Unfortunately, Gus, I don't think your idea will work. There will be
all kinds of effects from the transducer. What you might consider is
this: what if you send a continuous signal, have two separate
transducers (one TX, one RX), and then try to determine the phase
difference between transmitted signal and received signal. If you
calibrate out the system errors using several known distances, you
might get close to what you are suggesting. It would help to use as
high a frequency as possible. Ultrasound machines for medical use
often use ultrasound frequencies of several MHz, however, I don't know
if these can propagate very far in air.

Sean


On Sat, Aug 29, 2009 at 1:06 PM, Olin Lathrop<olin_piclist@embedinc.com> wr=
ote:
> AGSCalabrese wrote:
>> I am launching a pulse into the air and measuring time of flight down
>> to .0001 inches .
>
> I seriously doubt you're going to get 2.5um resolution from ultrasound. =
=A0The
> transducer alone will react slower than that. =A0Even if you sent a conti=
nuous
> signal and measured phase relative to a reference, I doubt you would get
> that kind of accuracy. =A0Unless these are very very special ultrasound
> transducers operating at a unusually high frequency, this isn't going to
> work.
>
> What frequency are the transducers rated at?
>
>
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