Tải bản đầy đủ - 0 (trang)
Explain how a client-server application works. Use diagrams for your explanations.

Explain how a client-server application works. Use diagrams for your explanations.

Tải bản đầy đủ - 0trang

ES154 Communications and Media 2001-2002

Questions and worked examples



UNIVERSITY OF WARWICK

School of Engineering

Lectures 11 to 20



D.D.Udrea



Q37

Explain how a static / dynamic /active web document is generated.

Answer

Lecture 14, Static/Dynamic/active document generation



Q38

Give examples of how digital images can be generated.

Answer

Lecture 15, CCD, C-MOS, scanning diode, scanner

Q39

Explain how a charged coupled device (CCD camera) works.

Answer

Lecture 15, CCD camera



Q40

Give examples of compression formats for still images and indicate whether they are lossy or lossless.

Answer

Lecture 15, Image formats



Q41

Explain how an image is formed on a CRT(cathode ray tube) display.

Answer

Lecture 15, CRT



Q42

Explain how an image is formed on an LCD (Liquid Crystal Display).

Answer

Lecture 15, LCD



mqz1529462202.doc



Page 10 of 15



ES154 Communications and Media 2001-2002

Questions and worked examples



UNIVERSITY OF WARWICK

School of Engineering

Lectures 11 to 20



D.D.Udrea



Q43

Give an example of microphone technology and explain, with the aid of diagrams, how a microphone

works.

Answer

Lecture 16, Microphone



Q44

Explain what is understood by ‘aliasing’ and how it can be avoided.

Answer

Lecture 16, Sampling and quantization



Q45

Explain briefly the principle of PCM (Pulse Code Modulation) and what are the advantages it brings.

Answer

Lecture 16, Coding and Decoding -PCM



Q46

Give an example of speaker technology and explain, with the aid of diagrams, how a speaker works.

Answer

Lecture 16, Speaker



Q47

Give examples of services that can be run over a TV Broadcast Network and discuss the requirements

of the terminals.

Answer

Lecture 17, Satellite/Broadcast networks



Q48

Give examples of services that can be run over a Cable TV Network and discuss the requirements of the

terminals.

Answer

Lecture 17, Cable networks



mqz1529462202.doc



Page 11 of 15



ES154 Communications and Media 2001-2002

Questions and worked examples



UNIVERSITY OF WARWICK

School of Engineering

Lectures 11 to 20



D.D.Udrea



Q49

Explain the concept of colour mixing and the difference between additive and subtractive colour

schemes.

Answer

Lecture 17, Colour theory



Q50

Explain briefly, in a qualitative manner, the similarities and the differences between the two analog TV

formats PAL and NTSC.

Answer

Lecture 17, Analog TV signal: PAL/NTSC



Q51

Explain briefly, in a qualitative manner, the similarities and the differences between the two digital TV

formats 4:2:2 and 4:2:0.

Answer

Lecture 17, Digital TV signal



Q52

Explain the similarities and the differences between DAT (Digital Audio Tape) and CD (Compact Disk)

when used for the storing of audio.

Answer

Lecture 18, DAT/CD



Q53

Explain, with the aid of diagrams, how the information is read from a CD.

Answer

Lecture 18, CD-optical reading



Q54

Explain, with the aid of diagrams, how the information is written to and read from a minidisk.

Answer

Lecture 18,Minidisk:magneto-optical recording, optical reading



Q55

Explain the similarities and the differences between CD (Compact Disk) and Minidisk.

mqz1529462202.doc



Page 12 of 15



ES154 Communications and Media 2001-2002

Questions and worked examples



UNIVERSITY OF WARWICK

School of Engineering

Lectures 11 to 20



D.D.Udrea



Answer

Lecture 18,CD/Minidisk



Q56

Explain, with the aid of diagrams, how the information is read from a double layer DVD.

Answer

Lecture 18, DVD: optical reading



Q57

Explain the similarities and the differences between CD (Compact Disk) and DVD (Digital Versatile

Disk)

Answer

Lecture 18,DVD vs CDROM



Q58

Explain the role of a Modem in multimedia communications.

Answer

Lecture 18, Modems



Q59

Give examples of wireless multimedia interfaces and suggest advantages and drawbacks for each of

them

Answer

Lecture 18, Wireless interfaces



Q60

Suggest a lossless compression algorithm for the following string of characters : BANANARAMA. The

ASCII codes (in decimal representation) for each letter are as follows: A = 65, B = 66, M =

77, N = 78 and R = 82. Calculate the compression rate obtained.

Answer

Lecture 19, Text compression: entropy encoding

BANANARAMA = 66 65 78 65 78 65 82 65 77 65 (decimal) = 42 41 4E 41 4E 41 52 41 4D 41 (hex) =

1000010 1000001 1001110 1000001 1001110 1000001 1010010 1000001 1001101 1000001

Total uncompressed bits= 7 bit/character x 10 characters = 70 bit

Proposed compression algorithm

A=1; N=01; B=001, R=0001, M=00001

BANANARAMA = 001 1 01 1 01 1 0001 1 00001

Total compressed bits= 20 bit

mqz1529462202.doc



Page 13 of 15



ES154 Communications and Media 2001-2002

Questions and worked examples



UNIVERSITY OF WARWICK

School of Engineering

Lectures 11 to 20



D.D.Udrea



Compression rate = total compressed bits/total uncompressed bits = 20/70 = 0.28

Or %compression = size difference/total uncompressed = (70-20)/70 *100 = 71%



Q61

Explain how dictionary compression works for a text. Give a short example

Answer

Lecture 19, Text compression: dictionary encoding



Q62

Explain how run length encoding works for an image. Give a short example.

Answer

Lecture 19, Image compression: run-length encoding



Q63

Calculate the first four DCT (Discrete Cosine Transform) coefficients of the signal block with the

amplitude sampled as s = [4 2 2 0 0 2 2 4], knowing that

1 M1

C (0) 

 s(k ) u =1,2,…

M k 0

C (u ) 



2

M



M1



 (2k  1)u 



2M



 s(k ) cos

k 0



Answer

Lecture 19, Image compression: DCT

1 7

1

1

C (0) 

s(k ) 

( s (0)  s (1)  s (2)  ...  s (7)) 

(4  2  2  0  0  2  2  4) 5.66



8 k 0

8

8

2 7



3

5

15

 (2k  1)  1

C (1) 

s(k ) cos 

 ( s(0) cos( )  s (1) cos( )  s(2) cos( )  ...  s (7) cos(

)) 





16

16

16

16

8 k 0

 16  2

1

(4 0.98  2 0.83  2 0.55  2 0.55  2 0.83  4 0.98) 0

2

2 7



3

15

 (2k  1)2  1

C ( 2) 

s (k ) cos 

 ( s (0) cos( )  s (1) cos( )  ...  s (7) cos(

)) 





16

8

8

8

8 k 0



 2

1

(4 0.92  2 0.38  2 0.38  2 0.38  2 0.38  4 0.92) 3.7

2

2 7

3

9

45

 (2k  1)3  1

C (3) 

s(k ) cos 

 ( s (0) cos( )  s(1) cos( )  ...  s(7) cos(

)) 





16

16

16

16

8 k 0



 2

1

(4 0.83  2 0.19  2 0.98  2 0.98  2 0.19  4 0.83) 0

2

Because C(1) and C(3) are zero, compression occurs by sending only C(0) and C(2) instead of all four

coefficients.



mqz1529462202.doc



Page 14 of 15



ES154 Communications and Media 2001-2002

Questions and worked examples



UNIVERSITY OF WARWICK

School of Engineering

Lectures 11 to 20



D.D.Udrea



Q64

Explain the difference between PCM (Pulse Code Modulation) and D-PCM (Differential-PCM).

Answer

Lecture 19, Audio compression: D-PCM

Lecture 16, Coding and Decoding -PCM



Q65

Explain what is understood by multimedia streaming and what the benefits of this technique are

Answer

Lecture 19, Streaming



Q66

Suggest a security measure for each of the following network problems: Virus attack; Improper or

accidental access to a system; Data intercepted in transit by unauthorized persons.

Answer

Lecture 20, Security measures



Q67

Suggest an encryption technique (and the keys) based on substitution and transposition for the

following plaintext:

This is a lovely day

Answer

Lecture 20, Encryption techniques

References

DDU – ES154 Communication and Media , Lectures 11 to 20, Lecture Slides 11 to 20.

Halsall, Fred – Multimedia communications: Applications, Networks, Protocols and Standards – Addison Wesley, 2001,

ISBN 0-201-39818-4 QA 78.51.H2

Comer, Douglas - Computer networks and Internets with Internet applications / Douglas E. Co. - 3rd ed. - Upper Saddle

River, N.J.; London: Prentice Hall, 2001. – ISBN 0-13-091449-5 QA 74.2.C6



mqz1529462202.doc



Page 15 of 15



Tài liệu bạn tìm kiếm đã sẵn sàng tải về

Explain how a client-server application works. Use diagrams for your explanations.

Tải bản đầy đủ ngay(0 tr)

×