Here's an example oblique ionogram.
While installing the GNU Chirp Sounder, I made some updates to the software. It still compiles with relative ease with GNURadio 3.7, which was a huge relief. Just make sure you have cmake, swig, and all the relevant libraries installed. The new release can be downloaded here: gr-juha-1.25.tar.gz
I've even setup a real-time ionogram here: