GLOBAL POSITIONING SYSTEM (GPS) – 21057
The Global Positioning System (GPS) is a network of wireless location and navigation apparatus that operates on a worldwide basis. The GPS employs several satellites, and allows determination of latitude, longitude, and altitude. It is used in some mobile robotic systems for guidance when extreme, localized precision is not necessary.
All GPS satellites transmit signals in the ultra-high-frequency (UHF) radio spectrum. The signals are modulated with codes that contain tim- ing information used by the receiving apparatus to make measurements. A GPS receiver determines its location by measuring the distances to four or more different satellites, and using a computer to process the in- formation received from the satellites. From this information the re- ceiver can give the user an indication of position accurate to within a few meters.