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RFID or Bluetooth detecting range?

I have a project in which I need a stationary device (A) to pair with/detect a mobile device (B) and only that device. Once detected/paired, I need device B to light up when pulled out of range from device A. I also need to be able to adjust this range in some manner. I was looking at RFID, but I am worried about interferance from other RFID tags. Not sure if bluetooth could even do what I want in the size that I need (no more than 2x2x.25 inches for either device.) ANyone have any suggestions?

BT would be the best method. RFIDs range, without extreme measures, is pretty limited.

BT modules can be VERY small - take a look at the Roving Networks RN41 for a clue.
Etrogann (author)  steveastrouk4 years ago
I have looked at similar chips. The question with them is can I adjust the range in which they are detected? I need the lights to turn off when moved outside a range of 1-3 feet.
You can't. Setting trigger ranges is a very tricky problem. RFID for these VERY short ranges would work, if you can read and discriminate the tags. Some tags shut up once they've been addressed, so that should stop confusion.

Steve