[Vibrant General] tornado76:
Here are some observations I have made in dealing with the GPS and compass.

Applications I used during this observation include:

GPS Test

Goolge Maps

MyTracks

Trapster

Compass

There are a few things that led me into looking into this. It started with my first Vibrant.

I bought it at the beginning of September and during that time I was working 6 12 hours days and didn't have a whole lot of time to play around with it.

In the middle of September I went out of town for a week. I went from Oklahoma to South Carolina. Basically on the trip my GPS worked pretty much spot on even though GPS Test showed a few in view and 1 or 2 in use. My compass never really worked all that good and it was real slow to update.

I used Google Maps for nav and was running Trapster. If you never used Trapster it shows your location with an animated radar wave emitting from it showing your direction of travel, this is important as you will see later in this post. I ran MyTracks a few times just to play around with it and it pretty much worked as expected. The arrow would correctly show which direction you are traveling, again important. So after traveling about 2600 miles round trip my GPS worked about as good as my Wife's MyTouch 3G. Sometimes it would take a while to lock, but once I had one it worked well.

On to the next phase. I was able to update to JI5 when it was available on Kies and tested the GPS right away. When I fired up GPS Test I had 12 in view and 8-9 in use and it locked in pretty fast. I thought to myself awesome, it's fixed! or was it? After updating I noticed that the accuracy was not as good as it was stock.

Later that night my wife and I went somewhere and I let her drive so I could mess around with the GPS and apps. I wasn't too happy with what I was seeing. Remember earlier how I said Trapster and MyTracks was showing correct direction of travel? Well after the update the arrow on MyTracks was going crazy and could not figure out which way to point and Trapster was showing it's radar icon as a circle around me as if I wasn't moving but my location on the map was moving. My position on the map was off at times and when we stopped my location would jump around. When I was stock I never had that issue. I flashed back to stock because I would rather deal with a longer fix but have the accuracy and my apps work right. After flashing to stock Trapster and MyTracks still could not show a correct direction of travel.

Around this time I came across the "hardware lock" issue and found out that phones were being replaced so I went down to the store I bought it from and exchanged it. When I was in the parking lot I loaded up the apps mentioned in the beginning of this post to test. Accuracy was still off a little and Trapster and MyTracks still could not display direction of travel. Google maps could display it correctly. GPS Test showed a few visible and 1 or 2 in use.

I figured I would just deal with it until the update came out. That day was today. I did not get the update OTA but did flash JI6 since that was what the OTA was showing on others phones.

I wiped everything after flashing and did a master reset. I then installed the mentioned apps again for some testing. GPS Test 12 in view 8-9 in use, accuracy was still not as good as my first Vibrant stock. Google Maps found me pretty close to where I was, but not spot on like the last phone and drifted a little bit. MyTracks arrow moved when I rotated the phone but did not point in the right direction. Started the compass app and it was way off and barely moving, I did the calibration and it actually started working pretty good even though it was a little off. I started MyTracks and low and behold the arrow was pointing in almost the exact direction i was facing. I though great everything should be ok!

I had to run to the store so I tested while driving. Accuracy was pretty good, Trapster and MyTracks could still not display correct direction of travel so I fired up the compass and it was all over the place and shaking around a lot trying to determine which way it was facing. When I got to the store and stopped the compass was working like it was at the house and MyTracks was pointing in the right direction again. I though how odd and tested more on the way home.

Here is where I think it gets interesting. As I was driving and in GPS Test I hit the button on the bottom left of the screen. That brings up a compass view. It was showing my heading correctly. Google maps showed my arrow pointing in the correct direction of travel as well but Trapster and MyTracks could not.

I made 2 observations that I think may be important. When I stopped and had GPS Test open to the compass part I noticed that the heading was now off a little. Google maps was the same, the arrow was just not stable. When I started driving again both apps started showing the correct heading. That is when it hit me. When stopped GPS Test and Google Maps must be relying on the compass when not in motion to get it's bearings and that Trapster and MyTracks must be relying on the compass alone for it's heading information! I confirmed this by opening the Compass app while in motion and taking a note on which way it though I was going and then opened MyTracks and would you believe it, the arrow was pointing in the same direction that the compass showed me going!. I was traveling straight west and the compass along with MyTrack were pointing south! I confirmed this after driving around for a while that whatever way the compass was pointing that is the direction the arrow in MyTracks pointed. When I stop everything points correctly, or at least close to being correct.

So now the million dollar question is since GPT Test and Google maps fall back on the compass when stopped could that affect accuracy? If it is pointing in an incorrect position but thinks it is pointing in the correct position could it think the satellites are in a different position in the sky thus some of the jumping around when you are stopped and once you are moving it gets it's bearings straightened out and is able to track you correctly? I am thinking it might have some play in it since sometimes when I am sitting still out in the yard and I rotate my phone my position will jump 1/4 mile away and move all over the place but if you click the arrow it shows accuracy to 10 or less meters.

What would make the compass show the correct postion when stopped, but all over the place when moving? Are the compass and GPS tied that close together?

Thoughts?

I tried to email this to Samsung but the web form was messed up and I'm not sure if it went through or not.