iphone 3g GPS vs. iphone 3g Assisted GPS. What is the difference between iphone 3g GPS and iphone 3g assisted GPS? iPhone specs says, it has assisted GPS. Does it mean that it will not be able to pinpoint the street location positioning ?

iphone 3g GPS uses satellites to get a fix on a position. iphone 3g A-GPS uses cell towers & wifi to get a quicker position while the GPS antenna gets a lock on satellites. A-GPS will pinpoint your location (to within a few meters), and it will do so faster than un-assisted GPS. Accurate location requires a fix on 3 satellites, and the signals do not penetrate buildings (even the roof of a car can attenuate the GPS signal). So, if you are not in view of 3 satellites, A-GPS can estimate your location based on 2 satellites plus cell tower data (less accurate). If you aren’t in view of at least 2 satellites, the iPhone uses WiFi (if available in the Skyhook database, I think coverage is minimal in AU) or cell-tower triangulation, which is not very accurate. Lower accuracy is represented by a larger circle on your map.

Tags: iphone 3g A-GPS, iphone 3g GPS, iphone gps