PCM系统帧同步

本文提出了采用脉冲塞入(速率调整)的PCM复接系统帧同步的一种新方法。在提出这种技术时,考虑了为现在的CCITT系统的兼容性。在平均保持时间,失步检测的平均时间和平均同步恢复时间等方面对所提出的方法和CCITT所建议的系统进行了比较。结果表明,所提出的方法是有意义的,其总的同步时间好而又不牺牲它的保持时间能力。     

基于FPGA的光纤通信系统中帧同步头检测设计

为实现设备中存在的低速数据光纤通信的同步复接／分接,提出一种基于FPGA的帧同步头信号提取检测方案,其中帧头由7位巴克码1110010组成,在数据的接收端首先从复接数据中提取时钟信号,进而检测帧同步信号,为数字分接提供起始信号,以实现数据的同步分接。买验表明,此方案成功地在光纤通信系统的接收端检测到帧同步信号,从而实现了数据的正确分接。     

正码速调整复接误码测量

一、引言由于复接信道存在误码,将使得各支路码流在复接过程中产生附加的误码,称复接误码。它可以分成两种,其一是由于信道误码引起高次群同步分离失帧,在此期间给支路码流造成的误码称失帧误码。这种失帧误码在普通同步复接器中也同样存在。另一种是由于信道误码引起支路塞入指示错误给支路码流引入的误码,称塞入误码。达种塞入误码是采用码速     

光电合架数字光纤通信端机及帧同步方式

本文讨论了异步系列复接和同步系列复接光电合架端机构成及帧同步方式;叙述了实现系统同步的方法;研究计算了光电端机的帧同步时间;并进行了计算机模拟实验和560Mbit/s光端机应用检验。     

一种软件实现的多业务复分接器

复分接技术在数据通信中起着重要的作用。本文介绍一种用软件实现帧同步、复接、分接的技术,此方法实用,灵活,可靠。     

1986年南京邮电学院硕士研究生入学试题及题解

试题名称:数字通信原理 一、填充题:(每个空格1分,共30分) 1.以ZMb/,为基群的PCM系统中,其二次群、三次群、四次群的速率分别为 启.PCM为过载冲M为过载、 3.选择传输码型的主要条件是 _一,一,一0 4.POM传偷码型主要有:,,—6.再生中继器的主要功能是_,_,6.数字复接系统采用的码速调整技术主要有_7.数字复接系统中,PLL的主要特性是_, 8.帧同步码的插入方式有 捕捉帧同步码的主要方法为 如帧同步码为,位,则信码中出现假同步码的概率为_。由于信道误码(误码率为八)而出现假失步的概率为_。 9.数字调制主要有:,_,一一。 功.”级移位寄存器…     

数字通信中一种具有长保持时间的新型帧同步系统

本文讨论了数字通信中一种具有长保持时间的新型帧同步系统,并与传统帧同步系统进行了比较。结果表明,在两个系统结构参数——校核次数α及保护次数β相同条件下,新系统平均失帧时间与传统系统基本相同,而平均同步保持时间增大了许多个数量级,因而特别适合于变参信道或高误码率条件下工作。     

多速率码流同步复接方案设计与实现

采用正／0／负码速调整方法,设计了一种多速率码流同步复接的帧结构方案,并对其相关性能及复接／分接的实现方法进行了详细介绍。     

基于话带的数据语音复接软件研究

介绍了一种以DSP为核心的数据语音复接器的复接软件设计,重点阐述了信令系统的设计、帧结构和数据语音的复接/分接实现。     

光纤同步网讲座（二）：光同步复接体制

概述了光同步复接体制的发展，然后着重讨论光同步复接体制的数字系列、ＳＤＨ网络节接口、同步传递模块的复接与帧结构、异步数字系列信号的划入方法及开销与指针的概念，最后分析了光同步复接体制的优越性，指出光同步复接体制的确定为挖掘光纤通信的巨大潜力创造了必要条件。     

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.     

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.     

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