wind meter

On Wed, 16 Feb 2005 10:29:46 GMT, Ron Hardin
wrote:

wrote:
Maybe the overflow varies according to what the average is,
or whether the meter is calculating in kilometers or miles?

I wouldn't be surprised that they're just adding up the wind displays
and divide by the number of additions, and the former overflows,
which means the time depends on the wind speed.

Why it goes to -15.3 I don't know, unless it's that they cease the
attempted division on overflow, and -15.3 is a typical result on
quitting for some reason. The average wind itself could well be
-15.3, so they're probably getting it as a result of a software
artifact on error.

I didn't try flipping to km knots or f/s to see if the displayed
amount changed. Perhaps in whatever the internal units are, it's
some nice power of 2, and only -15.3 in mph.

Dear Ron,

Aha! I think I've got the bug figured out after a few days.

No ride, too cold. Gave up thoughts of borrowing a small fan
and experimenting. I have my dignity, after all.

Next day, warm enough to ride, but wind meter fuss
interrupted by goathead thorn.

Yesterday, got a normal ride in, but the running average
never crashed--it lasted just under 50 minutes and worked
fine. I kept watching it all the way up the dam road and
then to the top of the ridge, but with a slight tail wind
the running average never dropped below 15.9 mph.

I thought that this was the bug--don't dip down to 15.3 mph,
and it will work.

I was wrong.

Today, a balmy Chinook was blowing into my face (I saw the
first tandem of spring out early), so I had a running
average over 20 mph on the wind meter up to the dam, where I
make a 90 degree turn, start to climb, and slow down--and
the wind goes silly anyway in the lee of the dam.

About 25 minutes out, with the running average still over 17
mph, I happened to be looking at the wind meter showing
about +10 mph when a mild gust reversed the wind direction,
the wind speed went to -3 mph for a moment--and the running
average instantly changed over thirty miles per hour to
-15.3 mph and stayed there until I cleared it.

The manufacturer mentions that a rapid shift from +60 to -60
mph will goof things up, but I expect that they aren't
mentioning this bug at a much smaller shift. Your 45 minute
loss on a pole might well correspond to how long it took
before your local wind managed to reverse quickly enough for
even a free-mounted wind meter to see a negative wind speed.

It's annoying, but at least the current wind speed seems
unaffected when the running average crashes to -15.3 mph.

Carl Fogel