Marshall,

After drawing a picture of two sensors doing a bit of geometry I think it can be found the Direction of arrival calculation can be shown to have symmetry either side of a line going through both sensors (assuming they\'re omnidirectional), regardless of using signed or unsigned arithmetic.

As Jez observed, you need three sensors to obtain a two dimensional position fix.

Would three sensors allow a three dimensional position fix if the sensors and sound emitter were not coplanar?

Bruce