01-09-2017, 21:14
Little story about why with the WeatherDuino you should use a 0.448 (or even 0.224) multiplier for wind speed and wind gust.
First, take at look at the user configurable settings on the RX software, there is a short explanation there.
Now the story: Davis weather stations measure wind just at 1mph resolution. WeatherDuino can do it a little better, and allows you to chose among three possible resolutions.
When you set this "#define VP2_WindRes" to 2 you get a resolution of 0.72Km/h (0.447mph), if you set that that value to 1, you get an even better resolution of 0.36Km/h(0.223mph), if you set it to 0 you get the standard Davis resolution of 1.62 Km/h (1mph).
So, as we are doing some trick with the Davis protocol, you also need to set on the weather software a multiplier, because it expects to receive values in mph.
This is why if you chose the standard Davis resolution, the multiplier should be 1, otherwise it should be set to the values described in the user configurable settings.
Please also note, that increasing the resolution will also decreases de maximum wind gust possible to be measured. Setting the resolution to 2 is a good compromise for most locations, with that value, the highest wind gust possible to be measured is 183.6 Km/h
Regarding any other adjustment to compensate for the height of the anemometer, I never tried that. In your case the value of 1.12 should be fine if you use the standard Davis resolution. My first impression is that just adding 0.12 to the 0.448 multiplier, will not give correct readings, perhaps something around 0.06 will work, but I'm not sure
First, take at look at the user configurable settings on the RX software, there is a short explanation there.
Now the story: Davis weather stations measure wind just at 1mph resolution. WeatherDuino can do it a little better, and allows you to chose among three possible resolutions.
When you set this "#define VP2_WindRes" to 2 you get a resolution of 0.72Km/h (0.447mph), if you set that that value to 1, you get an even better resolution of 0.36Km/h(0.223mph), if you set it to 0 you get the standard Davis resolution of 1.62 Km/h (1mph).
So, as we are doing some trick with the Davis protocol, you also need to set on the weather software a multiplier, because it expects to receive values in mph.
This is why if you chose the standard Davis resolution, the multiplier should be 1, otherwise it should be set to the values described in the user configurable settings.
Please also note, that increasing the resolution will also decreases de maximum wind gust possible to be measured. Setting the resolution to 2 is a good compromise for most locations, with that value, the highest wind gust possible to be measured is 183.6 Km/h
Regarding any other adjustment to compensate for the height of the anemometer, I never tried that. In your case the value of 1.12 should be fine if you use the standard Davis resolution. My first impression is that just adding 0.12 to the 0.448 multiplier, will not give correct readings, perhaps something around 0.06 will work, but I'm not sure