As defined by FS-1037C and ITU Radio Regulations, radiodetermination is: the determination of the position, velocity or other characteristics of an object, or the obtaining of information relating to these parameters, by means of the propagation properties of radio waves There are two main fields to radiodetermination: radionavigation: "used for the purposes of navigation, including obstruction warning", which is mainly active; radiolocation: "used for purposes other than those of radionavigation", which is mainly passive. Wikipedia