[Captivate Android Development] Ikonomi:
I wanted to share my results using Da_G's GPS fix. I'm running stock 2.1 JH7, rooted, using RyanZA's OCLF. I've done a version of the back plate contact mod. GPS performance on my phone, like on many other Captivates, has been unpredictable, and I'll spare you guys most of my personal history with it. I've tried a lot of stuff to get the GPS functional, and so far nothing has really worked. Sadly, this includes Da_G's excellent and incisive fixes, which he's obviously put a TON of time and effort into. My GPS with his fix is about as good as it's ever been. Previously, I got the best performance with the back plate contact mod, using the tried and true supl.google.com GPS settings.

At any rate, here's the situation with my Captivate. I chose to use Da_G's Google-version jupiter.xml, edited to work with 2.1, with the vehicle/pedestrian setting set to DYN_AUTOMATIC. I'm working from memory here at work, so my details may be a little off. I've tried using the AGPS in both MS Based and Standalone modes, and have not seen a huge difference in real life functionality. Standalone may provide a more accurate fix. LbsTestmode settings are otherwise as recommended in Da_G's original post. I did not have good results with the AT&T file, and have not tried the Control Plane.

All the observations below were made over several days of using the GPS on every car trip I made, with the phone mounted on the dash board. I mainly used a combination of GPS Test (available in the market), Google Navigation, and My Tracks.

Satellite locking is a strange ordeal. It's a bit slower now to pick up satellites, but GPS Test and LbsTest report a "lock" in about the same amount of time compared to my previous settings, but with much, much lower accuracy. I had never seen a "lock" at 400 meters before, but the good news is accuracy improves down to 30 meters, sticks there for a few seconds, and then narrows down to 5-10 meters and stays there (provided I have GPS Test or LbsTest in the foreground). Accuracy will generally bounce between 5 and 10 meters, except when I pass under or beside an obstruction. This is the same accuracy I was getting before, but it seems the GPS is much quicker to report changes in accuracy now, whereas before GPS Test would report 5 meters, and My Tracks would later show me off the road.

Tracking in all programs is overall improved, even compared to the best performance I got before using Da_G's fix. This is the main and most material benefit. With smoothing off, the GPS no longer overshoots corners. There is still the characteristic lag in my position in Navigation, Maps, and My Tracks. The problem seems more apparent now that the GPS is more responsive. It seems worse because it's working better, if that makes sense. Despite this, it reacts to turns more accurately and Navigation is able to re-route more quickly. I found that purely pedestrian mode reporting was too jumpy, and combined with lower accuracy locks (15-30 meters), Navigation would put me one or more blocks over more often. Of course, Navigation never had qualms about jumping me from one street to another, but the problem was exacerbated using pedestrian mode.

Overall, the GPS is absolutely usable for Google Navigation. However, and this is a huge however, IT IS NOT USABLE WITH NAVIGATION IN THE FOREGROUND. At all. This is another problem that is much, much more apparent using Da_G's files -- with Navigation, My Tracks, or Maps in the foreground, accuracy and tracking take a huge hit. Like, it's completely unusable. Accuracy hovers around 30 meters, Navigation shows me moving when I'm not and switches me to other blocks or the intersecting street at a stop light, and my position on the map lags up to a block behind my actual location. With GPS Test or LbsTest running in the foreground, accuracy stays at 5 meters most of the time, periodically jumping to 10 meters, and Navigation calls out mostly accurate directions, and seems to know my location fairly well.

Navigation in foreground? Horrible, unusable, frustrating. GPS Test in foreground? Very functional, for a Captivate. This is such a weird problem. I just can't understand how Samsung managed to introduce a bug like this into the system. Could this be a power supply issue? Is it possible that when running more CPU-intensive applications (Navigation, fancy new 3D Maps), the power to the GPS subsystem falters, slowing down or messing up that hardware crystal clock thingy and causing the phone to lose satellites? The difference between having GPS Test and Navigation in the foreground is night and day. It's absolutely staggering.

The only problem I've had that seems directly related to the new files, as opposed to a problem stemming from the overall faulty GPS, is that every once in a while the GPS will shut down a few seconds after initializing and before getting a satellite lock. I initially had a problem with the GPS not shutting off until I task killed everything GPS-related, but I think that was due to LbsTestmode still running Get Position Test in the background.

So, Da_G has put an unbelievable amount of work into this fix, and if your GPS is like mine, I can only recommend that you try it. It can only improve your performance. DO IT. Bear in mind that the GPS will "feel" vastly different, but mostly for the better. Da_G's observations about the problems with the GPS have been extremely illuminating. Unfortunately, even this amount of skill and effort can't overcome a system with the multiple problems our Captivates have. The GPS, if you have a phone like mine, will never be completely usable. I don't consider having to keep another program in the foreground while navigating an acceptable sacrifice.

I intend to exchange my Captivate based on the random shutdown warranty issue and see if the problems have been at least partially fixed in the newer production run. Based on Da_G's posts, it seems like there are some problems that only a redesign of the GPS or related systems would fix, which is kind of disheartening, but I've read the posts about later models having improved GPS functionality. I am in love my Captivate and intend to stick with it for a long time, until a truly superior Android phone hits AT&T. Well, not this specific Captivate, but you get the picture.

Sorry for the long post.