METHOD AND SYSTEM FOR PASSIVELY DETERMINING THE ALTITUDE OF AN OBJECT

摘要

A method and a system for determining an altitude of an object of interest, for example, an airplane that transmits electromagnetic radiation in the form of radar signals. A number of sub-units that can detect the radar signals are spread out in an area, preferably in a large geographical area, where the radar signals of the airplane/object are possible to detect. The sub-units communicate to the information centre when they are able to detect the radar signals. The information centre determines the altitude of the airplane based on the airplane line of sight, i.e. its radar horizon, and thus which sub-units can detect the radar signals.