I was abroad this week in-line skating, so I wanted to record my tracks and A-GPS wasn't available (no data roaming for me). I have had a lot of trouble with Sports Tracker and GPS data, so I took the LBSReference example, modified it to log NMEA sentences and print satellite signals etc. and tried to get some insight into when GPS location is and isn't available.
I found roughly this:
1) after a couple of hours and a phone restart, GPS does a "cold start" -- starting with 0 satellites in view, it slowly gathers the satellites, showing signal levels of ALL of them, eventually acquiring a fix in no more than 5 minutes
2) if I then stop the application and wait for something like 30 minutes and then run it again, it shows a big number of satellites in view (over 10), shows signal levels for only some of them (no more than 4, usually) after a couple of minutes, but is not able to acquire a fix (not in 5 minutes, not in 30 minutes, it's simply broken)
3) in this state where a fix can't be obtained, running another application like GPS data or Maps makes the location updates stop completely after a few minutes -- this means the application is not getting any location updates even though partial updates had been enabled, and the same thing would happen to GPS data after a few minutes, the satellite info display would be stuck with the same satellite info forever
4) to fix this, the phone must not use GPS for a couple of hours and be restarted
I believe this may be a firmware bug, but I still want to ask a few questions:
1) Is it possible to programmatically force the phone to forget all the ephemeris it has gathered and do a cold start again? That would make it usable for city navigation, at least.
2) Are any of you experiencing similar issues with unassisted GPS?
3) Is is possible to gather assited info for a week in advance (like Samsung phones do)?
4) Is there any chance Nokia will fix this or am I stuck with assisted or nothing? (according to some forums, this isn't a problem that only I have, seems like people are paying for things that don't work )
For the record, I have Nokia 5800 ExpressMusic, bought in Czech Republic, product code 0580331, firmware 21.0.25 (newer isn't available for this product code, is it? Should I take it to the service care center?).
Thanks in advance for any hints you might have on this issue.