Windmeter for Android

Here is the first test of my Android Windmeter.
It works with two small magnets attached to the anemometer axis and rotating above the smartphone's magnetometer.
This produces a very small fluctuation of the magnetic field. When applying a fast fourier transform you can get the rotation speed.
Then the App allows to calibrate the speed using the GPS and display it on a gauge.

Well, see it into action :
https://www.youtube.com/watch?v=jA16slSEuuM