I'm a recent user to Skydemon. It has worked perfectly for navigation with my old GPS receiver, an Emtac BTGPS III. No issues at all.

However, I've recently upgraded to a new receiver (here: http://www.gns-gmbh.com/index.php?id=79&L=1). It offers some benefits as it has a faster refresh, support for more constellations than just GPS, and SBAS. And also has a longer battery life.

The new receiver works flawlessly with Memory Map both on my PDA and my laptop, as well as with my Android phone. However, Skydemon will not work with it. When entering Navigation mode, it simply says "Seeking Satellites, 'n' found ('x' out there)". It never gets past that and never gets a fix, even though it often 'finds' as many as 15 or 16 satellites.

There is a standard set of GPS sentences which all such applications parse, giving very basic information such as where you are, the current date and time, your speed, heading and altitude. That protocol has been around, as mentioned, for a very long time and is not going to change any time soon. As a GPS application, SkyDemon does exactly what it should do.

Newer receivers sometimes include EXTRA GPS information which is of no practical use to SkyDemon so there is no point is us adding to our parsing code by processing that information.

We may add support for parsing GLONASS sentences in future, though, but at this stage we have no great knowledge of these or how best to integrate them with incoming parallel GPS data.