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2021年4月自考通信英語02368真題與答案

注意事項:

1.本試卷分為兩部分,第一部分為選擇題,第二部分為非選擇題。

2.應考者必須按試題順序在答題卡(紙)指定位置上作答,答在試卷上無效。

3.涂寫部分、畫圖部分必須使用2B鉛筆,書寫部分必須使用黑色字跡簽字筆。

一、單項選擇題:本大題共20小題,每小題1分,共20分。在每小題列出的備選項中只有一項是最符合題目要求的,請將其選出。

1. Each voice channel has a separate coder, the unit      ▲     converts sampled amplitude values to a set of pulses.

A. who

B. when

C. where

D. that

2. This interface is so called because the      ▲     data and the received data are not synchronized over any extended period.

A. transmit

B. to transmit

C. transmitting

D. transmitted

3. Alternative examples may be found within terrestrial systems where, although the message signal is strong,      ▲      the noise power.

A. such is

B. so is

C. asis

D. also is

4. Services might also include processes, software, or hardware      ▲     servers, such as support for specialized terminal emulations in a LAN to a mainframe link.

A. other than

B. similar to

C. remote from

D. independent of

5. If somebody else had something interesting stored on their computer, it was a simple matter

a copy.

A. to obtain

B. obtained

C. obtaining

D. obtain .

6. The fibres were fragile, and a way to protect them would have

A. found

B. find

C. to be found

D. finding 

7. Typically, in existing networks, simple point-to-point transmission technology is used      ▲      the network switches or customer locations.

A. link

B. to link

C. linking

D. linked

www.zikaosw.cn

8. DXC devices are classified      ▲     their line interface and switching level.

A. in way of

B. in terms of

C. under the group of

D. in the forms of

9. Two Ethernets, for example, would be linked with a bridge      ▲     a gateway

A. differently from B. other

C. rather than

D. more than

10. The television broadcasting service starts at 41 MHz and      ▲     up to 960 MHz. 

A. extends

B. continues

C. lengthens

D. develops

11. The ideal mobile telephone system would operate within a limited assigned frequency band and would serve an almost unlimited number of users in      ▲     

areas.

A. limited

B. limiting

C. unlimited

D. unlimiting

12. The use of digital radio transmission and the advanced handover algorithms between radio cells in GSM networks allows for significantly better frequency usage      ▲     in analogue cellular systems, thus increasing the number of subscribers that can be served.

A. that ，

B. which

C. the

D. than

13. ATM transfers information in short packets called“cells" with a fixed length of      ▲     bytes plus five header bytes.

A.38

B.43

C.48

D.53

14. A telex network_ ▲telex information. i. e. messages of characters, transported at very low speed.

A. transports

B. transported

C. to transport●D. transporting

15. The CD-ROM

to store data that represents visual imagery and current units can store up to 650 M bytes of data.

A. use

B. used

C. using

D. is used

16. To reiterate, a centralized network is one      ▲     primary computing is accomplished at a single site with all remote stations feeding into that site.

A. in whom

B. which .

C. in which

D. that

17. Similarly, the introduction of voice encoding techniques using pulse code modulation contributed      ▲     the concept's evolution.

A. on

B. to

C. with 

D.soasto

18. Each network is only capable of transporting one specific service for▲ it was intentionally designed.

A. which

B. one

C. where

D. when

19. Designers have found it convenient      ▲     these nodes into a hierarchy or tree topology, consisting of five classes of switching centers or nodes.

A. organization

B. organize

C. to organize 

D. organized

20. As more and more forms of information can be converted to digital form, the amount of available to Internet users continues to grow.

A. which

B. stuff

C. the

D. that

二、閱讀理解題:本大題共20小題,每小題1.5分,共30分。在每小題列出的備選項中只有一項是最符合題目要求的,請將其選出。

Passage 1

Since data signals are rarely in suitable form for transmission over the various types of transmission facilities， a signal coding process is normally performed. Ideally， the transmission medium should have linear attenuation and delay characteristics， but this is never so in practice, and transmission impairments are always present to disturb the data signals. As a comparison, in voice communications a high degree of transmission irregularities can be tolerated. If a voice circuit has a heavy loss or is noisy, the speakers compensate automatically by increasing the intensity of their voices. If words are missed because of transmission difficulties， they are often understood anyway because of the redundant nature of speech. In contrast, there is no inherent redundancy in data signals unless purposely inserted and, therefore, transmission variations can only be compensated for over a very small range. In addition, data signals are sensitive to other transmission impairments which have little effect on speech.

Coding is undertaken to alleviate transmission irregularities, to increase the information capacity of the system, to enable error detection, and to provide message security. The coding process in the data transmitter simply rearranges the applied data machine signals into some other format. At the receiving end the reverse processing (decoding) is performed to recover the original machine signals.

21. The reason a signal coding process is normally performed is that      ▲     .

A. the transmission medium has linear attenuation characteristics

B. the transmission facilities are always suitable

C. data signals in suitable form for transmission are to be made

D. the data signals are rarely present

22. A high degree of transmission irregularities can be tolerated in voice communications because

A. the transmission is difficult

B. speakers can increase the intensity of their voices

C. a voice circuit is noisy

D. the speakers ignore the difficulties in transmission

23. In data signals, transmission variation can be compensated for over a very small range, because

A. there is no inherent redundancy in data signals

B. data signals have little effect on speech

C. other transmission impairments are sensitive to data signals

24. Which of the following statements is NOT true?

A. Coding is used to make more transmission regularities.

B. Coding can provide message security.

C. Coding is able to detect errors.

D. Coding creates the information quantity of the system.

25. The decoding process in the data receiver

A. simply rearranges the data into some other format

B. is the same processing performed in the data transmitter

C. produces the same data machine signals as was applied to the transmitter

D. recovers the original machine signals to some other format

Passage 2

Although the technological barriers appeared formidable, the economic potential was very significant. As a consequence, research and development activity expanded rapidly, and a number of important issues were resolved during the early 1970s.

During the middle and late 1970s， the rate of progress toward marketable products accelerated as the emphasis shifted from research to engineering. Fibres with losses approaching the Rayleigh limit of 2 dB/km at a wavelength of 0.8 μm, 0.3 dB/km at 1.3 μm, andO.15 dB/km at 1. 55 μm, were produced in the laboratory. Microbend loss problems were overcome through the use of improved fibre coatings and cabling techniques. Rugged cables and multifibre connectors were produced for field installation. Room temperature threshold currents for commercial gallium aluminum arsenide (GaAlAs) lasers operating in the 0.8 to 0.85 μm spectral region were reduced to the 20 to 30 mA range, and projected lifetimes in the 100 000 to 1 000 000 hour range were claimed for both lasers and LEDs. Light sources and improved photodetectors which operated near 1.3 μm were developed to take advantage Of the low fibre loss and dispersion in this“longer wavelength region”. Several major field trials  were undertaken during this period, including AT & T's Atlanta experiment (1976) and Chicago installation(1977), and Japan's subscriber access project(1997).

26. Research and development activity expanded rapidly during the early 1970s because

A. the technological barriers were formidable

B. the economic potential was very significant

C. a number of important issues were resolved

D. the fibre technology was developed rapidly

27. Which makes the rate of progress toward marketable products accelerate during the 1970s?

A. Fibres were produced in the laboratory.

B. The researchers put the emphasis on engineering.

C. The losses were limited at 2 dB/km.

D. The problems of the fibre losses were overcome.

28. In the passage, the minimum Rayleigh limit is at a wavelength of      ▲     μm. .

A.0.3

B.0.8

C.1.3

D. 1.55

29. Room temperature threshold currents for GaALAs lasers can be reduced to the

range

A.from0.8to0.85μm

B. from 100 000 to 1 000 000 hours

C.from20to30mA.

D. from 1976 to 1977

30.      ▲     operating near 1.3 μm may be of low loss and dispersion.

A. Fibres

B. Lasers and LEDs

C. Light sources

D. Photodetectors

Passage 3

Any communication system which can provide customers with means to communicate from any place, at any time and at any distance gives social and economic advantages. This capability does not exist in many parts of the world. Assuming that it existed, such a system would be limited by the availability of the called person. This person may not be close to his telephone when he/she is called. Urgent communications ( police, firemen, hospitais.etc) which could not be established because of no reply at one end of the link could have dramatic consequences if the delay in response is too long or if the call remain unanswered. It is therefore essential to provide the person with a means to communicate. The operation of a communication network needs, for this reason,to be complemented by a messaging system (one-way or two-way) which can offer either an additional facility in the case of a sophisticated network or a primary communication means when the wired and mobile telephone network are embryonic and do not cover a whole territory.

31. Any communication system which can provide customers with means to communicate      ▲     .

A. does not exist

B. could have dramatic consequences

C. is embryonic

D. gives social and economic advantages

32. The underlined phrase“called person" refers to the person      ▲     .

A. who is calling others

B. who is mentioned by others

C. who is the originating subscriber

D. who is being called

33. This person may NOT be close to his      ▲     when he is called.

A. premises

B. telephone

C. terminal

D. access

34. The underlined phrase" sophisticated”

means      ▲     

A. computer

B. simple

C. complex

D. sample

35. Which of the following is NOT the reason mentioned here that fails urgent communications?

A. The call remains unanswered.

B. No reply at one end of the link.

C. Dramatic consequences.

D. The delay in response is too long.

Passage 4

By far the largest circuit-switched network is the public telecommunications network- the telephone network. This is actually a collection of national networks interconnected to form an international service. Although originally designed and implemented to service analog telephone subscribers, it handles substantial data traffic via modem, and is gradually being converted to a digital network.

The public telecommunications network, as with any communications network, can be described using four generic architectural components.

●Stations generally denoted as subscribers, these are the devices that attach to the  network. Interfaces the interface between the stations and the network, referred to in the phone system as the local loop.

●Nodes the switching centers in the network.

●Links

the branches between nodes, referred to as trunks.

Most of the subscribers on the network are telephones. The telephone contains a transmitter and receiver for converting back and forth between analog voice ( sound waves) and analog ( voice-frequency) electrical signals. With the introduction of the digital data system (DDS), some subscribers that transmit digital signals have been incorporated into the network.

The local loop is a pair of wires, generally twisted pair, that connects a subscriber to one of the nodes in the network. The local loop generally covers a distance of a few kilometers to a few tens of kilometers at most.

36. The public telecommunications network can be described      ▲     

A. using twisted pair of wires

B. using many thousands of subscribers

C. using four generic architectural components

D. using switching nodes

37. With the introduction of digital data system, some subscribers that     ▲      have been

incorporated into the network.

A. can provide video service

B. transmit broadband program

C. contain a transmitter and receiver

D. transmit digital signals

38. The telephone converts back and forth between analog voice and      ▲     .

A. analog electrical signals

B. digital signals

C. sound wave

D. digital data

39. The telephone network is originally designed and implemented to service      ▲     .

A. celphone subscribers

B. analog telephone subscribers

C. Internet user

D. TV user .

40. By far the largest circuit-switched network is      ▲      .

A. the mobile network

B. the Internet

C. the public telecommunications network

D. ATM

三、中譯英:本大題共5小題,每小題2分,共10分。請將下列詞或詞組譯成英語。

41.國際漫游

42.頻譜

43.抖動

44.空間站

45.凈負荷

四、英譯中:本大題共10小題,每小題1分,共10分。請將下列詞或詞組譯成漢語。

46. user interface

47. multimode fibre

48. Digital Cross-connect

49. carrier

50. signal processing nodes

51. interactive environment

52. underground cable

53. short message service

54. destination address

55. Asynchronous Transfer Mode

五、翻譯題:本大題共3小題,每小題10分,共30分。請將下列各段英文譯成漢語。

56. The goal of your use of the Internet is exchanging messages or obtaining information. What you need to know is that you can exchange message with other computers on the Internet and use your computer as a remote terminal on distant computers. But the internal details of the link are less important, as long as it works. If you connect computers together on a network, each computer must have a unique address, which could be either a word or a number. For example, the address of Sam's computer could be Sam, or a number. .

57. Air-to-ground systems use 118 to 136 MHz; military aircraft use 225 to 400 MHz. The maritime mobile service is located in the vicinity of 160 MHz. Also fixedstation services are allocated portions of the 30 to 100 MHz band. Therefore, it was hard for the FCC to  allocate a spectrum in the lower portions of the 30 to 400 MHz band since the services of this band had become so crowded. On the other hand, mobile radio transmission cannot be applied at 10 GHz or above because severe propagation path loss, multipath fading, and rain activity make the medium improper for mobile communications.

58. The first characteristic is achieved when a signal is digitally encoded to overcome degradation due to the transmission medium. As regards economy, early studies suggested that digital services offered significant advantages since a substantial quantity of interface equipment in the telephone exchange could be eliminated. Finally, digital service also provides flexibility in the transmission of voice, data, video, and other services with equal

ease. These new digital services were beginning to increase substantially in the early 70s but their potential growth was stunted by bandwidth limitations inherent in a 4 kHz voice channel which characterized the, analogue transmission and exchange facilities typical of that time.