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Wind gusts are not 10 minutes!

Posted: Sat 03 Nov 2012 3:08 am
by pvwxaustralia
Hi,

I've been using cumulus with my Davis vantage Vue for nearly a year now, the only problem I was having was with the classic Vue USB dropout issue.
Anyway, I recently installed virtual VP in an attempt to overcome the USB dropout issue, and this is working well for me so far.

However, since installing Virtual VP, and changing cumulus to get the data from virtual vp instead of the station itself i started to notice that the average wind and gust wind were always much closer than usual. For example, I had average of 21 km/h, gust of 22 km/h when usually they would never get that close at those speeds.

Anyway I was watching cumulus earlier today to see what was going on and I noticed this.
At 12:33pm we had a gust to 27km/h, after 3 minutes at 12:36pm cumulus was recording s gust of 25, then at 12:37pm 19km/h.

At 12:39pm we had a new gust to 25, by 12:42pm cumulus showed gust as 21.

I opened and checked the Nov12log.txt file and found that all gusts were only lasting for 3 minutes. So i checked the Oct12log.txt file and saw they were last for 10 minutes like they should, up until the day I installed virtual VP.

I added the "PeakGustMinutes=10" line to the cumulus.ini after finding it online, but that hasn't seemed to have fixed the problem?

Re: Wind gusts are not 10 minutes!

Posted: Sat 03 Nov 2012 10:18 am
by steve
Have you set VP2SleepInterval as described in the readme.txt?

Without that setting, with Virtual VP you will be getting many more readings, as VVP returns the data immediately, unlike a real station which has a short delay while the data arrives. This will fill up the buffer used for peak gust calculation much more quickly, such that there isn't 10 minutes worth of data in it.

Re: Wind gusts are not 10 minutes!

Posted: Mon 05 Nov 2012 2:43 am
by pvwxaustralia
steve wrote:Have you set VP2SleepInterval as described in the readme.txt?

Without that setting, with Virtual VP you will be getting many more readings, as VVP returns the data immediately, unlike a real station which has a short delay while the data arrives. This will fill up the buffer used for peak gust calculation much more quickly, such that there isn't 10 minutes worth of data in it.
Thanks heaps Steve. Adding the line "VP2SleepInterval=1100" to the cumulus.ini file has fixed the problem! Much appreciated.