Data and Computer Communications
LK英文翻译
郑州轻工业学院本科毕业设计（论文）——英文翻译题目差错控制编码解决加性噪声的仿真学生姓名专业班级通信工程05-2 学号 12院（系）计算机与通信工程学院指导教师完成时间 2009年4月26日英文原文:Data communicationsGildas Avoine and Philippe OechslinEPFL, Lausanne, Switzerlandfgildas.avoine, philippe.oechsling@ep.chAbstractData communications are communications and computer technology resulting from the combination of a new means of communication. To transfer information between the two places must have transmission channel, according to the different transmission media, there is wired data communications and wireless data communications division. But they are through the transmission channel data link terminals and computers, different locations of implementation of the data terminal software and hardware and the sharing of information resources.1 The development of data communicationsThe first phase: the main language, through the human, horsepower, war and other means of transmission of original information.Phase II: Letter Post. (An increase means the dissemination of information)The third stage: printing. (Expand the scope of information dissemination)Phase IV: telegraph, telephone, radio. (Electric to enter the time)Fifth stage: the information age, with the exception of language information, there are data, images, text and so on.1.1 The history of modern data communicationsCommunication as a Telecommunications are from the 19th century, the beginning Year 30. Faraday discovered electromagnetic induction in 1831. Morse invented telegraph in 1837. Maxwell's electromagnetic theory in 1833. Bell invented the telephone in 1876. Marconi invented radio in 1895. Telecom has opened up in the new era. Tube invented in 1906 in order to simulate the development of communications.Sampling theorem of Nyquist criteria In 1928. Shannong theorem in 1948. The invention of the 20th century, thesemiconductor 50, thereby the development of digital communications. During the 20th century, the invention of integrated circuits 60. Made during the 20th century, 40 the concept of geostationary satellites, but can not be achieved. During the 20th century, space technology 50. Implementation in 1963 first synchronized satellite communications. The invention of the 20th century, 60 laser, intended to be used for communications, was not successful. 70 The invention of the 20th century, optical fiber, optical fiber communications can be developed.1.2 Key figuresBell (1847-1922), English, job in London in 1868. In 1871 to work in Boston. In 1873, he was appointed professor at Boston University. In 1875, invented many Telegram Rd. In 1876, invented the telephone. Lot of patents have been life. Yes, a deaf wife.Marconi (1874-1937), Italian people, in 1894, the pilot at his father's estate. 1896, to London. In 1897, the company set up the radio reported. In 1899, the first time the British and French wireless communications. 1916, implementation of short-wave radio communications. 1929, set up a global wireless communications network. Kim won the Nobel Prize. Took part in the Fascist Party.1.3 Classification of Communication SystemsAccording to type of information: Telephone communication system, Cable television system ,Data communication systems.Modulation by sub: Baseband transmission,Modulation transfer.Characteristics of transmission signals in accordance with sub: Analog Communication System ,Digital communication system.Transmission means of communication system: Cable Communications,Twisted pair, coaxial cable and so on.And long-distance telephone communication. Modulation: SSB / FDM. Based on the PCM time division multiple coaxial digital base-band transmission technology. Will gradually replace the coaxial fiber.Microwave relay communications:Comparison of coaxial and easy to set up, low investment, short-cycle. Analog phone microwave communications mainly SSB / FM /FDM modulation, communication capacity of 6,000 road / Channel. Digital microwave using BPSK, QPSK and QAM modulation techniques. The use of 64QAM, 256QAM such as multi-level modulation technique enhance the capacity of microwave communications can be transmitted at 40M Channel 1920 ~ 7680 Telephone Rd PCM figure.Optical Fiber Communication: Optical fiber communication is the use of lasers in optical fiber transmission characteristics of long-distance with a large communication capacity, communication, long distance and strong anti-interference characteristics. Currently used for local, long distance, trunk transmission, and progressive development of fiber-optic communications network users. At present, based on the long-wave lasers and single-mode optical fiber, each fiber road approach more than 10,000 calls, optical fiber communication itself is very strong force. Over the past decades, optical fiber communication technology develops very quickly, and there is a variety of applications, access devices, photoelectric conversion equipment, transmission equipment, switching equipment, network equipment and so on. Fiber-optic communications equipment has photoelectric conversion module and digital signal processing unit is composed of two parts.Satellite communications: Distance communications, transmission capacity, coverage, and not subject to geographical constraints and high reliability. At present, the use of sophisticated techniques Analog modulation, frequency division multiplexing and frequency division multiple access. Digital satellite communication using digital modulation, time division multiple road in time division multiple access.Mobile Communications: GSM, CDMA. Number of key technologies for mobile communications: modulation techniques, error correction coding and digital voice encoding. Data Communication Systems.1.4 Five basic types of data communication system:（1）Off-line data transmission is simply the use of a telephone or similar link to transmit data without involving a computer system.The equipment used at both ends of such a link is not part of a computer, or at least does not immediately make the data available for computer process, that is, the data when sent and / or received are 'off-line'.This type of data communication is relatively cheap and simple.（2）Remote batch is the term used for the way in which data communication technology is used geographically to separate the input and / or output of data from the computer on which they are processed in batch mode.（3）On-line data collection is the method of using communications technology to provide input data to a computer as such input arises-the data are then stored in the computer (say on a magnetic disk) and processed either at predetermined intervals or as required.（4）Enquiry-response systems provide, as the term suggests, the facility for a user to extract information from a computer.The enquiry facility is passive, that is, does not modify the information stored.The interrogation may be simple, for example, 'RETRIEVE THE RECORD FOR EMPLOYEE NUMBER 1234 'or complex.Such systems may use terminals producing hard copy and / or visual displays.（5）Real-time systems are those in which information is made available to and processed by a computer system in a dynamic manner so that either the computer may cause action to be taken to influence events as they occur (for example as in a process control application) or human operators may be influenced by the accurate and up-to-date information stored in the computer, for example as in reservation systems.2 Signal spectrum with bandwidthElectromagnetic data signals are encoded, the signal to be included in the data transmission. Signal in time for the general argument to show the message (or data) as a parameter (amplitude, frequency or phase) as the dependent variable. Signal of their value since the time variables are or not continuous, can be divided into continuous signals and discrete signals; according to whether the values of the dependent variable continuous, can be divided into analog signals and digital Signal.Signals with time-domain and frequency domain performance of the two most basic forms and features. Time-domain signal over time to reflect changing circumstances. Frequency domain characteristics of signals not only contain the same information domain, and the spectrum of signal analysis, can also be a clear understanding of the distribution ofthe signal spectrum and share the bandwidth. In order to receive the signal transmission and receiving equipment on the request channel, Only know the time-domain characteristics of the signal is not enough, it is also necessary to know the distribution of the signal spectrum. Time-domain characteristics of signals to show the letter .It’s changes over time. Because most of the signal energy is concentrated in a relatively narrow band, so most of our energy focused on the signal that Paragraph referred to as the effective band Bandwidth, or bandwidth. Have any signal bandwidth. In general, the greater the bandwidth of the signal using this signal to send data Rate on the higher bandwidth requirements of transmission medium greater. We will introduce the following simple common signal and bandwidth of the spectrum.More or less the voice signal spectrum at 20 Hz ~ 2000 kHz range (below 20 Hz infrasound signals for higher than 2000 KHz. For the ultrasonic signal), but with a much narrower bandwidth of the voice can produce an acceptable return, and the standard voice-frequency signal gnal 0 ~ 4 MHz, so the bandwidth of 4 MHz.As a special example of the monostable pulse infinite bandwidth. As for the binary signal, the bandwidth depends on the generalThe exact shape of the signal waveform, as well as the order of 0,1. The greater the bandwidth of the signal, it more faithfully express the number of sequences.3 The cut-off frequency channel with bandwidthAccording to Fourier series we know that if a signal for all frequency components can be completely the same through the transmission channel to the receiving end, then at the receiving frequency components of these formed by stacking up the signal and send the signal side are exactly the same, That is fully recovered from the receiving end of the send-side signals. But on the real world, there is no channel to no wear and tear through all the Frequency components. If all the Fourier components are equivalent attenuation, then the signal reception while Receive termination at an amplitude up Attenuation, but the distortion did not happen. However, all the transmission channel and equipment for different frequency components of the degree of attenuation is differentSome frequency components almost no attenuation, and attenuation of some frequency components by anumber, that is to say, channel also has a certain amount of vibrationIncrease the frequency characteristics, resulting in output signal distortion. Usually are frequency of 0 Hz to fc-wide channel at Chuan harmonic lost during the attenuation does not occur (or are a very small attenuation constant), whereas in the fc frequency harmonics at all above the transmission cross Decay process a lot, we put the signal in the transmission channel of the amplitude attenuation of a component to the original 0.707(that is, the output signal Reduce by half the power) when the frequency of the corresponding channel known as the cut-off frequency (cut - off frequency).Cut-off frequency transmission medium reflects the inherent physical properties. Other cases, it is because people interested in Line filter is installed to limit the bandwidth used by each user. In some cases, because of the add channel Two-pass filter, which corresponds to two-channel cut-off frequency f1 and f2, they were called up under the cut-off frequency and the cut-off frequency.This difference between the two cut-off frequency f2-f1 is called the channel bandwidth. If the input signal bandwidth is less than the bandwidth of channel, then the entire input signal Frequency components can be adopted by the Department of channels, which the letter Road to be the output of the output waveform will be true yet. However, if the input signal bandwidth greater than the channel bandwidth, the signal of a Frequency components can not be more on the channel, so that the signal output will be sent with the sending end of the signal is somewhat different, that is produced Distortion. In order to ensure the accuracy of data transmission, we must limit the signal bandwidth.4 Data transfer rateChannel maximum data transfer rate Unit time to be able to transfer binary data transfer rate as the median. Improve data transfer rate means that the space occupied by each Reduce the time that the sequence of binary digital pulse will reduce the cycle time, of course, will also reduce the pulse width.The previous section we already know, even if the binary digital pulse signal through a limited bandwidth channel will also be the ideal generated wave Shape distortion, and when must the input signal bandwidth, the smaller channel bandwidth, output waveformdistortion will be greater. Another angle Degree that when a certain channel bandwidth, the greater the bandwidth of the input signal, the output signal the greater the distortion, so when the data transmissionRate to a certain degree (signal bandwidth increases to a certain extent), in the on-channel output signal from the receiver could not have been Distortion of the output signal sent to recover a number of sequences. That is to say, even for an ideal channel, the limited bandwidth limit System of channel data transfer rate.At early 1924, H. Nyquist (Nyquist) to recognize the basic limitations of this existence, and deduced that the noise-free Limited bandwidth channel maximum data transfer rate formula. In 1948, C. Shannon (Shannon) put into the work of Nyquist 1 Step-by-step expansion of the channel by the random noise interference. Here we do not add on to prove to those now seen as the result of a classic.Nyquist proved that any continuous signal f (t) through a noise-free bandwidth for channel B, its output signal as a Time bandwidth of B continuous signal g (t). If you want to output digital signal, it must be the rate of g (t) for interval Sample. 2B samples per second times faster than are meaningless, because the signal bandwidth B is higher than the high-frequency component other than a letter has been Road decay away. If g (t) by V of discrete levels, namely, the likely outcome of each sample for the V level of a discrete one, The biggest channel data rate Rm ax as follows:Rmax = 2Blog 2 V (bit / s)For example, a 3000 Hz noise bandwidth of the channel should not transmit rate of more than 6,000 bits / second binary digital signal.In front of us considered only the ideal noise-free channel. There is noise in the channel, the situation will rapidly deteriorate. Channel Thermal noise with signal power and noise power ratio to measure the signal power and noise power as the signal-to-noise ratio (S ignal - to -- Noise Ratio). If we express the signal power S, and N express the noise power, while signal to noise ratio should be expressed as S / N. However, people Usually do not use the absolute value of signal to noise ratio, but the use of 10 lo g1 0S / N to indicate the units are decibels (d B). For the S / N equal 10 Channel, said its signal to noise ratio for the 1 0 d B; the same token, if the channel S / N equal to one hundred, then the signal to noiseratio for the 2 0 d B; And so on. S hannon noise channel has about the maximum data rate of the conclusions are: The bandwidth for the BH z, signal to noise ratio for the S / N Channel, the maximum data rate Rm ax as follows:Rmax = Blog 2 (1 + S / N) (bits / second)For example, for a bandwidth of 3 kHz, signal to noise ratio of 30 dB for the channel, regardless of their use to quantify the number of levels, nor Fast sampling rate control, the data transfer rate can not be greater than 30,000 bits / second. S h a n n o n the conclusions are derived based on information theory Out for a very wide scope, in order to go beyond this conclusion, like you want to invent perpetual motion machine, as it is almost impossible.It is worth noting that, S hannon conclusions give only a theoretical limit, and in fact, we should be pretty near the limit Difficult.SUMMARYMessage signals are (or data) of a magnetic encoder, the signal contains the message to be transmitted. Signal according to the dependent variable Whether or not a row of values, can be classified into analog signals and digital signals, the corresponding communication can be divided into analog communication and digital communication.Fourier has proven: any signal (either analog or digital signal) are different types of harmonic frequencies Composed of any signal has a corresponding bandwidth. And any transmission channel signal attenuation signals will, therefore, Channel transmission of any signal at all, there is a data transfer rate limitations, and this is Chengkui N yquist (Nyquist) theorem and S hannon (Shannon) theorem tells us to conclusions.Transmission medium of computer networks and communication are the most basic part of it at the cost of the entire computer network in a very Large proportion. In order to improve the utilization of transmission medium, we can use multiplexing. Frequency division multiplexing technology has many Road multiplexing, wave division multiplexing and TDM three that they use on different occasions.Data exchange technologies such as circuit switching, packet switching and packetswitching three have their respective advantages and disadvantages. M odem are at Analog phone line for the computer's binary data transmission equipment. Modem AM modulation methods have, FM, phase modulation and quadrature amplitude modulation, and M odem also supports data compression and error control. The concept of data communications Data communication is based on "data" for business communications systems, data are pre-agreed with a good meaning of numbers, letters or symbols and their combinations.参考文献[1]C.Y.Huang and A.Polydoros,“Two small SNR classification rules for CPM,”inProc.IEEE Milcom,vol.3,San Diego,CA,USA,Oct.1992,pp.1236–1240.[2]“Envelope-based classification schemes for continuous-phase binary Frequency-shift-keyed modulations,”in Pr oc.IEEE Milcom,vol.3,Fort Monmouth,NJ,USA,Oct.1994,pp. 796–800.[3]A.E.El-Mahdy and N.M.Namazi,“Classification of multiple M-ary frequency-shift keying over a rayleigh fading channel,”IEEE m.,vol.50,no.6,pp.967–974,June 2002.[4]Consulative Committee for Space Data Systems(CCSDS),Radio Frequency and Modulation SDS,2001,no.401.[5]E.E.Azzouz and A.K.Nandi,“Procedure for automatic recognition of analogue and digital modulations,”IEE mun,vol.143,no.5,pp.259–266,Oct.1996.[6]A.Puengn im,T.Robert,N.Thomas,and J.Vidal,“Hidden Markov models for digital modulation classification in unknown ISI channels,”in Eusipco2007,Poznan,Poland, September 2007,pp.1882–1885.[7]E.Vassalo and M.Visintin,“Carrier phase synchronization for GMSK signals,”I nt.J.Satell. Commun.,vol.20,no.6,pp.391–415,Nov.2002.[8]J.G.Proakis,Digital Communications.Mc Graw Hill,2001.[9]L.Rabiner,“A tutorial on hidden Markov models and selected applications in speechrecognition,”Proc.IEEE,vol.77,no.2,pp.257–286,1989.英文译文：数据通信Gildas Avoine and Philippe OechslinEPFL, Lausanne, Switzerlandfgildas.avoine, philippe.oechsling@ep.ch摘要数据通信是通信技术和计算机技术相结合而产生的一种新的通信方式。
数据与计算机通信(英文) 教学大纲
数据与计算机通信(英文)一、课程说明课程编号：090326Z10课程名称：数据与计算机通信(英文)/Data and Computer Communications课程类别：专业教育课程学时/学分：32 / 2先修课程：高等数学、模拟电子技术、数字电子技术、信号与系统、通信原理适用专业：通信工程、电子信息工程教材、教学参考书：1.Behrouz A. Forouzan, Data Communications and Networking, 5th，McGraw-Hill, 20122.William Stallings. Data and Computer Communications, 9thEdition.Prentice Hall, 2010.3.Fred Halsall. Data Communications, Computer Networks and OpenSystems, 4th Edition. Addison-Wesley, 1996.4.David Salomon. Coding for Data and Computer Communications.Springer, 2005.5.Richard Stevens . Unix Network Programming - V olume 1 (2003) andV olume 2 (1999). Prentice Hall二、课程设置的目的意义《数据与计算机通信》课程是通信工程专业的一门选修的专业基础课。
课堂采用双语教学，使用经典的原版教材。
本课程的主要任务是从数据通信、计算机网络通信的视角来理解、分析、设计分布式的通信系统，使学生了解和掌握数据通信、计算机通信区别传统电信等语音业务承载网络的原理、技术等。
系统掌握数据通信所采用的技术，同时提高英语的阅读和理解能力。
三、课程的基本要求知识：理解数据通信的基本原理；熟练掌握数据通信、计算机通信所涉及的硬件、软件相关技术；理解计算机通信与传统电信等语音业务承载网络的区别；掌握原理计算机通信的原理；掌握科学研究的基本思路和方法，能力：掌握数据通信、计算机通信网的开发设计方法，将其用于解决实际的数据网络通信问题；熟练掌握网络编程的技能；针对数据通信新技术发展前沿问题，掌握英文科技文献综述的能力；在讨论中培养创新意识和国际前沿研究视野，培养追踪数据与计算机通信网的新技术前沿问题的能力，素质：建立原理－分析－综述-设计一体的观念，通过课程学习中的分析、讨论、辩论培养分析沟通交流素质，建立从原理分析到编程设计到实际应用的思维模式，提升发现问题、寻找解决问题方法的基本素质。
《数据通信与网络》课程教学大纲
《数据通信与网络》教学大纲一、课程地位与课程目标（一）课程地位本课程是互联网技术日新月异的新媒体和大数据时代的一门重要专业课。
目前该课程是电子信息类专业开设的双语选修课，该课程的学习，对于培养学生掌握计算机数据通信网的通信方法和关键技术、通信网协议体系结构，能够从事组网、网络通信软件设计和工程中数据通信网维护等相关工作、了解电子信息技术领域相关行业的国际状况和最新动态，为后续的毕业设计和从事网络通信方面的工作奠定必要的基础，是培养学生能够针对通信工程问题，开发、选择与使用恰当的通信技术、资源、现代工程工具和信息技术工具，包括对复杂工程问题的预测与模拟，并能够理解其局限性的重要途径，并帮助学生理解和评价针对通信工程问题的专业工程实践对环境、社会可持续发展的影响。
通过双语课程的学习，学生能够就通信领域的复杂工程问题与同行及社会公众进行有效沟通和交流，并具备一定的国际视野，能够在跨文化背景下进行沟通和交流；掌握文献检索、资料查询及运用多媒体技术获取信息和通信等领域相关信息的基本方法。
能够在多学科背景下的团队中承担个体、团队成员以及负责人的角色。
二、课程目标达成的途径与方法三、课程目标与相关毕业要求的对应关系四、课程主要内容与基本要求1、导读即课程简介通过导读部分理论学习和课外查阅网站资源向学习者展示出一张数据通信与网络的“总体图”，了解该课程教材提供的万维网网站资源以及与本课程内容相关的网站以及相关发布标准的组织，包括Network world，IETF，Vendors，IEEE Communications Society，ACM的通信特殊兴趣组，ITU-T，ISO、因特网协会等，以此帮助学生紧跟这一领域的发展，学习国外先进的技术和知识，探索未来通信技术前沿发展，通过了解通信及协议标准发布的相关国际组织，激励学生树立向世界看齐的信心，增强学生对国家自强发展的紧迫感和培养学生的爱国情怀。
方法：理论学习和自学。
数据与计算机通信dataandcomputercommunication课后习题答案
《数据与计算机通信》课后习题参考答案第2章的参考答案2.1答案：设发送消息的蓝军为A，另外一个蓝军为B。
再设步兵由一头到量外一头所用的时间为t，可以定义两军的通信协议如下：（1）A发送消息后2t时间内还灭有收到B的确认，则重发，直到收到确认。
（2）B收到消息后，立即发送去确认知道不再收到A的消息。
（3）若在中午之前t时刻，A还没有收到B的确认信息，或者B 在中午前的2t时间内还继续收到A发来的消息，则第二天进攻。
2．3答案：（1）预定（A）客人（Guest）向主人（Hosts）发出要Pizza的Request。
（B）主人接受请求，提起电话拨Pizza饼店，在电话中提出预定的种类和数量。
（C）Pizza店的外卖服务生(Order Clerk)填好订单，然后传送给Pizza Cook。
完成；（2）送货（A）Pizza Cook将做好的Pizza饼给服务生；（B）服务生在订单上签字后送给送货车司机，司机开车取送货，沿道路送往订货人的地点；（C）送货车司机到达后，拿出定单和主人交接；（D）主人将送来的Pizza饼再送给客人(Guest)答案A．(1)中国总理与英文翻译之间：(a)中国总理对自己的英文翻译说中文；(b)中国翻译将中文翻译成英文后给法国总理的英文翻译；(2)法国总理与英文翻译之间(a)法国总理的英文翻译接收中国总理的英文翻译给自己的英文翻译；(b)将英文翻译成法文，然后给法国总理，反之亦然。
B．这三者之间要实现一种类似于电信系统中三方通信之类的过程：(1)中国总理拿起电话，说中文给中文/德文翻译(2)德文翻译把中文翻译成德文，然后通过电话线传送给法国总理的德文/法文翻译(3)德文/法文翻译将接收到的德文翻译成法文(4)德文/法文翻译将翻译过来的法文给法国总理听2．7 答案a．在分段情况下，都需要包含N层数据首部的拷贝b．在组合的情况下，可以用一个N层的数据首部组合成单一的N－1层PDU。
第3章的参考答案3．1 答案a. 因为多点配置是共享的广播信道。
计算机通信与网络 课程资料 Computer Communications and Networking
CCN: Lecture Notes
Computer Comm. & Networking 13
Transport Layer
This layer ensures that data units are delivered error free, in sequence, with no losses or duplications.
Module 1
Computer Communications and Networking
Topic Covered
1. 7 layer model for computer communications 2. Network topologies 3. Network bearers 4. LANs and WANs 5. CSMA and token protocols 6. Networking protocol performance 7. Bridges and routing 8. Internet protocols 9. Network security
• Compatibility must be maintained
CCN: Lecture NotNetworking 3
How do we do all of this?
Consider a simple connection between computers
This layer also provides • Interaction management, i.e., full or half duplex • Synchronisation, i.e., inset synchronisation points and
Computer Networks(1)
翻译测试二
Each of the past three centuries has been dominated by a single technology. The 18th century was the era of the great mechanical systems accompanying the Industrial Revolution. The 19th century was the age of the steam engine. During the 20th century, the key technology was information gathering, processing, and distribution. Among other developments, we saw the installation of worldwide telephone networks, the invention of radio and television, the birth and unprecedented growth of the computer industry, and the launching of communication satellites.
1 Introduction
• • • • • • • • 1.1 Outline of computer networks 1.2 Network hardware 1.3 Network software 1.4 Reference models 1.5 Example networks 1.6 Example data communication services 1.7 Network standardization 1.8 Summary
军事方面英语词汇
军事方面英语词汇1 军事通信 military communications2 军事通信系统 military communications system3 无线电通信 radio communications4 超长波通信 super-long wave communications5 甚长波通信 very long wave communications6 长波通信 long-wave communications7 中波通信 medium wave communications8 短波通信 short-wave communications9 微波通信 microwave communications10 毫米波通信 millimeter wave communications11 无线电台通信 radio set communications12 无线电接力通信 radio relay communications13 散射通信 scatter communications14 卫星通信 satellite communications15 扩展频谱通信 spread spectrum communications16 移动通信 mobile communications17 无线电波通信 radio wave communications18 电离层 ionosphere19 有线电通信 wired communications20 被复线通信 field wire communications21 架空明线通信 open wire communications22 电缆通信 cable communications23 光通信 optical communications24 光纤通信 optical fiber communications25 运动通信 messenger service26 军邮 army postal service27 简易信号通信 simplified signal communications28 旗语通信 flag signal communications29 电话通信 telephone communications30 载波电话通信 carrier telephone communications31 电报通信 telegraphy communications32 载波电报通信 carrier telegraphy communications33 电码 code34 图像通信 image communications35 电视广播 videocast36 静态图像通信 still picture communications37 会议电视 video conferencing38 可视电话 video telephone39 交互型可视图文 videotex40 传真通信 facsimile communications41 数据通信 data communications42 计算机通信 computer communications43 数字通信 digital communications44 模拟通信 analog communications45 多路通信 multiplex communications46 无线电台网 radio communications works47 有线电通信网 telecommunications networks48 数据通信网 data communication networks49 计算机通信网 computer communication network50 综合业务数字网 integrated service digital networks51 军事通信装备 military communications equipment52 电话机 telephone set53 传真机 facsimile equipment54 超长波电台 super-long wave radio station55 甚长波电台 very long wave radio station56 长波电台 long wave radio station57 短波电台 short wave radio set58 超短波电台 ultra-short wave radio set59 调幅电台 amplitude modulation radio set60 单边带电台 single sideband radio set61 调频电台 frequency modulation radio set62 呼救电台 life-saving radio set63 跳频电台 frequency hopping radio set64 接力机 radio relay equipment65 卫星通信地面站 satellite communication earth station66 通信卫星 communication satellite67 天线馈线 antenna feeder68 调制解调器 modem69 电话交换机 telephone switching system70 人工电话交换机 manual telephone switching system71 自动电话交换机 automatic telephone swithing system72 程控电话交换机stored program control telephone switching system73 电报交换机 telegraph switching system74 数据交换机 data switching system75 被复线 field wire76 架空明线线路 open wire communication line77 通信电缆 communication cable78 光纤通信设备 optical fiber communication equipment79 光纤 optical fiber80 通信保密 communications security81 保密通信 secure communications82 无线电密语通信 radio cryptoword communications83 保密机 security equipment84 密码机 crypto equipment85 密钥 cipher key86 无线电通信对抗 radio communication electronic warfare87 通信对抗装备 communication electronic warfare equipments88 帧中继 Frame Relay(FR)89 全球定位系统 Global Position--finding System (GPS)90 移动通信特别小组 Group Special Mobile(GSM)91 高速率数字用户环路 High--bit--rate Digital Subscriber Line (HDSL)92 信息高速公路 Information Super Highway93 网络电话 Internet Phone(IP)94 局域网 Local Area Network95 城域网 Metropolitan Area Network (MAN)96 多媒体扩展技术 Multi--Media Extend (MMX)97 全动态视频压缩技术 Motion Picture Experts Group (MPEG)98 分组拆装设备 Packet Assembler Dissembler(PAD)99 微型计算机 PC: Personal Computer100 网络计算机 NC: Network Computer101 多媒体个人电脑 MMX: Multimedia Personal Computer102 千字节 KB:Kilo Byte103 兆字节 MB:Mega Byte104 千兆字节 GB:Giga Byte105 计算机辅助教学 CAI:Computer-Aided instruction106 计算机辅助设计 CAD:Computer-Aided design107 国际标准化组织 ISO:International Standard Organization 108 虚拟现实 VR:virtual reality109 模拟数据 ANALOG DATA110 附件 ATTACHMENT111 骨干网 BACKBONE112 带宽 BANDWIDTH113 波特率 BAUD RATE114 二进制数据 BINARY DATA115 比特 BIT116 书签 BOOKMARK117 每秒比特数 BPS118 浏览器 BROWSER119 电缆调制解调器 CABLE MODEM120 缓存目录 CACHE DIRECTORY121 通用网关节口 CGI:Common gateway interface122 频道 CHANNEL123 通讯端口 COM PORT COM124 数据库 DATA BASE125 数据压缩 DATA COMPRESSION126 拨号连接 DIAL-UP CONNECTION127 拨号连接软件 DIAL-UP NETWORKING SOFTWARE 128 数码相机 DIGITAL CAMERA129 域名系统 DNS:domain name system130 域名 DOMAIN NAME131 下载 DOWNLOAD132 电子邮件 E-MAIL133 电子邮件地址 E-MAIL ADDRESS134 加密 ENCRYPTION135 纠错 ERROR CORRECTION136 以太网 ETHERNET137 常见问题 FAQ:frequently asked question138 免费软件 FREEWARE139 文件传输协议 FTP:file transfer protocol140 网关 GATEWAY141 图形交换格式 GIF:graphic interchange format142 网页 HOME PAGE143 超文本标记语言 HTML:hyper text mark language144 超文本传输协议 HTTP:hyper text tranfer protocol145 超级终端 HYPER TERMINAL146 超文本 HYPER TEXT147 国际互联网 INTERNET148 网间协议 IP:internet protocol149 ip地址 IP ADDRESS150 目录服务器 LIST SERVER151 注册 LOGIN152 邮件服务器 MAIL SERVER153 邮寄目录 MAILING LIST154 多媒体 MULTIMEDIA155 网络 NETWORK156 节点 NODE157 在线 ON-LINE158 离线 OFF-LINE159 密码 PASSWORD160 增强保密邮件 PEM:privacy enhanced mail161 插件 PLUG-IN162 投寄 POST163 点对点通信协议 PPP:point to point protocol164 远程登录 REMOTE LOGIN165 路由器 ROUTER166 搜索器 SEARCH ENGINE167 共享软件 SHAREWARE168 签名 SIGNATURE169 简单邮件传输协议 SMTP:simple mail transfer protocol170 冲浪 SURFING171 传输控制协议/网际协议 TCP/IP:transfer control protocol/internet protocol 172 全球资源定位器 URL:uniform resource locator173 广域信息服务器 WAIS(Wide Area Information Servers)174 万维网页 WEB PAGE175 万维网站 WEB SITE176 万维网搜索器 WEB-WIDE SEARCH ENGINE177 万维网 WORLD WIDE WEB178 中央处理器 CPU(Central Processing Unit)179 网民 Cyber Citizen180 软件开发 Software Development181 内容开发 Content Development182 信息化 Informationization,Network-based Information Flow183 软件包 Software Packages184 申请注册域名 Domain Name Application and Registration185 虚拟空间 Virtual Space186 便携式电脑 Portable Computer,Laptop; Notebook Computer187 个人数字助理 PDA--Personal Digital Assistant188 掌上电脑 Palm Computer189 网络管理员 Network Administrator190 原始设备制造商 OEM:Original Equipment Manufacturer191 即插即用 PNPlug and Play战场英语1 缴枪不杀 Lay down arms,or we'll fire!2 我们优待俘虏 We are kind to captives!3 你们被包围了，出来投降吧！ You're surrounded!Come out and surrender!4 我们不杀俘虏 We don't kill our captives!5 不要受战争贩子的蒙骗 Don't be deceived by the warmonger!6 不要做无谓的牺牲 Don't die for nothing !7 赶快出来投降，保证你们生命安全！ Come out and surrender right away security of life will be guaranteed!8 谁迫使你们离开幸福的家庭,漂亮的妻子和可爱的孩子 Who made you leave your happy home,your charming wife and yourloving children?9 你们在打一场无指望的仗 You are fighting a losing battle!10 我们保证你们：生命安全 You are to be guaranteed:security of life!11 我们保证你们：不没收私人财务 You are to be guaranteed:chattle personal will not be confiscated!12 我们保证你们：不被虐待 You are to be guaranteed:freedom from maltreatment.13 我们保证你们：受伤者给予治疗 You are to be guaranteed:medical care if wounded.14 举起手来！ Hands up!15 举起手出来！ Come out with your hands up!16 一个一个的出来！ Come out one by one!17 不许动！ Freeze!18 站住，否则我们开枪了！ Stop,or will shoot!19 别耍花样！ Don't play any tricks!20 别害怕！ Don't be afraid!21 站队！ Line up!22 走！ Get moving!23 跟着那个人走！ Follow that man!24 我们尊重你们的人格！ We'll respect your personality!25 我们不搜你们的腰包 We'll never search your pocket!26 我们将释放你们 we'll set you free!27 长官快命令你们的人投向 Commanding officer,order your soldiers to surrender!28 这是你们的最后一次机会 This is the last chance for you!29 顽抗到底，死路一条 If you don't accept our advice,you will turn into a dead road.30 请你们珍惜生命 Please treasure your life!31 别误会 Don't misunderstand!32 你们进行的是一场侵略战争 You're arousing an aggressive war!33 你们的亲人在想念你们 Your family members are missing you!34 不要再为你们的长官卖命了 Don't again sacrifice your life to your commanding officer!35 我们说话算数，说到做到 Our words do count,you must believe us!36 把武器交出来 Hand out your arms!37 可以立功赎罪 Atone for your crimes by performing meritorious!38 不要说话 Please keep quiet!39 请服从我的命令 Please obey my order!40 退下子弹，把枪给我 Unload bullets,take gun to me!41 联合国 United Nations42 国防部 Department of defence43 总部司令部 Headquarters44 空军战术指挥中心 Tactical Air Control Center45 参谋 Staff officer46 机动 Manoeuvre47 军事 Military affairs48 军衔 Military Rank49 战斗分界线 Combat Boundary50 预备役部队 Reserve Component51 战斗兵种 Combat Arm52 进攻 Offence53 防御 Defence54 前进 Advance55 医疗中心 Medical Center56 军 Army Corps57 师 Division58 特遣队 Task Force59 旅 Brigade60 营 Battalion61 连 Company62 将军 General63 副长官 Adjutant64 连长 Company Commander65 上校 Colonel66 中校 Lieutenant colonel67 少校 Major68 陆军上尉 Captain69 中尉 Lieutenant70 少尉 second Lieutenant71 值班军官 Officer in charge72 军士长 Fires Sergeant73 上士 Sergeant First Class74 中士 Staff sergeant75 上等兵 Private First Class76 士兵 Sergeant77 战俘 Prisoner of war78 战场空中遮蔽 Battlefield Air Interdiction79 近距离空中支援 Close Air Support80 战斗电子战情报 Combat Electronic Warfare Intelligence81 射击指挥 Command/Fire82 战斗支援 Combat Support83 电子对抗 Electronic Counter Measures84 电子搜索目标 Electronic Warfare Support Measure85 电子战 Electronic Warfare86 战斗地域前沿 Forward Edge of The Battle Area87 火力支援 Fire Support88 军事情报 Military Intelligence89 战斗条例 Order of Battle90 作战计划 Operation Plan91 战斗命令 Operation Order92 战斗警戒 Operation Security93 调整线 Phase Line94 空中支援 Tine Over Target95 高射炮 Air Defence Artillery96 装甲直升机 Attack Helicopter97 装甲输送机 Armored Personnel carrier98 反坦克导弹 Anti Tank Guided Missile99 集束炸弹 Cluster Bomb Unit100 弹药筒 Cartridge101 制导炸弹 Guided Bomb Unit102 "霍克"防空导弹 Homing-all-the-way-killer103 多管火箭筒 Multiple Rocket Launcher104 观察直升机 Observation Helicopter。
通信工程专业英语Unit 2：Digital Communication System
专业英语的翻译
省略：根据汉语语法的修辞习惯，将原文中的某些词语略 去不译。（如英语中的冠词、代词和连词）
Air is a fluid but not a liquid.
空气是流体, 不是液体。（省略冠词） If you know the frequency, you can find the wave length. 如果知道频率，就能求出波长。（泛指的人称代词you 可省略不译）
TEXT
The use of digital methods for the transmission of analog signals is becoming increasingly common in telecommunication systems. There are two major reasons for this. digital :数字的, 数位的
Specialized English for Communication Engineering
专业英语的翻译
句子结构上有差异 词汇上很少对等
English
Chinese
死译 硬译 直译：基本上保留原文的表达形式及内容，不做大的改 动，同时译出的文字又明白易懂； 胡译 意译：在正确理解原意的基础上，重新遣词造句，把原 文的意思用通顺的汉语表达出来。
The reliability can be further improved by using errordetecting and error-correcting codes.
利用检错和纠错编码能进一步提高可靠性。（被动语态 转译为主动语态） Specialized English for Communication Engineering
计算机专业英语名词解释
计算机专业英语名词解释1 Data is a collection of un-organized facts, which can include words, numbers, images, and sounds. 数据是未经组织的事实的集合,数据可以包括单词,数字,图像和声音.2 A computer consists of a variety of hardware components that work together with software to perform calculations（计算）, organize data, and communicate with other computer.计算机由许多硬件部件构成,这些硬件与软件一起工作,以便执行计算,组织数据及与其他计算机通信的任务.3 These hardware components include input devices, output devices,a system unit, storage devices, and communications devices.硬件部件包括输入设备,输出设备,系统单元 ,存储设备和通信设备.4 An input device allows a user to enter data and commands into thememory of a computer. 输入设备让用户向计算机存储器输入数据和命令.5 Storage differs from memory ,which can hold these items permanently，whereas memory holds these memory holds items only temporarily(暂时的)。
外存储器与内存储器不同,外存储器能永久保存数据而内存储器仅临时保存.6 A hard disk provides much greater storage capacity than a floppy disk. 硬盘能比软盘提供更大的存储容量.7 Four common storage devices are a floppy disk drive, a hard disk drive, a CD-ROM drive, and a DVD-ROM drive. 四种常用的外存设备分别是:软盘驱动器,硬盘驱动器,CD-ROM驱动器和DVD-ROM驱动器.8 The central processing unit (CPU), sometimes referred to as the processor, interprets（解释）and carries out the basic instructions that operate a computer. 中央处理器(CPU)有时也称处理器,用来解释并执行基本的计算机操作指令.9 In the system unit, a computer’s memory stores data, instructions,and information. 在系统单元中，计算机的存储器存储数据,指令和信息.10 ROM(Read-Only Memory) is a memory chip that only can be readand used; that is , it cannot be modified(修改)。
【精品】军事方面英语词汇
【关键字】精品军事方面英语词汇1 军事通信 military communications2 军事通信系统 military communications system3 无线电通信 radio communications4 超长波通信 super-long wave communications5 甚长波通信 very long wave communications6 长波通信 long-wave communications7 中波通信 medium wave communications8 短波通信 short-wave communications9 微波通信 microwave communications10 毫米波通信 millimeter wave communications11 无线电台通信 radio set communications12 无线电接力通信 radio relay communications13 散射通信 scatter communications14 卫星通信 satellite communications15 扩展频谱通信 spread spectrum communications16 移动通信 mobile communications17 无线电波通信 radio wave communications18 电离层 ionosphere19 有线电通信 wired communications20 被单线通信 field wire communications21 架空明线通信 open wire communications22 电缆通信 cable communications23 光通信 optical communications24 光纤通信 optical fiber communications25 运动通信 messenger service26 军邮 army postal service27 简易信号通信 simplified signal communications28 旗语通信 flag signal communications29 电话通信 telephone communications30 载波电话通信 carrier telephone communications31 电报通信 telegraphy communications32 载波电报通信 carrier telegraphy communications33 电码 code34 图像通信 image communications35 电视广播 videocast36 静态图像通信 still picture communications37 会议电视 video conferencing38 可视电话 video telephone39 交互型可视图文 videotex40 传真通信 facsimile communications41 数据通信 data communications42 计算机通信 computer communications43 数字通信 digital communications44 模拟通信 analog communications45 多路通信 multiplex communications46 无线电台网 radio communications works47 有线电通信网 telecommunications networks48 数据通信网 data communication networks49 计算机通信网 computer communication network50 综合业务数字网 integrated service digital networks51 军事通信装备 military communications equipment52 电话机 telephone set53 传真机 facsimile equipment54 超长波电台 super-long wave radio station55 甚长波电台 very long wave radio station56 长波电台 long wave radio station57 短波电台 short wave radio set58 超短波电台 ultra-short wave radio set59 调幅电台 amplitude modulation radio set60 单边带电台 single sideband radio set61 调频电台 frequency modulation radio set62 呼救电台 life-saving radio set63 跳频电台 frequency hopping radio set64 接力机 radio relay equipment65 卫星通信地面站 satellite communication earth station66 通信卫星 communication satellite67 天线馈线 antenna feeder68 调制解调器 modem69 电话交换机 telephone switching system70 人工电话交换机 manual telephone switching system71 自动电话交换机 automatic telephone swithing system72 程控电话交换机stored program control telephone switching system73 电报交换机 telegraph switching system74 数据交换机 data switching system75 被单线 field wire76 架空明线线路 open wire communication line77 通信电缆 communication cable78 光纤通信设备 optical fiber communication equipment79 光纤 optical fiber80 通信保密 communications security81 保密通信 secure communications82 无线电密语通信 radio cryptoword communications83 保密机 security equipment84 密码机 crypto equipment85 密钥 cipher key86 无线电通信对抗 radio communication electronic warfare87 通信对抗装备 communication electronic warfare equipments88 帧中继 Frame Relay(FR)89 全球定位系统 Global Position--finding System (GPS)90 移动通信特别小组 Group Special Mobile(GSM)91 高速率数字用户环路 High--bit--rate Digital Subscriber Line (HDSL)92 信息高速公路 Information Super Highway93 网络电话 Internet Phone(IP)94 局域网 Local Area Network95 城域网 Metropolitan Area Network (MAN)96 多媒体扩展技术 Multi--Media Extend (MMX)97 全动态视频压缩技术 Motion Picture Experts Group (MPEG)98 分组拆装设备 Packet Assembler Dissembler(PAD)99 微型计算机 PC: Personal Computer100 网络计算机 NC: Network Computer101 多媒体个人电脑 MMX: Multimedia Personal Computer102 千字节 KB:Kilo Byte103 兆字节 MB:Mega Byte104 千兆字节 GB:Giga Byte105 计算机辅助教学 CAI:Computer-Aided instruction106 计算机辅助设计 CAD:Computer-Aided design107 国际标准化组织 ISO:International Standard Organization 108 虚拟现实 VR:virtual reality109 模拟数据 ANALOG DATA110 附件 ATTACHMENT111 骨干网 BACKBONE112 带宽 BANDWIDTH113 波特率 BAUD RATE114 二进制数据 BINARY DATA115 比特 BIT116 书签 BOOKMARK117 每秒比特数 BPS118 浏览器 BROWSER119 电缆调制解调器 CABLE MODEM120 缓存目录 CACHE DIRECTORY121 通用网关节口 CGI:Common gateway interface122 频道 CHANNEL123 通讯端口 COM PORT COM124 数据库 DATA BASE125 数据压缩 DATA COMPRESSION126 拨号连接 DIAL-UP CONNECTION127 拨号连接软件 DIAL-UP NETWORKING SOFTWARE128 数码相机 DIGITAL CAMERA129 域名系统 DNS:domain name system130 域名 DOMAIN NAME131 下载 DOWNLOAD132 电子邮件 E-MAIL133 电子邮件地址 E-MAIL ADDRESS134 加密 ENCRYPTION135 纠错 ERROR CORRECTION136 以太网 ETHERNET137 常见问题 FAQ:frequently asked question138 免费软件 FREEWARE139 文件传输协议 FTP:file transfer protocol140 网关 GATEWAY141 图形交换格式 GIF:graphic interchange format142 网页 HOME PAGE143 超文本标记语言 HTML:hyper text mark language144 超文本传输协议 HTTP:hyper text tranfer protocol145 超级终端 HYPER TERMINAL146 超文本 HYPER TEXT147 国际互联网 INTERNET148 网间协议 IP:internet protocol149 ip地址 IP ADDRESS150 目录服务器 LIST SERVER151 注册 LOGIN152 邮件服务器 MAIL SERVER153 邮寄目录 MAILING LIST154 多媒体 MULTIMEDIA155 网络 NETWORK156 节点 NODE157 在线 ON-LINE158 离线 OFF-LINE159 密码 PASSWORD160 增强保密邮件 PEM:privacy enhanced mail161 插件 PLUG-IN162 投寄 POST163 点对点通信协议 PPP:point to point protocol164 远程登录 REMOTE LOGIN165 路由器 ROUTER166 搜索器 SEARCH ENGINE167 共享软件 SHAREWARE168 签名 SIGNATURE169 简单邮件传输协议 SMTP:simple mail transfer protocol170 冲浪 SURFING171 传输控制协议/网际协议 TCP/IP:transfer control protocol/internet protocol 172 全球资源定位器 URL:uniform resource locator173 广域信息服务器 WAIS(Wide Area Information Servers)174 万维网页 WEB PAGE175 万维网站 WEB SITE176 万维网搜索器 WEB-WIDE SEARCH ENGINE177 万维网 WORLD WIDE WEB178 中央处理器 CPU(Central Processing Unit)179 网民 Cyber Citizen180 软件开发 Software Development181 内容开发 Content Development182 信息化 Informationization,Network-based Information Flow183 软件包 Software Packages184 申请注册域名 Domain Name Application and Registration185 虚拟空间 Virtual Space186 便携式电脑 Portable Computer,Laptop; Notebook Computer187 个人数字助理 PDA--Personal Digital Assistant188 掌上电脑 Palm Computer189 网络管理员 Network Administrator190 原始设备制造商 OEM:Original Equipment Manufacturer191 即插即用 PNPlug and Play战场英语1 缴枪不杀 Lay down arms,or we'll fire!2 我们优待俘虏 We are kind to captives!3 你们被包围了，出来投降吧！ You're surrounded!Come out and surrender!4 我们不杀俘虏 We don't kill our captives!5 不要受战争贩子的蒙骗 Don't be deceived by the warmonger!6 不要做无谓的牺牲 Don't die for nothing !7 赶快出来投降，保证你们生命安全！ Come out and surrender right away security of life will be guaranteed!8 谁迫使你们离开幸福的家庭,漂亮的妻子和可爱的孩子 Who made you leave your happy home,your charming wife and yourloving children?9 你们在打一场无指望的仗 You are fighting a losing battle!10 我们保证你们：生命安全 You are to be guaranteed:security of life!11 我们保证你们：不没收私人财务 You are to be guaranteed:chattle personal will not be confiscated!12 我们保证你们：不被虐待 You are to be guaranteed:freedom from maltreatment.13 我们保证你们：受伤者给予治疗 You are to be guaranteed:medical care if wounded.14 举起手来！ Hands up!15 举起手出来！ Come out with your hands up!16 一个一个的出来！ Come out one by one!17 不许动！ Freeze!18 站住，否则我们开枪了！ Stop,or will shoot!19 别耍花样！ Don't play any tricks!20 别害怕！ Don't be afraid!21 站队！ Line up!22 走！ Get moving!23 跟着那个人走！ Follow that man!24 我们尊重你们的人格！ We'll respect your personality!25 我们不搜你们的腰包 We'll never search your pocket!26 我们将释放你们 we'll set you free!27 长官快命令你们的人投向 Commanding officer,order your soldiers to surrender!28 这是你们的最后一次机会 This is the last chance for you!29 顽抗到底，死路一条 If you don't accept our advice,you will turn into a dead road.30 请你们珍惜生命 Please treasure your life!31 别误会 Don't misunderstand!32 你们进行的是一场侵略战争 You're arousing an aggressive war!33 你们的亲人在想念你们 Your family members are missing you!34 不要再为你们的长官卖命了 Don't again sacrifice your life to your commanding officer!35 我们说话算数，说到做到 Our words do count,you must believe us!36 把武器交出来 Hand out your arms!37 可以立功赎罪 Atone for your crimes by performing meritorious!38 不要说话 Please keep quiet!39 请服从我的命令 Please obey my order!40 退下子弹，把枪给我 Unload bullets,take gun to me!41 联合国 United Nations42 国防部 Department of defence43 总部司令部 Headquarters44 空军战术指挥中心 Tactical Air Control Center45 参谋 Staff officer46 机动 Manoeuvre47 军事 Military affairs48 军衔 Military Rank49 战斗分界线 Combat Boundary50 预备役部队 Reserve Component51 战斗兵种 Combat Arm52 进攻 Offence53 防御 Defence54 前进 Advance55 医疗中心 Medical Center56 军 Army Corps57 师 Division58 特遣队 Task Force59 旅 Brigade60 营 Battalion61 连 Company62 将军 General63 副长官 Adjutant64 连长 Company Commander65 上校 Colonel66 中校 Lieutenant colonel67 少校 Major68 陆军上尉 Captain69 中尉 Lieutenant70 少尉 second Lieutenant71 值班军官 Officer in charge72 军士长 Fires Sergeant73 上士 Sergeant First Class74 中士 Staff sergeant75 上等兵 Private First Class76 士兵 Sergeant77 战俘 Prisoner of war78 战场空中遮蔽 Battlefield Air Interdiction79 近距离空中支援 Close Air Support80 战斗电子战情报 Combat Electronic Warfare Intelligence81 射击指挥 Command/Fire82 战斗支援 Combat Support83 电子对抗 Electronic Counter Measures84 电子搜索目标 Electronic Warfare Support Measure85 电子战 Electronic Warfare86 战斗地域前沿 Forward Edge of The Battle Area87 火力支援 Fire Support88 军事情报 Military Intelligence89 战斗条例 Order of Battle90 作战计划 Operation Plan91 战斗命令 Operation Order92 战斗警戒 Operation Security93 调整线 Phase Line94 空中支援 Tine Over Target95 高射炮 Air Defence Artillery96 装甲直升机 Attack Helicopter97 装甲输送机 Armored Personnel carrier98 反坦克导弹 Anti Tank Guided Missile99 集束炸弹 Cluster Bomb Unit100 弹药筒 Cartridge101 制导炸弹 Guided Bomb Unit102 "霍克"防空导弹 Homing-all-the-way-killer103 多管火箭筒 Multiple Rocket Launcher104 观察直升机 Observation Helicopter此文档是由网络收集并进行重新排版整理.word可编辑版本！。
编码和调制技术
Chapter 5 Data Encoding
编码和调制技术
g(t) Encoder
数字或 模拟
x(t) Decoder 数字
g(t)
x(t)
t s(f) m(t)
Modulator 数字或 模拟
s(t)
Demodulator
m(t) fc f
编码名称编码规则不归零码nonreturntozerolevelnrzl高电平反向不归零码nonreturnzeroinvertednrzi间隔起始处有变化双极ami码正或负电平每一连续的1交变伪三元码无信号manchester编码manchester编码间隔的中央处总有变化间隔起始处无变化b8zs编码除了任何八个零的串被一有两个违例码的串替代以外其余类似ami编码hdb3编码除了任何四个零的串被一有一个违例码的串替代以外其余类似ami编码编码方法nonreturnzerolevelnrzltwodifferentvoltagesbitsvoltageconstantduringbitintervaltransitionie
Comparison of Encoding Schemes (1)
Signal Spectrum
ִLack of high frequencies reduces required bandwidth ִLack of dc component allows ac coupling via transformer, providing isolation ִConcentrate power in the middle of the bandwidth
Clocking
ִSynchronizing transmitter and receiver ִExternal clock ִSync mechanism based on signal
25种外文期刊目录
25种外文期刊目录1. 刊名：ACM SIGARCH (Computer Architecture): Computer Architecture News.中译名：美国计算机学会计算机体系结构专业组计算机体系结构新闻ISSN：0163-5964电子版来源数据库：ACM Digital Library2.刊名：ACM SIGMOD (Management of Data): SIGMOD Record..中译名：美国计算机学会数据管理专业组记录ISSN：0163-5808电子版来源数据库：ACM Digital Library3.刊名：ACM SIGOPS (Operating Systems): Operating Systems Review中译名：美国计算机学会操作系统专业组综论ISSN：0163-5980电子版来源数据库：ACM Digital Library4.刊名：ACM SIGCOMM (Data Communication): Computer Communication Review 中译名：美国计算机学会数据通信专业组计算机通信评论ISSN：0146-4833电子版来源数据库：ACM Digital Library5. 刊名：ACM SIGSOFT Software Engineering Notes.中译名：美国计算机学会软件工程专业组软件工程札记ISSN：0163-5948电子版来源数据库：ACM Digital Library6. 刊名：Proceedings of the Institution of Civil Engineers: Civil Engineering中译名：土木工程师学会会报：土木工程ISSN：0965-089X电子版来源数据库：国家科技文献中心（NSTL）宁波服务站7. 刊名：Proceedings of the Institution of Civil Engineers: Structures and Buildings中译名：土木工程师学会会报：结构与建筑ISSN：0965-0911电子版来源数据库：国家科技文献中心（NSTL）宁波服务站8. 刊名：Proceedings of the Institution of Civil Engineers: Geotechnical Engineering 中译名：土木工程师学会会报：土工技术工程ISSN：1353-2618电子版来源数据库：国家科技文献中心（NSTL）宁波服务站9. 刊名：Ground Engineering中译名：地面工程ISSN：0017-4653电子版来源数据库：国家科技文献中心（NSTL）宁波服务站10. 刊名：Concrete Construction中译名：混凝土建筑ISSN：1533-7316电子版来源数据库：Gale数据库/国家科技文献中心（NSTL）宁波服务站11. 刊名：ACI Materials Journal中译名：美国混凝土学会材料杂志ISSN：0889-325X电子版来源数据库：国家科技文献中心（NSTL）宁波服务站12. 刊名：International Journal of Intelligent Information Technologies.中译名：国际智能信息技术杂志ISSN：1548-3657电子版来源数据库：国家科技文献中心（NSTL）宁波服务站13. 刊名：International Journal of E-Business Research.中译名：国际电子商务研究杂志ISSN：1548-1131电子版来源数据库：国家科技文献中心（NSTL）宁波服务站14. 刊名：International Journal of E-Collaboration.中译名：国际电子协作杂志ISSN：1548-3673电子版来源数据库：国家科技文献中心（NSTL）宁波服务站15. 刊名：International Journal of Knowledge Management.中译名：国际知识管理杂志ISSN：1548-0666电子版来源数据库：国家科技文献中心（NSTL）宁波服务站16. 刊名：International Journal of Electronic Government Research.中译名：国际电子政府研究杂志ISSN：1548-3886电子版来源数据库：国家科技文献中心（NSTL）宁波服务站17. 刊名：International Journal of Business Data Communications and Networking.中译名：国际企业信息通讯与网络化杂志ISSN：1548-0631电子版来源数据库：国家科技文献中心（NSTL）宁波服务站18. 刊名：International Journal of Information and Communication Technology Education. 中译名：国际信息与通讯技术教育杂志ISSN：1550-1876电子版来源数据库：国家科技文献中心（NSTL）宁波服务站19. 刊名：Energy & Environment.中译名：能源与环境ISSN：0958-305X电子版来源数据库：国家科技文献中心（NSTL）宁波服务站20. 刊名：International review of finance中译名：国际金融评论ISSN：1369-412X电子版来源数据库：Ebscohost21. 刊名：Asian Economic Journal中译名：亚洲经济杂志ISSN：1351-3958电子版来源数据库：Ebscohost22. 刊名：International Journal of Constitutional Law中译名：国际宪法杂志ISSN：1474-2640电子版来源数据库：OUP（Oxford University Press）23. 刊名：ELT Journal. (English Language Teaching)中译名：英语教学杂志ISSN：0951-0893电子版来源数据库：OUP（Oxford University Press）24. 刊名：Journal of Applied Linguistics中译名：应用语言学杂志ISSN：1479-7887电子版来源数据库：ALJC（欧洲中小协学会出版社全文电子期刊）25. 刊名：Translation and Literature中译名：翻译与文学ISSN：0968-1361电子版来源数据库：EBSCOhost/ALJC。
数据通讯Data Communications中英文对照
英文资料：1、Data CommunicationsThe rapid growth of data communications has been influenced primarily by the increasing need to move information to and from computers. Modern time-shared computers can communicate with many data stations simultaneously. Other forms of data transmission which the telephone and telegraph lines are called upon to handle are batch data transmission, real-time transmission (as in the case of airline reservation systems), banking and credit data, man-computer conversation with the aid of graphics, data collection systems and automatic meter reading The combination of computers and data communication places such new requirements on the systems, which must handle them, that one can refer to them better as teleprocessing rather than telecommunications. Teleprocessing started with the airline reservation systems, where the distribution of computer data is not as important as the maintenance of an inventory of seats for the whole system and the ability to access such an inventory rapidly at a number of distant points. Another example is that of the banks, who desired to centralize their accounting and provide access to a central file for all their branches. Basically, there are three reasons for the development of teleprocessing systems: the requirement for centralized files, the need to distribute computer services and the advantage gained by having flexibility in location of the operating staff which utilizes the system.The most applicable model for data communications requirements is the central computer conversing with many simple terminals simultaneously. Differing from telephone communications, a data communications network must be able to interconnect a wide variety of subscriber’s equipment. Several different types of computer peripherals may appear as network terminals, and so also can computers functioning in several different ways. Terminal speeds ranging from 100 bits per sec to 10,000 bits per sec are likely to be important. Many terminals in current use are constrained by the available communications services, but many of the have variable speeds. One approach to this situation is to provide a buffer store at the terminal, but this approach is expensive. At present, multi-access computers usually handle terminals of only one speed or with a small number of fixed speeds. It has been proposed that feedback from the output device be used to permit one simple output program to drive terminals with different characteristics. Of course, such feedback signals would have to be handled by the communications network.At data technology develops, each multi-access computer is connected to an increasing number of terminals, making it expensive and difficult to provide separate lines from the computer to the network for each of the terminals. Thus, a need for multiplexed connections between the computer and the terminals arises. But this need cannot necessarily be met in a straightforwardmanner. One characteristic of a data communications network differing from conventional telephone networks is that the two ends of the communication link are very different. One end is a computer capable of flexible behavior, and the other end is a relatively slow terminal with no intelligence. Since the two ends are so different, it would appear that the network would communicate differently with them. The flow of information in a data communication system is intermittent just as it is in the case of telephone conversations However, instead of minutes of conversation, only a few seconds will elapse for the information flow in one direction, followed by a pause and some flow of information in the opposite direction, The access times for typical computers in use at this time are about 100 ms , but this will become faster as better memories are utilized . The time scale for the interchange of data messages needs to be of this order.2、Characteristics of Communication ChannelsData communications is the electronic transmission of information including data ,television pictures, sound and facsimiles. It usually involves s computer, a modem , software, and a printer. With this equipment, you can communicate with a friend in St. Louis, Missouri, or Paris, France, sending and receiving anything from a manuscript to a simple message over the telephone lines. Using the same method, a home-bound child can interact with a teacher in the classroom, an office worker can work at home, and a doctor can access a remote computer for research data.The reasons for using communications system are convincing. ItIs expedient and efficient,Lessens job stress,Decreases car pollution,Saves time and money,Allows the home to serve as an office,Promotes distant learning in which students can share information and computer research findings.When you connect one computer to another, you use hardware and software. In the majority of cases, the hardware consists of equipment that sends the data over some type of communications line, such as a telephone line. The software controls the flow of this data. The necessary hardware consist of a modem and telephone lines.The modem modulates the computer output to an acceptable signal for transmission and then demodulates the signal back for computer input. The modem on the transmitting computer converts the digital signals to modulated analog signal tones and transmits them over the telephone lines. The receiving computer’s modem transforms the incoming analog signals back to their digital equivalents in order to understand them.Transmission RateThe transmission rate of a communications channel is determined by its bandwidth and its speed. The bandwidth is the range of frequencies that a channel can carry. Since transmitted data can be assigned to different frequencies, the wider the bandwidth, the more frequencies, and the more data can be transmitted at the same time.The speed at which data is transmitted is usually expressed as bits per second or as a baud rate. Bits per second is the number of bits that can be transmitted in one second. Using a 10-bit byte to represent a character, a 2,400bps transmission would transmit 240 characters per second. At this rate, a 20-page, single-spaced report would be transmitted in approximately five minutes. The baud rate is the number of times per second that signal being transmitted changes. Wing each change, one or more bits can be transmitted. At speed up to 2,400 bps, usually only one bit is transmitted per signal change and, thus, the bits per second and the baud rate are the same. To achieve speeds in excess of 2,400 bps, more than one bit is transmitted with each signal change and, the bps will exceed the baud rate.Direction of TransmissionThe direction of data transmission is classified as either simplex, half-duplex, or full-duplex. In simplex transmission, data flows in one direction only. Simplex is used only when the sending device, such as a temperature sensor, never requires a response from the computer. For example, if a computer is used to control the temperature of a building, numerous sensors are placed throughout it. Each sensor is connected to the computer with a simplex transmission line because the computer only needs to receive data from the temperature sensors and does not need to send data back to the sensors.In half-duplex transmission, data can flow in both directions but in only one direction at s time. An example is a citizens band radio. The user can talk or listen but not do both at the same time. Half-duplex is often used between terminals and a central computer.In full-duplex transmission, data can be sent in both directions at the same time. A normal telephone line is an example of full-duplex transmission. Both parties can talk at the same time. Full-duplex transmission is used for most interactive computer applications and for computer-to-computer data transmission.1、数据通讯数据通讯迅速增长主要被增长的需要影响了移动信息计算机。
COMMUNICATIONS
Instant messaging--supports direct, "live“ electronic communication between two or more friends or buddies 即时消息——支持直接“住在”电子通讯中两 个或多个朋友或伙伴
Internet telephone--provides a very low-cost alternative to long-distance telephone calls using electronic voice delivery
连通性是一个通过使用计算机网络为广大 群众和资源提供相关链接的概念。 例如,连接意味着你可以通过电话或其他通信连 接你的微型计算机到其他任何地方的计算机和 信息。
With this connection ,you are linked to the world of larger computers and theinternet. This includes minicomputers and mainframes and their extensive information resources. Thus,becoming computer competent and knowledgeable becomes a matter of knowing not only about connectivity through networks to microcomputers, but also about larger computer systems and their information resoureces. 有了这个连接,你就能与世界的大型计算机和网络相连 系。 这包括大型机和小型机以及其广泛的信息资源。 因此,成为能胜任的、知识渊博的计算机的问题变 成一个不仅仅知道通过微机网络连通,还为更大的计算机 系统和信息建库的问题。
Symphony Enterprise Management和控制系统的Cnet高速数据通信网络说明
Features and Benefits Overview Control ITHarmony RackCommunications Control Network, Cnet, is a high-speed data communicationhighway between nodes in the Symphony™ Enterprise Man-agement and Control System. Cnet provides a data pathamong Harmony control units (HCU), human system inter-faces (HSI), and computers. High system reliability andavailability are key characteristics of this mission-criticalcommunication network. Reliability is bolstered by redun-dant hardware and communication media in a way that thebackup automatically takes over in the event of a fault in theprimary. Extensive use of error checking and messageacknowledgment assures accurate communication of criticalprocess data.Cnet uses exception reporting to increase the effective band-width of the communication network. This method offers theuser the flexibility of managing the flow of process data andultimately the process. Data is transmitted only when it haschanged by an amount which can be user selected, or when apredetermined time-out period is exceeded. The system pro-vides default values for these parameters, but the user cancustomize them to meet the specific needs of the processunder control.TC00895A■Fast plant-wide communication network: Cnet provides fastresponse time to insure timelyinformation exchange.■Efficient data transfer: Message packing and multiple address-ing increase data handlingefficiency and throughput.■Plant-wide time synchronization: Time synchronization of Cnetnodes throughout the entirecontrol process insures accuratedata time-stamping.■Independent node communica-tion: Each Cnet node operatesindependently of other nodes.Requires no traffic directors;each node is its owncommunication manager.■Accurate data exchange: Multi-ple self-check features including positive message acknowledg-ment, cyclic redundancy checks(CRC), and checksums insuredata integrity.■Automatic communications recovery: Rack communicationmodules provide localized start-up/shutdown on power failurewithout operator intervention.Each type of interface supportsredundancy.Harmony Rack CommunicationsOverviewHarmony rack communications encompasses various communication interfaces as shown inFigure1: Cnet-to-Cnet communication, Cnet-to-HCU communication, and Cnet-to-computercommunication.Figure 1. Harmony Rack Communications ArchitectureThe communication interface units transfer exception reports and system data, control, and con-figuration messages over Cnet. Exception reported data appears as dynamic values, alarms, and state changes on displays and in reports generated by human system interfaces and other system nodes. Exception reporting is automatic at the Harmony controller level. Specifically, the control-ler generates an exception report periodically to update data, after a process point reaches adefined alarm limit or changes state, or after a significant change in value occurs.Harmony Rack Communications Control NetworkCnet is a unidirectional, high speed serial data network that operates at a 10-megahertz or two-megahertz communication rate. It supports a central network with up to 250 system node connec-tions. Multiple satellite networks can link to the central network. Each satellite network supports up to 250 system node connections. Interfacing a maximum number of satellite networks gives a system capacity of over 62,000 nodes.On the central network, a node can be a bridge to a satellite network, a Harmony control unit, a human system interface, or a computer, each connected through a Cnet communication interface.On a satellite network, a node can be a bridge to the central network, a Harmony control unit, a human system interface, or a computer.Harmony Control UnitThe Harmony control unit is the fundamental control node of the Symphony system. It connects to Cnet through a Cnet-to-HCU interface. The HCU cabinet contains the Harmony controllers and input/output devices. The actual process control and management takes place at this level. HCU connection to Cnet enables Harmony controllers to:■Communicate field input values and states for process monitoring and control.■Communicate configuration parameters that determine the operation of functions such asalarming, trending, and logging on a human system interface.■Receive control instructions from a human system interface to adjust process field outputs.■Provide feedback to plant personnel of actual output changes.Human System InterfaceA human system interface such as a Signature Series workstation running Maestro or ConductorSeries software provides the ability to monitor and control plant operations from a single point. It connects to Cnet through a Cnet-to-computer interface. The number of workstations in a Sym-phony system varies and depends on the overall control plan and size of a plant. The workstation connection to Cnet gives plant personnel access to dynamic plant-wide process information, and enables monitoring, tuning, and control of an entire plant process from workstation color graphics displays and a pushbutton keyboard.ComputerA computer can access Cnet for data acquisition, system configuration, and process control. It con-nects to Cnet through a Cnet-to-computer interface. The computer connection to Cnet enablesplant personnel, for example, to develop and maintain control configurations, manage the system database, and create HSI displays remotely using Composer™engineering tools. There are addi-tional Composer and Performer series tools and applications that can access plant informationthrough a Cnet-to-computer interface.Cnet-to-Cnet Communication InterfaceThe Cnet-to-Cnet interfaces are the INIIR01 Remote Interface and the INIIL02 Local Interface.Figure2 shows the remote interface and Figure 3 shows the local interface.Harmony Rack CommunicationsFigure 2. Cnet-to-Cnet Remote Interface (INIIR01)Figure 3. Cnet-to-Cnet Local Interface (INIIL02)Harmony Rack Communications INIIR01 Remote InterfaceThe INIIR01 Remote Interface consists of the INNIS01 Network Interface Module and the INIIT12 Remote Transfer Module (Fig.2). This interface is a node on a central network that can communi-cate to an interface node on a remote satellite network. In this arrangement, two interfaces arerequired: one for the central network, and the other for the satellite network. Bidirectional commu-nication from the central network to the remote satellite network is through standard RS-232-Cports.The remote interface supports hardware redundancy. Redundancy requires a full set of duplicate modules (two INNIS01 modules and two INIIT12 modules on each network). The secondaryINIIT12 module continuously monitors the primary over dedicated Controlway. A failover occurs when the secondary module detects a primary module failure. When this happens, the secondary interface takes over and the primary interface is taken offline.INIIL02 Local InterfaceThe INIIL02 Local Interface consists of two INNIS01 Network Interface modules and the INIIT03 Local Transfer Module (Fig.3). This interface acts as a bridge between two local Cnets. One of the INNIS01 modules operates on the central network side and the other operates on the satellite net-work side. Bidirectional communication from the central network to the local satellite network is through cable connection to the NTCL01 termination unit. The maximum distance betweentermination units on the two communication networks is 45.8 meters (150feet).The local interface supports hardware redundancy. Redundancy requires a full set of duplicatemodules (four INNIS01 modules and two INIIT03 modules). The secondary INIIT03 module con-tinuously monitors the primary over dedicated Controlway. A failover occurs when the secondary detects a primary module failure. When this happens, the secondary assumes responsibility and the primary is taken offline.Cnet-to-HCU Communication InterfaceThe Harmony control unit interface consists of the INNIS01 Network Interface Module and the INNPM12 or INNPM11 Network Processing Module (Fig. 4). This interface can be used for a node on the central network or on a satellite network (Fig.1). Through this interface the Harmony con-trol unit has access to Cnet and to Controlway at the same time. Controlway is an internal cabinet communication bus between Harmony rack controllers and the communication interfacemodules.The HCU interface supports hardware redundancy. Redundancy requires a full set of duplicate modules (two INNIS01 modules and two INNPM12 or INNPM11 modules). The secondary net-work processing module (INNPM12 or INNPM11) continuously monitors the primary through a direct ribbon cable connection. A failover occurs when the secondary detects a primary module failure. When this happens, the secondary assumes responsibility and the primary is taken offline. Cnet-to-Computer Communication InterfaceThe Cnet-to-computer interfaces are the INICI03 and INICI12 interfaces. The INICI03 interfaceconsists of the INNIS01 Network Interface Module, the INICT03A Computer Transfer Module,and the IMMPI01 Multifunction Processor Interface Module (Fig. 5). The INICI12 interface con-sists of the INNIS01 Network Interface Module and the INICT12 Computer Transfer Module(Fig6).Harmony Rack CommunicationsFigure 4. Cnet-to-HCU InterfaceFigure 5. Cnet-to-Computer Interface (INICI03)Figure 6. Cnet-to-Computer Interface (INICI12)Harmony Rack CommunicationsA computer interface can be used for a node on the central network or on a satellite network (Fig.1). It gives a host computer access to point data over Cnet. The computer connects through either an RS-232-C serial link at rates up to 19.2 kilobaud or through a SCSI parallel port when using an INICI03 interface. The computer connects through an RS-232-C serial link at rates up to 19.2 kilobaud when using an INICI12 interface. Each interface is command driven through soft-ware on the host computer. It receives a command from the host computer, executes it, then replies to the host computer.Note: A workstation running Conductor VMS software does not use an INICI03 or INICI12 Cnet-to-Computer Interface but instead has its own dedicated version of the Cnet-to-computer interface (IIMCP02 and IIMLM01).Communication ModulesTable 1 lists the available Harmony rack communication modules. These modules, in certain combinations, create the various Cnet communication interfaces.Network Interface ModuleThe INNIS01 Network Interface Module is the front end for all the different Cnet communication interfaces. It is the intelligent link between a node and Cnet. The INNIS01 module works in con-junction with the transfer modules and the network processing module. This allows any node to communicate with any other node within the Symphony system.The INNIS01 module is a single printed circuit board that occupies one slot in the module mount-ing unit (MMU). The circuit board contains microprocessor based communication circuitry that enables it to directly communicate with the transfer modules and network processing module, and to interface to Cnet.The INNIS01 module connects to its Cnet communication network through a cable connected to an NTCL01 termination unit. Communication between nodes is through coaxial or twinaxial cables that connect to the termination units on each node.Cnet-to-Cnet Remote Transfer ModuleThe INIIT12 Remote Transfer Module supports bidirectional communication through twoRS-232-C ports. Port one passes system data only. Port two passes system data or can be used as a diagnostic port. The central network INIIT12 module can use a variety of means to link to the sat-ellite network INIIT12 module such as modems, microwave, and transceivers. The INIIT12Table 1. Harmony Rack Communication Modules ModuleDescription Cnet-to-Cnet Cnet-to-HCU Cnet-to-Computer INIIR01 INIIL02 INICI03INICI12 IMMPI01Multifunction processor interface •INICT03ACnet-to-computer transfer •INICT12Cnet-to-computer transfer •INIIT03Cnet-to-Cnet local transfer •INIIT12Cnet-to-Cnet remote transfer •INNIS01Network interface •••••INNPM11 or INNPM12Network processing•Harmony Rack Communicationsmodule directly communicates with an INNIS01 module. Many of the operating characteristics of the INIIT12 module are determined by function code202 (INIIT12 executive) specifications.The INIIT12 module is a single printed circuit board that occupies one slot in the module mount-ing unit. The circuit board contains microprocessor based communication circuitry that enables it to serially communicate with another INIIT12 module, to directly communicate with its INNIS01 module, and to interface to Controlway.The INIIT12 module connects through a cable to an NTMP01 termination unit. The two RS-232-C ports are located on the termination unit.Cnet-to-Cnet Local Transfer ModuleThe INIIT03 Local Transfer Module serves as the bridge between two local Cnet communication networks. It holds the node database and is responsible for transferring all messages between net-works. Messages include exception reports, configuration data, control data, and system status.This module directly communicates with the INNIS01 module of the central network and of the satellite network simultaneously.The INIIT03 module is a single printed circuit board that occupies one slot in the module mount-ing unit. The circuit board contains microprocessor based communication circuitry that enables it to directly communicate with its two INNIS01 modules and to interface to Controlway.Cnet-to-Computer Transfer ModuleThe INICT03A Computer Transfer Module and INICT12 Computer Transfer Module handle all communication with a host computer. These modules are command driven through software on the host computer. The module receives a command from the host computer, executes it, thenreplies. Its firmware enables the host computer to issue commands for data acquisition, process monitoring, and process control, and to perform system functions such as security, timesynchronization, status monitoring, and module configuration.The INICT03A and INICT12 modules are single printed circuit boards that occupy one slot in the module mounting unit. Their capabilities and computer connection methods differ. The INICT03A module can store up to 30,000 point definitions (depending on point types). The INICT12 module can store up to 10,000 point definitions.For the INICT03A module, the circuit board contains microprocessor based communication cir-cuitry that enables it to directly communicate with its INNIS01 module and to directlycommunicate with an IMMPI01 module. It communicates with the IMMPI01 module through a ribbon cable connection. The IMMPI01 module handles the actual host computer interface andsupports RS-232-C or SCSI serial communication.For the INICT12 module, the circuit board contains microprocessor based communication cir-cuitry that enables it to directly communicate with its INNIS01 module and to directlycommunicate with a host computer using RS-232-C serial communication. The module cable con-nects to an NTMP01 termination unit. Two RS-232-C ports are located on the termination unit. The NTMP01 jumper configuration determines DTE or DCE operation.Multifunction Processor Interface ModuleThe IMMPI01 Multifunction Processor Interface Module handles the I/O interface between thehost computer and the INICT03A Computer Transfer Module. The IMMPI01 module supportseither a SCSI or RS-232-C computer interface. When communicating through the RS-232-C port, the module can act as data communication equipment (DCE) or data terminal equipment (DTE).Harmony Rack Communications The IMMPI01 module is a single printed circuit board that occupies one slot in the module mount-ing unit. The circuit board contains microprocessor based communication circuitry that enables it to communicate with its INICT03A module through a ribbon cable connection.For RS-232-C computer interface, the module cable connects to an NTMP01 termination unit. Two RS-232-C ports are located on the termination unit. The NTMP01 jumper configuration determines DTE or DCE operation. The SCSI port is located at the module faceplate. In this case, notermination unit is required.Network Processing ModuleThe INNPM12 or INNPM11 Network Processing Module acts as a gateway between Cnet andControlway. The module holds the Harmony control unit database and handles the communica-tion between controllers residing on Controlway and the INNIS01 module.The INNPM12 or INNPM11 module is a single printed circuit board that occupies one slot in the module mounting unit. The circuit board contains microprocessor based communication circuitry that enables it to directly communicate with its INNIS01 module and to interface to Controlway.Rack Communications PowerHarmony rack communication modules are powered by 5, 15, and -15VDC logic power. Modular Power System II supplies the logic power. These operating voltages are distributed from thepower system through a system power bus bar mounted in the cabinet. A module mounting unit connects to this bus bar then routes the power to individual modules through backplaneconnectors.Rack Communications Mounting HardwareHarmony rack communication modules and their termination units mount in standard ABB cabi-nets. The option for small cabinet mounting is provided. The number of modules that can bemounted in a single cabinet varies. Modules of an interface are always mounted in adjacent slots.An IEMMU11, IEMMU12, IEMMU21, or IEMMU22 Module Mounting Unit and an NFTP01 Field Termination Panel are used for module and termination unit mounting respectively (Fig. 7). The mounting unit and termination panel both attach to standard 483-millimeter (19-inch) width side rails. Front mount and rear mount MMU versions are available to provide flexibility in cabinetmounting.A module mounting unit is required to mount and provide power to rack mounted modules. Theunit is for mounting Harmony rack controllers, I/O modules, and communication interfacemodules. The MMU backplane connects and routes:■Controlway.■I/O expander bus.■Logic power to rack modules.The Controlway and I/O expander bus are internal cabinet, communication buses. Communica-tion between rack controllers and HCU communication interface modules is over Controlway. The Cnet-to-Cnet interfaces use dedicated Controlway for redundancy communication. This dedicated Controlway is isolated from all other modules.Harmony Rack CommunicationsFigure 7. Rack I/O Mounting HardwareRelated DocumentsNumber Document TitleWBPEEUD250001??Harmony Rack Communications, Data SheetHarmony Rack Communications WBPEEUS250002C111Harmony Rack CommunicationsWBPEEUS250002C1Litho in U.S.A.May 2003Copyright © 2003 by ABB, All Rights Reserved® Registered Trademark of ABB.™ Trademark of ABB.For more information on the Control IT suiteofproducts,***************************.comFor the latest information on ABB visit us on the World Wide Web at /controlAutomation Technology Products Mannheim, Germany www.abb.de/processautomation email:*********************************.com Automation Technology ProductsWickliffe, Ohio, USA/processautomation email:****************************.com Automation Technology Products Västerås, Sweden /processautomation email:************************.com ™Composer, Control IT , and Symphony are trademarks of ABB.。
计算机通信与网络 课程资料 (2) Computer Security
Computer SecurityTwo main issues are current regarding security for computer communication systems •Data encryption•User authenticationEncryption and authentication between single users can be performed quite simply by ciphers and private keys etc.Once computer networks are involved the task takes on a new set of problems.•The number of possible users is huge.•Users with whom communication is required are often unknown.•The only communication path to the user is often the path that needs to be secured.We will firstly look at a block cipher technique (DES), then a public key algorithm (RSA)Data Encryption Standard (DES)This encryption system is of the conventional block cipher type.It has been certified by the US government and others as secure but not classified communications.It works on 64 bits of data at a time by using a 56 bit key.•The 64 bits of data are first permuted using a function.•This data is then permuted 16 times with subkey versions of the key which was also permuted on input.•After a 32 bit swap the data is permuted in the reverse of the initial function.•The sub keys are produced by a circular shift and a permutation.Concerns have been raised whether the S boxes are cryptographically strong.Another worry is the fact that there are only 256 (7.2 x 1016) possible keys.If a computer could try one key each microsecond it would take over 1000 years to try half the keys.Lots of money (parallel processing) can crack the key(Assuming you know the data when you see it)Plus development costsAn improvement over DES has been developed called Triple DESThis gives the system an effective key length of 112 bits thus improving the security.5.2 x 1033 combinations giving 8.2 x 1019 years to break at 1 microsecond per try for half the combinations.AuthenticationIf a message is encrypted then authentication is also performed when the message is correctly decoded. There are often times when we do not wish to encrypt but do need to authenticate the sender.•Sending a message to a large number of destinations. They would all have to have the same correct key or individual correct keys. This in itself is a security risk.•When high traffic at a destination means the time to decrypt all messages would beexcessive.•A code is produced from a key and the data to be sent•The code is appended to the data before sending•At the receive end the same procedure is performed•The code is comparedThis is similar to generating and checking a CRC on a data frame where the generating polynomial is kept secret.Hash FunctionsA hash function is a function that the data is passed through. It produces a code fingerprint identifying the data.H(x) = m H Hash functionx datam hash codeApart from being able to handle the size of data passed to it efficiently, it must •Have a one way property, ie you can generate the code from the data but not the data from the code. (Given m you can't find x)•Alternative messages with the same hash code cannot easily be found.(Can't find y ≠ x where H(x) = H(y)•Not easy to find two data sets with the same hash code(Can't find x & y where H(x) = H(y))A simple hash function is an XOR of the data arranged into blocks with the number of columns equal to the hash code sizec i=b i1⊕b i2⊕....⊕b imThis type of hash has no cryptographic strength itself.MD5MD5 is a very common function algorithm1.Data is padded to be 64 bits less than an integer multiple of 512 bits2.The 64 bits at the end are used to contain the length of the data (LSBs of it).3.Four buffers contain 128 bit, used to hold the hash code are initialised4. The data is then processed 512 bits at a timeThe data is broken up into 512 bit chunks and the MD5 algorithm appliedThe functions in the MD5 areX •Z)F(X,Y,Z)=(X•Y)+(′Z )G(X,Y,Z)=(X•Y)+(Y•′H(X,Y,Z)=X⊕Y⊕ZZ )I(X,Y,Z)=Y⊕(X+′5. The output from this is the 128 bit digestThe data is very well represented in the hash which produces a digest which satisfies the criteria for the hash.Before we look at public key encryption we should examine one more technique that is used very commonly. This is another algorithm for fast encryption of data for privacy.RC4 (Rivest's Cipher 4)RC4 is a symmetric key algorithm, but instead of operating on a block of bits at a time, it operates on a bitstream. It operates with a variable-length key up to 256 bits.This cipher has a 256-entry substitution-box, the entries are permutations of the numbers 0 through 255, and the particular permutation is a function of the key.To initialise the box first fill it linearly so that S0=0, S1=1, …, S255=255. Then fill another 256-byte array with the key, repeating the key as often as necessary to fill the whole array (K0, K1, …, K255).Set the index j = 0, then:For i = 0 to 255j = (j + S i + K i) mod 256swap S i and S jTo generate a byte for encryption, first take two counters (i and j) initialized to zero, then:i = ( i + 1) mod 256j = (j + S i) mod 256swap S i and S jt = (S i + S j) mod 256K = StThe byte K is then XORed with the plaintext to produce ciphertext, or XORed with the ciphertext to produce the plaintext.Encryption is about 10 times faster than DES in software.Public Key EncryptionThe system entails the generation of 2 keys for each participant•A public key which is placed in a register where anyone may get a copy of it•A private key that only the participant has access to•Either key can be used to encrypt the data.•The other key will then be used to decrypt it.•The heart of the system is the mathematical algorithm that generates the related key pair.•The cryptographic strength is related to the algorithm and the key length.•The system can be used for privacy and/or authenticationPublic key system for privacyPublic key system for authenticationRSA Public-Key Algorithm (Rivest, Shamir & Adleman)The system uses a block cipher for values < nFor Plaintext M and Ciphertext CC = M e modulo nM = C d modulo n = (M e)d modulo n = M ed modulo nBoth sender and receiver know n, the sender knows e and the receiver knows d. ThusK pub = K{e,n}K priv = K{d,n}•It is possible to find e, d & n such that M=M ed modulo n for all M < n •It is possible to calculate M e and C d for all M < n•It is not easy to find d given e and n when e and n are largeThe values for e, d and n need to be carefully chosen.Key generationSelect n as the product of two prime numbers p & qWe choose p = 11, q = 7 ( p and q might normally have 100's of digits)n = p x q = 11 x 7 = 77Now choose e where e is relatively prime to (p-1) x (q-1)(relatively prime means they have no common factors except 1)(p-1) x (q-1) = (11-1) x (7-1) = 10 x 6 = 60let us choose e = 7For d we must find a number where (e x d) -1 = 0 modulo (p-1) x (q-1)This means (e x d) -1 is evenly divisible by (p-1) x (q-1) = 60Choose d = 43(e x d) -1 = (7 x 43)-1 = 300(300 is divisible by 60)K pub = K{7,77}K priv = K{43,77}Encrypt a messageLets send a simple message containing the letters of the alphabet number 1-26. HELLO = 8, 5, 12, 12, 15(In real life we would send messages containing much more than one letter.) To encrypt we multiply out the message87modulo 77, 57modulo 77, 127modulo 77, 127modulo 77, 157modulo 77 =57, 47, 12, 12, 71Decrypt a message57, 47, 12, 12, 71is receivedRemember our keys wereK pub = K{7,77}K priv = K{43,77}We now raise these received numbers to 43rd power modulo 77.5743modulo 77, 4743modulo 77, 1243modulo 77, 1243modulo 77, 7143modulo 77 = 8, 5, 12, 12, 15= HELLOThe original message!!These calculations results in large numbers (especially if you try it on your calculator)Eg7143≈ 1079But it can be made simpler (computers can use this technique as well). Write it as a sum of powers of 27143 = 7132+8+2+1 = 7132 x 718 x 712 x 711Now 712 = 5041 = 36 modulo 77Similarly718 = (712)4 = 3647132 = (712)16 = 3616So7143 = 3616 x 364 x 36x 71 modulo 777143 = 3616 x 364 x 36x 71 modulo 77 We can continue further362 = 1296 = 64 modulo 77and so364 = (362)2 = 642 modulo 773616 = (362)8 = 648 modulo 77so7143 = 648 x 642 x 36x 71 modulo 77 continuing we get7143= 648 x 642 x 36x 71 modulo 77= 154 x 15x 36x 71 modulo 77= 712 x 15x 36x 71 modulo 77= 36x 15x 36x 71 modulo 77= 15 modulo 77= 15the correct answer.This encryption and authentication process works well when each partner has the appropriate keys.I can verify that it is you sending me data by using your public key. But how do I know the key that I am using is really YOUR public key and not the key of an imposter.If you send me a copy of it(a) I don't know it is you sending it(b) Someone may intercept it on the way and tamper with itTo solve these problems protocols have been developed.We will examine the most popular which is used for secure internet communications.SSL (Secure Socket Layer)This protocol was developed by Netscape for use in their WWW browser. It has since found use in many applications and is the present standard for secure WWW commerce (eCommerce) for all browsers (even IE4).It can•Authenticate the server to the client.•Allow the client and server to select the cryptographic algorithms that they both support.•Optionally authenticate the client to the server.•Use public-key encryption techniques to generate shared secrets.•Establish an encrypted SSL connection.Data from Netscape - /docs/manuals/security/sslin another good site is /rsalabs/faq/Strength category and recommended use Cipher suitesStrongest cipher suite.Permitted for deployment within the United States only. This cipher suite is appropriate for banks and other institutions that handle highly sensitive data.Cipher SuitesTriple DES, which supports 168-bit encryption,with SHA-1 message authentication. Triple DES is the strongest cipher supported by SSL, but it is not as fast as RC4. Triple DES uses a key three times as long as the key for standard DES. Because the key size is so large, there are more possible keys than for any other cipher--approximately 3.7 * 1050 . Both SSL 2.0 and SSL 3.0 support this cipher suite.SHA-1 is a Secure Hash Algorithm similar to MD5Strong cipher suites.Permitted for deployments within the United States only (now released to the world). These cipher suites support encryption that is strong enough for most business or government needs.RC4 with 128-bit encryption and MD5 message authentication. Because the RC4 and RC2 ciphers have 128-bit encryption, they are the second strongest next to Triple DES (Data Encryption Standard), with 168-bit encryption. RC4 and RC2 128-bit encryption permits approximately 3.4 * 1038 possible keys, making them very difficult to crack. RC4 ciphers are the fastest of the supported ciphers. Both SSL 2.0 and SSL 3.0 support this cipher suite.RC2 with 128-bit encryption . RC2 ciphers are slower than RC4 ciphers. This cipher suite is supported by SSL 2.0 but not by SSL 3.0. DES, which supports 56-bit encryption, with SHA-1 message authentication. DES is stronger than 40-bit encryption, but not as strong as 128-bit encryption. DES 56-bit encryption permits approximately 7.2 * 1016 possible keys. Both SSL 2.0 and SSL 3.0 support this cipher suite, except that SSL 2.0 uses MD5 rather than SHA-1 for message authentication.Exportable(old) (from US)cipher suites. These cipher suites are not as strong as those listed above, but may be exported to most countries (note that France permits them for SSL but not for S/MIME). They provide the strongest encryption available for exportable products.RC4 with 40-bit encryption and MD5 message authentication. RC4 40-bit encryption permits approximately 1.1 * 1012 (a trillion) possible keys. RC4 ciphers are the fastest of the supported ciphers. Both SSL 2.0 and SSL 3.0 support this cipher.RC2 with 40-bit encryption and MD5 message authentication. RC2 40-bit encryption permits approximately 1.1 * 1012 (a trillion) possible keys. RC2 ciphers are slower than the RC4 ciphers. Both SSL 2.0 and SSL 3.0 support this cipher.Weakest cipher suite.This cipher suite provides authentication and tamper detection but no encryption. Server administrators must be careful about enabling it, however, because data sent using this cipher suite is not encrypted and may be accessed by eavesdroppers.No encryption, MD5 message authentication only. This cipher suite uses MD5 message authentication to detect tampering. It is typically supported in case a client and server have none of the other ciphers in common. This cipher suite is supported by SSL 3.0 but not by SSL 2.0.The heart of SSL is the "handshake"1. The client contacts a secure web server (HTTPS) with SSL version, cipher settings, etc_________________________________________________________2. The server responds with its certificate and information about itself (SSL version, cipher settings etc)The client attempts to authenticate the server from the certificate it was sent. We need to see the contents of the certificate first.The certificate contains the servers public key plus information about the certificate including the distinguished name (DN) of the server.It also has the DN of an issueing Certifying Authority (CA) and a digital signature from this CA.A CA is a respected company or authority that deals in accrediting the identity of web server sites.Your web browser will already have certificates (containing public keys) from these CAs and more may be added.The correct public key for the CA who signed the server's certificate is used to authenticate the digital signature (which was encrypted using the CA's private key).If the expected DN of the server is revealed then the certificate must be authentic. This therefore forms a letter of introduction, for the server, from the CA.For full authentication the client must verify•Is the date of the certificate valid•Is the CA a trusted CA•Does the CA's public key validate the digital signature•Does the domain name in the server's DN match the domain name the certificate was sent from. (This is to prevent a "man-in-the-middle" attack)3. The client now uses the public key of the server to encrypt a "premaster secret" which it sends to the server.If the server has requested client authentication the client will also send its certificate containing its public key to the server. The server will perform authentication on the clients certificate._________________________________________________________4. The server takes the premaster secret from the client and performs a number of steps with it to create a "master secret". The client also does the same thing. Now both server and client have the same shared master secret._________________________________________________________5. Server and client both create a session key from the master secret6. Both server and client send messages to each other saying that the handshake is complete. Further communication is now conducted using a symetric key cipher (RC4 for example, 40 bits or 128 bits, or another supported cipher.)Symetric key ciphers are much faster than public key encryption.Public key encryption must use a very large key to achieve crytpographic strength. (Typically more than 500 bits) This makes it slow for general data encryption.CertificatesCertificates used in SSL conform to the X.509 certificate standard.Certificate:Data:Version: v3 (0x2)Serial Number: 3 (0x3)Signature Algorithm: PKCS #1 MD5 With RSA EncryptionIssuer: OU=Ace Certificate Authority,O=Ace Industry, C=USValidity:Not Before: Fri Oct 17 18:36:25 1997Not After: Sun Oct 17 18:36:25 1999 Subject: CN=Jane Doe, OU=Finance, O=Ace Industry, C=USSubject Public Key Info:Algorithm: PKCS #1 RSA EncryptionPublic Key:Modulus:00:ca:fa:79:98:8f:19:f8:d7:de:e4:49:80:48: e6:2a:2a:86:ed:27:40:4d:86:b3:05:c0:01:bb: 50:15:c9:de:dc:85:19:22:43:7d:45:6d:71:4e: 17:3d:f0:36:4b:5b:7f:a8:51:a3:a1:00:98:ce: 7f:47:50:2c:93:36:7c:01:6e:cb:89:06:41:72: b5:e9:73:49:38:76:ef:b6:8f:ac:49:bb:63:0f: 9b:ff:16:2a:e3:0e:9d:3b:af:ce:9a:3e:48:65: de:96:61:d5:0a:11:2a:a2:80:b0:7d:d8:99:cb: 0c:99:34:c9:ab:25:06:a8:31:ad:8c:4b:aa:54:91:f4:15Public Exponent: 65537 (0x10001) Extensions:Identifier: Certificate TypeCritical: noCertified Usage:SSL ClientIdentifier: Authority Key Identifier Critical: noKey Identifier:f2:f2:06:59:90:18:47:51:f5:89:33:5a:31:7a: e6:5c:fb:36:26:c9Signature:Algorithm: PKCS #1 MD5 With RSA Encryption Signature:6d:23:af:f3:d3:b6:7a:df:90:df:cd:7e:18:6c: 01:69:8e:54:65:fc:06:30:43:34:d1:63:1f:06: 7d:c3:40:a8:2a:82:c1:a4:83:2a:fb:2e:8f:fb: f0:6d:ff:75:a3:78:f7:52:47:46:62:97:1d:d9: c6:11:0a:02:a2:e0:cc:2a:75:6c:8b:b6:9b:87: 00:7d:7c:84:76:79:ba:f8:b4:d2:62:58:c3:c5: b6:c1:43:ac:63:44:42:fd:af:c8:0f:2f:38:85: 6d:d6:59:e8:41:42:a5:4a:e5:26:38:ff:32:78: a1:38:f1:ed:dc:0d:31:d1:b0:6d:67:e9:46:a8: dd:c4CA verification is often performed in a hierarchical chainThe chain must be authenticated until a trusted CA is found in the browser certificate database.。
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Solution is a communications network
Simplified Network Model
Wide Area Networks
Large geographical area Crossing public rights of ways Rely in part on common carrier circuits Alternative technologies
No fundamental diferences
LAN、MAN、WAN
A Communications Model
Source
generates data to be transmitted
Converts data into transmittable signals Carries data Converts received signal into data Takes incoming data & process
Data processing equipment
Data communication equipment
Data communication Voice communication
Video communication Single-processor computer Multi-processor computer
Semantics（语义）
Timing（定时）
Characteristics of protocols
Direct/Indirect Monolithic/Structured Symmetric/asymmetric Standard/nonstandard
Protocol Architecture
Data Communication
Wide Area Networks
Local Area Networks
Networking Protocols
Chapter 1 introduction
Computer science 1970s ~ 1980s Data communication merge
Transmitter
Transmission System
Receiver
Destination
பைடு நூலகம்
Simplified Communications Model - Diagram
Key Communications Tasks
Transmission System Utilization Interfacing Signal Generation Synchronization Exchange Management Error detection and correction Addressing and routing Recovery Message formatting Security Network Management
Task of communication broken up into modules For example file transfer could use three modules
File transfer application Communication service module Network access module
Simplified Data Communications Model
Networking
Point to point communication not usually practical
Devices are too far apart Large set of devices would need impractical number of connections
Systems
Entity and System Model
entity
Network
entity
system
system
Key Elements of a Protocol
Syntax（语法）
Data formats Signal levels Control information Error handling Speed matching Sequencing
Destination SAP Sequence number Error detection code
This gives a transport protocol data unit
Simplified File Transfer Architecture
A Three Layer Model
Network Access Layer Transport Layer Application Layer
Network Access Layer
Exchange of data between the computer and the network Sending computer provides address of destination May invoke levels of service Dependent on type of network used (LAN, packet switched etc.)
Integrated Services Digital Network
ISDN Designed to replace public telecom system Wide variety of services Entirely digital domain
Local Area Networks
Packet Switching
Data sent out of sequence Small chunks (packets) of data at a time Packets passed from node to node between source and destination Used for terminal to computer and computer to computer communications Unreliable communications No fixed connection Time delay is long
Asynchronous Transfer Mode
ATM Evolution of frame relay Little overhead for error control Fixed packet (called cell) length Anything from 10Mbps to Gbps Constant data rate using packet switching technique
Transport Layer
Reliable data exchange Independent of network being used Independent of application
Application Layer
Support for different user applications e.g. e-mail, file transfer
Data and Computer Communications
Chapter 1 Introduction
The main topics of this book:
Data communication
Exchange of data between two directly Connected devices Transmission interfacing data link control multiplexing WAN LAN
Net connection
Protocol
Protocol architecture
PLAN OF THE TEXT
Overview
Introduction of the topics Discussion of protocols Exchange of data/transmission/interfacing/link control/multiplexing Switching technologies (packet switching/circuit switching/ATM) Congestion control Transmission media Topologies Medium access control protocols Specific standardized LAN systems Protocol architecture
Frame Relay
Packet switching systems have large overheads to compensate for errors Modern systems are more reliable Errors can be caught in end system Most overhead for error control is stripped out
Smaller scope
Building or small campus
Usually owned by same organization as attached devices Data rates much higher Usually broadcast systems Now some switched systems and ATM are being introduced