Digitized RF transmission over fiber

With rapid growth in demand for broadband wireless and wired connectivity, a unified communication backbone network that seamlessly integrates the backhaul network of wireless broadband access networks with existing optical access network infrastructure can offer significant benefits to network operators through consolidation of network infrastructure. Direct transmission of microwave signals at radio frequencies over optical fiber (radio-over-fiber) has long been considered as a method for simplifying base-station architecture in antenna remoting applications where antenna base stations are located far away from a central processing unit [1], [2]. In such applications, multiple antenna base stations are normally connected via a backhaul or feeder network to a central office that performs key network functions such as switching and routing.     

High-capacity transmission over polymer optical fiber

Polymer optical fiber (POF) is a promising transmission medium to provide broad-band telecommunication services within the customer's premises. POF offers several attractive features for data transmission such as broad bandwidth and low cost for in-house, access, and local-area-network (LAN) applications. This paper presents a review on optical transmission systems using POF and their enabling technologies. A summary is given of experimental data links with record capacity over record transmission distances. To conclude, we discuss trends for further development and research     

507km超长站距无中继光传输系统

文章介绍了采用远泵掺铒光纤功率放大技术、远泵掺铒光纤前置放大技术、拉曼噪声抑制技术和前向误码纠错等技术,工程上常用的G.652光纤所构成的速率为2.5 Gbit/s、站距为507 km的超长站距无中继光纤通信系统.     

Investigation of the optimum alternate-phase RZ modulation format and its effectiveness in the suppression of intrachannel nonlinear distortion in 40-Gbit/s transmission over standard single-mode fiber

The results of a detailed study of the performance of 40-Gbit/s optical transmission over standard single-mode fiber with alternate-phase return-to-zero (AP-RZ) modulation formats are presented. While in the highly dispersed propagation regime, the use of RZ format signals with alternate phase between adjacent pulses can lead to a significant reduction in nonlinear interaction between pulses, allowing increased launch powers and, hence, increased transmission distances, this has not been systematically investigated. In this paper, we investigate the use of AP-RZ formats, both numerically and experimentally, to explain and quantify the effects of varying the peak-to-peak phase modulation, the amount of precompensation at the transmitter and the presence of multiplexer prefiltering for the case of wavelength-division multiplexing systems with high spectral efficiency. It is shown that, while the use of pulses with alternate /spl pi//2 rad phase shifts minimizes the build-up of shadow pulses in the zero bit slots due to intrachannel four-wave mixing, the best overall performance is obtained with /spl pi/ rad peak-to-peak phase modulation. We show experimentally, for the first time, that the optimum value of precompensation to minimize intrachannel nonlinear distortion is dependent on the signal format used.     

利用光纤传递高精度时间的研究

介绍了光纤网络中一种基于双向脉冲算法的时间传递技术,设计了原型设备并对其进行了性能测试;同时对于光纤传递高精度时间的优势和国内外对该领域的研究进行了描述.系统设计原理;在一个测量周期内,主端将测量的高精度时间秒脉冲信号装入STM-N光接口芯片的F1开销字节中,由接口芯片向从端发送数据,并接收从端发送的时间秒脉冲数据;同...     

超长站距光传输技术及其在电力系统的应用

超长站距光传输技术在电力系统具有广阔的应用前景。文章首先简单介绍了超长站距光传输的主要技术,重点探讨电力系统采用喇曼、遥泵放大器等进行组合应用的系统方案,并总结了工程实践中的经验与应用建议,同时介绍了电力系统测试研究和实际应用情况,对系统方案进行了验证,最后对未来技术发展进行了展望。     

High speed transmission system directional protection using anElman network

Detection of the direction of a fault on a transmission line is essential to the proper performance of a power system. It would be desirable to develop a high speed and accurate approach to determine the fault direction for different power system conditions. To classify forward and backward faults on a given line, a neural network's abilities in pattern recognition and classification could be considered as a solution. To demonstrate the applicability of this solution, neural network technique is employed and a novel Elman recurrent network is designed and trained. Details of the design procedure and the results of performance studies with the proposed network are given and analysed in the paper. System simulation studies show that the proposed approach is able to detect the direction of a fault on a transmission line rapidly and correctly. It is suitable to realize a very fast transmission line directional comparison protection scheme     

Diffusion simulation-based fiber tracking using time-of-arrival maps: a comparison with standard methods

Object

We propose a new tracking method based on time-of-arrival (TOA) maps derived from simulated diffusion processes.

Materials and methods

The proposed diffusion simulation-based tracking consists of three steps that are successively evaluated on small overlapping sub-regions in a diffusion tensor field. First, the diffusion process is simulated for several time steps. Second, a TOA map is created to store simulation results for the individual time steps that are required for the tract reconstruction. Third, the fiber pathway is reconstructed on the TOA map and concatenated between neighboring sub-regions. This new approach is compared with probabilistic and streamline tracking. All methods are applied to synthetic phantom data for an easier evaluation of their fiber reconstruction quality.

Results

The comparison of the tracking results did show severe problems for the streamline approach in the reconstruction of crossing fibers, for example. The probabilistic method was able to resolve the crossing, but could not handle strong curvature. The new diffusion simulation-based tracking could reconstruct all problematic fiber constellations.

Conclusion

The proposed diffusion simulation-based tracking method used the whole tensor information of a neighborhood of voxels and is, therefore, able to handle problematic tracking situations better than established methods.     

光纤差动保护及通道传输信号应注意的问题

简述了光纤差动保护的基本原理,并结合工程实例,介绍了差动保护光纤通道测试方法,提出光纤差动保护的检修及维护应特别注意的问题,最后分析了光纤通道传输保护信号时常见故障及其现场异常处理.     

OPPC和OPGW的光纤传输保护

探讨了OPPC和OPGW光缆中氢气对光纤传输性能的影响。使用吸氢填充膏可以防止氢气导致光纤传输损耗增加,对光缆起到长期保护作用。     

光纤复合架空地线国家标准与国际标准的差异

将要发布的国家标准《光缆第4部分：分规范光纤复合架空地线》与它采用的国际标准在技术要求，检验规则等施工方面都有较大的差异，论文详细介绍了这些差异，并说明了原因。     

Development of fault point locating system for underground transmission lines using optical fiber current sensors

Fault point locating systems based on surge current detection have recently been used for fast recovery of underground transmission lines from faults. Electromagnetic induction type sensors have mainly been used for the detection of surge current. However, they are susceptible to electromagnetic noise which causes unstable system operation. To solve this problem, Tokyo Electric Power Co., Toko Electric Corporation, and Fujikura Ltd. jointly developed a new system using optical fiber current sensors. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(1): 21–28, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.20981     

高速高动态数字光纤传输系统设计

在高动态条件下,高速串行数字信号的处理和传输,传统解决方案存在易失步、误码率高等方面的缺陷。近年来常用的并行同步解决方案也只是解决了整个传输系统的局部问题。本文结合新型高速光纤传输系统的研制,从物理层、链路层、数据层的角度出发,提出了数字化高速时钟恢复、并行比特同步、并行容错帧同步的组合设计方案,有效地减少了同步时间,提高了光纤系统数据传输效率,并成功应用于特种设备领域,取得了很好的效益。     

Multichannel soliton transmission and pulse shepherding inbit-parallel-wavelength optical fiber links

We study basic principles of the bit-parallel-wavelength (BPW) pulse transmission in multichannel single-mode optical fiber links for high-performance computer networks. We develop a theory of the pulse shepherding effect that allows simultaneous propagation of pulses in parallel bit slots by binding them into a multicomponent BPW soliton. We describe families of the BPW solitons and bifurcation cascades in a system of N incoherently coupled nonlinear Schrodinger equations that model the multichannel multiwavelength transmission in a single-mode optical fiber. We demonstrate high robustness of the composite BPW solitons, due to their underlying linear stability, to a moderate pulse walkoff     

继电保护光纤通信接口技术及标准

C37.94标准由IEEE于2002年制定,该标准规范了远方保护设备和数字复用设备之间的光纤通信接口的帧结构、时钟定时等内容。文章首先描述了继电保护线路纵差保护系统的结构,分析了光纤保护的应用现状及其局限性,介绍了IEEE C37.94标准的主要内容和意义,最后以一个典型案例说明了该标准的实际应用。     

公路外场监控数据传输与对象规范研究

随着智能交通系统(ITS)的发展,ITS通信网中出现了数据源与数据的多样性等诸多因素,造成了监控中心与外场设备之间不能建立实时信息沟通.在研究了ITS的通信协议架构的基础上,改进了协议体系和编码规则,规范了可变情报板等外场设备的数据对象,统一了数据格式与通信规约,更好的实现了监控中心与外场设备之间数据交互的互操作性和可...     

多模式无线视频码流的传输与控制

采用快速传送协议/用户数据报协议/IP方式实现了多模式无线网络（WLAN、GPRS、CDMA）的码流传输,并完成无线通信下的RTCP双向控制信息链路.针对无线IP网络的传输特性,选取了适当的QoS参数反馈控制传输质量.实验测试表明,多模式无线通信系统下的码流传输在接收端取得了较好的视频传输质量.     

无线超宽带通信原理及其应用标准

自从2002年FCC发布UWB的商业规范以来,UWB以其具有的高速率、高频谱利用率、低成本、低功耗和应用范围广等一系列优点,受到了业界前所未有的关注。文章从宏观的角度介绍了UWB的发展历史和现状、技术特性、市场前景,讨论了两大标准(IEEE 802.15.3a和IEEE802.15.4a)中UWB的相关标准,讨论了UWB技术给我国带来的机遇与挑战。     

我国高压输变电设备绝缘配合标准的特点与分析——简析GB311.1《绝缘配合第1部分定义、原则和规则》标准修订

本文介绍了GB 311.1-1997修订的环境背景和技术条件背景以及该标准修订的详细过程,重点介绍了此次修订版本与97版以及所采用的IEC标准之间的主要差异,并详细介绍了此次修订的主要技术内容.     

关于并联电抗器总烃超标的分析处理

对七台河发电有限公司1号并联电抗器故障原因进行了综合分析,并提出相应的处理方法,消除了电抗器的隐患,保障设备安全运行.