Global Positioning System Global system for mobile communications 65 Artificial satellites in navigation 41 Automatic tracking 34 Inertial navigation 30 Geographic information systems 25 GPS receivers 24 Monitoring systems 20 Mobile communication systems 19 Wireless communication systems 19 Arduino (Programmable controller) 16 Artificial satellites in surveying 15 Inertial navigation systems 15 Mobile computing 15 Ionospheric electron density 13 Mobile geographic information systems 13 Radio 13 Data processing 12 Kalman filtering 12 Technological innovations 12 Automobiles 11 Electron data processing 11 Ionosphere 11 Remote sensing 11 Computer networks 9 Design and construction 9 Earthquakes 9 Navigation 9 Security systems 9 Child care 8