High Earth Orbit FDA-SAR Imaging And Target Detection Under The Sea Clutter Background

The target detection and imaging in the background of sea clutter is a hotspot in the field of radar signal processing,which occupies an important position in China's construction of the 21 st century Maritime Silk Road strategy.The High Earth Orbit SAR,which can be used in long-time and frequently monitoring in large sea areas,have attract much attention.In this thesis,the concept of frequency diversity array is introduced on the basis of High Earth Orbit SAR,and the High-Orbit-FDA-SAR imaging algorithm and target detection in sea clutter background is studied.The main work is as follows:1.The distribution model of sea clutter is studied,and the sea clutter data is generated by modeling and simulation.Analyzes the backward scattering field of sea clutter characteristics,correlation and statistical characteristics of simulation compared the four kinds of distribution based on statistical feature model,and use the two methods:memoryless non-linear transform(ZMNL)and spherically invariant random process(SIRP),produced the sea clutter data of four kinds of distribution,and its amplitude and frequency spectrum characteristics is presented.2.Based on the analysis of the High-Orbit-FDA-SAR,the design method of its system and signal parameters is proposed.Firstly expounds the basic principles of frequency array,analyzes the time and range periodic characteristics of its pattern of transmission Then the derivations for the relationship between different coordinate systems,orbit characteristic and Doppler character has been proposed.Finally researched the design methods of paramaters like band wide,PRF,frequency increment between array elements,and pulse duration in the use of High-Orbit-FDA-SAR.3.The model of High-Orbit-FDA-SAR echo wave is established,and the imaging method of it is proposed.Based on the failure of the traditional strabismus model in high orbit,the polynomial approximation distance model is introduced,and the spectrum is deduced,and the RD imaging algorithm based on this model is presented.Constructed FDA transmit and phased array receive system,proved after the phase compensation,RD imaging algorithm that based on polynomial approximation can be applied to High-OrbitFDA-SAR echo signal processing.4.STAP is introduced to High-Orbit-FDA-SAR and the target detection method in the background of sea clutter is proposed.This thesis analyzed the clutter distance dependence of the High-Orbit-FDA-SAR signal and gives the compensation method.The clutter suppression of the High-Orbit-FDA-SAR echo data based on K distribution sea clutter has been carried out by using space-time adaptive algorithm,and the performance of clutter suppression is verified by simulation.To the signal after the clutter suppressing,RD imaging algorithm is used for calibration and accumulation,after that,the threshold value is used to CFAR detection.