基于SIMULINK的GNSS干扰仿真平台设计与实现

全球卫星导航系统(GNSS)在电磁环境下的脆弱性迫使开展GNSS干扰系统的研究变得尤为重要。为节约硬件资源和缩短开发周期,本文设计实现了基于SIMULINK的GNSS干扰仿真平台,分析了该平台的仿真性能,研究结果具有一定的工程应用价值。     

卫星导航系统入站干扰信号的综合分析

本文首先介绍了在使用GEO卫星组网的某卫星导航系统中卫星入站干扰信号的特征,然后结合2012年3月2日～3月9日一周的入站干扰电平数据,采用抗差谱分析方法进行了详细分析。结果表明：入站干扰信号电平含有明显的周期变化,主周期是2．67天、1．52天、1．07天、0．82天和0．50天的周期变化,其中2．67天和1．52天周期变化的贡献相对较大。     

载体外诱饵对抗单脉冲雷达研究

根据单脉冲雷达的固有特点,提出利用载体外雷达诱饵对单脉冲雷达实施干扰的基本方法和分类,并通过典型实例分析了其作战应用。     

Jamming patterns in a two-dimensional hopper

We report experimental studies of jamming phenomenon of monodisperse metal disks falling through a two-dimensional hopper when the hopper opening is larger than three times the size of the disks. For each jamming event, the configuration of the arch formed at the hopper opening is studied. The cumulative distribution functionsf _d (X) for hoppers of opening sized are measured. (HereX is the horizontal component of the arch vector, which is defined as the displacement vector from the center of the first disk to the center of the last disk in the arch.) We found that the distribution off _d (X) can be collasped into a master curveG(X) = f _d (X)μ(d) that decays exponentially forX > 4. The scaling factorμ(d) is a decreasing function ofd and is approximately proportional to the jamming probability.     

合成孔径雷达的噪声干扰

合成孔径雷达是一种成像雷达,在距离上和方位上都采用脉冲压缩技术,因此,具有极高的分辨力。本文通过给出的合成孔径雷达干扰方程,提出对一部具有两种不同匹配滤波器的雷达实施噪声干扰时,应采用两种不同带宽的噪声干扰信号,以及实施噪声干扰的方法。     

On the Study of Jamming Percolation

We investigate kinetically constrained models of glassy transitions, and determine which model characteristics are crucial in allowing a rigorous proof that such models have discontinuous transitions with faster than power law diverging length and time scales. The models we investigate have constraints similar to that of the knights model, introduced by Toninelli, Biroli, and Fisher (TBF), but differing neighbor relations. We find that such knights-like models, otherwise known as models of jamming percolation, need a “No Parallel Crossing” rule for the TBF proof of a glassy transition to be valid. Furthermore, most knights-like models fail a “No Perpendicular Crossing” requirement, and thus need modification to be made rigorous. We also show how the “No Parallel Crossing” requirement can be used to evaluate the provable glassiness of other correlated percolation models, by looking at models with more stable directions than the knights model. Finally, we show that the TBF proof does not generalize in any straightforward fashion for three-dimensional versions of the knights-like models.     

Flow overshooting in crossing flow of lattice gas

We study the lattice gas flow of two components of biased-random walkers at a crossing under a periodic boundary. The lattice gas mixture consists of two components of particles (walkers) in which one component of particles moves north and the other component of particles moves east. The current (flow) increases with ρ_x (density of the east-bound particles) at low density and displays overshooting at an intermediate density. The flow overshooting occurs only for a certain range of ρ_y (density of the north-bound particles). Then clogging occurs and the current saturates. Furthermore, when the density is high, the current decreases with increasing density. The overshooting shown in the current-density (fundamental) diagram is due to the formation of an unstable oscillating jam just before clogging occurs. It is shown that flow overshooting does not occur in unidirectional flow through a porous medium but occurs in unidirectional flow through a group of Brownian particles.     

Single tone jamming elimination scheme of multicarrier spread spectrum system

The proposed scheme is based on Discrete Fourier Transform (DFT) domain processing. The key technology of this scheme is jamming parameters‘ accurate estimation and jamming reconstruction. Compared with the “threshold exciser”scheme.the proposed scheme can eliminate more jamming energy on the whole frequency band with the minimum loss of useful signal energy. As shown in the research and simulation, the proposed scheme is much better than the “threshold exciser” scheme, especially in the case of high power jamming whereas the “threshold exciser” scheme might be invalid.     

自卫干扰位置可控式ISAR假目标合成方法

为提高逆合成孔径雷达(ISAR)图像欺骗干扰的逼真度,基于点散射调制模板构建了自卫式干扰(SSJ)条件下位置可控二维假目标干扰信号模型,研究了调制坐标、坐标偏移量以及转速对二维假目标图像合成的影响。理论分析表明,在雷达截获信号的快时间域增加与纵向调制坐标及偏移量对应的时延可以控制假目标的纵向位置;而在慢时间域增加与横向调制坐标及偏移量对应的相位变化因子可控制假目标的横向相对位置;调制转速则使得假目标图像发生横向扩展或压缩。仿真实验结果验证了理论分析的正确性,表明本文位置可控式ISAR假目标干扰信号合成方法有效,且干扰功率要求较低。