[Captivate General] MarcianoS:
A workaround

OK, take this with a liberal helping of salt, but I've tested this procedure for a few days now, and so far it seems to help. I've refrained from posting earlier because I wanted to gather more data, and also do some background reading. I think what I found is consistent with theories having to do with a bad/corrupted GPS almanac; see Mr. GPS's insightful posts on Android Forums (google).

First off, I'm on stock JH7 after an OTA upgrade. I am unlocked, but not rooted.

Second off :-) this is a workaround, not a permanent fix. It requires user intervention, and really SHOULD NOT be necessary AT ALL, if the Cap's GPS worked as intended.

OK, here goes. My GPS worked fine [maybe not as well as a dedicated GPS unit, but I could use Google Nav with no problem at all, etc.] when I got my phone. Then, it stopped working. So, I started checking out the LbsTestMode activity, WITHOUT changing any setting. I just wanted to look at the settings. I also played around with GPS Test: I could see satellites, but not get a lock.

Then, a few days ago I used LbsTestMode to switch from the default, which after the OTA update was "Custom Config" set to spirent-lcs, etc (again, I did not enter any of that: it was there when I got the phone), to "Auto Cofig". Bam! Running GPS Test, I got a lock in 10-20 seconds!

At first, I thought that was the "fix". BUT, after a couple of days, the very next day locking stopped working. So, I switched back to "Custom Config", again without changing any settings, and ran GPS Test. Again, Bam! I got a lock!

After more experimentation, I settled on the following procedure. As soon as GPS lock problems arise:

1. Run LbsTestMode and switch to the other setting (I don't see a difference between them: just SWITCH to whatever is not active at the time). After selecting the new setting, I think you must use the back key to go back to the main LbsTest menu---perhaps that saves the setting.

2. Run GPS Test.

Bottom line: since the Cap can actually see satellites, but does not "lock," I think the problem may be that, under some conditions, some kind of cache gets corrupted---again, I've seen mention of the GPS almanac, which keeps track of where satellites are. By switching to a different configuration, I think I'm forcing the software to clear the cache and start from scratch. Note that it is NOT enough to "Clear GPS data" using LbsTestMode (or the GPStest app), although I DO do that, too for added measure---it does not help by itself.

My impression is that this procedure becomes necessary (hence, the cache in question becomes corrupt) mainly when trying to get a lock without a clear, unobstructed view of the sky. But, once locking becomes problematic, it does not help to be out in the open.

Again, this is a workaround, and an ugly one at that, but it SEEMS to have kept me going for the past few days. Also, there is some semblance of theory behind it.

One implication is that changing the actual custom settings with different ones may or may not actually help get a lock. It may be that it's just switching to a different configuration that does the trick, at least for a while. Also, the fact that many people have reported that an initially working "fix" seemed to deteriorate over time is consistent with the cache corruption theory.

Finally, I have no idea how to compare the Cap's GPS with other phones' GPS. Once it locks, it seems OK, although it does get confused sometimes (usually when I'm surrounded by highrise buildings). And, I simply never got a lock indoors.