Quote:
Originally Posted by Maggie Leung
How is GPS going to work with wi-fi? Won't you essentially get a guesstimate of where you are, even if you can pick up a wi-fi signal?
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That depends on what you mean. Do you mean "How is a GPS chip going to work with wifi?" Or do you mean, "How is a system going to use wifi to find your location?" Or do you mean something else.
The GPS chip is independent of wifi, and, while it may be a part of the same unit as the 3G chip, it is technically separate from that, too. You can get GPS units that have neither wifi nor cell phone chips. The GPS chip does it all on its own.
You can get an approximation of your location without a GPS chip using only cell signals (if you have a cell phone chip) or only wifi. Wifi, I believe, will look at local wifi networks and compares them to some database or some ip-based naming structure to place them geographically. It's far from perfect, but on my wifi-only iPod touch it usually places me within a city block of where I am. But sometimes it can't find me at all or puts me in a whole other state, so in the best case it's not as precise as a GPS, and in a worse case it's useless. But more often then not it does pretty good if you're connected to a wifi network. Cell phones and other devices that use the cell phone network can do something similar by reporting how strong the signal is and what tower it's connected through. If it's in range of more than one tower, your position can be triangulated. If not, it just has to guess that you're within X feet/miles of a given tower.
My understanding of the iPad/iPhone is that they use a combination of GPS and cell towers. The cell towers give it a general position, which lets the GPS unit eliminate a lot of possibilities and narrow down your exact(ish) location more quickly.
So basically you can use any of the three (GPS, wifi, or cell) to find your location, but they vary in precision and reliability.