What Is GPS and How Does It Work?
GPS is an acronym standing for Global Positioning System. It is a space age technology based on radio communications with multiple satellites in a geo-synchronous orbits. A GPS Receiver picks up a signal from as many satellites as possible and calculates its distance from each of those satellites. Using a complex algorithm it can then pinpoint the location, altitude, and other information of the receiver.
GPS was originally designed by the U.S. Department of Defense in 1973 for military applications, but has since been declassified for civilian uses. The US system consists of 27 satellites in orbit 12,000 miles above the earth. Twenty-four of these are in orbits calculated to give coverage of at least four satellites to any point on earth at any given time, and the other three are reserves to be flown into position to replace any malfunctioning unit. It is a very sophisticated system. The Russian government also has its own independent GPS system, and several European States are collaborating to launch a third.
The satellites send out radio signals which can be received and timed by ground equipment (which has now reached the size of a small handheld device thanks to micro-circuitry). The time it takes the signal, which is a radio wave traveling at the speed of light, to reach the receiver tells the computer the distance from each of the satellites. By triangulating these distances it can determine exact information on the location of the receiver.
By imposing the latitude, longitude, and other information obtained from the satellites on a map stored in its memory the average handheld receiver of today can display its location on maps, even street maps complete with what stores or other businesses were there when it was programmed or updated. It is the navigation tool of the 21st Century, and as long as the receiver has a source of electric power, and the orbits of the solar powered satellites do not decay and send them burning back through the atmosphere without being replaced it is the best system ever devised. Smart navigators are still, however, familiar with older methods based on the compass and sextant, because there is always a chance of electric power failure on a boat or vehicle. This low tech backup is very important for solo and family sailors on long voyages.
It is a huge leap forward in navigation technology, and promises to change our world yet again. With computers that know exactly where they are at all times to within inches there is a tremendous opportunity for implementing robotic technologies that were previously only science fiction. Only time well tell how much it will change our world, and what form those changes will take. But I predict that if I live to see the year 2050 that there will be buses, trains, trucks, and a lot of other vehicles operating completely autonomously on set programs with various sensors added for human safety and convenience.
