Modeling And Analysis Of Radar Echo Signal Of Hypersonic Platform

Hypersonic vehicle has a broad prospect of military and civil applications,and it is an important research direction in many countries at present.Compared with the traditional airborne radar,the clutter environment faced by the hypersonic platform is more complex because of its high speed,high altitude and long detection distance.Clutter not only has the problems of range ambiguity and range dependence,but also has the problem of range migration.At the same time,because of the high maneuverability of hypersonic vehicle,its trajectory will be more complex.Therefore,it is of great significance to establish the radar echo signal model of hypersonic platform and analyze the characteristics of radar echo signal.Around the above problems,the main work of this thesis is as follows: 1.The radar echo signal model of hypersonic platform is established.The radar clutter unit division,clutter region selection and radar pattern of hypersonic platform are analyzed,and a method to simulate the radar echo signal of hypersonic platform is proposed.The simulation results show that this method is effective in simulating radar echo signal of hypersonic platform.2.Based on the radar echo signal model of hypersonic platform under uniform linear motion,the influence of range migration on space-time two-dimensional clutter spectrum is analyzed,and it is concluded that the range migration broadens the space-time two-dimensional clutter spectrum.The broadening is not only related to the platform velocity,spatial cone angle and pulse repetition frequency,but also to the signal bandwidth.The larger the signal bandwidth is,the more serious the broadening of the clutter spectrum is.A method of clutter range migration correction using keystone transform is proposed under the condition of uniform linear motion of hypersonic platform.The simulation results show that when there is no range ambiguity and Doppler ambiguity,this method can significantly reduce the broadening of clutter spectrum,narrow the notch of space-time two-dimensional response,and improve the performance of clutter suppression.At the same time,the range dependence of clutter is analyzed,and it is concluded that the clutter has distance dependence when the hypersonic platform radar array is classified as a non-positive side array.The influence of pulse repetition frequency on Doppler ambiguity and range ambiguity is analyzed.It is concluded that Doppler ambiguity occurs when pulse repetition frequency is small and range ambiguity occurs when pulse repetition frequency is large.Therefore,in practical application,it is necessary to select the appropriate pulse repetition frequency according to the actual scene.The simulation results prove the correctness of the above conclusions.3.The radar echo signal model of hypersonic platform in complex motion state is established,including uniform acceleration linear motion,subduction motion,parabola motion and variable acceleration linear motion.On this basis,through the analysis of clutter space-time two-dimensional spectrum and space-time adaptive processing two-dimensional response before and after keystone transform,it is concluded that keystone transform can correct clutter range migration,reduce clutter two-dimensional spectrum broadening and improve clutter suppression performance under the complex motion state of hypersonic platform without range ambiguity and Doppler ambiguity..The simulation results verify the correctness of the conclusion.