机载合成孔径雷达对地面防空力量的威胁及干扰对策研究

描述了机载合成孔径雷达的特点,分析某机载合成孔径雷达对地面防空力量的威胁,从有源干扰、无源干扰两方面研究地面部队对其实施干扰的技术对策。     

光热干涉检测系统的实验参数选择

为了研究实验参数对光热干涉检测结果的影响,根据等厚干涉测量原理,利用赛德倾斜像差建立了相应的光热干涉测量模型.通过对探测光源的分析,利用随机函数建立一般性光源模型,定义了光源均匀度.在此基础上通过数值模拟,对不同光源均匀性下实验现象进行仿真,分析了光源均匀性对干涉测量结果的影响.分析表明,探测光源均匀性对热吸收干涉测量结果的影响可以忽略.同时还对比分析了不同探测器接受口径对测量结果的影响.结果显示,当探测器接收口径R=0.315cm时,在0～0.6λ的光热位移内光热信号呈单调下降,而且条纹对比度相对较大.通过曲线拟合得到在弱吸收情况下光热信号与光热位移的一个简单经验公式.     

基于像素分类的自适应SAR图像融合算法

提高纹理清晰度、保护边缘信息是合成孔径雷达（SAR）图像融合的重要目标。针对该问题,提出了一种基于像素分类的自适应SAR图像融合算法。首先使用canny算子提取图像的边缘并分类,然后利用混合高斯模型和隐马尔可夫树模型对小波系数进行建模;在此基础上使用EM算法求得模型参数,并进一步得到隐状态的概率,也就确定了小波系数的混合高斯分布;接着对两个待融合小波系数不同的类型组合采用不同的融合策略,并以隐状态概率加权;最后通过小波反变换、边缘分类增强获得融合以后的图像。实验结果表明,和传统的融合算法相比,该算法取得了更好的融合效果。     

基于SAR辅助的INS/Doppler组合导航系统研究

INS/Doppler组合导航系统具有输出水平速度误差和平台角误差较小的优点,但经纬度误差仍随时间增大,故不能作为独立的精确导航定位系统;由于合成孔径雷达(SAR)能够提供高精度的经纬度和航向信息,文中对基于SAR辅助的INS/Doppler组合导航系统进行了研究。仿真结果表明,该系统导航定位精度高、自主性强,比较适用于对导航精度要求较高的大型飞机。     

SAR图像道路目标提取研究

和大多数侧重于后处理的算法不同,文中在研究了合成孔径雷达(SAR)图像中道路的灰度及几何特征之后,着重在图像预处理中提出了非线性自适应保边缘滤波及局部均方差加权边缘增强算法,在去除乘性斑点噪声的同时较好地保持了道路边缘特征,再从全局的角度考虑提出了一种改进的随机Hough变换(GRHT)算法来确立道路边缘线,继而进一步确定道路中心线.整个算法可以自动进行,具有很高的处理速度及较低的储存需求,实验证明该算法能够准确有效地提取SAR图像中道路目标.     

孔径径向扫描白光散斑干涉法的研究

提出了一种用于动态研究的新方法-孔径径向扫描白光散斑干涉法,介绍了两孔和直三孔径向扫描器.该方法是一种非接触式的用于动态测量的白光散斑法.分析了孔径径向扫描白光散斑干涉法的基本原理,给出了白光散斑全场滤波分析的平均光强解析式和实验结果.该方法的优点是利用散斑的调频技术能在一张白光散斑图上记录物体的连续动态变形的信息,在全场滤波分时,能将物体动态变形的信息方便地提取出来,得到清晰的全场白光散斑条纹图.直三孔径向扫描法能得到物体在x方向、y方向和45°方向上的变形信息.在实时全场滤波分析观察时,将滤波孔连续地沿径向扫描,可观察到物体连续动态变形的全过程,从而为物体的动态研究提供了一种新方法.     

High-resolution ISAR imaging of fast rotating targets based on pattern-coupled Bayesian strategy for multiple measurement vectors

Very high resolution inverse synthetic aperture radar (ISAR) imaging of fast rotating targets is a complicated task. There may be insufficient pulses or may introduce migration through range cells (MTRC) during the coherent processing interval (CPI) when we use the conventional range Doppler (RD) ISAR technique. With compressed sensing (CS) technique, we can achieve the high-resolution ISAR imaging of a target with limited number of pulses. Sparse representation based method can achieve the super resolution ISAR imaging of a target with a short CPI, during which the target rotates only a small angle and the range migration of the scatterers is small. However, traditional CS-based ISAR imaging method generally faced with the problem of basis mismatch, which may degrade the ISAR image. To achieve the high resolution ISAR imaging of fast rotating targets, this paper proposed a pattern-coupled sparse Bayesian learning method for multiple measurement vectors, i.e. the PC-MSBL algorithm. A multi-channel pattern-coupled hierarchical Gaussian prior is proposed to model the pattern dependencies among neighboring range cells and correct the MTRC problem. The expectation-maximization (EM) algorithm is used to infer the maximum a posterior (MAP) estimate of the hyperparameters. Simulation results validate the effectiveness and superiority of the proposed algorithm.     

Land surface deformation parameter estimation using persistent scatterer interferometry approach in an underground metal mining environment

Persistent scatterer interferometry (PSI) is a major advancement in radar interferometry for detecting and monitoring land deformation. PSI is the most advanced class of differential interferometric synthetic aperture radar (DInSAR) techniques. The technique conquers the main drawbacks of the conventional DInSAR technique by identifying radar targets having stable backscattering characteristics in time. These targets are termed as persistent scatterers (PSs). The higher the number of PSs for a study area the higher the accuracy of the results will be, which is most common for deformation analysis in urban areas. However, for non-urban or highly de-correlated areas, PSs density collapses significantly, which needs to increase for optimal results. For this purpose, partially coherent/distributed scatterers (DSs) are being exploited in addition to the PSs. The field surface of this study is one of the copper-rich mining belts in India, which consists of two major underground metal mines. Scatterer characterziation of the field surface under study suggests that most of the scatterers are DSs and very few scatterers under the influence of the mining zone are PSs. In addition to this, a preliminary investigation of deformation characteristics of the field surface under study reveals that the spatial extent of deformation is small/localized along with slow and non-linear deformation. Keeping in view scatterer and deformation characteristics of the field surface under study, in this research paper, a Quasi-Persistent Scatterer based PSI approach has been applied using high-resolution TerraSAR-X interferometric data stack (10 images) to generate deformation time series and deformation velocity. Furthermore, results obtained from the applied PSI approach and ground-based observations (using GNSS) have shown good agreement with each other, in the order of ?5.20?mm/year (LOS) and ?5.38?mm/year (subsiding), respectively.     

矩形孔径柱面镜面形拟合基底多项式研究

对矩形孔径柱面镜面形的拟合方法进行了研究,将矩形域的扩展Zernike多项式与Chebyshev多项式分别作为面形拟合基底,对导出面形数据进行波面复原,分析赛德像差与拟合基底的对应关系对比拟合结果,Chebyshev多项式较矩形域的扩展Zernike多项式有较好的像差分离能力。     

线性调频脉冲串制式合成孔径雷达实时成像算法和方案的设计和模拟

介绍了线性调频(LFM)脉冲串制式合成孔径雷达(SAR)提高距离向分辨率原理,并且提出线性调频SAR的信号处理算法和步骤,避免了为提高距离向分辨率而加大系统带宽的问题.通过模拟验证了算法的正确性,并分析了计算量.设计了相应的SAR实时成像处理器方案,满足了这种新体制SAR系统的大规模成像处理的要求.