GPS接收终端干扰仿真系统的设计与实现

针对GPS信号面临多种干扰的问题,本文设计并仿真实现了复杂电磁环境下GPS接收终端干扰仿真系统,对GPS接收终端受到的干扰进行了再现,并建立相关模型,使用户可以通过智能化的界面操作使用,分析干扰对正常信号的影响程度,为进一步的干扰排查提供依据。     

电磁兼容性设计在电子产品中的应用

本文从电磁兼容性设计的特点出发,结合电磁兼容性设计的内容,对干扰源的抑制、电场屏蔽、磁场屏蔽、滤波、接地、搭接、布局与线缆敷设的方法和注意事项进行了阐述.     

测控链路干扰防护措施

在分析测控系统抗干扰薄弱环节的基础上论述了测控链路干扰防护的重点,提出了几种测控链路干扰防护措施,包括能量干扰防护、信号干扰防护和信息干扰防护等.     

地波绕射超视距短波通信对抗系统

现代战争中,超视距打击已经成为一种重要的作战手段。为了延长预警时间并有效地干扰视距以外的电子目标,超视距电子对抗系统便成为未来军事斗争中的重要电子战装备。本文对地波绕射超视距短波通信对抗系统的可行性进行了论证。结果表明,该系统对海上(300～400km范围内)短波通信装备的侦察、干扰是可行的。     

有源干扰的能量在SAR图像中分布的研究

该文研究了对合成孔径雷达干扰中的能量问题, 提出了干扰能量的等同原则。指出如果雷达接收到相同能量的干扰,那么经成像处理后在雷达图像中的总干扰能量相同,不同相关性的干扰信号可以改变干扰能量在合成孔径雷达图像中的分布;这对选择合适的干扰方法和研制干扰系统具有参考意义。此外,文中还推导了合成孔径雷达干扰功率的计算公式。     

一种通信对抗干扰资源分配智能决策算法

针对战场通信对抗智能决策问题,该文基于整体对抗思想提出一种基于自举专家轨迹分层强化学习的干扰资源分配决策算法(BHJM),算法针对跳频干扰决策难题,按照频点分布划分干扰频段,再基于分层强化学习模型分级决策干扰频段和干扰带宽,最后利用基于自举专家轨迹的经验回放机制采样并训练优化算法,使算法能够在现有干扰资源特别是干扰资源不足的条件下,优先干扰最具威胁目标,获得最优干扰效果同时减少总的干扰带宽。仿真结果表明,算法较现有资源分配决策算法节约25%干扰站资源,减少15%干扰带宽,具有较大实用价值。     

基于改进离散布谷鸟算法的干扰资源分配研究

该文对二次雷达机制的协同式敌我识别系统的干扰资源分配问题进行研究,将离散布谷鸟算法(Discrete Cuckoo Search, DCS)引入敌我识别系统的干扰资源分配问题。首先给出协同式敌我识别系统的干扰效果评估指标,建立干扰资源分配模型,将模型简化为一对一、多对少模型,使用DCS算法求解模型。针对Levy飞行后期出现搜索速度慢和精度低的问题,将遗传算法中的交叉与变异操作引入DCS算法得到改进的离散布谷鸟算法(Improved Discrete Cuckoo Search, DCS),用以求解分配模型。仿真分析表明：所提干扰效果评估指标可以合理地评估干扰效果;IDCS算法比IDCS算法收敛更快、耗时更短;IDCS算法与做出相应改进的遗传算法(Improved Genetic Algorithm, IGA)相比具有更好的寻优能力。     

Effect of magnetic field orientation on fluidized beds of magnetic particles: Theory and experiment

Geldart-A fluidized beds of fine particles experience a jamming transition between a fluid-like state and a solid-like state at a certain superficial gas velocity, that depends on the relative strength of interparticle attractive forces with respect to particle weight. Interparticle forces provide the bed with a certain tensile strength in the jammed state. In the work presented here we analyze the behavior of a fluidized bed of magnetic particles subjected to an externally applied magnetic field, which contributes to enhance interparticle forces. The importance of the magnetic contribution to interparticle forces is measured by the changes in the tensile strength and the superficial gas velocity at the jamming transition. The link of the field orientation with the microstructure of the bed is discussed.     

Scheme for nonlinear frequency modulated signal cancelling system

A cancelling system for the four nonlinear frequency modulated (NLFM) signal (i.e. Taylor window, Tangent-based, Combination linear frequency modulation (LFM) and tan-FM, Stepped NLFM) is presented. It is mainly composed of a digital radio frequency memory (DRFM) and a field programmable gate array (FPGA) chip etc. The received signals are stored and reproduced by DRFM, and the system delay time is controlled by the FPGA chip. According to the target's radar cross section (RCS), the radar echo cancelling wave will be generated by the FPGA and DRFM on signal processing. The effect of error on the cancelling wave is analysed and the method for reducing nonlinear phase errors is presented. Theoretical analysis and simulation show that the system effectively reduces the signal power received by the radar receiver. Numerical simulation results show that about 11.3 dB target gain reduction can be achieved under the condition of large deviation.