What Is GPS?

GPS stands for Global Positioning System. A special radio receiver measures the distance from your location to satellites that orbit the earth broadcasting radio signals. GPS can pinpoint your position anywhere in the world. Pretty cool, huh? Aside from buying the receiver, the system is free for anyone. You can purchase an inexpensive GPS receiver, pop some batteries in it, turn it on, and presto! Your location appears on the screen. No map, compass, sextant, nor sundial is required. Just like magic. It’s not really magic, though, but has evolved from some great practical applications of science that have come together over the last 50 years.
Other satellite Global Positioning Systems are either in orbit or planned, but this book uses the term GPS for the Global Positioning System operated by the United States government.