On 24/03/2011 12:07, Olin Lathrop wrote:
> Michael Watterson wrote:
>> I saw a design using 4 x Ultrasonic transducers to measure speed and
>> direction.
> I know someone who built one of those a bunch of years ago and used a PIC=
 to
> produce the pulses, measured the times, and derive the wind speed and
> direction.
>
> I pointed out to him that it could be done with just three sensors before=
 he
> built it, but said he didn't want to do the "hard math".  Yes, I guess yo=
u'd
> have to have passed high school geometry to figure it out.  It is well
> within the capabilities of even a small PIC to do that.

True. It's not even hard maths.

However the transducers are usually sold in pairs. A commercial one=20
would want to use only 3.
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