Tracking a radio signal

[DonRotolo]

Originally Posted by Mike

Unfortunately a google of "doppler radio direction robotics"

Drop the "robotics"

The Ramsey kit is the size of a textbook (plus antennas), you need a radio receiver for the frequency of interest (you pick the size) and a power source (ditto). I could fit it all into a Cheerios box (but the antennas would poke out) with room for breakfast.

3 or 10 over a square mile as PoC is doable, but scalability will frustrate you even at the hundreds level. The only way around that is a fixed (land-based) antenna network, which doesn't sound practical here. (A friend's company does exactly this, providing equipment location within a hospital. Handy if you need that <equipment name> NOW to save a life)

Research Spread Spectrum, Alan's comment is absolutely valid and when you get past the PoC stage allows for scalability.

(Here's a thought experiment for you: Imagine instead that each device chirped an audio tone, and your 'antenna' was a microphone. How many chirpers before you can't tell one from another? Repeat with chirpers on any of 500 random frequencies (=spread spectrum). Now how many?)

By the way, the Ramsey kit is just an "antenna", you can easily connect up a spread spectrum receiver to it as well.