Isn't it a bummer when you're bidding a project, and it's proprietary?

That's the basis of the airborne radio direction finders I used to work on (not radar) :)

One of the problems is the effective signal velocity varies so much - a reference may be desirable. A transducer in a small box that has the same atmospheric conditions as the outside where the return distance is known precisely, for instance.

Cheers

PeteS

Might work with an electrostatic TD ala Polaroid. Assuming that this is in air rather than water or some other medium, the phase behavior of piezo TD's as fn of freq, temp, production tolerances, phase of the moon, etc would make things rather dicey.

Interesting problem!

Late at night, by candle light, Rich Grise penned this immortal opus:

The phase differences may not give enough resolution. And, as Don said, may suffer from too much variation between units.

How about using directional TDs with some overlap of the lobes and aiming for equal amplitude? May still have some angular off-set but that can be trimmed out.

A pair of wide-lobed TD's (each side of the thing) for acquisition and a narrow-lobed (in front) for lock-in.

- YD.

In general, getting direction from passive sensor / evaluator systems is not difficult; getting distance normally requires some kind of round trip (active) sensor / evaluator.

Actually, the leader (just a little pinger) and follower are part of a set, so a transponder would probably be pretty easy.

Thanks! Rich