Research On ISAR Imaging Methods Of Space Targtes

With the development of aerospace technology,in the fut ure,the countries in the field of space offensive and defensive game is inevitable.Then,the effective perception of the space environment,the effective tracking,imaging,recognition and classification of the space target,etc.,will become particularly important.Radar has a wider range of working conditions,and due to the mature development of ISAR imaging technology,ISAR has become one of the important means to monitor space targets.In this paper,the ISAR imaging method of space targets is studied in depth with ground-based radar as the main observation system.Firstly,the ISAR imaging method of stationary moving space target is studied.When the target is moving smoothly,the Range-Doppler(RD)imaging algorithm can be used to obtain 2D ISAR high-resolution image results.In ISAR imaging,motion compensation with envelope alignment and phase correction as the main processing steps is essential.In this paper,several motion compensation methods are studied and used in subsequent simulation experiments.Aiming at the ISAR imaging model of the space target,this paper introduces the orbit characteristics of the space target,and carries out satellite motion simulation and ISAR echo simulation based on STK.In order to obtain the ISAR observation data of the space target in orbit.Then,combined with motion compensation method and RD imaging algorithm to verify the effectiveness of the methods.Secondly,the ISAR imaging of the equivalent uniformly accelerated rotating space target is studied.Firstly,the echo model of the target in uniformly ac celerated rotational motion is derived,which is modeled as multi-component LFM signal.Next,two LFM signal parameter estimation methods are studied,and these two methods are used to compare the performance of parameter estimation of the ascertained signal.Finally,the two methods and the RD imaging algorithm are used to compare the images of uniformly accelerated rotating space targets.Then,considering the attitude change of the space target,the target is modeled as a variable acceleration rotation model,and the echo characteristics are analyzed.The obtained echo is in the form of multi-component cubic phase signal(CPS).Therefore,ISAR imaging problem is transformed into CPS parameter estimation problem.In this paper,two parameter estimati on methods are studied,and the estimation performance of specific observed signals is compared with experimental analysis.Finally,a parameter estimation method is used to perform ISAR imaging experiments on the attitude changing space targets to verify the effectiveness of the proposed algorithm.Finally,the method of In ISAR 3D imaging is studied in this paper.Firstly,the theory of In ISAR 3D imaging is introduced in detail,and the causes of image mismatch and phase entanglement are analyzed.Furthermore,the simulation experiment of space target is carried out by combining two methods of angular motion parameter estimation with orthogonal tri-antenna system.Finally,an orthogonal antenna array,combined with interference processing technology a nd motion parameter estimation method,is used to realize the 3D reconstruction of the target.The results verify the effectiveness of the method.