长短基线联合处理的星载SAR运动目标检测与成像方法研究

Multichannel SAR system play an important role in improving the detection performance of slow moving target with weak scattering, which was invalid in monostatic spaceborne SAR system. But the performance is decreased by the channel synchronization, Co-registration, and multi-baseline decoupling in Multichannel SAR system, with increasing the complexity and computation. A novel appoach was presented to detect and focus moving target,by interferometric phase with Long-short baselines and sparse reconstruction. Furthermore, the estimation accuracy of radial velocity was enhanced by interferometric phase processing of multi-baseline with optimal baseline configuration .And the estimation accuracy of tangential velocity was improved by multi-dimensional parameter estimation algorithm. Combined with the sparse characteristic of moving targets, and the spatial diversity of along-track distributed receive array, the measurement matrix basing and basis function were introduced. And the image of moving targets was obtained by the sparse reconstruction algorithm with Long-short baselines distributed array. The optimization imaging algorithm of multi-targets under low signal clutter ratio was presented, with approaches of Co-registraion, multibaseline decouplin and unwrapping were prewented to improve the performance of moving target detection. Experimental analysis verified the validity of this approach, the robustness performance was enhanced. The theory of imaging radar signal processing with non-uniform distributed array is exploring by sparse reconstruction theory, and the research is extended to an important application of radar signal processing and compressed sensing theory.The research has broad application in the currents monitoring, disaster survey, vehicle and vessel observing, military reconnaissance development.

单基星载SAR慢动、弱小目标检测性能低，多通道SAR虽增强了检测性能，但复杂性高、运算量大，通道同步性、配准及基线耦合等影响其发展。本研究采用长短基线联合干涉相位估计和稀疏信号重构方法，研究多通道星载SAR运动目标检测与成像问题。通过沿航迹长短基线联合处理，优化长短基线配置，利用多基线干涉相位法解决测速范围和最小可测速度的矛盾；利用多维参数估计法解决切向速度估计不准问题；利用非均匀稀疏阵列和运动目标投影空间稀疏性，构建观测矩阵和基函数，采用稀疏重构方法获得目标像。针对低信杂噪比、多目标检测提出优化算法，研究长短基线下通道配准、去耦合及相位解缠等问题，通过实验验证其有效性、稳健性。该研究是对非均匀多通道SAR动目标检测与成像理论的探索，极大丰富SAR-GMTI研究，拓展压缩感知理论在成像雷达上的应用范畴。研究成果在洋流监测、灾情勘查、海陆交通监视、军事侦察等方面具有广阔的应用价值和发展前景。

该项目研究长短基线联合处理的星载SAR运动目标检测与成像方法，属于国家重大需求和国际学术前沿问题。本研究项目针对运动目标检测问题，研究多通道SAR系统运动目标检测，采取沿航迹方向空间稀疏分布的阵列形式，利用长短基线组合，扩展测速范围并降低最小可检测速度，研究基于稀疏重构的运动目标检测方法，提高慢速、弱小目标检测能力。具体完成的内容如下：.（1）多基线SAR-GMTI系统模型及性能分析部分，完成了多基线SAR进行运动目标检测系统模型的建立，采用两种长短基线构建包括单发多收双基型和非均匀分布式构型，研究沿航迹方向虚拟阵列变换方法和最优沿航迹阵列构型，提出沿航迹非均匀阵列空间投影方法，分析系统带宽、覆盖范围、地物杂波特性等因素。.（2）运动目标检测与测速方法研究部分，完成了ATI与DPCA联合测检方法和多基线ATI检测方法研究，采用沿航迹长短基线组合干涉相位法估计径向速度，并进行多普勒分析方法研究，研究基于分数傅立叶变换的切向速度估计方法，通过多批实测星载SAR数据验证方法的有效性。.（3）多通道SAR运动目标稀疏重构算法研究部分，基于一发多收、非均匀分布阵列模型，分析沿航迹分布的非均匀阵列特性，提出互质采样和随机采样两种稀疏采样方法，分析稀疏变换域映射关系，构建运动目标散射系数稀疏重构的数学模型，提出运动目标稀疏信号重构算法，研究了基于硬门限OMP算法、贝叶斯算法和稀疏梯度投影算法，进行基于稀疏重构方法的运动目标检测方法的检测性能分析。.（4）基于稀疏重构的运动目标成像研究，基于运动目标的稀疏表征和稀疏观测约束，研究非模糊稀疏重建理论和方法，提出长短基线多通道SAR中运动目标散射系数稀疏重构的实现方法，完成运动目标二维成像。将分布式SAR运动目标检测系统接收回波获取方式按照单测量向量模型（SMV）和多测量向量模型（MMV）两种方式获取，进一步研究M-FOCUSS信号重构算法。采用分布式压缩感知处理获得目标散射系数，解决非完整全孔径数据的高分辨成像问题。开展实验研究，完成对长短基线多通道SAR中运动目标稀疏成像。.研究成果在洋流监测、灾情勘查、海陆交通监视、军事侦察等方面具有广阔的应用价值和发展前景。