Satellite Navigation: The User Segment

Abstract

Originally conceived as a global all-weather positioning system justified by its military applications, GPS was later opened up to the general public with the result that it has become an indispensable appurtenance of modern life. In addition to its familiar use to navigate on the highway, it has impacted fields as diverse as navigation, by land, sea, and air, surveying and geodesy, and large-scale construction projects such as mines, bridges, and tunnels. To utilize, the system requires of course a special multichannel radio receiver and microprocessor whose sophistication and cost are commensurate with the required capabilities and accuracy. There are professional receivers currently available on the market that go far beyond the units incorporated in handheld devices for the use of the general public. Among the more sophisticated units is the Proflex 800 [1] which uses advanced GNSS technology to enable it to obtain a precise fix using any available satellite signals, even under such adverse conditions that would preclude the use of other receivers. Many other prominent companies market “professional” instruments for satellite navigation of aircraft and ships; among them are names such as Garmin, Magellan, TomTom, etc., which also supply models for the general market, including motorists, hikers, and sailing enthusiasts, etc. GPS receivers are generally integrated into some form of computer or handheld wireless device.