Questions about wind readings
Posted: Thu 09 Nov 2017 5:50 am
I have my Davis 6410 temporarily installed at the front of the house (not a good position) just while I am testing and I think I am very close, it will soon be installed on the peak of a gable on the roof which should be in reasonably clear air.
On the Arduino I am reading the wind speed and wind direction from the Davis every 10 seconds. I save the readings and keep the last 5 readings, I then take the average of the 5 readings and that goes to the station as wlatest and bearing, I also send the maximum speed reading and its bearing of the 5 readings as windgust and windgustbearing. For the average I use the formula from http://www.webmet.com/met_monitoring/622.html with a lot of help from http://www.scadacore.com/2014/12/19/ave ... ind-speed/. If there is no wind for the 5 readings I set both wlatest and bearing to zero.
On the station I do the 10 minute averages for wind and wind gust using the same formula as above and also save the maximum wind gust.
For the dominant wind direction I started by saving avgbearing (and wspeed) every 10 minutes but only if there was wind. I then did a circular average on the number of saved values only and then convert it to a cardinal reading.
The wind rose, I guestimated that the 16 values were 16 cardinal points going clockwise from N so every 10 minutes I cleared the wind rose data and then added the saved wspeed values to their correct cardinal point and this seems to work.
For wind run I add all the saved wspeed readings and divide by the number of 10 minute periods since midnight to give me the true average km/h and then I divide by the number of hours since midnight (to 2 decimal places) to give me the wind run in klm.
Since finishing that I have changed the saving of avgbearing and wspeed from every 10 minutes to every 5 minutes giving me a maximum of 288 readings each day but I didn't notice any real change of what I saw on the gauges after I did this.
All I am asking is am I going in the right direction or have I made mistakes, the attached graphic is what the gauges look like. I've done all of this on a second Raspberry and I will transfer it to the main station when I am happy with it.
On the Arduino I am reading the wind speed and wind direction from the Davis every 10 seconds. I save the readings and keep the last 5 readings, I then take the average of the 5 readings and that goes to the station as wlatest and bearing, I also send the maximum speed reading and its bearing of the 5 readings as windgust and windgustbearing. For the average I use the formula from http://www.webmet.com/met_monitoring/622.html with a lot of help from http://www.scadacore.com/2014/12/19/ave ... ind-speed/. If there is no wind for the 5 readings I set both wlatest and bearing to zero.
On the station I do the 10 minute averages for wind and wind gust using the same formula as above and also save the maximum wind gust.
For the dominant wind direction I started by saving avgbearing (and wspeed) every 10 minutes but only if there was wind. I then did a circular average on the number of saved values only and then convert it to a cardinal reading.
The wind rose, I guestimated that the 16 values were 16 cardinal points going clockwise from N so every 10 minutes I cleared the wind rose data and then added the saved wspeed values to their correct cardinal point and this seems to work.
For wind run I add all the saved wspeed readings and divide by the number of 10 minute periods since midnight to give me the true average km/h and then I divide by the number of hours since midnight (to 2 decimal places) to give me the wind run in klm.
Since finishing that I have changed the saving of avgbearing and wspeed from every 10 minutes to every 5 minutes giving me a maximum of 288 readings each day but I didn't notice any real change of what I saw on the gauges after I did this.
All I am asking is am I going in the right direction or have I made mistakes, the attached graphic is what the gauges look like. I've done all of this on a second Raspberry and I will transfer it to the main station when I am happy with it.