Author Topic: *.9 wind speeds with a Davis  (Read 770 times)

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Offline Mchd17

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*.9 wind speeds with a Davis
« on: March 10, 2018, 08:45:40 AM »
I just installed my Davis Vantage Pro2 Plus, love it. I am using ambientweather weatherbridge. I have WU set to 5 seconds and I am seeing alot of .9 wind speeds. I dont think this is normal, is it? I see both *.0 and *.9 wind speeds. I have the ISS and Anemometer seperate and using the Anemometer Transmitter. Console is not showing any decimals and I do not think it does. I am guessing it's the Weatherbridge. I have been through the settings in Weatherbridge, just can't find anything. Ideas?

Offline Mattk

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Re: *.9 wind speeds with a Davis
« Reply #1 on: March 10, 2018, 04:43:48 PM »
What is the WeatherBridge, standard( flashed), or Pro, Red or Black. How is the Bridge receiving data from the VP2? 

Offline Mchd17

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Re: *.9 wind speeds with a Davis
« Reply #2 on: March 10, 2018, 04:50:44 PM »
The weatherbridge came from AmbientWeather, so its a standard (flashed). 6510USB davis datalogger plugged into VP2 console is how the bridge receives data.

Offline MonumentHillWeather

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Re: *.9 wind speeds with a Davis
« Reply #3 on: March 10, 2018, 05:54:26 PM »
Same thing happens with mine. Davis VP2 (standard wireless) with the 6510USB data logger, and I use the ambient weather weatherbridge to upload data to CWOP and WU. Iíve used the regular ISS and the anemometer transmitter and both show the same oddity, so I know itís not that. I also noticed that the wind occasionally shows the .9 increments. I find it odd as well and canít figure out why it does it. I just kind of ignore it now.

The other thing I noticed is the temp reported to WU doesnít always exactly match what it shows on my VP2 console. Itís sometimes off by a 0.1 of a degree. I find it odd, but again itís only a tenth of a degree, so Iím not too concerned about it.  :lol:

  - Matt
« Last Edit: March 10, 2018, 05:57:43 PM by MonumentHillWeather »
Monument Hill Weather... Leeds, Maine, USA
Davis Vantage Pro2 with USB Data logger and Ambient Weather Weatherbridge

http://monumenthillweather.webs.com/
https://www.wunderground.com/personal-weather-station/dashboard?ID=KMELEEDS7

Offline Mattk

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Re: *.9 wind speeds with a Davis
« Reply #4 on: March 10, 2018, 06:22:12 PM »
0.9? would that be in Km/h? In any case what is displayed is generally a conversion (exact or rounded) from the raw reading. 0.25m/s = 0.9km/h
You may find a similar thing with temperature, conversion or re-conversion of the raw reading

Offline MonumentHillWeather

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Re: *.9 wind speeds with a Davis
« Reply #5 on: March 10, 2018, 06:29:30 PM »
That makes sense. I have my readings in MPH and degrees F however. But I was under the assumption that it was some kind of conversion standard that was going into effect. Maybe the Weather Bridge is designed to accept and send out data in metric units, so when we have it set to standard units the conversion creates this discrepancy.
Monument Hill Weather... Leeds, Maine, USA
Davis Vantage Pro2 with USB Data logger and Ambient Weather Weatherbridge

http://monumenthillweather.webs.com/
https://www.wunderground.com/personal-weather-station/dashboard?ID=KMELEEDS7

Offline Mchd17

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Re: *.9 wind speeds with a Davis
« Reply #6 on: March 10, 2018, 06:51:00 PM »
Wind gust data is not showing any decimals, unless it matches wind speed. So many *.9's lol

Offline MonumentHillWeather

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Re: *.9 wind speeds with a Davis
« Reply #7 on: March 10, 2018, 06:53:23 PM »
Here is the link to my WU page.
https://www.wunderground.com/personal-weather-station/dashboard?ID=KMELEEDS7#history
Scroll down to the graphs and you can see that there are some wind readings in .9 MPH increments. I also noticed that wind gusts are only reported as whole numbers, but wind speeds sometimes show the .9's.

Or you can see it in the rapid fire updates for current conditions. The gust is always a whole # but the rapidly updating speed sometimes isn't.
« Last Edit: March 10, 2018, 06:55:33 PM by MonumentHillWeather »
Monument Hill Weather... Leeds, Maine, USA
Davis Vantage Pro2 with USB Data logger and Ambient Weather Weatherbridge

http://monumenthillweather.webs.com/
https://www.wunderground.com/personal-weather-station/dashboard?ID=KMELEEDS7

Offline Mchd17

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Re: *.9 wind speeds with a Davis
« Reply #8 on: March 10, 2018, 06:54:52 PM »
I already looked at your WU table, looks like my wind speeds.

Offline MonumentHillWeather

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Re: *.9 wind speeds with a Davis
« Reply #9 on: March 10, 2018, 06:56:52 PM »
I already looked at your WU table, looks like my wind speeds.
At least we know now that it's not just a one person issue!  :-) For a while I was worried it was just something I was doing wrong as well!
Monument Hill Weather... Leeds, Maine, USA
Davis Vantage Pro2 with USB Data logger and Ambient Weather Weatherbridge

http://monumenthillweather.webs.com/
https://www.wunderground.com/personal-weather-station/dashboard?ID=KMELEEDS7

Offline Mchd17

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Re: *.9 wind speeds with a Davis
« Reply #10 on: March 10, 2018, 06:58:53 PM »
Same here, or faulty device

Offline Mchd17

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Re: *.9 wind speeds with a Davis
« Reply #11 on: March 10, 2018, 11:17:08 PM »
If you look at the AmbientWeather Weatherbridge quick start guide, figure 15, Page 17, they show an example of Live Data. Look at the Wind and Avg Wind, *.9 and *.1 throughout those fields. Looks alot like what mine does. I guess it is what it is then.  :lol:

Offline MonumentHillWeather

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Re: *.9 wind speeds with a Davis
« Reply #12 on: March 11, 2018, 06:19:59 AM »
Good find!
Monument Hill Weather... Leeds, Maine, USA
Davis Vantage Pro2 with USB Data logger and Ambient Weather Weatherbridge

http://monumenthillweather.webs.com/
https://www.wunderground.com/personal-weather-station/dashboard?ID=KMELEEDS7

Offline Mchd17

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Re: *.9 wind speeds with a Davis
« Reply #13 on: March 11, 2018, 08:25:35 AM »
I sent an email to AmbientWeather. Curious to see what the reply is. I will copy/paste here once I hear back  :lol:

Offline MonumentHillWeather

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Re: *.9 wind speeds with a Davis
« Reply #14 on: March 11, 2018, 09:52:57 AM »
Sounds great!
Monument Hill Weather... Leeds, Maine, USA
Davis Vantage Pro2 with USB Data logger and Ambient Weather Weatherbridge

http://monumenthillweather.webs.com/
https://www.wunderground.com/personal-weather-station/dashboard?ID=KMELEEDS7

Offline Mchd17

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Re: *.9 wind speeds with a Davis
« Reply #15 on: March 11, 2018, 10:56:33 AM »
Heres a response and it's after he checked my WU

Since it is an average, yes, it can send a number less than 1. However, gust must be whole numbers. What you are seeing is normal. The Davis Station does send fractional numbers for wind speed since it is an average.

Offline MonumentHillWeather

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Re: *.9 wind speeds with a Davis
« Reply #16 on: March 11, 2018, 10:59:56 AM »
Wow quick response from them! Thanks for the heads up!
Monument Hill Weather... Leeds, Maine, USA
Davis Vantage Pro2 with USB Data logger and Ambient Weather Weatherbridge

http://monumenthillweather.webs.com/
https://www.wunderground.com/personal-weather-station/dashboard?ID=KMELEEDS7

Offline dj1111s

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Re: *.9 wind speeds with a Davis
« Reply #17 on: June 11, 2018, 09:56:42 PM »
I just installed my meteobridrge this last weekend and I too saw the .9's and some .1's.  And some whole numbers as well.  It bugged me a little then I became a little obsessed with it Sunday wondering if something was wrong.  So I cranked up MS Excel and did some cyphering.  And yep I was correct.  The problem comes from converting and rounding meters/sec to miles/hour with a precision of 1.  You will get .9 instead of 1, 2 will be 2, 3 will be 2.9, 4 will be 4, 5 will be 4.9, 6 will be 6 and so on.  8 will actually be 8.1.  So nothing is broke but it is kind of annoying.  I wonder if this could be resolved in a future firmware update.  I'm guessing the default for the device is metric.

I am also using a VP2 with a USB logger.  I made the move to meteobridge in the interest of not having my desktop pc running 24/7, which it has been doing now for over 4 years.
« Last Edit: June 11, 2018, 11:20:37 PM by dj1111s »
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Offline mcrossley

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Re: *.9 wind speeds with a Davis
« Reply #18 on: June 12, 2018, 04:00:39 AM »
Heres a response and it's after he checked my WU

Since it is an average, yes, it can send a number less than 1. However, gust must be whole numbers. What you are seeing is normal. The Davis Station does send fractional numbers for wind speed since it is an average.
No it doesn't, it always sends integer mph. As above it is likely a rounding error when converting units. They should round it back  again before sending it.
Mark

Offline Bashy

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Re: *.9 wind speeds with a Davis
« Reply #19 on: June 14, 2018, 11:18:43 PM »
The only time i see a davis station report wind as xx.x is when an offset has been added, so for one to show xx.x there must be something amiss if no offsets are in use
Kind regards
Bashy

Offline Mattk

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Re: *.9 wind speeds with a Davis
« Reply #20 on: June 15, 2018, 12:13:29 AM »
The only time i see a davis station report wind as xx.x is when an offset has been added, so for one to show xx.x there must be something amiss if no offsets are in use

Not so but may depend on just where one is looking? Console output can be different to archive data and other output such as WL.com. Certainly does not require an offset to output wind as xx.x

Offline Bashy

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Re: *.9 wind speeds with a Davis
« Reply #21 on: June 15, 2018, 12:15:55 AM »
Hence why i said "the only time i see....."
Kind regards
Bashy

Offline Mattk

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Re: *.9 wind speeds with a Davis
« Reply #22 on: June 15, 2018, 02:07:29 AM »
Hence why i said "the only time i see....."

You are obviously not seeing everything then :)