This might not be a GPS issue, but a phone issue as I have the problem (kind of) with an external bluetooth unit.
For a few days when I first started using it often (mostly with the Nokia Sports tracker). It worked fine, whole route. Used the internal GPS with the trip running on the built in GPS *AND* gps tracking using 3dtracking.
After a few days, at the end I would notice it stopped at around 0.6km. This was in the built in app and the sports tracker programme.
When I exported my route, it recorded the turns etc for that 0.6km.
Next time I went around, I checked again after 1km, it stopped at 0.6km. I tried to get it to fix again and it seemed to show all the satellites it needed (and the compass on the first screen). Sports Tracker showed GPS[Tick] but just wouldn't count any more distance (same for the built in app).
So annoyed buy this, I changed to using a bluetooth gps unit (via the internal API), and it still drops at around 0.6km. I also tried with the internal API using BOTH internal GPS and bluetooth GPS.
I usually get around 5-7 satellites before I set off, and its open countryside so no blocking. I mount the GPS in a thin pouch on my back.
I have since gone from v21 and v30 and the same issues.
Any idea?