>
> *snicker* What if he's doing it in a vacuum?
> Mike H.
>

Ooh.  That would be the stealth version!


Marechiare <marechiare@gmail.com> wrote:
> I seriously doubt you're going to get 2.5um resolution from
> ultrasound.  The transducer alone will react slower than that.
> Even if you sent a continuous signal and measured phase
> relative to a reference, I doubt you would get that kind of
> accuracy.  Unless these are very very special ultrasound
> transducers operating at a unusually high frequency, this
> isn't going to work.

Now, that...hmm...You could generate a pseudorandom stream of pulses, then
correlate the return stream against your generator.  HP did this in the '80s
with a TDR, which, come to think of it, is the same trick done with
electrons instead of air.

This would also play havoc with all those good "repetitive measurement"
ideas....Maybe we should just answer his question, which was, "Which 'scope
to rent?"
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