hi Marcel,

Marcel van Lieshout wrote:

>Stef,
>
>Well, Nijmegen - Heerde (between Zwolle and Apeldoorn) is only slightly more
>than 5 meters... ;-)
>
Maybe at a lower frequency ;-)

>
>You have got my attention with the 0.05 wavelength story you told. Do you
>have any more info about that?
>
Well it's some years ago, and distance was only 5 cm (we wanted to
measure very low air speed, fast).
We had a sawtooth running, synchronized with the transmitter, and
sampled the analog value of the sawtooth at a number (because you'll see
that the period of the subsequent detected waves isn't constant) of zero
crossings (another point you'll see is that you'll have far more than 5
received waves, even if you transmit just 1 half), then do some
averaging math, et voila.
One other trick, I don't remember if was essential, we did it
bi-directional.
Maybe it'll give you some ideas.

Stef

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