基于扩频通信的跳频射频源的设计

介绍了一种可通过PC机或SCM将窄带信号源和能够实现跳频功能的频率、相位控制宇输入到直接数字频率合成器DDS芯片AD9851中，从而实现跳频射频源的设计。其中重点介绍了DDS在跳频扩频通信系统中的应用和整个实现电路控制系统的硬件结构和软件设计。     

双通道DDS任意相位相关信号源

在通信系统,信号的同步很重要,一旦信号不能严格的同步,轻则误码率升高,重则系统瘫痪.通信技术发展,单路信号源已经不能满足要求,有必要研究基于多片DDS产生任意相位差信号源.设计以凌阳单片机SPCE061A作为控制核心,精确控制两片AD9850/AD9851 DDS芯片产生两路任意相位差的输出,成功实现两片DDS芯片合成器正交相位同步,完成一种特殊信号源设计.     

更上一层楼——手工打造频率超过10MHz的DDS信号源

在本刊2009年第12期,笔者讲解了通过DOS产生正弦波的原理,并介绍了一款具体的制作．使用的DDS芯片是AD9833。这次我们使用另两款芯片AD9850和AD9851来做这个信号源,使信号频率轻松地突破了10MHz和AD9883芯片相比,它们的特点是：使用更高的参考时钟频率,最高可达125MHz（AD9850）和180MHz（AD9851）,从而能够得到更高频率的输出。     

DDS芯片AD9851及其在跳频通信系统中的应用

本文介绍了直接数字频率合成技术的发展及原理,重点分析了DDS芯片AD9851的原理及其在跳频系统中的应用.     

DDS器件AD9851在信号源中的应用

介绍美国AD(模拟器件)公司采用先进的DDS直接数字合成技术生产的高集成度产口-AD9851芯片。连同他在直接数字式频率合成信号源中的应用。     

应用AD9851实现正弦波信号源

直接数字合成（Direct Digital Synthesis，DDS）是一种重要的频率合成技术，具有分辨率高、频率变换快等优点。介绍了采用ADI公司DD6芯片AD9851实现正弦波信号源。该信号源能产生的频率为0～70MHz，可控步长为1Hz。控制中心采用Atmel AT89S52单片机完成对AD9851、zlg7289的控制。     

频率相位可调的信号源设计

提出了一种直接基于DDS芯片AD9851的信号源的设计方法.介绍了DDS模块的设计,并给出了DDS与FPGA接口电路、DDS信号互补输出电路、DDS七阶低通椭圆滤波电路、DDS信号缓冲放大电路、DDS晶振电路.通过FPGA控制DDS并直接向DDS发送频率控制字,产生常见的正弦波、方波,并实现了频率与相位可调.     

AD9851与AT89C51在信号源中的应用

本文介绍了美国模拟器件公司采用先进DDS直接数字频率合成技术生产的高集成度产品AD9851芯片的引脚功能、特性和工作原理，同时介绍了单片机芯片AT89C51的特性及这两个芯片在信号源中的应用。     

CPLD-EPM7064和AD9851在跳频信号源中的应用

给出了一种基于DDS技术的跳频信号源的设计方法。首先简要介绍了跳频扩频通信和直接数字频率合成技术的相关知识，然后介绍一种复杂的可编程逻辑器件CPLD-EPM7064和直接数字频率合成器芯片AD9851在跳频信号源设计中的应用。     

基于单片机的频率特性测试仪设计

本文介绍了基于DDS技术的频率特性测试仪的设计方法。在设计中扫频信号源采用DDS芯片AD9851实现,以单片机AT89C52为控制核心,控制整个系统协调工作并实时对所测数据进行处理,LCD显示幅频特性和相频特性曲线,实现了系统的小型化和全数字化。     

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.     

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.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

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