ISAR Imaging Of Maneuvering Target Based On Multi-Component Cubic Phase Signal

The rapid development of modern technologies and techniques of Radar imaging provides a way to observe the objects accurately.The Inverse Synthetic Aperture Radar(ISAR)system is a well-known kind of radar imaging where it is an efficient tool in the field of radar signal processing to obtain focused images for non-uniformly rotating targets.However,ISAR imaging has always been a challenging task due to the time-varying Doppler parameter;the quality of the ISAR image is related with the target motion nature.After the translation motion compensation,the azimuth part of the echo can be depicted as a multicomponent polynomial phase signal(m-PPS),witch a focused ISAR image can be obtained via the combination of the estimated parameters of m-PPS and the Range Instantaneous-Doppler(RID)technique.In this thesis,we focused on the ISAR imaging of high maneuvering target based on multi-component Cubic Phase Signal(m-CPS),which we propose and develop some techniques for purpose of ISAR images enhancement for the observed targets in different angles.However,the m-CPS parameters estimation with accuracy play a very important role.For this reason,the general objective of this thesis is to propose novel techniques for the m-CPS parameters estimation,in order to improve the ISAR images qualities of the observed targets.In particularize the following specific issues are considered in this work:1.How to achieve well-focused ISAR images from collected echoes of target characterized by non-comparative motion? It still a critical task for scene analysis in ISAR images.In order to improve the previous method that based on the DPT technique,we present a new method for m-CPS signal parameters estimation based on the MDPT technique.The effectiveness of the proposed method is proved via numerical examples,simulated model of target and real data.2.We present a new method named IPHAF to estimate the third phase coefficient of the m-CPS signal;it is an improved technique of HAF method.The proposed technique is an effective tool to obtain a high focused ISAR image compared with the HAF technique.The experimental work confirm the effectiveness of the proposed methods and prove that IPHAF algorithm i s efficient than HAF algorithm.3.For a target with a high maneuvrability,the occurrence of scatterers Migration Through Resolution Cells(MTRCs)caused by the rotational movement could be appearing.That is why the variation in amplitude of the echo during the time of observation cannot be neglected.We propose two techniques to estimate the time varying amplitude(TVA).The first technique is based on Dechirp technique combined with the inverse FT,and the IPHAF algorithm is extended to estimate the phase coefficients.The second technique is based on Special Narrow Spectrum Filter,and the MCPF technique is used to estimate phases parameters.The experimental work prove the effectiveness of the two proposed methods IPHAF and MCPF with time varying amplitude compared with IPHAF and MCPT in situation of constant amplitude,respectively.