Application Of Emd Algorithm In Radar Imaging

Due to its merits of all weather conditions, long distance as well as wide range, imaging radar has been utilized in such fields as military reconnaissance, remote sensing and topographic mapping. SAR and ISAR are the key radar imaging techniques, which has been used to obtain high resolution images. However, the high resolution does not yet satisfied some special application. Therefore, research on improving the image resolution of SAR and ISAR continuously has been a hot as well important topic. Time series echo signal can be decomposed to IMFs (Intrinsic mode function) by EMD(Empirical mode decomposition) algorithm, which is distributed following frequency. Actually, the initial use of EMD algorithm is not in radar field, which is derived and utilized initially on the ocean or earthquake wave analysis. Firstly, the EMD algorithm adapted for the radar signal is examined in the dissertation. Secondly, resolution improving in SAR and multi-targets with non-uniform speed imaging in ISAR is studied by using EMD algorithmThe main work of the dissertation is as following:a) By analyzed the EMD decomposing results before and after matching filtering, the right position of EMD decomposition in the imaging process is determined. In the same time, a better algorithm to suppress side lobe after match filtering is presented, which is based on the analysis of component and residual of IMFs. It is found that the algorithm reduces the shortage of EMD algorithm and the high resolution image of SAR is obtained under noise condition.b) In ISAR imaging of moving targets with high speed and acceleration, the echo signal is decomposed by EMD, which is used to remove the high frequency component induced by high speed or acceleration. After decomposing the optimized residual is used for ISAR imagingc) Multi-targets imaging problem caused by multi-submissile is studied. According to the speed difference between different submissiles, the relationship between IMF component and multi-targets is analyzed after...