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Wind direction trend and rose issues on MX
Posted: Tue 21 Jun 2016 6:48 am
by Dan
Hi,
Cumulus MX (v3.0.0 (3038)) on my Pi has suddenly gone a bit haywire for wind direction. The average bearing seems to be okay, but the bearings swing wildy between set compass points. See attached for detail.
Rebooted Pi, rebooted indoor unit, next to reboot is outdoor unit when I get up onto the roof, but from the set behaviour this looks like a Cumulus thing?
Thoughts? Ideas? Seen it before?
Thanks
Dan
Re: Wind direction trend and rose issues on MX
Posted: Tue 21 Jun 2016 7:41 am
by steve
Unlikely to be Cumulus. This is a common 'feature' of Fine Offset stations. Have you observed the wind vane when this happens? It's likely that you'll see it constantly changing direction, possibly even spinning around in circles.
Re: Wind direction trend and rose issues on MX
Posted: Tue 21 Jun 2016 8:39 am
by AllyCat
Hi Dan,
Yes, that's absolutely typical for a "Fine Offset" (the manufacturer) weather vane. The predominance of the 8 "major" directions (N , NE, etc.) over the 8 minor (NNE , ENE, etc.) is because the major directions are detected by one of 8 magnetic reed switches. The minor directions require two adjacent reeds to close and the moving magnet isn't strong enough! It can be improved by adding one or more magnets to the rotor.
The vane rotor is also very "lively" and again on this forum there are suggestions on how to "damp" its movement. I guess you are only noticing it now, either because the "averaging" time has changed in your (software) setup, or simply the wind currently has more turbulence than usual (or the speed might be very low and the direction is changing a lot).
I happen to be developing a purely "electronic" (microcontroller hardware) project which can "clean up" the output from the FO Vane. Perhaps I will post details soon, but don't hold your breath.
Cheers, Alan.
Re: Wind direction trend and rose issues on MX
Posted: Fri 24 Jun 2016 5:13 am
by endfm
Hey,
I've got the same weather station this happens to me when the wind is turbulent, wind station is about 90m above SL even when the wind is strong The only time I've seen the wind vain working is when there's constant wind and no real gusts. I've seen it switch from N to a fierce southerly and the wind direction graph is bang on.
but yes, what AllyCat said in regards to damping the wind vain down would be an advantage!
cheers