Originally Posted by Dubdub
If it has been 7 or more days since you last used GPS, the device needs to download the ephemeris table first so it knows where to look for which satellites.
I never knew that. Any idea how long that should take, and where it downloads it from? Do dedicated GPSs do this, e.g. Garmin with no SIM?
If you have moved a considerable distance from the last use, it also takes a few minutes to locate the satellites and determine your position.
I didn't know that either. If both these things are correct then it sounds like irregular users of the GPS function should plan to use it at least until it gets a fix the day before they need it, and perhaps daily if they're travelling.
My 9800 is usually ok, can even get a fix indoors sometimes, but is occasionally erratic. I don't use it regularly, so this might explain some of its behaviour.