Research On Polarization Characteristics And Feature Extraction Of Ballistic Midcourse Target

Polarization characteristic is one important property in the field of radar target recognition and has great potential in the domain of feature extraction and recognition. In this paper, the polarization characteristic of midcourse target and its feature extraction are widely researched. Based on the analysis of radar target's narrowband and wideband echoes, the paper studies the polarization characteristics of midcourse target, polarization feature extraction and optimization. The detailed content includes the analysis of polarization characteristic, the feature extraction and optimization.In the aspect of midcourse target's polarization characteristic analysis, the following problems have been included: (1)Aimed to the calculation of dynamic full-polarization radar echoes of spatial targets, the movement of midcourse target is modeled. The model includes the macroscopic movement of warhead's centroid and the precession of warhead. Then the whole midcourse movement is simulated. After that we generate the narrowband and broadband echoes of the giving situation; (2)For the analysis of polarization characteristic, a time-varying and dynamic viewpoint has been leading-in to re-examine the polarization scattering matrix. With the use of time-varying polarization scattering matrix, the narrowband and broadband polarization correlation property of four warhead-similar targets have been analysed. Through the experiment, the qualitative and quantitative description are carried out in the different aspects of midcourse target's polarization characteristics.In the aspect of midcourse target's polarization feature extraction and optimization, the other three problems have been studied: (1)Based on the different motion characteristics between warheads and decoys, an approach for identification of midcourse target has been proposed, where we calculate the time-entropy H t and the average scattering angle ? t. Simulation results show that the method can identify the warheads and decoys effectively and robustly in a certain SNR; (2)For the optimization of polarization features, a group of narrow-band polarization invariant features and four sets of wideband polarization features with clear physical-meaning are preselected. With the use of simulation data, the separability of target polarization features is analysed, and the separability of the narrowband and broadband polarization features are compared. In the foundation of the experiment, the polarization features are optimized; (3)A target recognition simulation system is built based on the optimal polarization features. The results show that the system can identify the different midcourse targets effectively and robustly with the prior-information given, which verifies the correctness and effectiveness of the optimization results.The research helps to improve radar's capability of target recognition under the background of missile countermeasure, and also provides a reference for the design of radar target identification system.