基于SDH地面链路传送的全网时间同步技术研究

电力系统全网时间同步系统是电力行业近年来重点发展和推广的关键技术,基于SDH网络的E1接入和传输时延误差修正需要接入外频率保障。文章结合电网时间同步示范工程及相关实验测试数据,分析SDH传输链路的时延、抖动和漂移,论证了频率同步对SDH链路传送时间同步的重要性,提出电力系统基于SDH的全网时间同步组网建议,解决电力通信时间同步规划组网,实现基准时间信号全网覆盖等目标。     

基于大气激光通信的高精度时间传送

提出了一种全新的时间信号的传送方法，即通过大气激光信道传送高精度时间信号。它可以用于解决中短距离范围内高精度时间同步的问题。相对于光纤、微波等其它方法，它具有较低的成本和较好的灵活性。     

利用SDH网络建立统一的同步网传送、分配平台

讨论了北京通信同步网的发展过程和现状，对现有PDH传送同步信号的方式与SDH传送同步信号的方式进行了比较、论述。提出了利用SDH设备的Retiming功能，在SDH传输系统上建立统一的同步网传送、分配平台的观点。     

基于OTN的光传输网络同步系统优化设计

由于传统的光传输网络同步系统,在进行光传输网络同步处理时所造成的通用以太网延迟时间长,因此同步能力差,无法实现光传输网络同步。为此,对基于OTN的光传输网络同步系统进行优化设计,通过选用型号APC1154854389OTN时钟传送设备,相较于传统时钟传送设备增加OTN交叉板,减少对通用以太网延迟时间的采集时间,从而优化硬件性能;将接收到的时间信号发送至骨干层;传送至BC边缘节点;通过OTN接入层对时间信号进行G. 798终端ITU-T建议;汇总至服务器。实验结果表明,所设计的同步系统光传输延迟时间在0.5 ms以下,远远低于实验对照系统,具有较高的同步性,可实现对光传输网络同步。     

TD－SCDMA基站基于传送网的时间同步方案

1引言 由于3G／LTE基站工作的切换、漫游等都需要精确的时间控制,不仅需要0．05ppm的时钟频率精度,而且还有±1．5μs的时间同步要求。现有传送网只提供频率同步功能,时钟同步网精度不能满足无线技术的要求,因此当前已部署的网络通常采用GPS解决时间同步。     

采用DWDM系统光监控波道传送同步定时信号的分析与实践

结合工程应用的实例，介绍了采用密集波分复用系统光监控波道传送同步信号的方法。     

PTN承载高精度时间同步协议技术研究

对于时分同步码分多址（TD-SCDMA）和时分长期演进（TD-LTE）无线系统,采用全球定位系统（GPS）提供时间同步具有施工难、成本高和不安全等弊端。利用同步协议通过光纤系统传输高精度时间同步信号将是主流技术。文章对采用分组传送网（PTN）承载IEEE1588v2提供时间同步的精度影响因素进行了分析,通过实验和试点测试初步验证了PTN承载1588v2提供高精度时间同步信号的可行性,并比较了PTN承载1588v2的不同模式。     

利用SDH系统传送同步链路剖析

首先介绍了SDH设备的定时功能原理．然后分析了利用SDH线型系统和环型系统传送同步链路的基本形式及发生故障时的定时状态变化。最后根据分析结果指出利用SDH系统传送同步链路要注意的事项     

用光纤传送6.4Tbit/s信号186km

日本电气公司成功进行了用光纤将 6 .4 Tbit/ s信号传送 186 km的实验。这是用一根光纤传送各自载着 4 0 Gbit/ s信号的 16 0个波长的实验 ,使每隔一个波长的偏振光反向 ,传送 186 km距离的误码率为十亿分之一。作为用于公用线路基干网的超高速光通信技术在一两年内将实用化用光纤传送6.4Tbit/s信号186km@车会生     

时间同步的业务需求和几种时间传送技术

主要介绍了各种电信业务对时间同步的要求及时间的几种传送技术。     

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.     

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.     

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