Radio navigation or radionavigation is the application of radio frequencies to determine a position of an object on the Earth, either the vessel or an obstruction. Like radiolocation, it is a type of radiodetermination.
The basic principles are measurements from/to electric beacons, especially
- Angular directions, e.g. by bearing, radio phases or interferometry,
- Distances, e.g. ranging by measurement of time of flight between one transmitter and multiple receivers or vice versa,
- Distance differences by measurement of times of arrival of signals from one transmitter to multiple receivers or vice versa
- Partly also velocity, e.g. by means of radio Doppler shift.
Combinations of these measurement principles also are important—e.g., many radars measure range and azimuth of a target.