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1、1 通信英语综合练习题（即课后练习题）（第一章）一请将下述词组译成英文: 抽样量化与编码话路幅值抽样频率抽样速率脉冲流重复率编码过程模拟信号传输质量数字通信数字传输含噪声的环境传输路由信噪比信号电平地面系统噪声功率二进制传输反向操作8 位码序列接收端帧格式同步字二请将下述词组译成中文：1. the schemes for performing these three functions 2. the series of amplitude values 3. the speech channel of telephone quality 4. the sequence of 8-binary
2、digits 5. the minimum theoretical sampling frequency 6. the voice channel occupying the range 300 Hz to 3.4 kHz 7. the 8-digits per sample value 8. the sparking of a car ignition system 9. the stream of the pulses with a repetition rate of 64 kHz 10. the relationship of the true signal to the noise
3、signal 11. the signal received from a satellite 12. the complete information about a particular message 13. the shape of the transmitted signal 14. the attenuation introduced by transmission path 15. the unit that converts sampled amplitude value to a set of pulses 16. the sequence relating to chann
4、el 1,2 and so on 17. the unique sequence of pulses called synchronization word 18. the terrestrial system 19. the presence or absence of the pulse 20. the high-speed electronic switch 21. the time division multiplexer 22. the Time Division Multiplexing 五请将下述短文译成中文：1. If we consider binary transmissi
5、on, the complete information about a particular message will always be obtained by simply detecting the presence or absence of the pulse. By comparison, most other forms of transmission systems convey the message information using the shape, or level of the transmitted signal; parameters that are mo
6、st easily affected by the noise and attenuation introduced by the transmission path. Consequently there is an inherent advantage for overcoming noisy environments by choosing digital transmission. 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 1 页，共 4 页 - - - - - - -
7、 - - 2 2. The reader may ask, how does the demultiplexer know which group of 8-digits relates to channel 1, 2, and so on? Clearly this is important! The problem is easily overcome by specifying a frame format, where at the start of each frame a unique sequence of pulses called the frame code, or syn
8、chronization word, is placed so as to identify the start of the frame. A circuit of the demultiplexer is arranged to detect the synchronization word, and thereby it knows that the next group of 8-digits corresponds to channel 1. 3 Noise can be introduced into transmission path in many different ways
9、; perhaps via a nearby lightning strike, the sparking of a car ignition system, or the thermal low-level noise within the communication equipment itself. It is the relationship of the true signal to the noise signal, known as the signal-to-noise ratio, which is of most interest to the communication
10、engineer. 4 Basically, if the signal is very large compared to the noise level, then a perfect message can take place; however, this is not always the case. For example, the signal received from a satellite, located in far outer space, is very week and is at a level only slightly above that of the n
11、oise. Alternative examples may be found within terrestrial systems where, although the message signal is strong, so is the noise power. 5So far we have assumed that each voice channel has a separate coder, the unit that converts sampled amplitude values to a set of pulses; and decoder, the unit that
12、 performs the reverse operation. This need not be so, and systems are in operation where a single codec is shared between 24, 30, or even 120 separate channels. 6A high-speed electronic switch is used to present the analog information signal of each channel, taken in tern, to the codec. The codec is
13、 then arranged to sequentially sample the amplitude value, and code this value into the 8-digit sequence. Thus the output to the codec may be seen as a sequence of 8 pulses relating to channel 1, then channel 2, and so on. This unit is called a time division multiplexer. （第九章）一. 请将下述词组译成英文: 个人通信通信标准
14、固定电话业务网络容量移动交换中心国际漫游宽带业务接口转换频谱分配模拟方式蜂窝通信原理拥塞蜂窝裂变基站移动交换中心寄存器收费功能接入方法突发脉冲传输方式开销信息切换算法短消息服务技术规范二. 请将下述词组译成中文： 1. the total access communication system 2. the global mobile communication system 3. the time division multiple access 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - -
15、 - - 第 2 页，共 4 页 - - - - - - - - - 3 4. the facsimile and short message service 5. the fixed communication networks 6. the more personalized system 7. the cost and quality of the link 8. the market growth 9. the fixed telephone service 10. the coaxial cable 11. the interface conversion 12. the cellu
16、lar communication principle 13. the frequency reuse and cell splitting 14. the cochannel interference 15. the theoretical spectral capability 16. the micro-cellular system 17. the base station transceiver 18. the subscriber register 19. the burst transmission mode 20. the overhead information 21. th
17、e advanced handover algorithms 22. the facsimile and short message service 23. the GSM technical specifications 五请将下述短文译成中文：1. The success of mobile systems across the world is a sign that communication is moving towards a more personalized, convenient system. People who have to use a mobile phone o
18、n business soon begin to realize that the ability to phone any time, any place in ones personal life rapidly becomes a necessity, not a convenience. 2. The fixed telephone service is global and the interconnection varies from coaxial cable to optical fiber and satellite. The national standards are d
19、ifferent, but with common interfaces and interface conversion, interconnection can take place. For mobile the problem is far more complex, with the need to roam creating a need for complex networks and systems. Thus in mobile the question of standards is far more crucial to success than fixed system
20、s. 3. The GSM system is based on a cellular communications principle which was first proposed as a concept in the 1940s by Bell System engineers in the US. The idea came out of the need to increase network capacity and got round the fact that broadcast mobile networks, operating in densely populated
21、 areas, could be jammed by a very small number of simultaneous calls. The power of the cellular system was that it allowed frequency reuse. 4. The cellular concept is defined by two features, frequency reuse and cell splitting. Frequency reuse comes into play by using radio channels on the same freq
22、uency in coverage areas that are far enough apart not to cause cochannel interference. This allows handling of simultaneous calls that exceed the theoretical spectral capacity. Cell splitting is necessary when 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 3 页，共 4 页
23、- - - - - - - - - 4 the traffic demand on a cell has reached the maximum and the cell is then derived into a micro-cellular system. 5. The cell coverage area is controlled by a base station which is itself made up of two elements. The first element is the transmission system which communicates out t
24、o the mobile and also receives information from it to set up and maintain calls when actually in operation. The base station transceiver is controlled by the base station controller, which communicates with the mobile switching center- the essential link to the local public switched telephone networ
25、k, and to the subscriber data which is stored in registers within the system. 6. The GSM system operates in a burst transmission mode with 124 radio channels in the 900 MHz band, and these bursts can carry different types of information. The first type of information is speech, which is coded at 6.5
26、 kbit/s or 13 kbit/s. The second type is data, which can be sent at 3.6 kbit/s, 6 kbit/s or 12.6 kbit/s. These two forms of information are the useful part of the transmission, but have to be supported by overhead information which is sent in control channels. 7. The use of digital radio transmissio
27、n and the advanced handover algorithms between radio cells in GSM networks allows for significantly better frequently usage than in analogue cellular systems, thus increasing the number of subscribers that can be served. Since GSM provides common standard, cellular subscribers will also be able to u
28、se their telephones over the entire GSM service area. Roaming is fully automatic between and within all countries covered by GSM system. 8. In addition to international roaming, GSM provides new user services, such as high speed data communication, Facsimile and short message service. The GSM techni
29、cal specifications are designed to work in concert with other standards, e.g. ISDN. Interworking between the standards is in this way assured. In the long term perspective cellular systems, using a digital technology, will become the universal method of telecommunication. 通信英语综合练习题答案说明：由于通信英语的综合练习题全部选自教材中第一、九单元的课后练习，而这些练习又都出自课文，所以可在课文中查找答案，这里就不再给出答案。特此说明。名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 4 页，共 4 页 - - - - - - - - -