信号处理硬件平台及参差MTI工程实现

结合某雷达信号处理系统硬件平台,介绍了雷达信号处理硬件平台的结构和组成, 以及算法实现方案,给出了参差 MTI 中的 AMTI 滤波器在单杂波和多杂波情况下,实现对杂波抑制的方法,并重点介绍了系统中通讯控制器的软件设计及功能实现,最后通过硬件的平台搭建和硬件程序的调试,实现了参差 MTI 中的 AMTI 滤波器对单杂波和多杂波的抑制功能。     

一种多频道运动杂波抑制技术

研究雷达在杂波环境下的自适应杂波抑制技术,介绍了参差时变多凹口滤波器设计方法,给出了一种带通滤波器实现方法,从而说明全频道杂波轮廓图的工作原理,利用杂波轮廓图信息确定杂波所在的多普勒频率范围,以此选择相应频道的MTI滤波器,实现AMTI,事实已证明该技术的可行性。     

自适应杂波抑制技术在雷达中的应用

动目标显示(MTI)技术是雷达在杂波环境中发现运动目标的有效手段。首先讨论了雷达信号处理中常用的自适应动目标显示技术,即在多杂波环境下的自适应杂波抑制技术。然后针对雷达杂波抑制中常用的级联MTI滤波器,提出了一种新的设计方法,即采用时变加权原理,通过对动杂波速度估值,实现对运动杂波抑制滤波器权值的优化。最后给出了这2种杂波抑制级联型MTI的工程实现。     

MTI雷达中基于子空间分解的杂波抑制算法

最优MTI滤波器的权值与目标的多普勒频率有关，传统的MTI雷达需要利用一组能覆盖目标多普勒频率范围的并行滤波器组来实现最佳滤波。本文提出了一种算法，通过子空间分解法直接求取滤波器的权系数，由于无需多普勒滤波器组，系统的复杂度得到了降低。为了适应杂波的变化，本文还推导了该算法基于幂迭代的自适应过程。仿真结果表明：在不同的杂波环境下，该算法均有良好的MTI改善因子。     

高频雷达射频干扰抑制的自适应接收滤波设计

为抑制高频雷达中的射频干扰,本文提出了一种自适应滤波器设计方法。首先,基于海杂波和射频干扰的多普勒特性,设计了海杂波区域自适应检测算法,以有效地估计射频干扰特性。然后,对海杂波、噪声和射频干扰的功率谱进行分析,并采用连续均值剔除算法,以检测射频干扰是否存在及其频率范围。最后,引入基于相似度约束的接收滤波器算法,根据射频干扰频带自动计算约束参数,从而实现了接收滤波器的自适应设计,以稳健地抑制射频干扰。仿真结果表明,相比传统白化滤波器,本文所设计滤波器可以有效地抑制宽带和窄带射频干扰,提高雷达抗干扰能力。     

对空雷达杂波抑制技术的研究

杂波抑制在雷达信号处理中起到了非常重要的作用,它的性能好坏能够直接影响到信号处理机的整体性能。由于对固定地物杂波有较理想抑制效果的对消器会带来盲速,本文引入盲速消除方法是采用多个重复频率参差工作,但是参差频率滤波器引起改善因子降低。从而利用特征矢量法详细地推倒了要使改善因子最大,则MTI滤波器的权矢量应取输入杂波的自相关函数的最小特征值所对应的特征向量,基于这种改善因子最大准则得出最佳权MTI滤波器。通过仿真,表明此最佳权MTI滤波器有较好的杂波抑制效果。     

用于杂波抑制滤波器优化设计的混合遗传算法 及其收敛性分析

参差时变动目标显示(MTI)滤波器是在强运动杂波背景下检测弱目标和缓解盲速问题的一种有效方法.选择适当参差码使参差时变MTI滤波器的第一零点尽可能浅,可在有效抑制杂波的同时避免陷入其中的弱目标丢失.本文采用了结合梯度的混合遗传算法(HGA)选择最优参差码,与标准遗传算法(SGA)相比,该算法只需要很小的种群规模.采用马尔可夫链方法证明了HGA是以概率1收敛的全局随机搜索算法.将该算法应用于米波雷达中,性能分析和仿真实验表明,基于混合遗传算法的杂波抑制滤波器设计是可行和有效的.     

基于Z域的时变加权参差MTI滤波器设计方法的研究

动目标显示（MTI）是提高雷达在杂波背景下的检测概率的一种重要方法,而参差MTI还具有能改善盲速的优点,但是由于其采样是参差的,因而难以得到其性能函数的解析表达式。根据数字雷达的特点,提出了一种基于Z域的参差MTI滤波器的性能分析方法,推导了其传输函数的解析表达式,并应用传输函数得到了一种时变加权MTI滤波器权系数的计算方法。     

一种MIMO雷达非高斯杂波中的信号分离方法

针对传统匹配滤波方法对非高斯相关杂波下MIMO雷达信号分离性能下降的问题,本文基于线性约束最小功率波束形成器原理,给出了一种适用于非高斯相关杂波条件下的MIMO雷达自适应信号分离算法。该方法将需要分离的发射信号以外的信号和相关杂波作为干扰,利用接收信号的分数低阶统计量在线性约束最小功率准则下导出了滤波器权系数,实现了非高斯相关杂波中对信号实时有效的分离。最后采用本文方法在SG-Alpha稳定分布杂波背景下进行了仿真实验,结果表明,本文方法可有效实现非高斯相关杂波中的MIMO雷达信号分离。      

采用自适应杂波白化滤波器和多卜勒滤波器组的雷达杂波抑制算法的性能

本文描述了一种采用自适应杂波白化滤波器(WF)和多卜勒滤波器组(DFB)的雷达杂波抑制算法。如与由动目标显示(MTI)和多卜勒滤波器组(DFB)级联所组成的常规的非自适应杂波抑制算法相比较,其性能得到了改善。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.