分布式GEO SAR:编队构型设计及性能分析

Formation design and performance analysis for distributed geosynchronous SAR

地球同步轨道合成孔径雷达(GEO SAR)具有短重访周期、大覆盖范围的优势,在防灾减灾方面具有重大潜力.本文提出包含远近编队的伴随分布式GEO SAR系统,在单星GEO SAR基础上,通过增加仅接收信号的从星伴随飞行,形成多个相位中心,具有功能丰富、成本低的优点;但不同功能对编队的空间基线要求不同.本文针对近距编队构型,提出基于坐标旋转的相对运动方程修正方法,可获得地球自转影响下空间基线解析计算方法;进一步提出基于半长轴修正的线性时变基线设计方法,可应用于SAR层析任务.针对远距编队,提出全局可测约束下最小定位精度系数准则,可实现具有最佳视角组合的远距编队设计,实现三维形变反演任务.最后,仿真并分析了伴随分布式GEO SAR编队各功能的系统性能,包括基线的日变化、高度向分辨率和典型观测区域的三维形变反演精度等.

Geosynchronous Synthetic Aperture Radar(GEO SAR) has the advantages of short revisit period and wide coverage,and has great potential in disaster prevention and mitigation.In this paper,a distributed GEO SAR system containing both close and sparse formation is proposed.On the basis of monostatic GEO SAR,multiple phase centers are formed by adding companion satellites only receiving signals,which has the advantages of rich tasks and low cost.However,different tasks require different spatial baselines for formation.Aiming at the configuration of close formation,this paper proposes a method of correcting the relative motion equation based on coordinate rotation,through which the analytical expression of spatial baseline under the influence of earth rotation can be obtained;furthermore,a method of linear time-varying baseline design based on semi-major axis correction is proposed,which can be applied to SAR tomography.For sparse formation,the minimum Position Dilution of Precision criterion under the measurable constraints of global scene is proposed,which can realize the design of sparse formation with the best combination of line of sight(LOS) thus can achieve the best three-dimensional(3 D) deformation retrieval performance.Finally,the system performances of the designed distributed GEO SAR formation are simulated and analyzed,including the diurnal variation of baseline,the resolution in altitude direction and the 3 D deformation retrieval accuracy in typical observation areas.