Global positioning systems seem to appear everywhere these days, from your cars to your mobile phones to even video games. But how does the Global Positioning System work? They are not as complex as you think.
Global positioning systems use satellites in Earth orbit to transmit signals to GPS receivers on the surface. For the Global Positioning System to work properly, it requires an accurate time reference. That is why all GPS satellites are equipped with atomic clocks, which are always synchronized not only with each other, but also with all GPS units on earth.
Each GPS receiver uses at least four separate satellites to determine your position on Earth. Each satellite uses a spherical system that helps the device judge your location. Depending on how far the satellite is from your location on Earth, the greater the area. Using these spheres as a basis, a GPS device can determine its exact location within each of the spheres generated by satellites, as well as on the surface of the planet based on the intersection of the spheres.
In the United States alone, there are at least twenty-four GPS satellites in orbit, and there are hundreds of satellites from different countries around the world using many different GPS networks, but they all operate on the same atomic-time principle. In short, it means that no matter what GPS device you have, no matter where you are, your GPS receiver will be able to tell you exactly where you are.
So how accurate is a GPS device? Well, a typical GPS device that you can buy from your local outdoor equipment retailer is accurate, usually ranging from ten to twenty meters. Other GPS devices typically produced by the federal government to military forces may be accurate within three meters.
