.


:




:

































 

 

 

 


IV.




13. require a)

14. transmitter b)

15. increase c)

16. encrypt d)

e)

V. , :

17. Compatible hardware platforms:

a) c ;

b) c ;

c) ;

d) .

18. Open Systems Interconnection architecture:

a) ;

b) ;

) ;

d) .

19. A particular operating system complexity:

a) ;

b) ;

) ;

d) .

20. Networks access requirements:

a) ;

b) ;

c) ;

d) .

 

VI. , :

21. Some digital communications networks contain one or more routers to transmit information to the correct user.

a) , .

b) .

c) .

d) , .

22. Modulation can also be used to transmit information of low-frequency analog signals at higher frequencies.

a) , , .

b) , .

c) .

d) .

23. Consumers are demanding a better user experience along with more advanced and useful applications on a more ergonomic device.

a) .

b) .

c) .

d) .

24. Consumer expectations for mobile handsets and similar products are becoming more and more sophisticated.

a) .

b) , .

c) .

d) .

 

VII. . : T (true), ; F (false), ; N (no information), .

Compression reduces the size of video, data, image, and voice files. This decreases the amount of network capacity needed to transmit files. Compression increases throughput without changing the actual speed of the line.

With compression, a song can be downloaded in seconds rather than in minutes because fewer bits will be sent. At the receiving end, compatible compression software or hardware re-creates the compressed chunks into close to or the same image or sound that was sent. Text is recreated exactly as it was before it was compressed so that numeric information or product information is not altered. However, when it is received, compression might re-create video and voice in varying degrees of lower video resolution or voice quality with acceptable, often barely noticeable, alterations.

Compression used with text and facsimile often reduces the amount of data to be transmitted by removing white spaces and by abbreviating the most frequently appearing letters. For instance, repeated letters are abbreviated into 3-bit codes instead of 8-bit codes. In similar fashion, one method of video compression transmits only the changed image, not the same image over and over. In a video conference, nothing is transmitted after the initial image of a person until that person moves or speaks. Fixed objects such as walls, desks and background are not repeatedly transmitted. There are a number of standardized compression algorithms (mathematical formulae used to perform operations such as compression) that enable compressed text and video to be transmitted in a format that can be easily decompressed at the receiving end. The most frequently used compression protocols are:

- various MPEG standards are used to compress and decompress audio and video. (MPEG stands for Moving Picture Experts group);

- MP3 is used for downloading music files iPods;

- Apples iPod uses Advanced Audio Coding (AAC);

- Most Windows-based PCs have WinZip compression;

- Zipit is installed on Macintosh computers running OS 10.x.x.

25. Compression greatly increases the actual speed of the transmission line.

26. Compressing makes the time for downloading a music file shorter reducing the number of bits to be sent.

27. In case of text compression, no change in the information is observed upon decompression.

28. Unlike compression, multiplexing does not alter the actual data sent.


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