相比均匀线阵(Uniform Linear Array,ULA),相同阵元数目下稀疏线阵(Sparse Linear Array,SLA)的抗耦合效应更好,阵列孔径更大,到达方向(Direction of Arrival,DOA)估计的自由度(Degrees Of Freedom,DOF)更高,因而近年来得到了广泛的研...相比均匀线阵(Uniform Linear Array,ULA),相同阵元数目下稀疏线阵(Sparse Linear Array,SLA)的抗耦合效应更好,阵列孔径更大,到达方向(Direction of Arrival,DOA)估计的自由度(Degrees Of Freedom,DOF)更高,因而近年来得到了广泛的研究。为了可以进行高DOF的DOA估计,学者们开始研究SLA的差分虚拟阵元,差分虚拟阵元对应的协方差矩阵相比原阵元对应的协方差矩阵维度更大,因而估计的DOF更高。当SLA的差分虚拟阵元连续取值时,可以利用已有阵元的接收信息,得到SLA的协方差矩阵,在该矩阵的基础之上构建差分虚拟阵元的协方差矩阵进而进行DOA估计。然而,当SLA的差分虚拟阵元存在孔洞时,即差分虚拟阵元不能连续取值时,不能直接利用重构的协方差矩阵进行DOA估计,需要恢复完全增广协方差矩阵的信息再进行DOA估计。对于该问题,本文基于矢量化后原协方差矩阵和虚拟差分阵协方差矩阵的误差分布情况,并结合完全增广协方差矩阵的低秩特性和半正定特性来构建优化问题。通过求解该问题来恢复维度更高的完全增广协方差矩阵。最后对该矩阵进行奇异值分解,利用多重信号分类(Multiple Signal Classification,MUSIC)算法就可以获得多源的空间谱。本文最后通过数值仿真试验验证了所提算法可以实现高DOF的DOA估计,并且相比于现有算法,本文所提算法对欠定DOA估计的效果更好,多源DOA估计的精度更高,产生的误差更小。展开更多
Downward Looking Sparse Linear Array Three Dimensional SAR(DLSLA 3D SAR) is an important form of 3D SAR imaging, which has a widespread application field. Since its practical equivalent phase centers are usually distr...Downward Looking Sparse Linear Array Three Dimensional SAR(DLSLA 3D SAR) is an important form of 3D SAR imaging, which has a widespread application field. Since its practical equivalent phase centers are usually distributed sparsely and nonuniformly, traditional 3D SAR algorithms suffer from low resolution and high sidelobes in cross-track dimension. To deal with this problem, this paper introduces a method based on back-projection and convex optimization to achieve 3D high accuracy imaging reconstruction. Compared with traditional SAR algorithms, the proposed method sufficiently utilizes the sparsity of the 3D SAR imaging scene and can achieve lower sidelobes and higher resolution in cross-track dimension. In the simulated experiments, the reconstructed results of both simple and complex imaging scene verify that the proposed method outperforms 3D back-projection algorithm and shows satisfying cross-track dimensional resolution and good robustness to noise.展开更多
当载机存在偏航角速度时,载机航线会偏离理想航线,对稀疏阵列下视3维合成孔径雷达(DLSLA 3D SAR)成像产生影响。该文建立了载机在飞行过程中存在偏航角速度下的DLSLA 3D SAR成像模型,通过理论推导得到了信号的多普勒调频率表达式,多普...当载机存在偏航角速度时,载机航线会偏离理想航线,对稀疏阵列下视3维合成孔径雷达(DLSLA 3D SAR)成像产生影响。该文建立了载机在飞行过程中存在偏航角速度下的DLSLA 3D SAR成像模型,通过理论推导得到了信号的多普勒调频率表达式,多普勒调频率与目标被调制后的跨航向坐标有关,而与被调制后的方位向坐标无关。进一步,完成跨航向信号处理之后,在平台的速度和偏航角速度不准的情况下,利用参数化稀疏表征方法实现了平台的速度和偏航角速度的估计,并完成了方位向稀疏场景的重构,最后提出了一种形变校正方法。仿真实验验证了该算法的有效性。展开更多
文摘相比均匀线阵(Uniform Linear Array,ULA),相同阵元数目下稀疏线阵(Sparse Linear Array,SLA)的抗耦合效应更好,阵列孔径更大,到达方向(Direction of Arrival,DOA)估计的自由度(Degrees Of Freedom,DOF)更高,因而近年来得到了广泛的研究。为了可以进行高DOF的DOA估计,学者们开始研究SLA的差分虚拟阵元,差分虚拟阵元对应的协方差矩阵相比原阵元对应的协方差矩阵维度更大,因而估计的DOF更高。当SLA的差分虚拟阵元连续取值时,可以利用已有阵元的接收信息,得到SLA的协方差矩阵,在该矩阵的基础之上构建差分虚拟阵元的协方差矩阵进而进行DOA估计。然而,当SLA的差分虚拟阵元存在孔洞时,即差分虚拟阵元不能连续取值时,不能直接利用重构的协方差矩阵进行DOA估计,需要恢复完全增广协方差矩阵的信息再进行DOA估计。对于该问题,本文基于矢量化后原协方差矩阵和虚拟差分阵协方差矩阵的误差分布情况,并结合完全增广协方差矩阵的低秩特性和半正定特性来构建优化问题。通过求解该问题来恢复维度更高的完全增广协方差矩阵。最后对该矩阵进行奇异值分解,利用多重信号分类(Multiple Signal Classification,MUSIC)算法就可以获得多源的空间谱。本文最后通过数值仿真试验验证了所提算法可以实现高DOF的DOA估计,并且相比于现有算法,本文所提算法对欠定DOA估计的效果更好,多源DOA估计的精度更高,产生的误差更小。
基金Supported by the National Natural Science Foundation of China General Programs(Nos.61072112,61372186)the National Natural Science Foundation of China Key Program(No.60890071)
文摘Downward Looking Sparse Linear Array Three Dimensional SAR(DLSLA 3D SAR) is an important form of 3D SAR imaging, which has a widespread application field. Since its practical equivalent phase centers are usually distributed sparsely and nonuniformly, traditional 3D SAR algorithms suffer from low resolution and high sidelobes in cross-track dimension. To deal with this problem, this paper introduces a method based on back-projection and convex optimization to achieve 3D high accuracy imaging reconstruction. Compared with traditional SAR algorithms, the proposed method sufficiently utilizes the sparsity of the 3D SAR imaging scene and can achieve lower sidelobes and higher resolution in cross-track dimension. In the simulated experiments, the reconstructed results of both simple and complex imaging scene verify that the proposed method outperforms 3D back-projection algorithm and shows satisfying cross-track dimensional resolution and good robustness to noise.
文摘当载机存在偏航角速度时,载机航线会偏离理想航线,对稀疏阵列下视3维合成孔径雷达(DLSLA 3D SAR)成像产生影响。该文建立了载机在飞行过程中存在偏航角速度下的DLSLA 3D SAR成像模型,通过理论推导得到了信号的多普勒调频率表达式,多普勒调频率与目标被调制后的跨航向坐标有关,而与被调制后的方位向坐标无关。进一步,完成跨航向信号处理之后,在平台的速度和偏航角速度不准的情况下,利用参数化稀疏表征方法实现了平台的速度和偏航角速度的估计,并完成了方位向稀疏场景的重构,最后提出了一种形变校正方法。仿真实验验证了该算法的有效性。
