How does GPS know where you are?

Answer 1

A GPS receiver determines its location by analyzing signals it receives from GPS satellites orbiting around Earth. Signals from satellites that are farther away take longer to reach the GPS receiver. Distances to several satellites are calculated based on the amount of time their signals took to reach the receiver. After determining its distance from at least three satellites, the GPS receiver can calculate its own position using triangulation. (Any location can be identified using distances from three other know locations.)

Answer 2

GPS, or "Global Positioning System" uses signals bounced off of satellites to know where you are. Three or four satellites can pinpoint a position very accurately, and approximately 30 satellites in the NAVSTAR system, which is what is used by the United States, and there are similar systems in place or planned by other governments.

Answer 3

By evaluating the strength of the signal emitted by the cell phone at various towers.

The strength of the signal as measured at any given tower gives a region around the tower where the cell phone could be located. If you do this from, say, three or four towers, and see where the regions overlap, then you can narrow down the position quite a bit.

It's not precise, because the cell phone might be inside something that partially blocks the signal, giving an unusually low reading, or it could be high in the air (atop a building, for example), which would give an unusually strong signa (since the signal wouldn't be partially blocked by other buildings and ground clutter). Still, it's usually good enough to make a very good estimate of the position.

All this assumes the cell phone doesn't have a built-in GPS unit which is capable of reporting the phone's precise location to within a couple of feet.

Answer 4

A GPS knows where you are because of satellites in space.

Answer 5

actual mathematics is complicated, but basically by triangulating with multiple satellites by measuring signal time delay and solving a set of simultaneous equations to best convergence.