Classification of air targets including a rejection stage for unknown targets

In this paper an algorithm for Non-Cooperative Target Identification (NCTI) of airplanes is presented. The advantage of NCTI over Identification Friend - Foe-systems (IFF-systems) is its ability to identify positively not only friendly airplanes but also neutral or hostiles ones. The approach described here uses one-dimensional radar images, so-called High Range Resolutionprofiles (HRR-profiles) for NCTI. However only the locations of the local maxima of the HRR-profiles were used for classification instead of using the whole HRR-profiles. Furthermore a statistical test procedure is presented that is carried out prior to the classification procedure to determine if an airplane belongs to a known or to an unknown class of airplanes without distinguishing the known classes of airplanes.