Sigfox Device to Device communication details
As far as I can see there‘s just little information about operating SiPy in FSK mode.
I have some newbie questions like, is this mode just like broadcasting? So if there are 100 devices in a 5km radius around me and they all send something, will I receive it with my single device in RCV mode (assumed theyre using FSK)?
Yes that is the idea but you'll struggle to reach 5Km using FSK unless you have high gain (directional) antennas, the link budget using FSK is significantly less than Sigfox's protocol (BPSK) or LoRa.