Analysis And Application In Structure Of Multi-baseline Spaceborne SAR

Synthetic aperture radar(SAR)has the advantages of,all-weather and high resolution imaging.It has developed rapidly since the second world war.In recent years,based on SAR,a concept of distributed small satellite SAR is proposed,which uses many satellites formation to cooperate with each other.This type of SAR system with multi direction multiple baseline is also called Multi-baseline Spaceborne SAR.Multi-baseline SAR imaging is superior to the traditional SAR due to its multi baseline.This paper studied SAR imaging technology under the background of multi-baseline SAR,puts forward the effective algorithm of 2D and 3D imaging,and analyzed the influence of baseline structure on its imaging performance.Finally,the analysis results are applied to the improvement of imaging resolution and imaging conditions.The main research contents of this dissertation are as follows:(1)This paper establishes multi-baseline spaceborne SAR 2D and 3D model.Traditional SAR collects signals via multi navigation,and is subject to a lot of interference.The multi satellite SAR can also have multiple directions on the baseline,so the physical model and the traditional SAR is different.(2)In this paper,a two-dimensional BP algorithm for single star imaging is studied and compared with the traditional RD algorithm.It is proved that the algorithm can perform two-dimensional imaging correctly,and the spatial resolution is consistent with the theory.Then,in order to reduce the computation time,the fast BP algorithm was studied,and it was found that the number of operations was reduced at the expense of resolution.At the end of the multi spectrum synthesis technology star,the technology makes full use of multi satellite SAR in different directions on the baseline information,breaking the single star imaging spatial resolution limitation,the resolution is improved after the combined imaging,and the correctness of the theory is verified by simulation.(3)This paper is based on the two-dimensional BP imaging,in height to add the compressed sensing imaging,solves the single pass multi baseline spaceborne SAR may be sparse and non-uniform problem.This method combines multi-baseline spaceborne SAR model,establish the measurement matrix satisfies the conditions of sparse,multi satellite data through two-dimensional BP imaging after the treatment,the experimental results show that the height of the good focusing effect.This method only needs one voyage in theory,which is superior to the conventional imaging method of SAR tomography.(4)Based on the previous two and three dimensional imaging algorithms,the influence of the baseline configuration on the imaging performance is analyzed.And the analysis results and characteristics of multi spaceborne SAR baseline configuration,studied how to improve the spatial resolution of spaceborne multistatic SAR imaging.The experimental results of 3D tomography in this background are also given.