Originally Posted By: Outdoor_Quest
I am researching to find out how a iPhone/Anroid cell phone GPS works.
Both iphone and Android have internal GPS. When they don't recieve a satellite signal (for example indoors) my understanding is that they triangulate from cell towers, which is less accurate.

Originally Posted By: Treeseeker
However, I have read that most smart phones don't maintain local copies of the maps, so you still need to be in cellphone range to use GPS mapping. I also wonder if you can get topo maps on a cellphone.
There are aps available for the iphone with which one can download local copies of maps. I have not tried them, so I cannot speak to how well they work.

While I use my iphone extensively as a GPS in town, and sometimes carry it as a back when hiking, I don't consider it a substitute for a regular GPS for wilderness use. My experience is that using the GPS sucks the iphone batteries down rather fast. Also, iphones are somewhat fragile and don't like getting wet. Other smart phones may be less susceptable to these problems.

I really like my iphone for in town use, but out in the woods, I rely primarily on traditional navigation with a map and compass, using a stand alone GPS when necessary.
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