Devices that chirp at each other

Timing every pair of devices both ways, the trick behind two-way radio and phone ranging, cancels their clock offsets, so the layout comes out cleanly. A steady breeze shifts the timings almost exactly as clock offsets would, so it stays hidden, but air swirling around a loop of devices shows through. Three microphones in a triangle on one device make the breeze measurable in principle, if the speed of sound and the clock rates are known. It’s theory and simulation so far, with a bench prototype designed but not yet built.

Sound slowed 90 times and its drift drawn 16 times larger, in steady air with no turbulence. Timing noise is 2 µs on each one-way time and 0.12 µs per microphone, both design targets rather than measurements. The devices find the layout up to rotation, shift and mirror image; the figure lines it up with the true one, and the speed of sound sets the scale.