巴克编码信号抑制旁瓣滤波器的等旁瓣设计方法

本文在对巴克编码信号旁瓣抑制滤波器的副瓣代数式进行了细致分析的基础上,提出了一种可获最低峰值副瓣电平的抑制旁瓣滤波器等旁瓣设计方法。并将这种方法与其他设计方法进行了比较,结果表明:这种方法设计的滤波器除峰值副瓣最低外,滤波器的信噪比损失也最小,仅均方根副瓣较其他方法中的最佳者略差一点。等旁瓣法还显示了对具有负副瓣电平的巴克码的良好适用性。此外还以七位巴克码七阶滤波器为例,证明了新方法设计的滤波器具有最低的峰值副瓣电平。     

恒增益处理损失的最佳编码旁瓣抑制滤波器

雷达距离/时间旁瓣抑制滤波器的设计通常以旁瓣电平最低为设计目标,未考虑增益处理损失的控制,在某些情况下会导致输出信噪比损失过大,影响弱信号的检测.本文研究增益处理损失任意给定条件下的旁瓣抑制滤波器的设计,并以巴克码为例具体设计了恒增益处理损失的最佳积累旁瓣电平滤波器和最佳峰值旁瓣电平滤波器.     

失配滤波器在数字脉压旁瓣抑制技术中的应用

通过使用加权迭代最小二乘法来设计失配滤波器，用于数字脉压旁瓣抑制技术中，并通过优化权系数，可以使得输出信号的旁瓣电平压得很低。份真结果表明，通过迭代，选择适当的权系数使得失配滤波器的输出具有较低的旁瓣电平，且峰值旁瓣电平比未优化前降低了6dB。     

多相脉压缩码在旁瓣抑制下的多普勒性能

由频率调制导出的P3、P4多相码是一类常见的脉冲压缩信号，已提出的几种旁瓣抑制技术可用于降低这类脉压信号的压缩输出旁瓣。本文主要研究在使用这几种旁瓣抑制技术时，多普勒频移对P3、P4多相码压缩输出性能的影响，包括多普勒频移对输出峰值旁瓣电平（PSL）以及信噪比（SNR）损失的影响。文中给出了计算机仿真结果。     

新型短波信道探测序列研究

针对脉冲压缩体制短波信道探测对探测序列的自相关特性要求很高的问题,将周期自相关特性十分理想的Zadoff-Chu序列应用到短波信道探测中,设计了能充分利用其周期自相关特性的序列扩展方式,对Zadoff-Chu序列、m序列和巴克码的相关函数及相关函数的主旁瓣峰值比、品质因数、联合旁瓣电平率、峰均功率比四个参数进行了仿真和实测,对所得数据进行了讨论分析。分析表明:Zadoff-Chu序列比m序列和巴克码具有更好的自相关特性,其相关函数的主瓣峰值与旁瓣峰值之比、品质因数等四个参数比m序列和巴克码的相应参数更优越。     

多相脉压编码在旁瓣抑制下的多普勒性能

由频率调制导出的 P3、P4多相码是一类常见的脉冲压缩信号 ,已提出的几种旁瓣抑制技术可用于降低这类脉压信号的压缩输出旁瓣。本文主要研究在使用这几种旁瓣抑制技术时 ,多普勒频移对 P3、P4多相码压缩输出性能的影响 ,包括多普勒频移对输出峰值旁瓣电平 (PSL )以及信噪比 (SNR)损失的影响。文中给出了计算机仿真结果。     

MIMO雷达中的谱修正旁瓣抑制技术研究

谱修正是一种简单有效的抑制脉压旁瓣的方法,通过对信号的频谱整形,抑制信号带内起伏,并采用频域加窗达到控制脉压信号距离旁瓣的目的。MIMO雷达常用的正交信号经脉冲压缩后存在不希望的距离旁瓣,若直接将谱修正技术用于MIMO雷达各个子带信号脉压处理,由于子带间信号互相关的影响,将不能获得较好的距离旁瓣抑制效果。本文针对该问题,提出了一种对MIMO雷达综合信号进行谱修正和频域加窗的方法,可以更有效地抑制脉压距离旁瓣。仿真结果显示,该方法能取得40dB以上的主副比,且能有效降低系统的复杂度和运算量,在多普勒和角度偏差不大的情况下,其峰值旁瓣电平明显低于传统的匹配滤波。      

P4多相码的性能评估

简要介绍了P4多相码的模糊函数、积累旁瓣电平等多项性能指标,详细分析了经过采样滑窗旁瓣抑制后P4多相码的多普勒性能,给出了脉压后主峰幅度及主副比随多普勒变化的MATLAB仿真结果,证明了采样滑窗旁瓣抑制方法的有效性,为工程应用提供了理论依据。     

SAW 15位m序列相位编码信号的最小峰值旁瓣滤波器

本文介绍用线性规划方法求解[4,3,0]反馈连接的、起始状态为1001的15位m序列相位编码信号的最小峰值旁瓣滤波器(LP滤波器)的计算结果。长度为15的LP滤波器的峰值旁瓣电平降到－21.47dB,比匹配滤波器改善7.49dB,当滤波器的长度增加时,LP滤波器可把峰值旁瓣抑制到更低电平。并介绍用声表面波(SAW)技术制作15位m序列相位编码信号(起始状态为1001)的LP滤波器,实验结果,其峰值旁瓣电平为－19dB,与理论值相差2.47dB。     

m序列相位编码信号的最小峰值旁瓣滤波器

m序列相位编码信号最小峰值旁瓣滤波器(LP滤波器)的冲激响应序列可以通过解线性规划问题求得。对于15位和31位全部m序列的计算结果表明,LP滤波器对峰值旁瓣有较大的抑制。对[4,3,0]反馈连接的起始状态为1001的15位码,它的长度为15的LP滤波器的峰值旁瓣电平降到—21.47dB,比用匹配滤波器改善7.49dB;对[5,3,2,1,0]反馈连接的起始状态为11101的31位码,它的长度为31的LP滤波器的峰值旁瓣电平降到—23.80dB,比用匹配滤波器改善6.01dB。当滤波器的长度增加时,LP滤波器可把峰值旁瓣抑制到更低电平。     

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.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

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.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

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.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

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.     

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.