I plan on using the nav app in the car and want location based services with apps and pictures. I would love an explanation of the three levels of GPS as well.

 

If y'all are talking abut the three icons that with the stock launcher, they are Wifi (used to connect to a wireless network, which disconnects you from the phone's (i.e. Verizon's) 3G network. This is usually a much faster way to download data and access the internet); satellite (which is used for GPS navigation and usually necessary for google maps, navigation, etc.) and bluetooth (used to connect to bluetooth wireless devices. Headphones, ear pieces, etc.). The fourth icon is for airplane mode which turns off the services that will interfere with an airplane's navigation system.

Hope that helps, and sorry if I did not answer your questions correctly.

 

Gotcha, sorry about that. I will have to let someone more familiar with the aGPS answer then, as mine is turned off and I have not used it all. I have used nav and google maps, and the *regular* GPS has found me every time. It doesn't work all that well inside my office though (unless I stand by the window), so I will enable the aGPS tomorrow at work and see if that helps!

 

Well, I turned everything off and then toggled the gps widget and went back to location settings and the satellite was turned on.

 

Satellite only. Turn it off (while leaving wireless on) and see that apps that use location still work, but your location may not be very precise.

Well, obviously all of them off will give you the best battery life. Supposedly, none of them will be used until an app explicitly requests a location, so if things are operating properly I don't think you'll see much of a difference in power drain.

It is redundant, some of the time. However, wifi will usually work in locations where GPS may not -- e.g. indoors. Same with tower assistance, but it's my understanding that the main benefit of using aGPS over GPS is to give a quicker, but less accurate, lock (so your app can continue, and when you get a satellite lock, it'll update your location more precisely).

You may be interested in this page for more info: SKYHOOK Wireless: How It Works > Overview

 

Satellite is regular GPS - just like in a standalone GPS system. aGPS is something that virtually all phones add - it still uses the satellites, but it assists in finding a faster lock (or a lock when satellites are hard to reach) by referencing nearby cellular towers.

Wireless networks is Google's addition where it collected public wireless network data and it attempts to provide yet another piece to the puzzle.

In theory, all three being active will provide you with the best lock - and the least battery life, since it requires activation of three different chips. However, in practice, it matters what algorithms have been built into the phone. Theoretically, the aGPS and WiFi should only be used to refine and speed up with satellite readings. In practice, you may find that, say, the WiFi network gets weighted in the equation and you lose accuracy. You'd have to experiment to find out which is best for your usage in your area.

 

Very interesting information - thanks to all who answered correctly and cleared up my blundering attempts to!

ETA - I enabled all three while sitting at my desk this morning, and the phone had no clue where I was.....

 

I believe satellite is "Fine location" while aGPS is "Coarse location". Fine meaning down to a few feet off your actual location, while coarse meaning could be 500 feet or a mile off. aGPS will also get you started quicker while the regular GPS need a few extra seconds to lock in it's satellites. Lastly I think the wifi one mainly is for use indoors or with no view to the sky. Try them all separately while running Google maps to see what happens with them. My regular is always spot on, while aGPS always ends up a mile or two off over by the nearby freeway.