[Captivate Android Development] Rrryan2:
General GPS Tips

General Overview of Unaided/Standalone GPS:

http://gpsd.berlios.de/gps-hacking.html

Pay particular attention to the "Locking and Loading" section as it helps give an idea of what GPS is doing on startup in the various scenarios.

General Overview of GPS in Samsung Galaxy S series phones:

I had been considering writing a discussion of sorts of the general issues involved, but frankly I think this really excellent post would be tough to improve upon:

http://xdaforums.com/showthread.php?t=842694

Be sure to give the author a well-deserved thanks.

General GPS Tips:

In Settings -> Location and Security make sure "Use GPS satellites" (duh) as well as "Use Wireless networks" are enabled. This is especially helpful when getting an initial fix in an area where you haven't used the GPS recently

It's best to leave WiFi on when navigating if possible. Google has mapped the location of wifi networks and can use their location to help figure out where it is even if it's not connected to WiFi

"Use Sensor Aiding" should not be turned on. This was mostly intended for pedestrian use. The sensors really aren't sensitive enough to provide useful info at vehicle speeds, and the use is problematic unless the phone is held at a fixed position relative to the direction of travel

Avoid reorienting the screen if possible when navigating. Using the GPS and Google Navigator actually involves a lot of simultaneous computation between determining the position and downloading and rendering the map data. Reorienting the screen seems to pull too much power and causes the GPS to lose fix and re-acquire a lock.

Plug in the car power adapter if you have one. More than a few people report that this helps substantially, lending more credence to the power starvation theories

Position the unit if possible where it has as much unobstructed view of the sky as possible. There's a reason in-car nav systems are mounted either on the windshield or the dash. If it's sitting on a lap or seat, between the ceiling doors and engine block the ability to get good reception to enough satellites is very limited. Even an expedient mount can make a real difference

You can try cleaning the antenna contacts on the inside of the battery cover with a pencil eraser. Just scrub a little at the white parts; don't remove the white material completely. I *do not* recommend bending up the contact as some suggest as it's extremely fragile and can break.

Acquisition times will be best under a "warm start" i.e. when the GPS already has current almanac (within a week-ish since last extended GPS use) and ephemeris (expires after 4 hours) data downloaded and when its last computed position is fairly close to its current location. In practice this means that initial acquisition times will be best when the GPS has been activated in the last few hours. A weather widget or similar that updates itself by GPS location every 4 hours or so accomplishes this neatly with a fairly small impact on battery life. Fancy Widgets seems to work just great for me.

GPS Troubleshooting Techniques:

Test the complete GPS + AGPS Augmentation:

As best I can determine, LbsTestMode will apply AGPS data if it has already been downloaded, but doesn't ever actually download AGPS supplement on its own no matter what configuration is specified.

To Test the overall functioning of the complete system:

Apply whatever fix or configuration settings to be tested

Use LbsTestMode to delete GPS data

Reboot

Use an app like Google Maps or GPS Status & Test to force download of AGPS data

Once you've followed these steps, LbsTestMode acquisition times will be much faster.

Test the GPS Only:

A great way to test the functionality of the GPS on its own is to turn on airplane mode and the use LBSTestMode or an app like GPS Test to see if you can get a fix.

If you get a fix quickly, this means that a)the GPS itself is capable of functioning, and b)the almanac data is already stored on the phone and is current

If you use LBSTestMode to delete GPS data and then try to get a fix this way, it's normal for it to take several minutes to get an initial fix, and as long as 15 minutes or so before attaining an accurate (<30m) fix. This is because the almanac data is being slowly accumulated over the satellite signal, which takes a long time

There is some indication that doing this once a week or so (almanac data usually expires after 7 days) can be helpful as it forces a complete alamanac reconstruction. It seems likely that Samsung's driver may not be updating the GPS-only almanac properly when using AGPS so doing this will help keep it "fresh."

Some users have reported that using other GPS apps (or even loading the AT&T Navigator app and letting it sit at the disclaimer screen for 15 min) improves GPS performance. This is probably why — it's forcing an almanac update.