Hi,
My gnuradio hackfest project was to migrate code to 3.7. With the help of a lot of the other more programming savvy participants, I managed to migrate everything fairly cleanly. As a byproduct of this, my chirp sounder receiver code now works with gnuradio 3.7 too! I did a lot of cleanup and removed the dependency on GNU R. I also added a new feature that allows you to filter out HF broadcast band interference before chirp downconversion.
I wrote a small posting about the release here (with a nice video using the new HF broadcast band filtering):
And the new version of the code can be found here:
http://www.sgo.fi/~j/gnu_chirp_sounder/
You should be able to get this working if you have a N200 series device, a GPSDO, and a broad band HF antenna (it doesn't have to be excellent).
juha