How it Works: Going from 'lost' to 'here at last' with GPS
IT@Intel Technology Tips, Intel Information Technology, March 2011
How it Works: Going from ”lost‟ to ”here at last‟ with GPS
With this search tool, you’ll always know where you’re headed
The Global Positioning System—better known as GPS—is hardly a surprise item anymore. If you need to find your way somewhere—such as from an airport to a business—this 21st century compass can point you in the right direction, offering block-by-block instructions that can make getting lost nearly impossible. It’s also being used to prevent auto theft, help complete the United States 2010 Census, and enable golfers to improve their swing. And the system is available in your cell phones, in your cars, on your boats, and on planes. Yes, truly amazing, this GPS. But how exactly does it work? Here’s a look at what’s under the hood of this pocket-sized marvel.
Give me space
The GPS is actually a receiver pulling in signals from 29 Earth-orbiting satellites (24 standard plus 5 backups) making up the NAVSTAR system. The U.S. military originally developed and implemented this satellite network—often referred to as an Earth constellation—as a military navigation system in 1978, but in the 1980s opened it up for public use. At any given time, at least four satellites are visible in the sky. Designed to last for about 10 years, these satellites are constantly being replaced by newer, more efficient models. GPS determines your location via a mathematical principle called trilateration (not to be confused with triangulation). In essence, a signal places your location within a specific radius; the corresponding signals overlap until they narrow down that location to within a few feet of where you happen to be (technically, trilateration is the wrong term, as there’s always at least four satellites in use at any one time. The more appropriate term would be multilateration).
Read the full How it Works Technology Tips.