It's been amazing how the use of GPS technology has grown over the past twenty years. What started out as a tightly controlled tool used primarily by the military has turned into a host of consumer products that have worked their way into our everyday lives. Nearly every new car comes with a GPS receiver for emergency purposes as well as a navigation aid built into the car. Most new cell phones are similarly equipped and yet, a majority of people don't really understand how it all works.
Most people know that GPS works using satellites, but not much more. This is true of course! There are actually 27 satellites that all work together. These satellites orbit the earth in a very precise pattern and on a precise timetable, such that a signal from at least four of them can be received at any time and at any location on the earth. It's a pretty amazing accomplishment!
A GPS receiver works using a technique called triangulation. It takes the signals from...