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From: davet@tsdiag.ccur.com (Dave Tiller N2KAU)
Newsgroups: sci.electronics
Subject: Re: Weather sensors
Message-ID: <1497@tsdiag.ccur.com>
Date: 27 Mar 91 18:08:15 GMT
References: <1991Mar27.033853.14775@ms.uky.edu>
Distribution: usa
Organization: Concurrent Computer Corp. Oceanport NJ
Lines: 35

In article <1991Mar27.033853.14775@ms.uky.edu> hucaby@mri.uky.edu (David Hucaby) writes:
>I'm trying to build a home weather station and would like to find sources
>for wind speed and wind direction sensors...
>Anybody got a good source or some ideas on how to build and calibrate
>wind sensors?

Try using a transparent plastic with opaque markings on it to represent
speed and direction.  The speed disk simply has regularly spaced tick
marks along the edge so that an opto-interupter can count them as the disk
rotates.  The direction disk has 4-bit binary markings radially on the
disk, so that 4 opto-interupters can tell each of 16 positions apart.
Note that there is no mechanical drag associated with obtaining the data.

An 8-spoke example of the direction wheel:


              1       0       1
                0     1     1
                  1   1   1
                    0 0 0
             0 0 1 0     0 0 0 0
                    0 0 0
                  0   0   0
                1     1     0
              1       0       1

Notice that the codes are backwards on the left side of the wheel.
You could use Gray codes, if you wanted to.  Make sure that the marks
cleanly merge into one another so you don't get bogus readings.
Hope this helps...
-- 
David E. Tiller         davet@tsdiag.ccur.com  | Concurrent Computer Corp.
FAX:  201-870-5952      Ph: (201) 870-4119 (w) | 2 Crescent Place, M/S 117
UUCP: ucbvax!rutgers!petsd!tsdiag!davet        | Oceanport NJ, 07757
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