摘要
摘要
养肝护肝的药近年来，米波雷达在反隐身和抗反辐射导弹方面的优势引起了雷达界的重新重视。但是，由于米波雷达波长较长，受天线尺寸的限制，雷达波束较宽，角分辨力差，在探测低仰角目标时，雷达接收回波中不仅有直达波信号，还有经地（海）面反射的多径信号，多径反射波和直达波具有很强的相关性，会对目标测高精度产生严重影响。因此，米波雷达低仰角目标探测的分辨力和精度都非常低，无法满足对多目标分辨和精确定位的需求。本文针对米波雷达在低仰角目标探测中存在的多径问题，在提升米波雷达空间探测分辨力和精度等方面进行了研究，主要工作分为以下两个方面：
1、对于比较平坦的阵地，多径信号主要是镜面反射信号，漫反射功率比较小。传统阵列雷达的空间分辨率受天线孔径的限制，对位于一个波束宽度内的空间目标是不可分的，基于时空随机辐射场的微波关联成像方法具备突破天线孔径限制的高分辨能力，本文借鉴基于时空随机辐射场的成像体制并将压缩感知算法应用到米波雷达多目标探测上，提出了多径情况下基于时空随机辐射场的米波雷达多目标探测方法。首先建立多径情况下基于时空随机辐射场的米波雷达多目标探测信号模型，利用镜面反射提升时空辐射场的伪随机性，从而将多径信号由不利因素转化为有利因素，以提高目标探测的分辨力；其次，将功率较小的漫反射信号归结为辐射场随机误差，采用辐射场存在误差时的具有稳健性的压缩感知算法来
进行目标重构，以达到多径情况下米波雷达超分辨探测的目的。最后通过仿真分析验证了所提方法的有效性。
2、针对比较复杂的阵地，由于反射面的粗糙程度非常大，不满足瑞利准则，镜面反射和漫反射多径同时存在，表面越粗糙，雷达仰角越低，漫反射功率越占主导地位，多径信号的能量在空间形成一定的分布，此时多径服从分布源。本文分析了分布源多径信号模型，利用合成导向矢量方法推导了该模型下的感知矩阵，然后利用目标的稀疏性，将压缩感知算法应用到该信号模型的求解中，达到了利用较少的快拍数来超分辨、高精度估计目标仰角的目的，仿真结果验证了所提方法的有效性。
关键词：米波雷达，多径，压缩感知，时空随机辐射场，分布源深圳有哪些好玩的地方
ABSTRACT
叶锦添ABSTRACT
In recent years, the potential advantages of VHF radar in anti-stealth and anti-ARM have attracted renewed attention in the field of radar. However, the wavelength of VHF radar is long, so its beam is wide with limited aperture, which cau the bad angle resolution. In the detection of low angle target，the received signals include the direct path echo from targets and the multipath echo reflecte
银行卡激活流程d by the ground (a) surface. The multipath echo is highly correlated with the direct path echo, which reduces the accuracy of the target localization. Therefore, the resolution and accuracy of VHF radar are too low to meet the demand of target localization. The existing target detection methods usually suppress the multipath to improve the performance of the VHF radar systems. In this thesis, aiming at the problems of multipath in the detection of low angle target, the methods are analyzed to improve the resolution and accuracy of the target detection. The main contributions of this thesis are summarized as the following two aspects:
1. For the flat ground, the multipath echo includes specular reflection component and a little diffu reflection component. The spatial resolution of the traditional array radar is limited by the aperture size of the antenna. The temporal-spatial stochastic radiation fields bad microwave correlated imaging can obtain high spatial resolution, which is beyond the restriction of antenna aperture. In this thesis, a multi-target detection method is propod bad on the temporal-spatial stochastic radiation fields. Firstly, multi-target detection model of the VHF radar is established and temporal-spatial stochastic radiation fields in the multipath conditions is constructed. The specular multipath signals is ud to enhance the spatial-temporal random property. So the multipath signal is changed from unfavorable factors to favorable factors. Secondly, a robust compresd nsing algorithm is us
ed to suppress the effect of the diffu multipath signal to reconstruct the targets with super-resolution. Finally, the effectiveness of the propod method is verified by the simulation results.
2. For the complex ground, the reflective surface is very rough and the roughness dissatisfies the Reileigh rule. The reflective surface is rougher, the power of diffu reflection
the obrvation matrix in this model is derived. Then a compresd nsing algorithm is applied to achieve the super-resolution and high precision estimation of target elevation with less number of snapshots. Finally, the effectiveness of the propod method is verified by the simulation results.
Keywords: VHF radar, multipath, random radiation field, compresd nsing, distributed source泡脚桶品牌
插图索引
图1.1中国海军深圳舰上的米波雷达 (4)
图1.2中国JL3D-91B米波三坐标雷达 (4)
图2.1米波雷达多径回波几何模型 (10)
图2.2平坦反射面不同阵地条件下的反射系数 (12)
图2.3估角结果 (14)
图2.4原始目标场景 (19)
图2.5两种算法的重构结果 (20)
图3.1基于时空随机辐射场的多目标探测系统结构 (24)
图3.2多径情况下米波雷达系统几何构型 (26)
图3.3时空随机辐射场 (32)
今天阴历初几
图3.4某时刻无多径情况下的辐射场 (33)
图3.5某时刻镜面反射多径情况下的辐射场 (33)
图3.6原目标场景 (34)
图3.7无噪声背景下不考虑多径的目标重构结果 (34)
图3.8无噪声背景下利用镜面反射多径的目标重构结果 (35)
图3.9信噪比为10dB利用镜面反射多径的目标重构图 (35)
图3.10信噪比为10dB且漫反射和镜面反射多径同时存在的目标重构图 (36)
图4.1复杂阵地米波雷达多径回波几何模型 (38)天下美景
打水漂图4.2角度信号分布函数 (39)
图4.3分布源模型下的估角结果 (42)
图4.4点源模型下的估角结果 (43)
图4.5信噪比变化时分布源模型下不同仰角处的估角误差 (44)
图4.6分布源模型与点源模型下的的估角误差对比 (44)
图4.7漫反射功率非常大时不同信噪比下两种方法的估角性能比较 (45)
表格索引
表2.1典型表面的电特性 (11)
表3.1交替下降法求解S-TLS优化问题的流程 (32)
