Transponder circuit

[Kipper4]

I concede not having seen the movie

Rich, you have an assignment...

Oddly enough I hardly watch any TV these days let alone films.
I'll put it on the list of must do's. Just one more circuit first though.

[PRR]

> I was thinking ultrasonic too

Similar here. Send a short blip, catch the reflection, repeat.

Over a long air path the repetition time is long, low pitch. At short range, quick repetition, high pitch.

For 10 feet one way, the pitch is about 50Hz; at 1 foot about 500Hz.

But catching a weak echo after a powerful blip is tricky switching (also transducer damping). And it is likely to echo off everything in the room.

We could postulate paired blippers that respond only to each other. But this is getting too much like a wartime radar problem than a party stunt.

[pappasmurfsharem]

Something like this?

http://blog.afkham.org/2013/02/how-to-build-arduino-audible-distance.html


Edit:
Nevermind this is more like "Sonar" than what you want.