If the two objects are close enough for optical line-of-sight communication, how about an infra-red beacon and receiver? There are quite a few threads on the fourm about IR communication, usually something to do with an IR remote control.
If the two objects are close enough for optical line-of-sight communication, how about an infra-red beacon and receiver? There are quite a few threads on the fourm about IR communication, usually something to do with an IR remote control.