Research On GEO And GEO-LEO SAR Imaging And Interferometric Processing

With the development of large aperture array antenna technology,GEO SAR attracted the attention of the SAR researchers once again.GEO SAR has the advantage of large mapping bandwidth,short revisit time and strong field survival ability,so it has a good prospect in the field of civil and military remote sensing.In the recent years,the research on GEO SAR system design and imaging algorithm has made a great progress,but the research about the effects of non-ideal factors for GEO SAR system has been little published.So in the first part of the article,a few kinds of non-ideal factors affecting the GEO SAR system features have been analysed and given simulation verification.For improving the field survival ability of LEO SAR,researchers proposed the GEO-LEO bistatic SAR system configuration.In the second part,we proposed the GEO-LEO Bi SAR system geometrical configuration and verified the feasibility of the system for high-precision interferometry measurement by simulation method.The main work of the article is summarized as follows.Chapter 2 gives the GEO SAR moving trajectory in the earth centered fixed coordinate frame according to the two body model and coordinate transformation relation,and has an intuitive understanding to the GEO SAR movement characteristics.Then we give the vector expression about the impact of "Stop-go" assumption on GEO SAR slant range and analyze the influence of slant range error on imaging.In next two chapters we theoretically analyze and simulate the non-ideal factors affecting the GEO SAR performance.Firstly we give the main categories of non-ideal factors,briefly present the influence of non-ideal factors on GEO SAR system,and give the comparison with LEO SAR system.The forth chapter analyze the ionosphere effect emphatically,theoretical analyze the influence of background ionosphere effect on GEO SAR imaging and interferometry.Then we use the multiple-phase-screen model to simulate the ionospheric irregularity,and analyze the influence of ionospheric irregularity on GEO SAR imaging.Finally,in order to estimate and correct the ionosphere phase screen influencing the GEO SAR application,we use the improved sub-band In SAR method processed the GEO SAR SLC images added the ionosphere phase and get the planned results.In the second part,we study the GEO-LEO Bi SAR system emphatically,and verify the accuracy of GEO-LEO Bi SAR 2-D resolution expression.Then we simulate the scene for interference process in the model of LEO SAR double antenna,and use the BP algorithm imaged the raw data,then through the traditional In SAR process we get the interferometric phase after phase unwrapping.At last,using the improved Bi SAR positioning equation we get the high precision elevation result.The research result supplies valuable references for the later In SAR processing of GEO-LEO Bi SAR real data.