电子信息工程专业英语翻译清华出版社English-for-IT-and-EE-04.上课讲义.ppt

电子信息工程专业英语翻译清华出版社English-for-IT-and-EE-04.信息科学与电子工程专业英语Part ITelecommunication New Wordssemaphore semaphore 旗语旗语旗语旗语heliograph heliograph 日光仪日光仪日光仪日光仪revenue revenue 收入，税收收入，税收收入，税收收入，税收gross product gross product 总产值，总产量总产值，总产量总产值，总产量总产值，总产量transceiver transceiver 收发器收发器收发器收发器degrade degrade 退化，降级退化，降级退化，降级退化，降级threshold threshold 阈值，上限，下限阈值，上限，下限阈值，上限，下限阈值，上限，下限 intact intact 完好的，完整的完好的，完整的完好的，完整的完好的，完整的router router 路由器路由器路由器路由器switch switch 交换器，交换交换器，交换交换器，交换交换器，交换repeater repeater 中继器，转发器中继器，转发器中继器，转发器中继器，转发器combat combat 抗击抗击抗击抗击attenuation attenuation 衰减衰减衰减衰减render render 表示，表现，再现表示，表现，再现表示，表现，再现表示，表现，再现indistinguishable indistinguishable 难以分辨的难以分辨的难以分辨的难以分辨的allocate allocate 分派分派分派分派recur recur 复发，再发生复发，再发生复发，再发生复发，再发生keying keying 键控键控键控键控(法法法法)superimpose superimpose 叠加，重叠叠加，重叠叠加，重叠叠加，重叠DJ(DJ(disk jockey)disk jockey)播音员，节目主持播音员，节目主持播音员，节目主持播音员，节目主持21Telecommunication is the transmission of signals over a Telecommunication is the transmission of signals over a distance for the purpose of communication.distance for the purpose of communication.In modern times,In modern times,this process typically involves the sending of electromagnetic this process typically involves the sending of electromagnetic waves by electronic transmitters,but waves by electronic transmitters,but in earlier times in earlier times telecommunication may have involved the use of smoke telecommunication may have involved the use of smoke signals,drums or semaphore or heliograph.signals,drums or semaphore or heliograph.在早期远程通信包括使用烟火在早期远程通信包括使用烟火在早期远程通信包括使用烟火在早期远程通信包括使用烟火信号，鼓或旗语或日光仪信号，鼓或旗语或日光仪信号，鼓或旗语或日光仪信号，鼓或旗语或日光仪31Today,telecommunication is widespread and devices that Today,telecommunication is widespread and devices that assist the process such as television,radio and telephone are assist the process such as television,radio and telephone are common in many parts of the world.There are also many common in many parts of the world.There are also many networks that connect these devices,including computer networks that connect these devices,including computer networks,public telephone networks,radio networks and networks,public telephone networks,radio networks and television networks.Computer communication across the television networks.Computer communication across the Internet is one of many examples of telecommunication.Internet is one of many examples of telecommunication.42Telecommunication systems are generally designed by Telecommunication systems are generally designed by telecommunication engineers.Early inventors in the field telecommunication engineers.Early inventors in the field include Alexander Graham Bell,Guglielmo Marconi and John include Alexander Graham Bell,Guglielmo Marconi and John Logie Baird.Logie Baird.Telecommunication is an important part of the Telecommunication is an important part of the world economy with the telecommunication industrys world economy with the telecommunication industrys revenue being placed at just under 3 percent of the gross revenue being placed at just under 3 percent of the gross world product.world product.通信在当今世界经济中起着举足轻重的通信在当今世界经济中起着举足轻重的通信在当今世界经济中起着举足轻重的通信在当今世界经济中起着举足轻重的作用，通信产业的财政收入占总产值的作用，通信产业的财政收入占总产值的作用，通信产业的财政收入占总产值的作用，通信产业的财政收入占总产值的比例已接近百分之三。比例已接近百分之三。比例已接近百分之三。比例已接近百分之三。53 Basic elements Each telecommunication system consists of three basic Each telecommunication system consists of three basic elements:a transmitter that takes information and converts it elements:a transmitter that takes information and converts it to a signal,a transmission medium to a signal,a transmission medium over whichover which the signal is the signal is transmitted,and a receiver that receives the signal and transmitted,and a receiver that receives the signal and converts it converts it back intoback into usable information.usable information.64Consider a radio broadcast for example.The broadcast tower Consider a radio broadcast for example.The broadcast tower is the transmitter,the radio is the receiver and the is the transmitter,the radio is the receiver and the transmission medium is free space.Often telecommunication transmission medium is free space.Often telecommunication systems are two-way,and a single device acts as both a systems are two-way,and a single device acts as both a transmitter and receiver,or transceiver.For example,a mobile transmitter and receiver,or transceiver.For example,a mobile phone is a transceiver.phone is a transceiver.75Telecommunication over a phone line is called point-to-point Telecommunication over a phone line is called point-to-point communication because it is between one transmitter and one communication because it is between one transmitter and one receiver.Telecommunication through radio broadcasts is receiver.Telecommunication through radio broadcasts is called broadcast(or point-to-multipoint)communication called broadcast(or point-to-multipoint)communication because it is between one powerful transmitter and numerous because it is between one powerful transmitter and numerous receivers.receivers.86 Analogue or digitalSignals can either be analogue or digital.In an analogue Signals can either be analogue or digital.In an analogue signal,signal,the signal is varied continuously with respect to the the signal is varied continuously with respect to the information.information.In a digital signal,the information is encoded as In a digital signal,the information is encoded as a set of discrete values(for example,ones and zeros).a set of discrete values(for example,ones and zeros).信号根据（要传输的）信号根据（要传输的）信号根据（要传输的）信号根据（要传输的）信息而连续变化。信息而连续变化。信息而连续变化。信息而连续变化。96During transmission,the information contained in analogue During transmission,the information contained in analogue signals will be degraded by noise.signals will be degraded by noise.Conversely,unless the noise Conversely,unless the noise exceeds a certain threshold,the information contained in exceeds a certain threshold,the information contained in digital signals will remain intact.digital signals will remain intact.This represents a key This represents a key advantage of digital signals over analogue signals.advantage of digital signals over analogue signals.相反，只要噪声不超过一定的阈值，相反，只要噪声不超过一定的阈值，相反，只要噪声不超过一定的阈值，相反，只要噪声不超过一定的阈值，数字信号中的信息是不会丢失的。数字信号中的信息是不会丢失的。数字信号中的信息是不会丢失的。数字信号中的信息是不会丢失的。107 NetworksA collection of transmitters,receivers or transceivers that A collection of transmitters,receivers or transceivers that communicate with each other is known as a municate with each other is known as a network.Digital Digital networks may consist of one or more routers that route data to networks may consist of one or more routers that route data to the correct user.An analogue network may consist of one or the correct user.An analogue network may consist of one or more switches that establish a connection between two or more switches that establish a connection between two or more users.more users.1 1数字网络由一个或多个路由器组成，路由器数字网络由一个或多个路由器组成，路由器数字网络由一个或多个路由器组成，路由器数字网络由一个或多个路由器组成，路由器正确地将数据发送给用户。模拟网路由一个正确地将数据发送给用户。模拟网路由一个正确地将数据发送给用户。模拟网路由一个正确地将数据发送给用户。模拟网路由一个或多个交换器组成，交换器在两个或多个用或多个交换器组成，交换器在两个或多个用或多个交换器组成，交换器在两个或多个用或多个交换器组成，交换器在两个或多个用户间建立连接。户间建立连接。户间建立连接。户间建立连接。117For both types of network,repeaters may be necessary to For both types of network,repeaters may be necessary to amplify or recreate the signal when it is being transmitted amplify or recreate the signal when it is being transmitted over long distances.over long distances.This is to combat attenuation that can This is to combat attenuation that can render the signal indistinguishable from noise.render the signal indistinguishable from noise.2 2（中继器）用来抗击衰减，再现（中继器）用来抗击衰减，再现（中继器）用来抗击衰减，再现（中继器）用来抗击衰减，再现噪声中难以分辨的信号。噪声中难以分辨的信号。噪声中难以分辨的信号。噪声中难以分辨的信号。128 ChannelsA channel is a division in a transmission medium so that it can A channel is a division in a transmission medium so that it can be used to send multiple streams of information.be used to send multiple streams of information.3 3信道在传输媒介中分隔区域，以用于信道在传输媒介中分隔区域，以用于信道在传输媒介中分隔区域，以用于信道在传输媒介中分隔区域，以用于使传输媒介传送多个信息流。使传输媒介传送多个信息流。使传输媒介传送多个信息流。使传输媒介传送多个信息流。138 For example,a radio station may broadcast at 96 MHz while For example,a radio station may broadcast at 96 MHz while another radio station may broadcast at 94.5 MHz.In this case,another radio station may broadcast at 94.5 MHz.In this case,the medium is divided by frequency and each channel receives the medium is divided by frequency and each channel receives a separate frequency to broadcast on.a separate frequency to broadcast on.148Alternatively,one could allocate each channel a recurring Alternatively,one could allocate each channel a recurring segment of time over which to broadcast this is known as segment of time over which to broadcast this is known as time-division multiplexing and is sometimes used in digital time-division multiplexing and is sometimes used in digital munication.4 4另一种方法是给每个信道分配重复的时间段，另一种方法是给每个信道分配重复的时间段，另一种方法是给每个信道分配重复的时间段，另一种方法是给每个信道分配重复的时间段，在这种时间段中进行广播，称为时分多路技在这种时间段中进行广播，称为时分多路技在这种时间段中进行广播，称为时分多路技在这种时间段中进行广播，称为时分多路技术，有时用于数字通信中。术，有时用于数字通信中。术，有时用于数字通信中。术，有时用于数字通信中。159 ModulationThe shaping of a signal to convey information is known as The shaping of a signal to convey information is known as modulation.modulation.Modulation can be used to represent a digital Modulation can be used to represent a digital message as an analogue waveform.This is known as keying message as an analogue waveform.This is known as keying and several keying techniques exist(these include phase-shift and several keying techniques exist(these include phase-shift keying,frequency-shift keying and amplitude-shift keying).keying,frequency-shift keying and amplitude-shift keying).Bluetooth,for example,uses phase-shift keying to exchange Bluetooth,for example,uses phase-shift keying to exchange information between devices.information between devices.传输信息的信号的传输信息的信号的传输信息的信号的传输信息的信号的形成称为调制。形成称为调制。形成称为调制。形成称为调制。例如，蓝牙就是通过相移键控例如，蓝牙就是通过相移键控例如，蓝牙就是通过相移键控例如，蓝牙就是通过相移键控在不同设备之间交换信息的。在不同设备之间交换信息的。在不同设备之间交换信息的。在不同设备之间交换信息的。1610Modulation can also be used to transmit the information of Modulation can also be used to transmit the information of analogue signals at higher frequencies.This is helpful because analogue signals at higher frequencies.This is helpful because low-frequency analogue signals cannot be effectively low-frequency analogue signals cannot be effectively transmitted over free space.transmitted over free space.Hence the information from a Hence the information from a low-frequency analogue signal must be superimposed on a low-frequency analogue signal must be superimposed on a higher-frequency signal(known as a carrier wave)before higher-frequency signal(known as a carrier wave)before transmission.transmission.所以低频模拟信号中的信息在发送所以低频模拟信号中的信息在发送所以低频模拟信号中的信息在发送所以低频模拟信号中的信息在发送之前必须叠加在高频载波上。之前必须叠加在高频载波上。之前必须叠加在高频载波上。之前必须叠加在高频载波上。1710There are several different modulation schemes available to There are several different modulation schemes available to achieve this(two of the most basic being amplitude achieve this(two of the most basic being amplitude modulation and frequency modulation).modulation and frequency modulation).An example of this An example of this process in action is a DJs voice being superimposed on a 96 process in action is a DJs voice being superimposed on a 96 MHz carrier wave using frequency modulationMHz carrier wave using frequency modulation(the voice (the voice would then be received on a radio as the channel“96 FM”).would then be received on a radio as the channel“96 FM”).例如，电台主持人的声音就是通过频率例如，电台主持人的声音就是通过频率例如，电台主持人的声音就是通过频率例如，电台主持人的声音就是通过频率调制加载在调制加载在调制加载在调制加载在96 MHz 96 MHz 的载波上发送的的载波上发送的的载波上发送的的载波上发送的 18信息科学与电子工程专业英语Part II Data Transmission New Wordsconveyance conveyance 运送，运输运送，运输运送，运输运送，运输courier courier 信使，送急件的人信使，送急件的人信使，送急件的人信使，送急件的人bonfire bonfire 篝火篝火篝火篝火Morse code Morse code 莫尔斯电码莫尔斯电码莫尔斯电码莫尔斯电码optical fiber optical fiber 光纤光纤光纤光纤laser laser 激光激光激光激光infra-red infra-red 红外线的，红外线红外线的，红外线红外线的，红外线红外线的，红外线browser browser 浏览器浏览器浏览器浏览器legible legible 可识别的可识别的可识别的可识别的,清楚的清楚的清楚的清楚的favor favor 支持支持支持支持serial serial 串行串行串行串行parity parity 奇偶性奇偶性奇偶性奇偶性parallel parallel 并行并行并行并行asynchronous asynchronous 异步异步异步异步signify signify 告知，预示告知，预示告知，预示告知，预示intermittently intermittently 间歇地间歇地间歇地间歇地bold bold 黑体的，粗体的黑体的，粗体的黑体的，粗体的黑体的，粗体的synchronous synchronous 同步同步同步同步handshaking handshaking 握手握手握手握手baud baud 波特波特波特波特201Data transmission is the conveyance of any kind of Data transmission is the conveyance of any kind of information from one space to another.Historically this could information from one space to another.Historically this could be done by a courier,a chain of bonfires or semaphores,and be done by a courier,a chain of bonfires or semaphores,and later by later by Morse code over copper wiresMorse code over copper wires.通过铜质导线传输通过铜质导线传输通过铜质导线传输通过铜质导线传输莫尔斯电码莫尔斯电码莫尔斯电码莫尔斯电码212In recent computer terms,it means sending a stream of bits or In recent computer terms,it means sending a stream of bits or bytes from one location to another using any number of bytes from one location to another using any number of technologies,such as copper wire,optical fiber,laser,radio,or technologies,such as copper wire,optical fiber,laser,radio,or infra-red light.infra-red light.Practical examples include moving data from Practical examples include moving data from one storage device to another and accessing a website,which one storage device to another and accessing a website,which involves data transfer from web servers to a users browser.involves data transfer from web servers to a users browser.实际的应用包括数据在不同存储设备之间实际的应用包括数据在不同存储设备之间实际的应用包括数据在不同存储设备之间实际的应用包括数据在不同存储设备之间的传输及网络连接，网络连接实现数据在的传输及网络连接，网络连接实现数据在的传输及网络连接，网络连接实现数据在的传输及网络连接，网络连接实现数据在网络服务商和用户浏览器之间的传送。网络服务商和用户浏览器之间的传送。网络服务商和用户浏览器之间的传送。网络服务商和用户浏览器之间的传送。223A related concept to data transmission is the data transmission A related concept to data transmission is the data transmission protocol used to make the data transfer legible.Current protocol used to make the data transfer legible.Current protocols favor packet based communication.protocols favor packet based communication.与数据传输有关的一个概念是数据传输与数据传输有关的一个概念是数据传输与数据传输有关的一个概念是数据传输与数据传输有关的一个概念是数据传输协议，使得传输的数据清晰可懂。目前协议，使得传输的数据清晰可懂。目前协议，使得传输的数据清晰可懂。目前协议，使得传输的数据清晰可懂。目前协议都支持基于分组的网络通信。协议都支持基于分组的网络通信。协议都支持基于分组的网络通信。协议都支持基于分组的网络通信。234 Types of data transmissionSerial transmission:Bits are sent over a single wire Serial transmission:Bits are sent over a single wire individually.individually.WhilstWhilst only one bit is sent at a time,high transfer only one bit is sent at a time,high transfer rates are possible.rates are possible.This can be used over longer distances as a This can be used over longer distances as a check digit or parity bit can be sent along it easily.check digit or parity bit can be sent along it easily.尽管一次只传送一个比特，仍可尽管一次只传送一个比特，仍可尽管一次只传送一个比特，仍可尽管一次只传送一个比特，仍可实现很高的传输速率。实现很高的传输速率。实现很高的传输速率。实现很高的传输速率。245Parallel transmission:Multiple wires are used to transmit bits Parallel transmission:Multip