user17135: I'm trying to build a cat motion detector but, to avoid getting false alarms when a person walks by, I was thinking of using RFID. i.e. the cat has a collar and the detector senses the collar when they get within a couple of feet and makes a noise.
The problem there seems to be with RFID is that the range is so short - e.g. 4".
Anyone have a better solution?

user6628: Place an additional motion sensor such that it can only detect motion from things significantly taller than cats, and use that as an inhibitor/classifier of the cat motion signal.

17135: <p>I'm trying to build a cat motion detector but, to avoid getting false alarms when a person walks by, I was thinking of using RFID. i.e. the cat has a collar and the detector senses the collar when they get within a couple of feet and makes a noise.</p>

<p>The problem there seems to be with RFID is that the range is so short - e.g. 4".</p>

<p>Anyone have a better solution?</p>
 6628: <p>Place an additional motion sensor such that it can only detect motion from things significantly taller than cats, and use that as an inhibitor/classifier of the cat motion signal.</p>
