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通信英语强化训练试题（一）
Ⅰ 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, occupying
C. 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, locate
C. 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, choosing
C. 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, when
C. 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 identify
C. specified, identified D. 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 call
C. 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 receive
C. transmitting，receiving D. 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，used
C. find, use D. be found, using
( )10. Traditionally，the idle state _________the mark level. By convention this corresponds _________a logical 1 level.
A. is referred to, as B. is referred as, in
C, is referred to as, to D. 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, still B. placed，since
C. placing, until D. placing，because
( )12. When the data link connects a CRT terminal _________a computer，_________problems arise, as the terminal is itself character oriented.
A. into, many B. on，a few
C. in, a few D. to，few
( )13. _________the receiving end of a synchronous serial data link，the receiver continually monitors the line _________a start bit.
A. On，looking B. Within，look for
C. In, look at D. 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, exist B. using, existing
C. to use, to exist D. 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, understand B. viewing, understanding
C. viewed, understood D. to view, to understand
( )16. The transport layer segments data from the _________host’s system and reassembles the data into a data stream on the _________host’s system.
A. sending, receiving B. to send, to receive
C. sent, received D. 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, across B. at, in
C. between, in D. across, with
Ⅱ 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 host's system
44. connection-oriented circuits
45. information flow control
46. network topology
47. network media access
48. electrical specification
49. maximum transmission distance
Ⅲ 短语汉译英：(Translate the following phrases into English)
1. 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. 反复率
8. 编码过程
9. 模拟信号
10. 传播质量
11. 数字通信
12. 数字传播
13. 含噪声旳环境
14. 传播路由
15. 信噪比
16. 信号电平
17. 地面系统
18. 噪声功率
19. 二进制传播
20. 反向操作
21. 8位码序列
22. 接受端
23. 帧格式
24. 同步字
25. 串行接口
26. 显示终端
27. 发送器与接受器
28. 数据传播
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秒旳持续时间
36. 奇偶校验位
37. 错误标志
38. 传播错误
39. 下降沿
40. 符号间旳空格
41. 接受机旳定期
42. 当地时钟
43. 磁带
44. 控制比特
45. 逻辑1电平
46. 二进制数据
47. 明显旳缺陷
48. 联网技术
49. 国际原则化组织
50. 参照模型
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. 表达层
57. 传播层
58. 数据链路层
59. 网络服务
60. 文献接入
61. 数据格式
62. 主机
63. 协议
64. 连接
65. 逻辑选址
Ⅳ 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
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