VERFAHREN ZUR VERARBEITUNG DER VIDEOSIGNALE EINER FLUGZEUG-KOHAERENZ-RADARANLAGE MIT SYNTHETISCHER ANTENNE

摘要

The auto focus system uses focus error data derived by dividing the synthetic array into three sub-arrays. The resultant outputs are processed together to extract data corresponding to the degree of total array defocus. For purposes of imagery generation, the phase and amplitudes of these three sub-array resultants are vectorially summed together and the resultant is magnitude detected to yield imagery output corresponding to the full synthetic array. For derivation of focus error data, the mean bisector of the relative phase angle between the two end sub-array resultant vectors is measured. This derived phase angle is compared to the phase angle of the central sub-array resultant vector. The angle of the bisector relative to the central sub-array resultant is representative of the degree of defocus, and the sign of the angle is indicative of whether the array is over or under-defocused.