一种卷积与交织编码直扩系统的性能仿真

为了分析卷积纠错编码与不同的交织方式相结合时直扩系统的性能,设计了一种基于卷积与交织相结合的纠错编码直扩通信系统,并利用Matlab/Simulink仿真平台建立了系统仿真模型,仿真分析了在高斯白噪声信道条件下,随机交织、矩阵交织加通用块交织2种交织方式分别与卷积编码相结合时的直扩系统性能。仿真结果表明,在高斯白噪声信道中,与未编码的直扩系统相比,所设计的采用卷积与2种交织相结合的编码直扩系统均能在信噪比高于-1.35 dB时获得更好的系统性能。     

数字电视传输中的关键技术

纠错编码在实际应用中往往要结合数据交织技术。因为许多信道差错是突发的，即发生错误时，往往是有很强的相关性，甚至是连续一片数据都出了错。这时由于错误集中在一起，常常超出了纠错码的纠错能力。所以在发送端加上数据交织器，在接收端加上解交织器，使得信道的突发差错分散开来，把突发差错信道变成独立随机差错信道，这样可以充分发挥纠错编码的作用。交织器就是使数据顺序随机化，分为周期交织和伪随机交织两种。     

矩阵交织器的通用CPLD实现方法

交织编码在3G系统中已经大量使用，数据通过卷积编码后进行分组交织，在接收端完成反交织，将连续误码分散成非连续误码，从而使得误码在纠错允许的范围内得到纠正；CPLD(复杂可编程逻辑器件)具有方便的在线编程功能，可以用来实现交织编码；考虑到矩阵交织器的多样性而设计的通用矩阵交织器，只须通过修改一些参数值即可实现不同的交织器，大大节省了设计时间。     

数字视频广播卫星传送标准(DVB-S)中的卷积交织

卷积交织是卫星数字传送前向纠错编码中用来解决突发性干扰的有效手段。文章分析了用ＦＩＦＯ移位寄存器方式组成的卷积交织器的工作过程，数据构成形式及抗突发性干扰性能。     

数字视频广播卫星传送标准（DVB—S0中的卷积交织

卷积交织是卫星数字传送前向纠错编码中用来解决突发性干扰的有效手段。文章分析了用ＦＩＦＯ移位寄存器方式组成的卷积交织器的工作过程，数据构成形式及抗突发性干扰性能。     

数字卷积交织与排列置换

数字交织机和纠错编码结合是对付传输中突发错误的一种有效方法，本文在数字交织中引入数学中排列置换的概念，基于这个观点，提出了一种新的卷积交织器结构，它类似于程控交换机中的时分接线器，该方法比ＡＤＨＤ ＴＶＧＡ中提出的实现方法简便，效果相同。     

卷积交织器和解交织器的VHDL设计和FPGA实现

介绍了信道编码中所采用的前向纠错编码(FEC)方案中的重要技术——卷积交织器和解交织器的原理，并在此基础上提出了一种VHDL设计和FPGA实现方案，给出了具体的实现方法，该方法具有实现简单和占用资源少的优点。     

前向纠错技术中卷积交织器的FPGA实现

介绍了信道编码中所采用的前向纠错编码（FEC）方案中的重要技术——卷积交织器和解交织器的原理,并在此基础上提出了基于FPGA的卷积交织器的设计方案。丈中对卷积交织器设计的关键部分,即读写地址的产生方法进行了详细分析,给出了一种新的地址计算方法,并通过对FPGA内部EAB资源的双口RAM的存储单元的读写操作的合理控制,实现了卷积交织。该设计具有实现简单、占硬件资源少等优点。     

针对串行MPEG-2传输流的卷积交织

在对数字电视DVB标准的MPEG-2传输流采用差错控制技术时是以字节为单位并行处理的。研制开发的某QPSK调制解调数字通信系统只能输入输出串行数字信号，当用其传输使用DVB SSI或PDH接口加有RS前向纠错编码的串行MPEG-2传输流时可以参考DVB标准设计串行卷积交织与解交织器，整个设计在FPGA中具体实现。经实验验证，使用设计的卷积交织与解交织器与未使用相比QPSK数字通信系统性能明显提高。     

交织编码在TETRA数字集群系统语音业务信道中的性能研究

本文详细地研究了交织编码在数字集群系统语音业务信道中的应用，结合CRC和RCPC编码以及ACELP语音编码，讨论了交织编码对于不同QoS语音数据的纠错性能影响，通过计算机仿真给出了在不同条件下有交织与无交织编码的系统纠错性能曲线，为数字集九系统的实际应用提供了重要的理论依据。     

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.     

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.