5490km Ultra Long Haul WDM System

1IntroductionSinceexperimentof160opticalchannelstransmit-tedinasinglefiberwasfulfilledbyLucentin2000,anewtechnologycompetitionhasbeenraisedamongopti-caltelecommunicationequipmentproducers.Uptonow,equipmentssupportingmorethanonehundredopticalchannelsinasin…     

Design of BLDCM Driving and Control System for Motorized Treadmill

To satisfy the requirement of developing a new generation of motorized treadmill for a famous domestic manufacturer, a brushless DC motor （BLDCM） driving and control system for motorized treadmill is developed. High integration and reliability of this system are ensured under the condition that intelligent power module （IPM） is used and the protection module is included. Periodic current control method is applied to reduce the average current flowing through the armature winding of the motor when the treadmill is required to start with low speed while large load is added. Piecewise proportion-integration-differentiation （PID） control algorithm is applied to solve the problem of speed fluctuation when impulse load is added. The motorized treadmill of a new generation with the driving and control system has the advantages of high reliability, good speed stability, wide timing scope, low cost, and long life-span. And it is very promising for practical applications.     

Research and Design of Monolithic Decision Circuit for Optical Communication System

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The Effect of System and Amplifier Parameters on the Performance of Average Soliton Transmission System Using PSA as In-Line Amplifier

In this paper,the effect of system and amplifier parameters on the performance of soliton transmission systemusing Phase Sensitive Amplifier(PSA)as in-line amplifier has been researched theoretically by computer simulation.Since in PSA soliton system the performance of average soliton regime is much better than that of dynamic soliton regime,in our simulation we only considered average soliton regime.Our simulation results show that although using PSA as in-line amplifiers in soliton system can not only overcome Gordon-Haus restriction but also suppress solitons interaction,lengthen soliton stable transmission distance significantly,the system and amplifier parameters have to be chosen carefullyin order to get a better system perorformance.     

Design of Photoelectric Detection Circuit in Linear Measuring System

The tructure,equivalent circuit,noise souces of silicon photodiode are analyzed.In order to improve the measuring linearity,we must choose the silicon photodiode with a large Rd,small Rs and I0 and under an operation state of output short-circuit.We must let the operation amplifier work in the current-voltage transfer form.Also we analyzed the effects of the input noise voltage,the input noise current,the input offset voltage,the input offset current of the operation amplifier and the noises of the silicon photodiode on the combined circuit of the operation amplifier with the silicon photodiode.Considering these factors,we can design the detective circuit with high response,sensitivity,stability,linearity and SNR.     

Design of 95 GHz, 2 MW Gyrotron for Communication and Security Applications

The design and the numerical simulation of the 95 GHz, 2 MW gyrotron for various kinds of communication, sensing and security applications is presented. The gyrotron is designed for the TE_24,8 operating mode. Various in-house developed and commercially available computer codes are used for the design purpose. A 4.25 MW electron gun is designed for the 2 MW of output power. The mode selection, cold cavity and the beam–wave interaction analysis are discussed for the design of weakly tapered open resonator type of interaction cavity. The parametric analysis of the interaction cavity and the electron gun is also presented.     

Optimal Higher-order Dispersion Management Methods in WDM Transmission Systems

In order to reduce the four-wave mixing crosstalk and avoid the signal waveform distortion in long-haul dense-wavelength division multiplexing systems, helpful methods on how to choose suitable local parameters in higher-order dispersion managed line are presented, which are used to increase the system capacity and improve the system performances.     

A Study of Social System Design and Social System Problems in the Course of Reform

lintroductionAccordingtotheprinciplesofsystemscience,havingpurposesisthecommonnaturetoanysystemsll].Infact,thefunctionsofsystemshaveneverbeenseparatedfromtheirpurposes,andthebehaviorofthesystemsistheprocesstoachievetheirpurposesormoreclearlytheirobje...     

Discussion of Optimal Allocation of Resources Theory for Communication Enterprises

1　Introduction　Successorfailureinmarketcompetitionsome timesdoesn tdependonhowmanyresourcesyouhave ,buthowwellyouallocatethem .Itisanim manentrequirementofmarketeconomyforcommu nicationenterprisestooptimallyallocatetheirre sources .Wellthen ,howtogettheoptimalresourcesallocation ?Abriefanalysisforthequestionisgivenasfollows.　Themanagementofcommunicationenterpriseshasthecharacterofnaturalmonopoly ,sothecom petitionconditionisincompletecompetition .Thekeyofoptimalallocationofresourcesistores…     

Fault-Tolerant Communication Network System for the Super Stored Program Control Exchange

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2.5GHz光孤子传输

利用半导体光孤子源和掺铒光纤放大器成功地实现了２．５ＧＨｚ光孤子２１ｋｍ传输，并利用简化的半导体光孤子传输系统理论模型对实验系统进行了数值模拟计算，计算结果与实验结果基本一致。     

光孤子传输和误码测量的实验系统

进行了孤子通信的误码测量,成功地将2．5Gbit／s的孤子传输了52km,通过了2h的测量无误码。对实验中的关键技术——超短光脉冲产生、高速外调制器、电信号和光信号的放大、光孤子脉冲序列与调制信号的同步以及正负色散位移光纤搭配技术进行了介绍和分析,对实验中的现象进行了理论分析。     

光孤子通信技术及其展望

光孤子通信是一种新颖的非线性全光长距离通信,是新一代高速长距离通信的优选方案。它利用强脉冲在光纤传输中产生非线性压缩效应补偿脉冲的色散展宽效应,实现高速孤子脉冲稳定地传输。文章介绍了光孤子通信的特点、基本组成,叙述了光孤子通信的几种传输方式,分析了光孤子通信技术的优势：高容量、长距离、抗噪声干扰、低误码率。文章最后介绍了国内外光孤子通信的现状和技术发展前景。     

光孤子通信系统的仿真

光孤子通信技术充分利用了光纤中色散参数和非线性效应的相互作用,可以使光脉冲在光纤中无畸变的进行传输,不受外界条件的影响,从而可以实现脉冲的超长距离传输。利用OptiSystem提供的强大的工具箱,模拟了光孤子通信系统的模型。并在给定的参数下,实现了系统的仿真,证实了仿真模型的可行性和正确性,为将来在此基础上实现改进的光孤子通信系统提供了有力的实验依据。     

光纤非线性效应中孤子传输稳定性的分析

要抑制Gordon-Haus效应引起的光孤子脉冲到达时间的抖动,在光通信系统中插入窄带滤波器,以补偿窄带滤波器的损耗,其额外的线性增益会放大与孤子链同时存在的线性波,导致背景的不稳定。如果光的强度足够强,光纤中会产生非线性增益,利用这种效应,不需要补偿窄带滤波器的损耗,而使孤子实现稳定传输。从理论上研究了光纤具有非线性增益情形下,孤子稳定传输的条件。     

三阶孤子在EDFA中的传输特性

对三阶孤子传输特性进行了数值研究,研究表明:三阶孤子在无增益光纤中传输时,脉冲会发生分裂、重合的周期性变化;在EDFA中传输时会有一次分裂和重合发生,之后分裂的两脉冲将不再重合,且产生新的子脉冲,子脉冲将会继续分裂、重合的传输下去;在三阶色散的影响下,孤子脉冲也会有一次分裂和重合,之后左边延迟脉冲会发生分裂,并产生小子脉冲;当对三阶孤子引入初始啁啾后,三阶色散引起的小子脉冲将不会产生。     

光孤子通信原理及发展前景

介绍了光孤子的产生、光孤子通信的基本原理及其关键技术,展望了光孤子通信的前景.     

非线性光孤子通信技术研究

非线性光孤子通信是一种全新的、大容量、超长距离通信技术，它是线性光纤通信技术的发展，是21世纪最有发展前景的通信方式。本文系统介绍非线性光孤子通信的基本原理、关键技术、研究现状和发展前景。     

光孤子通信及其展望

利用光孤子(solito)n传输信息的新一代光纤通信系统能真正做到全光通信,无须光电转换,可在超长距离、超大容量传输中大显身手,是光通信技术上的一场革命。文章介绍了光孤子通信的基本原理、光孤子的产生、光孤子通信系统的基本结构及其关键技术,描述了近几年光孤子研究取得的进展和传输试验情况,最后展望了光孤子通信的前景,它是21世纪最有发展前途的通信方式。     

光孤子误码测量的实验系统

在国内最先进行了孤子通信的误码测量,成功的将２．５Ｇｂ／ｓ的孤子传输了５２ｋｍ,经过连续２小时测量无误码。