FPGA在雷达定时器中的应用

定时器是雷达系统的重要部分,它为雷达全机提供所需的各种主脉冲定时信号和波门定时信号.介绍了FPGA(现场可编程门阵列)在定时器中的应用,着重叙述了定时器原理.该定时器的特点是:采用大容量FPGA,尽可能在FPGA内部实现所有功能,减少外围器件,以达到统一板级设计、提高定时精度及可靠性、降低成本、实现硬件的灵活配置的目的.     

基于FPGA双振荡电路定时器的设计

考虑冲击环境下定时器会遇到的问题,并分析了单一的晶体振荡器和谐振振荡器都不能很好地满足抗冲击性和高精度两方面要求,因此提出了一种基于FPGA设计的双振荡定时器。此定时器能有效地解决爆破作业中延时雷管起爆精度和抗冲击性能之间的矛盾。更主要的是CPLD的时序比集成芯片更加容易控制。在FPGA实现,该设计的定时精度达到纳秒级,很好地满足系统性能要求。本方法具有结构简单、成本低、可靠性高、精度高等优点。     

基于定时时序数字化的雷达定时器设计

定时时序数字化是一种新的定时器设计方法,文中先对定时时序的特点进行分析, 再介绍定时时序的时间分割方法以及数字化的方法,最后结合 MPU+FPGA 的硬件设计模式实现了一种比较稳定规范的雷达定时器设计模式,缩短了设计周期,提高了设计质量,满足了雷达定时器设计的通用性的需求。     

宽带雷达接收机数字下变频技术研究

数字下变频（Digital Down Conversion,DDC）是宽带雷达中频接收机的关键技术之一,传统DDC实现方法在现有FPGA上无法满足带宽和滤波器精度对硬件资源的要求.针对这一问题,提出了一种数字下变频结构优化方法,给出了分布算法实现FIR滤波器的结构,研制出了一种最优化免混频数字下变频器,并已经成功应用于某宽带雷达系统.     

LFMCW雷达数字化测距测速的工作参数设计

LFMCW雷达测距和测速的应用中,测量精度是主要考虑的因素.由于需兼顾距离和速度的测量精度要求,雷达系统参数和信号处理技术指标的设计就变得复杂.从雷达工作原理出发,在数字化信号处理中分析了时域的测距测速精度与频率分辨力的关系,着重讨论了距离分辨力与距离、速度测量精度要求的关系;提出了雷达系统工作参数设计的方法步骤,从而满足较高的测距和测速精度要求.     

韦布尔分布海杂波的建模与FPGA实现

雷达回波模拟器在雷达设计中是不可缺少的一部分,对于雷达系统的设计发挥着重要作用,而海杂波模拟又是雷达回波模拟器设计中的关键一环.文章选取杂波建模中常用的韦布尔分布模型进行了分析,给出了其ZNML产生方法,并在FPGA实现,最后给出了实现的结果并与理论值比较,达到了很好的效果,可应用于雷达回波模拟器的设计中.     

一种二维有源相控阵雷达信号处理机的设计

为了满足二维有源相控阵雷达信号处理机快速和实时性的需求,本文设计和实现了一种基于DSP和FPGA的二维有源相扫雷达信号处理机.本信号处理机采用多核DSP搭配FPGA的设计架构,实现了高性能实时信号处理平台,可满足雷达系统算法需求,具有较高的实用性.     

基于SPU的雷达信号处理技术

研究了基于信号处理单元（SPU）平台的雷达信号处理技术,结合某雷达系统需求,采用高性能双数字信号处理器（DSP）和现场可编程门阵列（FPGA）的SPU硬件处理平台实现雷达信号处理,使用串行设计技术提高雷达信号处理的实时性、通用性、可靠性,同时减少信号处理的硬件设备量。实验结果验证了基于单块SPU雷达信号处理的可行性。     

机动性三坐标雷达的结构精度分析北大核心CSCD

为了减小机械结构误差对雷达系统精度的影响,从基本误差分析理论出发,结合装配误差分析、机构精度分析,提出机动性三坐标雷达的机械结构精度分析方法,包括方位角和俯仰角的误差计算;同时,结合实例分析了影响雷达结构精度的各种因素,并给出具体计算方法和计算结果,该方法可广泛应用于机动性三坐标雷达的系统结构精度分析。文中还总结了提高结构精度的措施,包括提高结构系统刚度、提高制造和安装精度、控制温度变形、消除系统误差等,可为机动性三坐标雷达结构精度设计提供借鉴。     

探地雷达中PCI总线高速数据采集卡的设计

高速数据采集是探地雷达系统的关键部分,利用PCI总线的高速传输特性,给出了一种设计方法.简要阐述了探地雷达中数据采集系统的硬件结构及其工作原理,重点分析了数据采集系统的核心--基于现场可编程门阵列(FPGA)器件控制逻辑的实现,并介绍了软件驱动的实现方法.实践表明,该采集系统能够达到探地雷达中高速数据传输和处理的实时性要求.     

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.     

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.     

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.     

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.     

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.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.