Research On Image Simulation And Target Recognition Of ISAR

Inverse synthetic aperture radar(ISAR),which can obtain high-resolution images of targets throughout the day and in complex environments.It has important applications in military and civilian applications,especially in the field of military target recognition.ISAR image simulation technology has been applied in ISAR system design,imaging processing algorithm verification and target classification.ISAR image simulation technology based on computational electromagnetic is studied in this paper.Based on the physical optics(PO)method,the ISAR image simulation of the target is realized from the angle of electromagnetic simulation,and the simulation data set is used to study the aerial target classification technology.The research contents of this paper mainly include the following aspects:(1)Calculating the far field radar cross section(RCS)of the target using the PO method.The key of ISAR image simulation is to calculate the scattering electric field of the target at different angles and frequencies.The targets of ISAR simulation is usually electrically large targets,the simulation calculation is large and the memory requirements are high.Using PO method can achieve a good balance between the accuracy of the results,the simulation speed,and the memory.The PO method in this paper is based on the target triangle geometric mesh model,the surface current calculation formula of a triangular facet is first derived,and then the far field scattering field of the triangular facet in the illuminated area is calculated according to the occlusion judgment,and finally the total scattering of the object is solved field.Through experimental simulation,not only the accuracy of the calculation results of the PO method used in this paper is verified,but also the calculation speed is obviously more advantageous.(2)The principle of ISAR imaging and the process of ISAR image simulation are introduced in detail.First,the principle of ISAR imaging is introduced.Based on the turntable model and the linear frequency modulation signal is used as the transmitting signal model,the imaging formulas of one-dimensional range profile and one-dimensional cross-range profile are derived,and then the ISAR echo model and the imaging algorithm are given.The process of ISAR image simulation is given according to the imaging principle of ISAR.The simulation parameters such as imaging angle,number of sampling points,frequency resolution and angle resolution is introduced in detail,and a complete simulation example is given.Finally,some typical military targets such as tanks,aircraft and ships are simulated,and their electromagnetic scattering characteristics are analyzed.(3)Finally,based on the ISAR image data set obtained through simulation,four types of aircraft targets are classified using support vector machines.Using the low-frequency features after wavelet transformation,in order to reduce the amount of calculation,PCA is used to reduce the dimension,and then the simulated ISAR image data is classified by the support vector machine classifier.The experimental results show that for the simulation data set used in this paper,the support vector machine has achieved good results in recognition rate and speed,which verifies the effectiveness of the algorithm.