I'm working on a project which essentially would warn someone if their dog (for example) got too close to let's say, a particular item.
I was thinking NFC tags but to my knowledge the max range is 4 - 6 inches, while I'm looking for 4 - 6 feet ideally.
Infared is of course a possibility, but I need it so an alarm of some kind would only go off if a certain "culprit" goes near the item, not just anyone.
I was thinking maybe xbee? Any thoughts would be appreciated.