Bright band height assignment with precipitation radar data based on multi-resolution analysis (MRA) of wavelet analysis

A method for reconstruction of cross-section of rainfall situations with precipitation radar data based on wavelet analysis of multi-resolution analysis (MRA) which allows extract a peak of the radar reflectivity is proposed in order to detect bright band height. It is found that the bright band height can be estimated by using the MRA with the basis of Daubechies wavelet family. It is also found that the boundaries in rainfall structure can be clearly extracted with MRA.     

改进的特征匹配雷达视频运动目标跟踪算法

针对密集杂波和复杂多目标情况下,特征匹配跟踪算法定位跟踪精度较低的问题,提出一种改进的特征匹配雷达视频运动目标跟踪算法。首先,从单帧雷达图像检测结果中提取目标的面积、位置、不变矩信息,在运动目标得到判定后,利用卡尔曼滤波的预测位置以及上一帧特征信息进行目标匹配;然后,根据匹配位置和预测位置给出目标估计位置,并进行特征信息更新;最后,输出目标的特征信息、位置信息和运动参数。利用某型导航雷达上采集的实测数据验证了算法的有效性。     

一种导弹目标宽带雷达相位测距的新方法

微动是反导系统中识别真假弹头的重要依据之一,然而传统的通过距离像包络提取微动的方法分辨率较低,无法反映章动等幅度较小的运动,针对这个问题,提出了一种利用宽带雷达距离像相位分析导弹目标微动的新方法.该方法通过共轭相乘、时频域滤波及解模糊等步骤,从散射点的相位序列中提取散射点之间的距离微小变化,从而作为分析目标微动状况的依据.通过Feko软件仿真数据对提出的方法进行了验证,实验结果表明,相比于传统的通过距离像包络分析微动的方法,新方法对于微动导致的散射点距离变化的分辨能力提高了4倍以上,能够清晰地反映出目标的章动现象;并且,时频域滤波与解模糊的处理方法也能进一步提高该方法的鲁棒性,有效降低噪声和脉冲重复频率低导致的解模糊出错的概率.     

高保真卫星电源负载场景重现系统设计

卫星工作期间整星负载变化较大，多次高精度重现卫星电源负载场景，有助于卫星供配电系统的性能测试和故障排查；但使用真实卫星负载、蓄电池，存在安全性、难以快速重复建立状态的问题，会对蓄电池寿命和单机安全造成影响。设计了一套卫星电源负载场景重现系统，高保真度地记录与重现卫星外电、内电与负载场景，可快速重现供配电现场，辅助卫星测试与故障排查。     

Identification of uncatalogued LEO space objects by a ground-based EO array

A ground-based electro-optical (EO) array, deployed at the Jilin Space Tracking Base of Changchun Observatory, China, has been in operation since April 2017. The array has 8 small telescopes, each has an aperture of 15 cm and a field of view of 14° × 14°. On average, the array can collect angles data over 3–4 thousand Very Short Arcs (VSAs) of Low Earth Orbit (LEO) space objects each night. Correlation of the VSA angles data with the NORAD catalogue objects results in about 85% of all the VSAs being correlated to NORAD objects. The remaining 15% VSAs angles data could be supposed from uncatalogued objects. The Initial Orbit Determination (IOD) solutions of the VSAs with the range-search method and the association results of the IODs with the geometrical method are presented. The mean IOD success rate is about 91% and the True Positive (TP) rate is more than 86%. In addition, the classical Gauss, Laplace, Gooding and Double-r angles-only IOD methods are applied to process VSA angles data and their performance is assessed. The CBTA method is used to associate the IOD tracks and compared with the geometrical method. A set of procedures for identifying the uncatalogued objects based on the VSA angles data is designed. Processing of the VSA angles data from Aug 4 to Sep 30, 2017 reveals there are possibly 415 uncatalogued LEO objects.     

基于马氏距离的雷达网有源假目标干扰鉴别技术

针对雷达网有源假目标干扰问题,为了消除长基线雷达组网时地球曲率对数据处理的影响,通过坐标转换,将各雷达站的目标的量测数据转化到了地心直角(ECEF)坐标系内,得到统一坐标系下的目标量测信息,完成空间上的对准;在此基础上,基于虚假目标的量测与雷达站位置有关,真实目标量测与雷达站无关,因而依据卡方分布的性质,在ECEF坐标系内对各个量测进行卡方检验,鉴别出虚假目标;最后,通过仿真验证了分析的正确性,该算法与工程实际接轨,实用性较强。     

结构吸波材料多层阻抗渐变设计及应用

对多层阻抗渐变的吸波结构设计思想进行了分析,介绍了多层阻抗渐变思想在吸波层板和泡沫两类结构吸波材料设计上的应用。理论计算与试验验证结果均表明,采用多层阻抗渐变设计能够使吸波层板和泡沫的吸波带宽向低频拓展,同时显著提高吸波泡沫的吸收强度。具有三个阻抗渐变吸收层的4 mm厚吸波层板在5~18 GHz频段反射率小于-10 d B;具有六个阻抗渐变吸收层的22 mm厚吸波泡沫在2~18 GHz频段反射率小于-10 d B,其中在6~18 GHz频段反射率小于-20 d B,8~12 GHz频段反射率小于-30 d B。多层阻抗渐变设计是提高结构吸波材料吸波性能的有效手段。     

Lunar ground penetrating radar: Minimizing potential data artifacts caused by signal interaction with a rover body

Ground-penetrating radar (GPR) is the leading geophysical candidate technology for future lunar missions aimed at mapping shallow stratigraphy (<5 m). The instrument’s exploration depth and resolution capabilities in lunar materials, as well as its small size and lightweight components, make it a very attractive option from both a scientific and engineering perspective. However, the interaction between a GPR signal and the rover body is poorly understood and must be investigated prior to a space mission. In doing so, engineering and survey design strategies should be developed to enhance GPR performance in the context of the scientific question being asked. This paper explores the effects of a rover (simulated with a vertical metal plate) on GPR results for a range of heights above the surface and antenna configurations at two sites: (i) a standard GPR testing site with targets of known position, size, and material properties, and; (ii) a frozen lake for surface reflectivity experiments. Our results demonstrate that the GPR antenna configuration is a key variable dictating instrument design, with the XX polarization considered optimal for minimizing data artifact generation. These findings could thus be used to help guide design requirements for an eventual flight instrument.     

一种导航扫描天线监测系统的天线罩倾斜影响分析

文章通过天线罩倾斜时所产生的反射波对一种导航系统相控阵扫描天线监测系统影响的分析,得到了监测系统的监测角漂移与天线罩倾斜角及距离的关系,并提出解决监测角漂移问题的思路.     

A Raw Signal Simulator for Bistatic SAR

This article proposes a new efficient raw signal simulator for the bistatic synthetic aperture radar (SAR) based on 2D fast Fourier transform (FFT) to deal with cases of both ideal trajectory and trajectory deviation. It begins with analyzing the geometric configuration and the range history of the bistatic SAR in side-looking and squint modes of ideal trajectory as well as trajectory deviation. Then a detailed and mathematical study is conducted on the equivalence relation of bistatic-to-monostatic applications (BTMA) in the case of ideal trajectory and trajectory deviation. Also a set of formulas are derived for the equivalence relation between bistatic SAR and monostatic SAR on some reasonable assumptions. Therefore, the application of the simulation method based on the 2D FFT for the monostatic SAR can be extended to the case of bistatic SAR. Finally, the simulation results prove the validity of this method. By comparing the efficiency of the proposed method with that of the time domain method, it is shown that the former is a few orders of magnitude higher.