Wind Speed/Gust Rounding CWOP

[hemmits]

I recently set Cumulus mx to apply a gust multiplier of 1.1. Today I had a wind gust that registered as 39 mph in the Cumulus software and associated web pages. I have Cumulus set to round wind speeds. However, the gust registered as 38 mph in the CWOP. In checking Weather Underwound, the gust was sent out as 38.5 mph. My guess is that either the CWOP is taking the integer value or Cumulus is sending the integer. I hadn't seen this before, but maybe Cumulus only sends out the rounded value if a multiplier is not applied? Is there a way you could have Cumulus send out the rounded wind speed values to data networks?

[mcrossley]

The Davis system only supplies integer MPH wind values. Applying a multiplier will generate decimal values.

I guess if Cumulus is set to round wind speeds then it should send the rounded value externally as well. I'll put it on the the ToDo list...

[hemmits]

Sounds good, thanks Mark!

[hemmits]

Mark has rounding of the wind gust been applied to all uploads of Cumulus Mx? I noticed that my wind gust in Weather Underground is the integer of the gust, not the rounded value. It does look like the wind gust is being rounded correctly in my CWOP uploads and on my webpage though.

[mcrossley]

Sorry, it had slipped off my radar, I'll remind myself to look at this as it should not be hard to fix.

[hemmits]

Sounds good, thanks!

[mcrossley]

Right, I've had a look at this and I'm not sure the Round Wind Speeds is working as intended.

What it is actually doing is... not a lot!
It sets the default number of decimal places for output to zero, so CMX will output rounded values to logs and web tags unless you override the number of decimals in the advanced settings.
It also rounds the mph values sent to WU, WOW, and PWS. But not APRS/CWOP.
And the same rounding for the m/s values sent to Windy.

(which begs another question why did your WU show a max gust of 8.5, it should have been rounded)

The actual values are still decimal values.

What I thought it would do would be to round all your wind speeds to integer values, which would then be used everywhere (except some internal functions which use the raw uncalibrated values).
I would expect the mph values sent to third parties to represent an accurate decimal conversion of your rounded value. So, if you use mph natively, then the rounded value will be sent with zeros as decimals, but if you use km/h, knots etc. then a decimal mph value would be sent so when you convert back to km/h (say) on the third-party web site you should get the integer value back again. The same applies to sending m/s values to Windy.

I had thought I could slip this into the next release, which is almost ready to go, but this complexity means I will not do that until we thrash out what we want CMX to do.

[broadstairs]

I have an issue with rounding wind speeds although somewhat different to that described here. I have rounding set off (unticked in Station Settings/Common Options/Speed rounding unticked) so I would expect my speeds to have at least 1 decimal point however mine all show with no decimal point so that means they are rounded or zero decimal points is set. My display on my website is all using webtags and I do not send to CWOP etc!

So as has already been set this setting is useless. I'd expect with this unticked to get 1 decimal point shown assuming it is not 0! Any whole number wind speed in mph is not common since my Ecowitt station sends speed in kilometres/hour and therefore needs conversion.

Stuart

[mcrossley]

How many display decimals do you have set in the units settings?

[broadstairs]

How many display decimals do you have set in the units settings?

Since that is in the advanced settings I had not looked at it so it was set as default of 0. Don't really understand why wind would be different from the others. Very confusing in my view especially when you have rounding as well. Now set go 1 which I think should be default.

Stuart

Thinking about it not sure why it's in the advanced section with that warning, had it been a normal entry on its own I would have taken a look at it.

[SamiS]

Since that is in the advanced settings I had not looked at it so it was set as default of 0. Don't really understand why wind would be different from the others. Very confusing in my view especially when you have rounding as well. Now set go 1 which I think should be default.

This must have something to do with the selected wind unit. Because I have a clean installation with ecowitt station, wind unit is m/s and I do have one decimal shown by default.

—
Sami

[mcrossley]

Now set go 1 which I think should be default.

If you think you have a station that can accurately measure wind speed to 0.1 mph then you have one hell of a fantastic station

I do use decimal mph for average values but stick with integer values for the single gust measurements. Ecowitt display 0.01 mph in their app!!!!

[broadstairs]

Irrespective of whether or not 0.1mph is valid or not I think my main point here is that the decimal place value settings are in what in my view is a strange place effectively hidden in a menu item which has a warning about 'Here be dragons'.

I don't see why this is the right place to hide what is in effect a display option about decimal places. In my view it does not need a warning it is something which should be placed somewhere obvious so folks are aware of it. That warning suggests to me that what is behind that option is something which can cause huge issues and that is certainly not the case with decimal places. That explains why I was not aware of it.

I think one decimal place is valid since we are converting from metres/second which is that unit of measurement sent by Ecowitt and 30.0 and 30.9 are significantly different.

Stuart

[mcrossley]

Perhaps the warning is a bit strong, people in the past though haven't realised that it also affects the precision of data storage.

Ecowitt claim an accuracy on the WS90 of ± 0.5 m/s below 10 m/s. That is ± 1.1 mph, so I think rounding to integer mph is a sensible default for the latest values, the average mph speeds default to 1 decimal place.

Davis VP2 is similar, greater of ± 2mph or +/- 5%

Above 10 m/s WS90 is ± 5%, so at 30 mph that is a range of 3 mph, quoting gust values to a tenth of a mph implies a precision that just isn't there.

[davepaterson]

Mark Is there any way of getting the current gust reading into realtime.txt or realtimegauges.txt and not the last high.?