Hi Ivconic,
I agree, Franco showed us a fascinating study. I can't help much with designing a suitable reciever, but I am interested to see what you find at these frequencies that you are interested. I would hope that maybe you can find a way to demodulate some of these signals and see if they carry man-made information, or maybe only geophysical signals,
I will be waiting anxiously to see what you discover when you complete your reciever. Best of luck
