A parametric method for non-stationary interference suppression in direct sequence spread-spectrum systems

The problem of non-stationary interference suppression in direct sequence spread-spectrum (DS-SS) systems is considered. The phase of interference is approximated by a polynomial within the considered interval. According to the local polynomial Fourier transform (LPFT) principle, the received signal is dechirped by using the obtained phase approximation and the interference is, in turn, suppressed by excising the corrupted low-pass frequency band. For the estimation of polynomial coefficients, we use the product high-order ambiguity function (PHAF), known for its capability to successfully resolve components of a multicomponent polynomial-phase signal (PPS). The proposed method can suppress interferences with both polynomial and non-polynomial phase. In addition, it can suppress both monocomponent and multicomponent interferences. The simulations show that the proposed method outperforms time-frequency (TF) methods, that successfully deal with multicomponent interferences, in terms of the error probability and computational complexity.     

Layered multicast congestion control by particle swarm optimization in heterogeneous environment

To enhance multicast throughput in heterogeneous environment,a new layered multicast congestion control scheme is proposed.With the goal of maximizing global satisfaction of the whole group,allocating sending rate in each layer is formulated to an optimization problem.Since the problem is noncovexity,the sender uses particle swarm optimization to search a set of optimal layers rates.The new scheme also eliminates ’lowest-first’ phenomenon by proposing a feedbacks suppression algorithm named equal-probability sampling (EPS).Upon EPS all the receivers send feedbacks at equal probability without bias.Simulation results prove that the new scheme can enhance global satisfaction and multicast throughput efficiently,compared with the traditional layered multicast congestion control scheme based on representatives.     

基于半定规划的阵列天线方向图旁瓣抑制

基于半定规划理论提出了一种新的阵列天线方向图旁瓣抑制算法。与传统旁瓣抑制方法不同,该方法通过合理设计优化准则,避免了在凸优化问题建模过程中引入近似,保证了波束形成器的最优性;并且使得在压低旁瓣的同时,可准确控制信噪比增益和主瓣宽度到期望的范围之内。该方法对阵列流形没有限制,计算机仿真结果验证了其有效性。     

国外军用烟幕隐身剂的现状和发展

烟幕隐身技术作为一种现代战役、战斗保障的积极手段,一直受到各国军方的高度重视.简要介绍了国外军用烟幕剂的作用机理、发展历程、种类,并对军用烟幕隐身剂的发展前景做了初步预测.     

对发烟剂烟幕组分的定量分析

建立了发烟剂烟幕组分的采样方法和条件,采用直接刮样溴化钾压片制样技术,应用FTIR光谱仪和Quant Basic定量软件,对有机酸类发烟剂燃烧产物中的主要组分进行了定量分析,实现了烟幕组分的快速测定,并对烟幕中的己二酸组分进行了定量测定,测定结果符合微量分析的误差要求.     

烟幕材料对太赫兹波的屏蔽特性研究

介绍了透射型太赫兹时域光谱系统实验装置和相关参数的提取方法,分别对绿色和黄色两种烟幕材料在太赫兹波段的光谱特性进行了实验研究,得到了这两种材料的折射率曲线和屏蔽效能曲线。实验表明,这两种材料对可见光和红外波段有较好的遮蔽特性,而对太赫兹辐射的屏蔽效能却较差,太赫兹侦察探测具有较强的抗干扰能力,能够弥补传统可见、红外探测系统的不足。     

出租车计价器辐射骚扰的诊断和抑制

针对出租车计价器辐射骚扰超标的问题,分析产生机理和原因,进行有效抑制.通过并接高频陶瓷电容器和在导线上套用磁珠两种方法改进后,辐射骚扰达到相关标准的要求.     

光分组交换系统中载波抑制光标签的研究

为了研究高带宽利用率和大容量的光分组交换系统,对载波抑制调制原理进行理论分析,提出了一种载波抑制调制光标签的方案,并对基于载波抑制调制的光标签系统进行了仿真分析和实验研究。结果表明,载波抑制光标签的中心载波抑制比达到21.3dB;在622Mbit/s和1.25Gbit/s的标签调制速率下,系统传输距离超过40km时,依然能保持低于10-10的误比特率;以误比特率10-10为标准,在传输距离为40km时,两种标签调制速率的功率代价分别为1.7dB和1.9dB。此结果说明载波抑制光标签在光分组交换系统中具有串扰小、功率代价低等特点,信号质量好,适合远距离传输。     

基于多圈环绕结构的超流体陀螺噪声抑制方法

超流体陀螺是新一代惯性传感器,其面临的关键问题是：输出存在较大的噪声,引起其高测量精度的潜力不能发挥。为此,基于对管路多圈环绕时的流体感抗分析,构建了多圈环绕时超流体陀螺噪声的数学模型;并综合考虑多圈环绕对超流体陀螺的影响,研究最优环绕圈数,提出基于多圈环绕结构的噪声抑制方法。研究结果表明,随着环绕圈数的增加,超流体陀螺的噪声呈现逐渐下降的趋势。根据通用参数,采用最优圈数进行多圈环绕时,超流体陀螺的噪声值被抑制为无多圈环绕时的1/4. 因此基于该方法,超流体陀螺的测量精度得到了显著提高。     

基于极化敏感阵列的导航抗干扰方法

对于全球卫星导航系统的接收终端,抗干扰处理能够提高其干扰容量,是一项非常重要的工作。提出了一种改进的基于双极化天线阵列的联合极化-空域自适应处理方法进行干扰抑制。仿真实验表明,此方法能够有效降低干扰性,并且不需要知道干扰信号的先验信息,能够适用于卫星导航信号处理。