I figured out how my iphone gps works.

I figured out how my iphone gps works.

It needs two inputs.

1. It needs a gps signal from the gps satellites. At least three of them so it can triangulate a position.

2. It also needs a data signal -- two ways -- so it can send the gps info to a data base somewhere and get a map onto the iphone showing the exact location.

A very sophisticated gps, for example, in a car or on a boat, has a dvd with all the gps maps on it. The little iphone doesn't, so it has to access a data base.

I figured this out because we turned on the "airplane" mode, tried "map", and the iphone gave us an error message saying we needed wifi to function. So it definitely needs the data link. And it obviously needs at least 3 satellites, since that is how gps works.

So I figured it out.