A datalink is a means of transmitting information from one point to another. When the transmission is accomplished using a wireless means, the datalink may also be referred to as a 'radio link' or 'radio modem'.
The technology behind the sensors involved in inertial navigation has improved over the last few years, with precision increasing whilst both size and cost have reduced.
The navigation function forms part of the Guidance, Navigation and Control (GNC) system and consists of calculating a platform's location and velocity (also known as the state vector), as well as its orientation (or attitude).
UAV Navigation in depth: Precision Laboratory Equipment For Testing and Calibration of Air Data System
Air data information is a key issue for use onboard aircraft in order to estimate current altitude and airspeed. Such flight parameters may be measured using a variety of different sensors.
The Global Positioning System (GPS) system is designed so that from any point on the surface of the planet at least four satellites of the GPS constellation are always visible.