I need some type of radio communication between 2 mobile robotic devices, they need to be aware of each other when they are too close, 1-2 metres.

They don't need to communicate (data) with each other, just be aware of each other. A microcontroller will control the logic.

The big problem is that I haven't got a scope, so it's a bit difficult to design my own thing. There are lots of circuits available on the net, I've built some of them and they haven't worked. I can't afford to go through a massive learning curve because I've got two or three projects on the go.

What I'm asking for is some advice, what should I be looking at, frequency, modulation etc., and if there's a tried and tested circuit you could recommend.

*power 9v rechargeable power pack
*aerial if vertical 6" max

 

Radio would be exceptionally difficult to arrange as a guide to distance. A continuous broadcast is not going to have some sharp detection limit.

A possible method is to have each equipped with an oscillator and speaker. The tone could be received by the other robot with a microphone and filtered amplifier. The loudness could be the determinant of how close they are.