SDR (Software Defined Radio) » rtl-sdr

Windows builds are available, see https://osmocom.org/projects/rtl-sdr/wiki/Rtl-sdr#Binary-Builds
As for UAT there appears to be https://github.com/mutability/dump978 - i'm not familiar with it, since it's US-only.

Hoernchen, I am aware of the Windows builds and use rtl_adsb. I like this application because it is light and provides raw messages (not decoded). I am also aware of dump978 but: 1. I could not find a Windows version; 2. as far as I know, it provides decoded information only.

Ah, my bad, I managed to read this as "is there a windows version of rtl-sdr"..
As far as modifying rtl_adsb is concerned, that tool was originally contributed by someone else (keenerd according to the header in the source file) - you might want to contact him directly, he's usually hanging out in the irc channel (freenode, ##rtlsdr). Asking in that channel would probably a good idea anyway, I've lost track of all the forks and versions, who knows, there might already be a Windows version of what you're looking for.

Thanks, I'll give it a try.