Virtual instrumentation-based system in a real-time applications of GPS/GIS

Global Positioning System (GPS) is a satellite-based radio positioning and navigation system providing accurate, common 3-D grid position, velocity and time information to users anywhere on or near the earth. It consists of a constellation of 24 satellites with atomic clocks, along with the global satellite tacking network and the sophisticated ground processing stations, that together provide precise navigation coordinates to whom processes a small, readily available GPS receiver. Depending on the number of GPS satellites in view and the geometry involved, the presence of nearby objects may interfere with or degrade the reception of signals from one or more satellites, and other factors. It provides navigation services including 3-D positioning (Longitude, Latitude, Altitude), velocity and precise time under all weather and continuous real-time operation; Support to unlimited number users and areas. Including NMEA command and GIS technology, this study includes the flexible GUI functions of LabVIEW combining with the analysis programme of MATLAB to develop a novel real-time prototype of GPS positioning and geodetic datum transformation. Indeed, this concise module will be in its all aspect of low-cost, flexibility, and graphic-user-interface under the PC-based platform design Moreover, this system can be corporate directly with different types of GPS receiver as desired. It will functionally achieves and decodes NMEA-0183 sentence, and then shows the measured and calculated pseudo-range positioning and velocity in WGS84 and/or TWD97 coordinates as desired. Therefore, GPS users in Taiwan could not only simply integrate GPS applications into the geodetic/geocentric positioning and navigation, but also have a concise way to develop some versatile teaching and learning programs on GPS usage.