421 421 421 - fmcet.infmcet.in/eee/ec2311_auque.pdf · electrical and electronics engineering ec...

Reg. No. :

B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2010

Fifth Semester

Electrical and Electronics Engineering

EC 2311 — COMMUNICATION ENGINEERING

(Regulation 2008)

Time : Three hours Maximum : 100 Marks

Answer ALL questions

PART A — (10 × 2 = 20 Marks)

1. Mention the disadvantages of single sideband transmission.

2. The carrier frequency of an FM broadcast transmission is 100 MHZ and

maximum frequency deviation is 75 KHZ. Find the Bandwidth of the signal

when the highest audio frequency modulating the carrier is 15 KHZ.

3. What are the elements of digital communication system?

4. How does the phase of carrier vary for the message ( ) { },...1,0,1,1,0,1=nm ?

5. An event has six possible outcomes with probabilities {1/2, 1/4, 1/8, 1/16, 1/32,

1/32}. Find the entropy of the system.

6. Find the Hamming distance between the following code words

{ }11100011 =C and { }11010002 =C .

7. Mention the advantages of CDMA system.

8. Specify uplink and downlink frequency ranges for satellite communication.

9. State the advantages of fiber optic system.

10. What is geosynchronous satellite?

PART B — (5 × 16 = 80 Marks)

11. (a) (i) Explain the principle of indirect method of frequency modulation

with neat sketch. (8)

(ii) A carrier wave of 10 MHZ is amplitude modulated to 50% level with

a tone of 5000 HZ. Sketch the waveform and amplitude distribution in

time and frequency domain. Assume carrier amplitude as 10 V. (8)

Or

Question Paper Code : 53127 4

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53127 2

(b) (i) Draw the block diagram for generation and demodulation of a VSB

signal and explain the principle of operation. (10)

(ii) With suitable sketch discuss about square law detector. (6)

12. (a) With a neat block diagram explain the PAM modulation and

demodulation process and derive an expression for PAM wave and depth

of modulation. (16)

Or

(b) (i) Explain working principle of ASK modulator and detector with neat

diagram. (10)

(ii) Draw ASK, FSK, PSK signal to transmit the data stream

1111000111. (6)

13. (a) (i) Brief the properties of entropy. (4)

(ii) Five symbols of the alphabet of discrete memory less source and

their probabilities are given below.

{ }43210 ,,,, SSSSSS =

( ) { }1.0,1,0,2.0,2.0,4.0=SP

Code the symbols using Huffman coding. (12)

Or

(b) (i) Briefly discuss on various error control codes and explain in

detail with one example for convolution code. (12)

(ii) Draw the polar, unipolar, bipolar and Manchester NRZ line code

format for an information {1 0 11 0 0}. (4)

14. (a) (i) Discuss the BSC and BEC with their channel diagram and

transition matrix. (12)

(ii) Consider that a source is transmitting equiprobable 1/0 at the rate

of 103 b/s and the probability of error is 161=eP . Determine the

rate of transmission. (4)

Or

(b) Discuss the various multiple access techniques used in wireless

communication with their merits and demerits. (16)

15. (a) (i) Compare optical fiber cable with RF cable. (6)

(ii) Distinguish among single mode step index, multimode step index

and multimode graded index optical fibers. (10)

Or

(b) Give short notes on the following :

(i) Satellite subsystems (8)

(ii) Power line carrier systems. (8)

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Reg. No. :

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2011

Fifth Semester

Electrical and Electronics Engineering

EC 2311 — COMMUNICATION ENGINEERING

(Regulation 2008)

Time : Three hours Maximum : 100 marks

Answer ALL questions

PART A — (10 × 2 = 20 marks)

1. Write down the basic principle used in super heterodyne receivers?

2. Draw the frequency spectrum of the amplitude modulated signal

tttts355 102cos5102cos3102cos5)( πππ += .

3. What is meant by the term aliasing?

4. How is PPM obtained from PWM?

5. Define entropy.

6. Draw the NRZ signaling format of given binary sequence 1101001.

7. Briefly explain the multiple access technique used in satellite link.

8. Mention the applications of multiple access technique in wired communication.

9. Write down the uplink and downlink frequencies used in satellite communication systems.

10. Mention the types of sources and detectors used in optical fiber communication systems.

PART B — (5 × 16 = 80 marks)

11. (a) (i) Explain a method of generation of an amplitude modulated signal and sketch the time domain waveform of message, carrier and modulated signals. (10)

(ii) Derive the power relationship of Amplitude modulated signal. (6)

Or

(b) (i) Explain the generation of frequency modulated signal using reactance modulation scheme with neat diagram. (10)

(ii) Describe the relationship between FM and PM. (6)

Question Paper Code : 11293

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11293 2

12. (a) (i) With neat sketch Explain the generation of Delta Modulated signal and derive the expression for SNR. (12)

(ii) State the drawbacks of DM and suggest a method to overcome it. (4)

Or

(b) (i) Explain the QPSK modulation schemes with its constellation diagram. (10)

(ii) Briefly describe the concept of QAM and draw the constellation diagram of 16 QAM. (6)

13. (a) (i) Write in detail the procedure of Shannon-Fano coding scheme. (8)

(ii) Apply the above method to a source which generates symbols

4321 ,,, xxxx with the probabilities 1/8, 1/2, 1/4 and 1/8

respectively and determine the coding efficiency. (8)

Or

(b) (i) Compare the coding schemes HDBP and MBnB codes in terms of bandwidth, SNR and transmission efficiency. (10)

(ii) Describe Bandwidth – SNR trade off. (6)

14. (a) With neat block diagram explain the Frequency Division Multiple Access Technique. Discuss its application in communication.

Or

(b) (i) Explain the application of CDMA in wireless communication. (10)

(ii) Compare the performance of CDMA with FDMA and TDMA. (6)

15. (a) (i) Draw the block diagram of satellite link and explain. (10)

(ii) Write a brief note on INSAT. (6)

Or

(b) (i) Describe the principle of operation of power line carrier communication. (8)

(ii) Draw the block diagram of optical fiber communication link and explain. (8)

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421 421 421 - fmcet.infmcet.in/eee/ec2311_auque.pdf · electrical and electronics engineering ec...

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