METHOD FOR DETECTING, LOCATING AND DETERMINING THE SPEED OF MOBILE TARGETS FROM RAW RADAR DATA OF A COHERENT IMAGING SYSTEM

摘要

In order to form the image of the terrestrial surface with various backscattering ratios, azimuthal spectra succeeding each other in time are formed continuously over a given period of time and a frequency offset (DELTAF (t)) of the backscattering ratio fraction is obtained. by determining the position of the maximum of the correlation between two azimuth spectra formed immediately one after the other in time. Then, to establish a map of frequency offsets (DELTAF (t, r)), we evaluate the frequency shifts of the set of raw radar data and we obtain a Doppler rate map (D (t, r)) . By searching for values deviating from a nominal Doppler rate (Dnom) on the Doppler rate map, a moving target (B) is detected and the center of gravity of an image of this target is formed. By neglecting the radial acceleration of the moving target, its tangential velocity (VT) is determined by a Doppler rate (DmB) seen on the Doppler rate map (D (t, m)) and its radial velocity (VR) from the ratio between the length (rB) of the target in the direction of the distance on the map of the Doppler rates and the duration (tB) of illumination by the antenna.