@Bratac: Exactly!

I will also consider the distortion in the frequencies next to frequence of the sender.


In the first step I will save the results in the receiver as wav-files.
Then I will look at those wav-files with audacity.
I am sure that I will find a charateristic for each direction.


(Concernig the other post: Speaker and phone are not sensible enough to the earthmagnetic field: air-waves. But fm-waves are electro-magnetic waves. The earthmagnetic field is a magnetic field.)