基于FPGA的直序扩频系统的同步设计

针对直序扩频系统中伪随机码同步捕获的问题,提出了一种扩频码捕获方法,来解决低信噪比条件下伪码序列的捕获问题。首先对直接序列扩频系统做了讨论,而后重点研究了匹配滤波器法的原理及其功能,研究了利用数字匹配滤波器法对扩频码序列进行同步捕获,从而解决了在扩频系统中对伪码的快速捕获,并在Altera公司的Quartus Ⅱ软件平...     

m序列多环路分段捕获及状态预测捕获方案

提出了两种直接序列扩频通信系统中ｍ 序列的新的捕获方法,即多环路分段捕获及基于状态预测捕获法,并给出了各自的硬件实现原理框图及简明的性能分析,其中,“一当多”数字匹配滤波器使状态预测电路大大简化。     

扩频通信中伪随机序列的捕获

１伪随机序列捕获的方法伪随机序列捕获的方法可分为串行搜索法和并行判决法两种。１．１串行搜索法串行搜索捕获是在本地伪随机序列和接收伪随机序列不同步的情况下，调整本地序列相位，逐一进行试验，直到发现某本地序列相位和接收序列相位基本一致为止，如图1所示。假设扩频系数为M，每码片两个采样时，需要进行2M次试验,则每次试验费时为伪随机序列一个周期的时间，即一个符号的时间。也就是说，在其它参量已同步且检测到无错误时，最多需要2M个符号后，才能对伪随机序列实现捕获。串行搜索捕获是以输入数据中伪随机序列相位为参考，…     

匹配滤波器的多相实现

本文介绍了匹配滤波器在直接序列扩频通信系统的同步捕获中的应用，研究了数字匹配滤波器的实现方法，提出了基于多相分解的实现结构。与传统的直接实现形式和折叠滤波器等改进形式相比，多相形式具有占用资源少的优点。     

一种零中频直接序列扩频数字接收技术

直接序列扩频技术在现代无线通信系统中有着广泛的应用,该信号的数字接收是实现对其侦察截获的关键技术之一。本文介绍了直接序列扩频技术原理及其在cdma2000移动通信系统中的应用,提出一种针对cdma2000直接序列扩频信号的零中频数字接收算法,并详细给出了码捕获及跟踪算法、载波同步算法的数学模型推导。实验结果显示,该算法成功地实现了码同步及载波同步,有较好的解调效果。     

一种主动子序列搜索的跳频同步捕获方法研究

传统的跳频同步捕获方法中,串行捕获方法捕获时间较长,并行捕获方法系统复杂度高,而使用同步引导码又容易受到干扰.为了解决这些问题,学界提出了一种基于子序列搜索,以跳频序列本身来表征时间信息的捕获策略.该策略的一种实现是基于序列部分频点匹配的同步捕获方案,使用类似并行捕获方法的系统结构,通过多支路检波的方法,得到跳频序列的...     

扩频码捕获及其FPGA实现

介绍了直接序列扩频通信中m序列的构造及其滑动相关同步捕获方法,并对其同步时间和抗噪声性能进行了理论分析和实验比较。结果表明,滑动相关法在直接序列扩频码同步捕获中具有优越的抗噪性能。文章同时给出了MATLAB的抗噪声估计及其滑动相关法的FPGA实现方法。     

一种数字化直接序列扩频信号接收技术

直接序列扩频技术无论在军事通信还是民用通信都有广泛的应用。介绍了一种基于FPGA大规模可编程芯片的数字直接序列扩频接收技术,着重介绍了该数字接收机模型、PN码捕获及PN码同步技术,并且给出了该数字接收机的实际测量结果。     

数字匹配滤波与自适应门限检测技术在扩频中的应用

文中给出了数字匹配滤波技术和自适应门限检测技术的基本原理,并对其性能进行了分析。运用数字匹配 滤波结合自适应门限检测技术进行直接序列扩频伪码(周期为N)捕获,可以缩小捕获时间,增大捕获的动态范围和提高扩频 系统在快速变化信道中的误码性能,尤适于突发扩频通信。     

基于局部序列匹配的跳频自同步法性能分析

局部序列匹配自同步法是一种新的跳频自同步方案。在跳频工作状态,接收机使用很少的支路接收具有某种特征的发送序列,将此序列与本地序列匹配,确定接收端与发射端的跳频序列相位差,调整相位完成同步捕获。文中给出了局部序列自同步法的原理描述和设计方案,并在高斯白噪声环境下进行了性能分析。分析结果表明,该方案不需要同步引导码和勤务频率,具有较强的抗侦察能力和抗干扰能力。     

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.     

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.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks     

Call for Papers—Feature Topic,Vol.12,No.7,2015

正Information Centric Networking Information-Centric Networking(ICN) is an emerging direction in Future Internet architecture research,gaining significant tractions among academia and industry.Aiming to replace the conventional host-to-host communication model by a data-centric model,ICN treats data content as the first