Radio Geodetic System

a set of radio equipment used in aerial photographic surveys, in geodetic, hydrographic, and geophysical work, and in air and marine navigation; it is used to measure distances between mobile and fixed objects or points, such as airplanes, satellites, ships, and points on the earth’s surface or to determine the coordinates of these points or objects. Such systems consist of radio transmitting and receiving units installed on a vehicle or at a point whose position is to be determined and on reference objects or points whose coordinates are known. The coordinates of the vehicle are determined by measuring the distances or the difference of the distances between the vehicle and the reference points according to time and the known velocity of radio-wave propagation. Alternatively, the coordinates can be determined by measuring the increase in the distances or the increase in the difference of the distances.