet, you need to be using an active tag, and probably one that's actively transmitting RF instead of backscattering, at which point it's really just a small radio transmitter, with a microcontroller if you need the ID functionality, and not really a traditional RFID system at all. If you build a small transmitter like that, then you can try to measure the signal strength at the receiver to get an idea of distance... search for RSSI (Received Signal Strength Indication)
    http://en.wikipedia.org/wiki/Rssi

    But I have to warn you, don't expect it to be an easy project. I had a friend attempt an RSSI-type radio transmitter location project for his senior project as a EE student and ended up having to give up and switch to IR to get it done on time.
     
    Last edited: Jun 16, 2006
  11. philba

    philba New Member

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    I don't think signal strength is going to be sufficient as antennas are not perfectly uniform point sources - orrientation will matter. Of course, you could use accelerometers in the mobile unit and broadcast orrientation, too. getting kind of complex, though.

    frankly the more I think about this more it sounds like a dead-end.

    why not look into using motes? search for tinyos. have a number of the receivers sprinkled about. the "mobile item" would broadcast and the sensors would receive and report. you could then do a "centroid" analysis on which motes report receiving the mobile signal and determine a likely location. Maybe even vary the mobile's broadcast strength to better isolate the closest mote. Won't give you exact location.

    seems like a lot of work to find lost keys. we still don't know what problem you are trying to solve.
     
  12. swagatam

    swagatam New Member

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  13. jojomucho

    jojomucho New Member

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    anyone know how to build a rectangular spiral antenna ?? plz need urgent help
     
  14. brholmes

    brholmes New Member

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    I am doing a project for RFID and i am just trying to put it in to a cuircuit. I know how when a tag goes through its ranges the curcuit activates. Are there any cheap applications out that i could just buy?
     

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