A Bluetooth LE device similar to Tile[1] might be a cheap and reliable signal source in a package small enough to attach to a collar. If you had two Bluetooth r

A Bluetooth LE device similar to Tile[1] might be a cheap and reliable signal source in a package small enough to attach to a collar. If you had two Bluetooth receivers on either side of your camera's visual field, you could compare signal strengths during motion and positively identify your cat (assuming feline motion detection is a solved problem). [1] https://www.thetileapp.com/ https://www.thetileapp.com/