[iPhone 3G] GPS functionality.. ?

[idavid]

Steve talked about the A GPS. The system works like Cell Tower> WIFI > and last GPS satellite. What is the advantage of this order of operation? Why not always route using GPS satellites like (tom tom) and later if no signal attempt the Cell towers and WIFI? Anyone with more technical understanding?

Please post the concepts............

[NewWayAround]

It's actually GPS satellite > Wifi > Cellular towers.
Click Here (http://www.apple.com/iphone/features/gps.html) for details.

Watching the demo, I don't see turn by turn voice prompt at all. I guess we have to look.

[arrplayr]

Actually, its the other way around. Phone first searches for GPS signal, then WIFI, and then Cell Tower. Read about it here: http://www.apple.com/iphone/features/gps.html under 'Get the signal' heading.

[thecompkid]

Regular GPSs take a few minutes to initialize because they need to start from scratch each time, essentially. They have no prior knowledge of the satellites they should be looking for other than a last known location.

The new iPhone's GPS uses cell tower triangulation first so it can get a fix much faster than your average GPS unit.

A-GPS initially sounds like a half-baked implementation, but it's actually better.