高级通信工程师考试复习题.doc

通信英语强化训练试题（一） 单项选择题：(Choose the best one)( )1. Furthermore, we shall prove that a minimum theoretical sampling frequency of order 6. 8 kHz is required _a voice channel _the range 300Hz to 3. 4 kHz.A. convey, occupy B. to convey, occupyingC. conveying, occupied D. convey, to occupy( )2. For example, the signal _from a satellite, _in far outer space, is very weak.A. received, located B. receive, locateC. receiving, locating D. to receive, to locate( )3. If we consider binary transmission, the complete information about a particular message will always _by simply _the presence or absence of the pulse.A. obtain, detect B. be obtained, detecting C. obtained, detected D. obtaining, detected( )4. 4. There is an inherent advantage for _noisy environments by _digital transmission.A. overcoming, choose B. overcome, choosingC. overcome, choose D. overcoming, choosing( )5. Each voice channel has a separate coder，the unit _converts sampled amplitude values to a set of pulses; And decoder, the unit _performs the reverse operation.A. who, who B. when, whenC. where, where D. that, that( )6. The problem is easily overcome by _a frame format, where at the start of each frame a unique sequence of pulses is placed _the start of the frame.A. specify, identify B. specifying, so as to identifyC. specified, identifiedD. specify, identifying( )7. An asynchronous serial data link is said _character oriented，as information is transmitted in the form of groups of bits _characters.A. be，calling B. to being，to callC. been，call D. to be，called( )8. This interface is so called because the _data and the _data are not synchronized over any extended period.A. transmit，receive B. to transmit，to receiveC. transmitting，receivingD. transmitted，received( )9. Serial data transmission systems _in the telephone，Morse code, and even the smoke signals once _by native Americans.A. are finding，using B. are found，usedC. find, useD. be found, using( )10. Traditionally，the idle state _the mark level. By convention this corresponds _a logical 1 level.A. is referred to, asB. is referred as, inC, is referred to as, toD. is referred，within( )11. The transmitter then sends the character，1 bit at a time，by _each successive bit on the line for a duration of T seconds, _all bits have been transmitted.A. place, stillB. placed，sinceC. placing, untilD. placing，because( )12. When the data link connects a CRT terminal _a computer，_problems arise, as the terminal is itself character oriented.A. into, manyB. on，a fewC. in, a fewD. to，few( )13. _the receiving end of a synchronous serial data link，the receiver continually monitors the line _a start bit.A. On，lookingB. Within，look forC. In, look atD. At，looking for( )14. As companies realized they could save money and gain productivity by _networking technology, they added networks and expanded _networks almost as rapidly as new network technologies and products could be introduced.A. use, existB. using, existingC. to use, to existD. used, existed( )15. The OSI reference model allows you _the network functions that occur at each layer. More importantly, the OSI reference model is a framework you can use _how information travels throughout a network.A. view, understandB. viewing, understandingC. viewed, understoodD. to view, to understand( )16. The transport layer segments data from the _hosts system and reassembles the data into a data stream on the _hosts system.A. sending, receivingB. to send, to receiveC. sent, receivedD. send, receive( )17. The data link layer provides the transit of data _a physical link. In so doing, the data link layer is concerned _physical addressing, network topology, network media access, and error detection.A. with, acrossB. at, inC. between, inD. across, with 短语英译汉：(Translate the following phrases into Chinese)1. the schemes for performing these three functions 2. a series of amplitude values 3. a speech channel of telephone quality 4. a sequence of 8-binary digits 5. a minimum theoretical sampling frequency 6. a voice channel occupying the range 300 Hz to 3. 4 kHz 7. 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 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. a sequence relating to channel 1,2 and so on 17. a unique sequence of pulses called synchronization word 18. terrestrial system 19. the presence or absence of the pulse 20. a high-speed electronic switch 21. the time division multiplexer 22. Time Division Multiplexing 23. asynchronous serial data transmission 24. the most popular serial interface 25. the transmitted data 26. the clocks at the transmitter and receiver 27. the era of teleprinter 28. the dots and dashes of a character 29. three times the duration of intersymbol space 30. the group of bits called characters 31. the invariable units comprising 7 or 8 bits of information 32. a clock generated locally by the receiver 33. the received parity bit following the character 34. the falling edge of the start bit 35. the character-oriented nature of the data link 36. networking technology 37. proprietary networking system 38. the International Organization for Standardization 39. compatibility between the various types of networks 40. seven numbered layers 41. standardization of network components 42. error recovery 43. receiving hosts system 44. connection-oriented circuits 45. information flow control 46. network topology 47. network media access 48. electrical specification 49. maximum transmission distance 短语汉译英：(Translate the following phrases into English)141. 抽样量化与编码 2. 话路 3. 幅值 4. 抽样频率 5. 抽样速率 6. 脉冲流 7. 重复率 8. 编码过程 9. 模拟信号 10. 传输质量 11. 数字通信 12. 数字传输 13. 含噪声的环境 14. 传输路由 15. 信噪比 16. 信号电平 17. 地面系统 18. 噪声功率 19. 二进制传输 20. 反向操作 21. 8位码序列 22. 接收端 23. 帧格式 24. 同步字 25. 串行接口 26. 显示终端 27. 发送器与接收器 28. 数据传输 29. 数据流 30. 闲置状态 31. 传号电平 32. 空号电平 33. 起始位 34. 停止位 35. T秒的持续时间 36. 奇偶校验位 37. 错误标志 38. 传输错误 39. 下降沿 40. 符号间的空格 41. 接收机的定时 42. 本地时钟 43. 磁带 44. 控制比特 45. 逻辑1电平 46. 二进制数据 47. 明显的缺点 48. 联网技术 49. 国际标准化组织 50. 参考模型 51. 数据分组 52. 应用程序 53. 网络媒体 54. 分层 55. 硬件和软件 56. 表示层 57. 传输层 58. 数据链路层 59. 网络服务 60. 文件接入 61. 数据格式 62. 主机 63. 协议 64. 连接 65. 逻辑选址 请将下述短文译成中文（短文英译汉）：(Translate the following passages into Chinese)1. If we consider binary transmission, 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 system convey the message information using the shape, or level of the transmitted signal; parameters that are most 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.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 synchronization 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; 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 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 weak and is at a level only slightly above that of the noise. Alternative examples may be. Found within terrestrial systems where, although the message signal is strong, so is the noise power.5. So 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 performs the reverse operation. This need not be so, and systems are in operation where a single codes is shared between 24, 30, or even 120 separate channels.6. A high-speed electronic switch is used to present the analog information signal of each channel, taken in turn, to the codec. The codec is 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.7. An asynchronous serial data link is said to be character-oriented, as information is transmitted in the form of groups called characters. These characters are invariable units comprising 7 or 8 bits of information plus 2 to 4 control bits and frequently correspond to ASCII-encoded characters. Initially, when no information is being transmitted, the line is in an idle state. The idle state is referred to as the mark level and corresponds to a logical 1 level.8. When the transmitter wishes to send data, it first places the line in a space level for one element period. The transmitter then sends the character, 1 bit at a time, by placing each successive bit on the line for a duration of T seconds, until all bits have been transmitted. Then a single parity bit is calculated by the transmitter and sent after the data bits. Finally, the transmitter sends a stop bit at a mark level for one or two bit period.9. At the receiving end of an asynchronous serial data link, the receiver continually monitors the line looking for a start bit. Once the start bit has been detected, the receiver waits until the end of the start bit and then samples the next N bits at their centers, using a clock generated locally by the receiver. As each incoming bit is sampled, it is used to construct a new character.10. The most obvious disadvantage of asynchronous data transmission is the need for a start, parity, and stop bit for each transmitted character. If 7 bit characters are used, the overall efficiency is only 70 percent. A less obvious disadvantage is due to the character-oriented nature of the data link. Whenever the data link connects a CRT terminal to a computer, few problems arise, as the terminal is itself character oriented. 11. The most critical aspect of the system is the receiver timing. The falling edge of the start bit triggers the receivers local clock, which samples each incoming bit at its nominal center. Suppose the receiver clock waits T/2 seconds from the falling edge of a start bit and samples the incoming data every T seconds thereafter until the stop bit has been sampled. As the receivers clock is not synchronized with the transmitter clock, the sampling is not exact.12. By far the most popular serial interface between a computer and its CRT terminal is the asynchronous serial interface. This interface is so called because the transmitted data and the received data are not synchronized over any extended period and therefore no special means of synchronizing the clocks at the transmitter and receiver is necessary. In fact, the asynchronous serial data link is a very old form of data transmission system and has its origin in the era of the teleprinter.13. Most computer terminals transmit and receive ASCII characters, and we know that the ASCII characters require 7 bits. Therefore, 7 bits of data plus a parity bit are sent each time a character is transmitted or received by the terminal. The two most obvious ways to send the characters are by parallel transmission or by serial transmission. Most terminals have been designed to transmit and receive ASCII characters as serial data.14. The early development of LANs, MANs, and WANs was chaotic in many ways. The early 1980s saw tremendous increases in the numbers and sizes of networks. As companies realized they could save money and gain productivity by using networking technology, they added networks and expanded existing networks almost as rapidly as new network technologies and products could be introduced.15. Proprietary systems are privately developed, owned, and controlled. In the computer industry, proprietary is the opposite of open. Proprietary means that one or a small group of companies controls all usage and evolution of the technology. Open means that free usage of the technology is available to the public.16. The OSI reference model allows you to view the network functions that occur at each layer. More importantly, the OSI reference model is a framework you can use to understand how information travels throughout a network. In addition, the OSI reference model can be used to visualize how information, or data packets, travels from application programs, through a network medium, to other application programs that are located in another computer on a network, even if the sender and the receiver have different types of network media.17. The application layer is the OSI layer that is closest to the user. It pro