Author Topic: WMR-968 Windspeed Not Accurate  (Read 4897 times)

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Offline dewey

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WMR-968 Windspeed Not Accurate
« on: April 17, 2009, 05:37:26 PM »
I have a WMR-968 that is several years old.  It has been working great, except for wind speed.  I have no way to accurately measure wind speed, but local stations, including the local airport have many times reported winds far higher than what I record.  For example, during a recent storm, the airport was reporting 60 mph gusts, and friends with the same weather station were reporting 50 to 60 mph winds.  Mine never gets over 24 mph no matter how hard the wind is blowing.  My sensor is about 15 feet high on an antenna tower, and is in the clear.  Does this just indicate a malfunctioning wind sensor?

Offline d_l

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Re: WMR-968 Windspeed Not Accurate
« Reply #1 on: April 17, 2009, 06:49:54 PM »
The airport's anemometer should be at 33 ft.  How high are your friends anemometers?

The measurement height off the ground makes a big difference in wind speeds.  If your anemometer is in an area with typical suburban to semi-rural surface roughnesses, your measured wind speeds might be 20 to 60% higher if you extended your mast to the 33 ft standard.

I'm not saying that your anemometer isn't having problems such as a tight bearing, but just pointing out that there can be other factors such as height, neighborhood surface roughness length, distant wind shadows, etc. that can complicate the comparisons. 
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Offline Downlinerz2

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Re: WMR-968 Windspeed Not Accurate
« Reply #2 on: April 17, 2009, 07:06:09 PM »
dewey,   
I too have a WMR968  and one of the first things I learned was that they are notorious for being low as to wind speed.  It was recommended to me by members of this forum was to enter a gain of 1.25 in the calibration menu.  Good luck!!
            Mark

Offline sam2004gp

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Re: WMR-968 Windspeed Not Accurate
« Reply #3 on: April 17, 2009, 09:50:51 PM »
dewey,   
I too have a WMR968  and one of the first things I learned was that they are notorious for being low as to wind speed.  It was recommended to me by members of this forum was to enter a gain of 1.25 in the calibration menu.  Good luck!!
            Mark

Dewey, I also have a gain of 1.25 and I think Anthony may have as well.  My numbers are soon to be verified by a handheld anemometer.  Again, get as high as you can, and as far away from obstructions that you can.  I have had windspeed numbers around 40MPH on the main console before the "gain" adjustment.  So I know the anemometer can get higher, unless you have a problem with your unit.
SAM --->>> http://www.mountcrawfordweather.org
OS WMR-968 with a Dedicated PWS Weather Computer running VWS v13.01 p09


Offline dewey

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Re: WMR-968 Windspeed Not Accurate
« Reply #4 on: April 18, 2009, 12:45:24 AM »
The airport's anemometer should be at 33 ft.  How high are your friends anemometers?

The measurement height off the ground makes a big difference in wind speeds.  If your anemometer is in an area with typical suburban to semi-rural surface roughnesses, your measured wind speeds might be 20 to 60% higher if you extended your mast to the 33 ft standard.

I'm not saying that your anemometer isn't having problems such as a tight bearing, but just pointing out that there can be other factors such as height, neighborhood surface roughness length, distant wind shadows, etc. that can complicate the comparisons. 
My friends anemometers are on short poles in their yards.  Not over 6-feet tall.  I have never seen winds over 24 mph since I have owned the WMR-968, yet the winds have been so high that limbs have been torn from nearby trees.  I am going to mount the anemometer on the roof of the house later this year.  That should give it at least 20-feet above the ground.  I would put it higher on the tower, but the u-bolts interfere with raising and lowering the tower.

Offline SlowModem

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Re: WMR-968 Windspeed Not Accurate
« Reply #5 on: April 18, 2009, 04:00:03 AM »
This got me curious so I decided to look back at mine. :-k

I have a 32 mph and a 43 mph gust and 26.6 mph avg on my 968 for 2008.  In 2009, I have a 28.4 and a 26.6.

This may have something to do with the sampling rate, the way the average is calculated, or it could  have to do with the software. I donno.

                         

I have a WS-2315 on the same pole, and it has a 27.0 mph gust for this year, so I guess that is in line with the 968.
« Last Edit: April 18, 2009, 04:02:40 AM by Slow Modem »
Greg Whitehead
Ten Mile, TN USA

Offline mackbig

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Re: WMR-968 Windspeed Not Accurate
« Reply #6 on: April 18, 2009, 07:26:03 AM »
I have also seen my wind much more in line since doing the 1.25 thing.  I know wind is very relative to your location, but if everyone within 5 km's has a constant 40k breeze and you are sitting at 30 it just makes sense.  But I have never worried too much about gusts.

Andrew

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Offline Anthony

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Re: WMR-968 Windspeed Not Accurate
« Reply #7 on: April 18, 2009, 07:33:24 AM »
I also use the 1.25 gain adjustment. But the biggest factor with the low wind speed/gusts is the sample rate. It;s just way way to slow to be accurate. I had hoped as OS came out with new stations thats this issue would be addressed. But it hasn't. Crappy wind speed is just something is OS station owners are going to have to live with.



Thanks,
Anthony
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Offline SlowModem

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Re: WMR-968 Windspeed Not Accurate
« Reply #8 on: April 18, 2009, 08:08:33 AM »
Crappy wind speed is just something is OS station owners are going to have to live with.

The 968 samples the wind every 14 seconds if I remember right.  The LaCrosse 2315 (which I also have) samples every 128 seconds (if the wind is < 22 mph) and every 32 seconds if the wind is > 22 mph.  So, it could be worse!

Greg Whitehead
Ten Mile, TN USA

Offline Anthony

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Re: WMR-968 Windspeed Not Accurate
« Reply #9 on: April 18, 2009, 02:17:19 PM »
I think it's the gusts that are sampled every 14 seconds. Wind speed or average wind speed is every minute I think. So while the OS deffinayely stinks. Sounds like the LaCross is even worse. You would think if Davis can do what they do. The others could atleast do better.





Thanks,
Anthony
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Offline SlowModem

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Re: WMR-968 Windspeed Not Accurate
« Reply #10 on: April 18, 2009, 02:24:17 PM »
I think it's the gusts that are sampled every 14 seconds. Wind speed or average wind speed is every minute I think. So while the OS deffinayely stinks. Sounds like the LaCross is even worse. You would think if Davis can do what they do. The others could atleast do better.

The LaCrosse samples at that rate to save batteries, I think (it's not solar powered)
Greg Whitehead
Ten Mile, TN USA

Offline Weather Display

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Re: WMR-968 Windspeed Not Accurate
« Reply #11 on: April 18, 2009, 03:20:27 PM »
if you have the 2310 cabled it updates faster
you can use instead say a vortex windspeed anenometer (every 1 second updates) with the wmr968 or ws2310 type stations (with WD)
Brian
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Offline sam2004gp

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Re: WMR-968 Windspeed Not Accurate
« Reply #12 on: April 19, 2009, 03:10:55 PM »
It would be great if there was a hack that would increase the sampling frequency of the WMR986 anemometer.  I know I have seen it for other non OS stations elsewhere.
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Offline W Thomas

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Re: WMR-968 Windspeed Not Accurate
« Reply #13 on: April 19, 2009, 05:07:22 PM »
The 1.25 gain offset seems to be the "nominal setting" I have used that since about a month after the original install and it appears my speeds are more in range with what local reference points I have to compare with. I am in almost a mini micro-climate here as my temps routinely range 5-10 degrees from those less than a mile away..usually to the plus side... and I have trees which is an anemometers worst nightmare as far as accuracy is concerned.

I have to agree with you Anthony, I do wish there was an update, a hex edit or most anything other than the Inspeed replacement that would increase the over all sample rate as it is awfully easy to miss a gust with these sample rates.

Other than that I can't gripe too much  :lol:


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Offline Strgazr27

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Re: WMR-968 Windspeed Not Accurate
« Reply #14 on: August 09, 2009, 10:40:07 PM »
if you have the 2310 cabled it updates faster
you can use instead say a vortex windspeed anenometer (every 1 second updates) with the wmr968 or ws2310 type stations (with WD)

GB,

The Ane. on the 968 has been a sore spot since day 1 for me. Exactly which Inspeed can be made to work with the 968?

Thanks for any info..

Bobby
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Offline Weather Display

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Re: WMR-968 Windspeed Not Accurate
« Reply #15 on: August 09, 2009, 10:48:54 PM »
Inspeed vortex, which you can now use with a hobby boards windspeed board and connect that to the software
Brian
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Offline W Thomas

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Re: WMR-968 Windspeed Not Accurate
« Reply #16 on: August 13, 2009, 03:10:58 PM »
I have a 968 also which reads low at 30 feet. A gain of 1.25 made it much closer in accuarcy. Definitely worth a try.


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     Wayne

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