北京邮电大学通信英语教材ppt课件.ppt

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1、UNIT 1,同位语跟在所修饰的名词之后，可表示相同的事物或人，也可对该名词进行说明。同位语与所修饰的名词之间可以用各种标点符号隔开，这时同位语可以对标点符号前的整个句子进行说明。,PCM is dependent on three separate operations, sampling, quantizing, and coding.,Substances fall into three groups: conductors, semiconductors and insulators.,The laser is able to amplify light one unique prop

2、erty.,(9 -4) can only be applied provided that the unsaturated gain coefficient exceeds the losses , a necessary requirement for oscillation.,这里列举了同位语位于句尾，修饰最后一个名词或整个句子的情况。还有其它的情况，课文中遇到时在讲。,介词短语 for doing something 作后置定语，表示目的，意思为用于的。,Schemes for performing these three functions have evolved, and sha

3、ll describe the main ones.,algorithms for decoding received signals,这里的 ones 是代词, 避免重复。,A working equation expresses the unknown quantity in terms of the known ones.,These equations are called differential equations, and now their study forms one of the most challenging branches of mathematics.,We s

4、hall see how a speech channel be conveyed as a series of amplitude values, each value being represented as a sequence of 8 binary digits.,分词短语出现在句尾，用逗号隔开，表示伴随情况说明，非常常见。,这时分词短语的逻辑主语经常省略。,被省略的逻辑主语多数情况下指的是主句的主语或逗号前整个句子的含义，点也有少数列外。具体情况以后结合课文讲解。,It is that (which, when, who) 强调句型，如,It is the document tha

5、t is very important.It was Faraday who first discovered electromagnetic induction.,known as the signal-to-noise ratio 过去分词短语作后置定语，常见，译为 称之为。,of the most interest to , 对最感兴趣的of interest = interesting of importance = important,名词逗号同位语+逗号 进行说明,An American, Edison, invented the first small electric lamp

6、.,g, the acceleration of gravity at the earths surface, has the value 32 ft/sec2.,正是数字传输为克服这种噪声环境提供了一种有力的方法。数字传输正是对于克服这种噪声环境提供了一种有力的方法。最高频率为3.4kHz的话音信号是用64kHz的信号来表示的，这是一个我们昨天所学的事实。编码器是将采样幅值转换成一组脉冲的单元，它对数字传输是非常重要的。编码的问题是一个极为重要的问题。PCM这个术语是一个通信术语。每采样值8位（码）的重复速率比4位的重复速率高。话音信号是一个模拟信号，通过采样、量化和编码，我们可以实现话音信

7、号的数字传输。,汉译英练习：（除第8题外每题只用一个谓语动词）,正是数字传输为克服这种噪声环境提供了一种有力的方法。It is digital transmission that provides a powerful method for overcoming the noisy environment.数字传输正是为克服这种噪声环境提供了一种有力的方法。 It is for overcoming the noisy environment that digital transmission provides a powerful method.最高频率为3.4kHz的话音信号是用64kHz

8、的信号来表示的，这是一个我们昨天所学的事实。The speech signal of maximum frequency 3.4kHz has been represented by a signal of frequency 64 kHz, a fact that we learned yesterday.,编码器是将采样幅值转换成一组脉冲的单元，它对数字传输是非常重要的。The coder, a unit that converts amplitude values to a set of pulses, is very important to digital transmission.

9、编码的问题是一个极为重要的问题。The problem of coding is a very important one.PCM这个术语是一个通信术语。The term PCM is a communications one.,每采样值8位（码）的重复速率比4位的重复速率高。The repetition rate of 8-digits per sample value is higher than that of 4-digits.话音信号是一个模拟信号，通过采样、量化和编码，我们可以实现话音信号的数字传输。The speech signal is a analog one, and we

10、 can perform its digital transmission by sampling, quantizing and coding.,UNIT 2,部分否定与完全否定：对于集合中的个体，否定动词为部分否定，否定名词为完全否定。,Instruments here are not good.,这里的仪器并非都是好的。,No instruments here are good.,这里的所有仪器都不是好的。,All the data are not to be checked.,None of the data are to be checked.,所有的数据都不核对。,并非所有数据都要

11、核对。,Both the transistors on the table are not good. 桌子上两个晶体管并不都是好的。Neither of the transistors on the table are good.桌子上两个晶体管都不是好的。,并列复合句中的省略：在并列复合句中，后一复合句中与前一复合句相重复的部分可以省略。Matters consist of molecules and molecules of atoms.The earth attracts the moon and the moon the earth. The meter is the standar

12、d for length, the gram for weights.Electrons are injected into the P region, and holes into the N region.,samples the next N bits at their centers, using a clock,using a clock generated locally by the receiver,严格的语法修饰：,分词作定语,单个分词作定语，位于所修饰名词之前。分词短语作定语，位于所修饰名词之后。 moving electrons electrons moving with

13、in the wire the applied voltage the voltage applied across the resistance (易加修饰） the voltage applied by the circuit across the resistance to amplify the incoming signal used method （不易加修饰） commonly used method the most commonly used method,英译汉练习：（要求用本课所学句型翻译）字符中的比特位并非全部用于表示数据。所有起始位都不被设定为信号电平。我们将字符的起

14、始位设置成空号电平，而将字符的终止位设置成信号电平。在计算机与其显示终端之间最为常见的串行接口是异步串行接口，而在程控交换机与其电话终端之间最为常见的串行接口是同步串行接口。由发送器所送出的停止位总是被设置成信号电平。现在我们来考虑一个包含12比特的字符。PCM是用以将模拟信号转换成数字信号的一种重要方法。,字符中的比特位并非全部用于表示数据。All bits of a characters are not used to represent data.所有起始位都不被设定为信号电平。No (None of) start bits are placed in the mark level.我们

15、将字符的起始位设置成空号电平，而将字符的终止位设置成信号电平。The start bit of a character is placed in the space level, and the stop bit the mark level.,在计算机与其显示终端之间最为常见的串行接口是异步串行接口，而在电路交换机与其电话终端之间最为常见的串行接口是同步串行接口。By far the most popular serial interface between a computer and its CRT terminal is the asynchronous serial interfac

16、e, and between a circuit switch and its telephone terminal, the synchronous one. 由发送器所送出的停止位总是被设置成信号电平。Stop bit send by transmitters are always placed in the mark level.,现在我们来考虑一个包含8个信息比特加4个控制比特的字符。Now consider a character consisting of 8 information bit plus 4 control bits.PCM是用以将模拟信号转换成数字信号的一种重要方法

17、。PCM is a important method used to convert an analog signal into a digital one.,UNIT 3,形容词短语作后置定语： a form suitable for transmission over these facilities.,常见的有：suitable for , similar to , capable of , different from , available to , able to (do ), necessary to (do ), a LSI chips available to the des

18、ign engineer motion parallel to the earths surface a quantity greater than any number something as small as a worm,插入语,插入语与其他部分没有直接语法关系，一般有逗号隔开，但也可以没有。插入语位置不定，位于句首或主语之后较为常见。Even worse, a preface may resemble an advertisement for the text.Well-grounded students can absorb Chapters 4 and 5 in say thre

19、e weeks.What, you may wonder, does 54/74 stand for?The author concentrated on what he thought he could do best.,编者主要集中在他认为他能写得最好的那些内容上。,We could apply these two vectors, which it will be noticed are in polar form, to any network characteristic.,我们可以把这两种矢量应用于任何网络特性，而读者会注意到，这两种矢量均为极坐标形式。,插入语主要起承上启下的作用

20、或表示作者的态度。Conversely, substances of small resistivity are good conductors.This device consists in fact of five parts.Who made the first generator in the world, then?An increase in temperature, though, tends to make a gas expand.Roughly speaking, microwaves are radio waves whose wavelength is less tha

21、n 30 cm.Velocity, we have noted before, is a vector quantity.A few kiloohms will, I believe, be enough.,常用的插入语有： 一般来说，general speaking,更为重要的是，more important,最为重要的是，the most important, 人们断言，it has been claimed,我们将会看到，it will be noticed, we can see,我认为，I believe,确实，it is true,我们认为，we think,倒装句,Among t

22、he experiments to be conducted is a search for Martian lifeIn the drawing are another pair of similar right triangles.Before long, out came the water.There exists a very important relationship between current, voltage and resistance.There has been developed a method for producing vastly more powerfu

23、l rays.Orbiting the nucleus are negatively charged particles called electrons.,英译汉练习These forces act on the electrons able to move freely within the wire.The more the spring is stretched, the greater is the force necessary to stretch it.Neutron has a mass slightly larger than that of a proton.In the

24、 measurement of time intervals much shorter than a second, the decimal system is used.A method of timing accurate to millionths of a second is necessary.An effect similar to post-deflection（后偏转） acceleration could, it is true, be achieved by increasing the voltage on the second anode（阳极）.,Figure 3-5

25、 pictures an addition of velocities that our common sense tells us must be right.Electrical inventors who followed Edison did not have to experiment with the substances which, he had found, would not work. For several years after radio was invented it existed in the form of radio telegraphy. Then ca

26、me radio telephony.Also plotted on Fig. 1 are some allowable operating bands for several systems.There is thus set up a transverse strain（应力） in addition to the longitudinal（纵向的） strain.Only when x is 5 is it true that 3x+12=27.,UNIT 4,take: 需要，It takes two men to do this. 做这项工作需要两个人。 what it would

27、take to survive a nuclear war 避免核战争所需要的 for 短语为 to survive 的逻辑主语 by doing sth 为 to survive 的装语,要求后置定语的名词,something, anything, everything, nothing; somebody, anybody, everybody, nobody; someone, anyone, everyone, no one 等Everything electronic will be done digitally.In what follows we shall learn that

28、 there is nothing mysterious.There is something peculiar that should be noted about the left side of the graph.Coherent oscillators are nothing new.,单个分词作后置定语的情况,the departments concerned, 有关各方，The greater the force applied, the greater the acceleration.Each of the terms omitted was very small.The l

29、ine shown is the least-squares line.The measurement made is very accurate.The work done can be expressed as follows.Hydrogen is the lightest element known.The assumption made will affect the type of series obtained.,UNIT 5,不及物动词的名词化,A动词（不及物）介词B,名词of+A+介词B,Fiber emerge as a industry.,the emergence of

30、 fiber as a industry ,y vary with x.,the variation of y with x ,The response of a body to a net force F is an acceleration a proportional to F.,The actions of certain chemical solutions on metals sets up an e.m.f.,(act on),(respond to),We have discussed the passage of an electric current through liq

31、uid solutions of acids.,(pass through),及物动词的名词化,动词A介词B,名词ofA介词B,use fibre for interconnecting central offices,The use of fibre for interconnecting central offices is increasing rapidly.,A comparison of Eq.(4) with Eq.(5) leads to this relations,compare Eq.(4) with Eq.(5),The resolution of a force in

32、to x and y components is possible. (resolve A into B)Extensions of some of the theorems which follow, to this kind of series, are mentioned in Exercise 15. (extend A to B),在指出主语时用by: 名词（动词转化）ofAby逻辑主语The discovery of the Periodic Table by Mendeleev in 1869 suggested another way of estimating atomic

33、masses.,形容词作状语,With the help of a computer, this machine can work unattended.Most of the -particles went through the foil unchanged in direction.The signal waveform is transmitted undistorted so long as the instantaneous amplitude remains smaller than the bias voltages.In the absence of any friction

34、, the pulse started by the hand in Fig. 8-1 would continue down the rope undiminished.,介词短语作表语,The MKS system is also in common use.One of the most valuable ways of representing functions is by graphical representation.This digital computer is for laboratory use.The root is between 0.23 and 0.24.These controllers are not without other disadvantages.The usefulness of logarithms in advanced mathematics remains of great importance.,