VALLIAMMAI ENGINEERING COLLEGE Semester/EC6651...4. i) Draw the block diagram for generation and...

EC6651 CE_Qbank_2017-18(Even) VI Sem_EEE G.Saravanan_M.A.Seenivasan

VALLIAMMAI ENGINEERING COLLEGE

SRM Nagar, Kattankulathur – 603 203

DEPARTMENT OF

ELECTRONICS AND COMMUNICATION ENGINEERING

QUESTION BANK

VI SEMESTER

EC6651 Communication Engineering

Regulation – 2013

Academic Year 2017 – 18

Prepared by

Mr. G.Saravanan, Assistant Professor/ECE

Mr. M.A.Seenivasan, Assistant Professor/ECE


VALLIAMMAI ENGINEERING COLLEGE

SRM Nagar, Kattankulathur – 603 203.

DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING

QUESTION BANK SUBJECT : EC6651 Communication Engineering

SEM / YEAR : VI/ III Year B.E EEE.

UNIT I - ANALOG COMMUNICATION

AM – Frequency spectrum – vector representation – power relations – generation of AM –

DSB, DSB/SC, SSB, VSB AM Transmitter & Receiver; FM and PM – frequency spectrum –

power relations: NBFM & WBFM, Generation of FM and DM, Armstrong method &

Reactance modulations : FM & PM frequency.

PART - A

Q.No Questions BT

Level

Competence

1. State the need for modulation. BTL 1 Remembering

2. Define the modulation index of FM. BTL 1 Remembering

3. Draw the frequency spectrum of AM. BTL 1 Remembering

4. Tell about amplitude modulation? BTL 1 Remembering

5. Recall sensitivity of radio receiver? BTL 1 Remembering

6. What is super heterodyne receiver? BTL 1 Remembering

7. Obtain the relationship between phase and frequency

modulation. BTL 2 Understanding

8. Mention the advantages and disadvantages of SSB

transmission.

BTL 2 Understanding

9. Summarize modulation coefficient and percent modulation. BTL 2 Understanding

10. Describe the envelope of AM waveform and its significance? BTL 2 Understanding

11. A carrier signal with power of 40 watts is amplitude

modulated by a sinusoidal signal. Calculate the power of the

modulated signal if the modulation index is 0.7.

BTL 3 Applying

12. Interpret pre-emphasis? How is it used to improve the signal

to noise ratio of the FM transmission? BTL 3 Applying

13. When a super heterodyne receiver is tuned 555 kHz, its local

oscillator provides the mixer with an input at 1010 kHz.

Calculate the image frequency.

BTL 3 Applying

14. Compare AM and FM. BTL 4 Analysing

15. Explain Carson’s rule of FM bandwidth. BTL 4 Analysing


16. A 107.6 MHz carrier is frequency modulated by a 7 kHz sine

wave. The resultant FM signal has a frequency derivation of

50 kHz. Analyse the modulation index of the FM wave.

BTL 4 Analysing

17. AM Transmitter radiates 9 kW with the unmodulated carrier

and 10.125 kW when the carrier is modulated. Estimate the

modulation index.

BTL 5 Evaluating

18. An AM transmitter is modulated by three sources of audio

with m1=0.5, m2=0.7, m3=0.4. The unmodulated carrier

power is 50 kW. Predict the modulated power output.

BTL 5 Evaluating

19. The carrier frequency of a broadcast signal is 100 MHz. The

maximum frequency deviation is 75 kHz. If the highest audio

frequency modulating the carrier is limited to 15 kHz,

formulate the approximate bandwidth of the modulating

signal?

BTL 6 Creating

20. One input to a conventional AM modulator is a 500kHz

carrier with an amplitude of 20 Vp. The second input is a

10kHz modulating signal that is of sufficient amplitude to

cause a change in the output wave of 7.5−+ Vp. Determine

Upper, lower sideband frequency and Modulation efficiency.

BTL 6 Creating

PART – B (13 Marks)

1. i) Identify an Expression for the amplitude modulated wave,

its current and power relations. (9)

ii) How would you explain double conversion AM receiver?

(4)

BTL 1 Remembering

2. With the neat circuit diagram explain the operation of round

travis detector and ratio detector. (13) BTL 1 Remembering

3. i) Describe a method of generating of an amplitude modulated

signal and sketch the time domain waveform of message,

carrier and modulated signals. (8)

ii) Name the methods used for suppression of unwanted

sideband in AM transmission? Discuss the working of any

one of them. (5)

BTL 1 Remembering

4. i) Draw the block diagram for generation and demodulation

of a VSB signal and explain the principle of operation.

(8)

ii) How FM is generated with the help of varactor diode?

Explain with the help of neat diagram. (5)

BTL 1 Remembering

5. i) Explain a method of generating a DSBSC using balanced

modulators. (7)

ii) Discuss the principle of AM super heterodyne receiver

with block diagram. (6)

BTL 2 Understanding

6. i) With suitable sketch discuss about Envelope and square law

detector. (7)

ii) Demonstrate high level and low level transmitters. (6)

BTL 2 Understanding


7. i) Interpret the expressions for narrowband and Wideband FM

wave. (8)

ii) Relate the circuit diagram of FET reactance modulator with

its operation. (5)

BTL 2 Understanding

8. In a FM system the frequency deviation is 1 kHz/V. A

sinusoidal modulating voltage of amplitude 15 V and

frequency 3 KHz is applied. Calculate the maximum

frequency deviation and Modulation index. (13)

BTL 3 Applying

9. Illustrate the Armstrong method of FM generation and

compare NBFM and WBFM. (13)

BTL 3 Applying

10. Analyse the operation of Foster-seeley discriminator with the

Schematic diagram, Vector diagrams for 𝑓𝑖𝑛 = 𝑓𝑜 , 𝑓𝑖𝑛 < 𝑓𝑜

and 𝑓𝑖𝑛 > 𝑓𝑜. (13)

BTL 4 Analysing

11. Discuss two transmitters that generate FM by modulating the

carrier frequency directly. (13) BTL 4 Analysing

12. i) What is Pre-emphasis and De-emphasis? Why it is

required? (5)

ii) Compare the features of FM with AM. Also write the

merits and demerits of FM. (5)

iii) Write notes on PLL FM demodulator. (3)

BTL 4 Analysing

13. A telephone transmitter using AM has unmodulated carrier

output power of 20 kW and can be modulated to a maximum

depth of 80% by a sinusoidal modulating voltage without

causing overloading. Evaluate the value to which

unmodulated carrier power may be increased without

resulting in overloading if the maximum permitted

modulation index is restricted to 60%. (13)

BTL 5 Evaluating

14. Describe the relationship between FM and PM along with

modulation index, Bandwidth requirement and Average

power. (13)

BTL 6 Creating

PART – C (15 Marks)

1. i) Summarize the operation of diode detector in the process of

demodulating of AM Signal. (8)

ii) Discuss the Armstrong method for the generation of FM

Signal. (7)

BTL 5 Evaluating

2. i) Derive the expression for the power calculation in DSB-SC

–AM wave. (8)

ii) A broadcast transmitter radiates 20KW when the

modulation percentage is 75%. Calculate carrier power

and power of each sidebands. (7)

BTL 6 Creating


3. Construct frequency discrimination method of generating

SSB modulated wave and a method to demodulate it. Discuss

the design issues involved in this method of generation. What

is the cause and effect of phase error in demodulated signal?

(15)

BTL 6 Creating

4. Compare the various analog communication systems with

appropriate waveforms and expressions.

(15)

BTL 5 Evaluating

UNIT II - DIGITAL COMMUNICATION

Pulse modulations – concepts of sampling and sampling theorem, PAM, PWM, PPM, PTM,

quantization and coding: DCM, DM, slope overload error. ADM, DPCM, OOK systems –

ASK, FSK, PSK, BSK, QPSK, QAM, MSK, GMSK, applications of Data communication.

PART - A

Q.No Questions BT

Level

Competence

1. List out the few demerits of DPCM. BTL 1 Remembering

2. Define sampling theorem. BTL 1 Remembering

3. What is the principle of delta modulation? BTL 1 Remembering

4. State Shannon capacity limit BTL 1 Remembering

5. List the primary differences between QPSK and MSK

systems. BTL 1 Remembering

6. What are the elements of digital communication systems? BTL 1 Remembering

7. Outline on quantization error? BTL 2 Understanding

8. Show the difference between coherent and non-coherent

receiver. BTL 2 Understanding

9. Write the advantages of GMSK. BTL 2 Understanding

10. Describe the methods of pulse modulation? BTL 2 Understanding

11. Illustrate the term slope overload noise. BTL 3 Applying

12. Sketch ASK, FSK, PSK signal for the data stream 1101001. BTL 3 Applying

13. How would you explain aliasing? BTL 3 Applying

14. State Nyquist rate and Nyquist interval. BTL 4 Analysing

15. Analyze the advantages of QPSK. BTL 4 Analysing

16. Explain why binary ASK is called on-off keying? BTL 4 Analysing

17. Compare between PAM and PWM. BTL 5 Evaluating

18. Formulate the performance of FSK and PSK based on power

and BW efficiency. BTL 5 Evaluating


19. Determine the minimum bandwidth for a BPSK modulator

with a carrier frequency of 40 MHz and an input bit rate of

500 kbps.

BTL 6 Creating

20. Can you elaborate on Companding? BTL 6 Creating


1. i) Explain PCM systems with neat diagram. (8)

ii) Evaluate the process of “Companding” and its

Characteristics. (5)

BTL 1 Remembering

2. i) With a neat block diagram, describe the PAM modulation

and demodulation process and develop an expression for

PAM wave. (8)

ii) Compare PAM, PWM and PPM. (5)

BTL 1 Remembering

3. List the advantages of digital carrier system and describe

MSK techniques with neat diagram. (13) BTL 1

Remembering

4. i) Explain in detail the applications of digital modulation

techniques. (7)

ii) Briefly describe the concept of QAM and draw the

constellation diagram of 16 QAM. (6)

BTL 1

Remembering

5. With neat sketch explain the generation of DM signals. State

the drawbacks of DM and suggest a method to correct it. (13)

BTL 2 Understanding

6. i) How does ADM differ from DM, Support your answer

with block diagram and waveform. (6)

ii) Enumerate the generation of PWM wave with neat sketch.

(7)

BTL 2 Understanding

7. Explain with the block diagram QPSK Transmitter and

Receiver. Also analyse about the bandwidth considerations

for QPSK. (13)

BTL 2 Understanding

8. With a neat block diagram, explain BPSK transmitter and

receiver. Also analyse the spectrum and bandwidth

considerations of BPSK. (13)

BTL 3 Applying

9. Explain DPCM with required diagram. How does it differ

from PCM? (13) BTL 3 Applying

10. (i) Describe in detail Frequency shift keying method with

necessary diagrams. (7)

(ii) Discuss GMSK with advantages and disadvantages. (6)

BTL 3 Applying

11. (i) Discuss about the working principle of ASK modulator and

detector with neat diagram. (6)

(ii) What is DPSK? Discuss its operation with the required

diagrams. (7)

BTL 4 Analyzing


12. i) Analyse modulation and demodulation of PPM? (6)

ii) Tell about uniform quantization, noise and SNR in PCM.

(7)

BTL 4 Analyzing

13. State and prove sampling theorem. Obtain the reconstructed

signal and explain about aliasing? (13) BTL 5 Evaluating

14. (i) Compare between ASK, BPSK, QPSK and FSK digital

modulation techniques. (7)

(ii) Represent QPSK signals in the signal space to find the

distance between the signal points. Give the spectrum of

QPSK signal. (6)

BTL 6 Creating


1. Draw the transmitter and receiver block diagram of Binary

Phase shift keying scheme and compare its error performance

with Binary Frequency Shift keying scheme. (15)

BTL 5 Evaluating

2. i) Explain the QPSK modulation schemes with its

constellation diagram. (10)

ii) Briefly describe the concept of QAM and draw the

constellation diagram of QAM. (5)

BTL 6 Creating

3. i) A data bit sequence consists of the following string of bits

10 11 10 10. Evaluate and draw the nature of waveform

transmitted by BPSK transmitter. (8)

(ii) For an 8 PSK modulator with an input data rate equal to

10 Mbps & a carrier frequency of 70 MHz, measure minimum

double sided Nyquist bw, Baud rate, Sketch the output

spectrum. Judge the results with BPSK & QPSK modulators.

(7)

BTL 5 Evaluating

4. How would you compare the various digital communication

systems? (15) BTL 6 Creating

UNIT III - SOURCE CODES, LINE CODES & ERROR CONTROL

Primary communication – entropy, properties, BSC, BEC, source coding: Shannon Fano,

Huffman coding: noiseless coding theorem, BW – SNR trade off codes: NRZ, RZ, AMI, HDBP,

ABQ, MBnB codes : Efficiency of transmissions, error control codes and applications:

convolutions & block codes.

PART - A

Q.No Questions BT

Level

Competence

1. What is entropy and give its mathematical equation. BTL 1 Remembering

2. Define source coding. State the significance of source coding. BTL 1 Remembering

3. Draw the NRZ and RZ waveform for the pulse stream

10101011. BTL 1 Remembering


4. What is BSC? BTL 1 Remembering

5. What is the rule for AMI code? BTL 1 Remembering

6. Name few error control codes. BTL 1 Remembering

7. Why is Huffman code called as minimum redundancy code? BTL 2 Understanding

8. Describe information rate? BTL 2 Understanding

9. Outline the features of convolutional code? BTL 2 Understanding

10. Mention the significance of AMI code BTL 2 Understanding

11. An event has six possible outcomes with probabilities {1/2,

1/4, 1/8, 1/16, 1/32, 1/32}. Solve for the entropy of the system. BTL 3 Applying

12. Interpret how many errors can be detected and corrected by a

(7, 4) Hamming code? BTL 3 Applying

13. Calculate the amount of information if 𝑝𝑘 =1/4. BTL 3 Applying

14. List out the properties of Hamming distance. BTL 4 Analysing

15. Compare block and convolution codes. BTL 4 Analysing

16. Differentiate error detection from error correction. BTL 4 Analysing

17. Evaluate the Hamming distance between the following code

words C1={1,0,0,0,1,1,1} and C2={0,0,0,1,0,1,1}. BTL 5 Evaluating

18. Explain the disadvantages of convolutional codes BTL 5 Evaluating

19. How would you list the main methods used for error control

coding BTL 6 Creating

20. Can you elaborate on syndrome? BTL 6 Creating


1. Enumerate Shannon’s Fano algorithm and Huffman coding

with a suitable example. (13) BTL 1 Remembering

2. Explain convolutional coding with time domain and

transform domain approach. (13)

BTL 1 Remembering

3. i) Brief the properties of entropy. (8)

ii) Describe the BSC and BEC with their channel diagram

and transition matrix. (5)

BTL 1 Remembering

4. Describe about the Viterbi algorithm by showing the possible

path through the trellis of a coder. Assume the state diagram

of any coder. (13)

BTL 1 Remembering

5. Six symbols of the alphabet of discrete memory less source

and their probabilities are given below, S={S0, S1,S2,S3,S4)

P(S)={0.4,0.19,0.16,0.15,0.15}. Code the symbols using

Huffman coding and Shannon Fano coding and compare the

efficiency. (13)

BTL 2 Understanding


6. Discuss the concept of coding and decoding methods of block

codes with its mathematical frame work and diagram. (13)

BTL 2 Understanding

7. The parity check matrix of a particular (7,4) linear block code

is given by,

[𝐻] = [1 1 11 1 0 1 0 1

0 1 01 0 11 0 0

0 0 1

]

i) Find the generator matrix (G).

ii) List all the code vectors.

iii) What is the minimum distance between code vectors?

iv) How many errors can be detected? How many errors can

be corrected? (13)

BTL 2 Understanding

8. Write short notes on :

i) Code tree, trellis and state diagram for

convolutional encoder. (7)

ii) Sequential decoding for convolutional codes. (6)

BTL 3 Applying

9. The generator matrix for a (6, 3) block codes given below.

Inspect all code vectors of this code.

𝐺 = [1 0 00 1 00 0 1

: 0 1 1: 1 0 1: 1 1 0

] (13)

BTL 3 Applying

10. i) Explain the Bandwidth-SNR trade off of a communication

system. (3)

ii) Plot the output wave form for the bit stream 10011100 on

NRZ, RZ, AMI and split phase. (10)

BTL 4 Analysing

11. i) Compare Linear and Convolution codes. (4)

ii) Analyse the conditions which hamming codes has to

satisfy. (4)

iii) Explain the following terms Code efficiency, Channel

data rate and code rate. (5)

BTL 4 Analysing

12. Explain various digital data formats (line coding techniques)

and compare them. (13)

BTL 4 Analysing

13. 9 i) Write notes on HDBP, ABQ and mBnB. (7)

ii) What is the use syndromes? Explain syndrome decoding?

(6)

BTL 5 Evaluating

14. A rate 1/3 convolution encoder has generating vectors as

g1=(1 0 0) , g2=(1 1 1) and g3 = (1 0 1)

i) Sketch the encoder configuration. (7)

ii) Draw the code tree, state diagram and trellis

diagram. (6)

BTL 6 Creating


1. The source of information A generates the symbols {A0, A1,

A2, A3 & A4} with the corresponding probabilities {0.4, 0.3,

0.15, 0.1 and 0.05}. Encoding the source symbols using

binary encoder and Shannon-Fano encoder and compare its

efficiency. (15)

BTL 5 Evaluating


2. i) Predict the main idea of Source Coding Theorem with

suitable examples. (8)

ii) The binary erasure channel has two inputs and three

outputs. The inputs are labeled 0 and 1, and the outputs are

labeled 0, 1 and e. A fraction α of the incoming bits are erased

by the channel. Measure the capacity of the channel. (7)

BTL 6 Creating

3. Consider a systematic block code whose parity check

equation are P1=m1+m2+m4, P2=m1+m3+m4,

P3=m1+m2+m3, P4=m2+m3+m4 Where mi is the message

digits and Pi are the parity digits.

(i) Evaluate the generator matrix and parity check matrix for

this code. (8)

(ii) Show how many errors can be detected and corrected? If

the received code word is 10101010, find the syndrome.

(7)

BTL 5 Evaluating

4. The generator polynomial of a (15, 11) Hamming code is

given by 𝑔(𝑋) = 1 + 𝑋 + 𝑋2. Design encoder and

syndrome calculator for this code using systematic form.

(15)

BTL 6 Creating

UNIT IV MULTIPLE ACCESS TECHNIQUES

SS&MA techniques : FDMA, TDMA, CDMA, SDMA application in wire and wireless

communication: Advantages (merits)

PART A

Q.No Questions BT

Level Competence

1. List the primary applications of FDMA. BTL 1 Remembering

2. Explain about DSSS technique. BTL 1 Remembering

3. Define Pseudo noise sequence. BTL 1 Remembering

4. List out the merits of TDMA system. BTL 1 Remembering


5. Explain CDMA technique. BTL 1 Remembering

6. Give out the merits of FDMA system. BTL 1 Remembering

7. Describe near –far problem. BTL 2 Understanding

8. What are the different multiple access techniques BTL 2 Understanding

9. Define multiple access. BTL 2 Understanding

10. Demonstrate about FHSS technique. BTL 2 Understanding

11. Mention the applications of multiple access

techniques in wired communication. BTL 3 Applying

12. Classify SS techniques based on modulation

employed. BTL 3 Applying

13. Brief about SDMA technique. BTL 3 Applying

14. Explain about the working principle of TDMA. BTL 4 Analyzing

15. Describe briefly about FDMA. BTL 4 Analyzing

16. Summarize the application of spread spectrum

modulation. BTL 4 Analyzing

17. Compare TDMA and FDMA. BTL 5 Evaluating

18. Generalize the advantages of SDMA technique. BTL 5 Evaluating

19. Difference between multiple access and

multiplexing. BTL 6 Creating

20. Give the advantage of CDMA system. BTL 6 Creating

PART –B (13 Marks)

1. (i) Distinguish between FDMA and TDMA

technique. (8)

(ii) Explain the application of CDMA in wireless

communication. (5)

BTL 1 Remembering

2. State the need for spread spectrum modulation and

explain its operation with neat block diagram. (13) BTL 1 Remembering

3. List out various multiple access techniques and

explain any two in detail. (13) BTL 1 Remembering

4. Explain the principle of operation of direct

sequence spread spectrum with its noise

performance parameters. How pseudo noise is

generated? (13)

BTL 1 Remembering

5. With neat block diagram explain the frequency

division multiple access technique. Discuss its

application in communication. (13)

BTL 2 Understanding


6. What is Code Division Multiple Access technique

in detail and mention its merits and demerits. (13) BTL 2 Understanding

7. Explain the principle of operation of FHSS with

necessary diagrams. (13) BTL 2 Understanding

8. (i) How is interference avoided by using code

division multiplexing? Explain. (7)

(ii) What is the role of SDMA in wireless

communication? (6)

BTL 3 Applying

9. (i) Compare the performance of TDMA, FDMA

and CDMA. (8)

(ii)Describe briefly about the applications of SS

modulation. (5)

BTL 3 Applying

10. Describe in detail SDMA and explain how it works

in wireless communication systems. (13) BTL 4 Analyzing

11. Illustrate the operation of a typical TDMA system

with neat block diagram. And compare it with

FDMA. (13)

BTL 4 Analyzing

12. Demonstrate how TDMA is used in mobile

communication. (13) BTL 4 Analyzing

13. Draw the block diagram and explain in detail the

model of spread spectrum digital communication

system. (13)

BTL 5 Evaluating

14. Classify SS modulation technique based upon the

operating concept and explain in detail DSSS and

FHSS. (13)

BTL 6 Creating


1. i) Validate the properties of Pseudo noise

sequences. (5)

ii) Summarize the direct sequence spread spectrum

techniques with neat block diagram. (10)

BTL 5 Evaluating

2. i) A spread spectrum communication system is

characterised by the following parameters

Tb=4.09ms, Tc=1µs. Propose the processing gain

and jamming margin if Eb/N0=20 and the average

probability of error Pe=0.5×10-5. (5)

ii) A PN sequence generator using a feedback shift

register of length 4. If the chip rate is 108 chips/sec.

Calculate the chip and PN sequence duration. (5)

iii) A slow FH/MFSK system has the following

paramters: The number of bits/MFSK symbol=4,

The number of MFSK symbol per hop =10.

Estimate the processing gain in dB. (5)

BTL 6 Creating

3. i) In the AMPS system, the system bandwidth is

12.5mHz, the channel spacing is 30KHz, and the

edge guard spacing is 10KHz. The number of

BTL 5 Evaluating


channel allocated for control signalling is 21.

Evaluate

a) The number of channels available for message

transmission.

b) Spectral efficiency of FDMA. (8)

ii) If a normal GSM time slot consists of six trailing bits,

8.25 guard bits 26 training bits, and two traffic bursts of

58 bits of data, find the frame efficiency? (7)

4. Discuss in detail the multiple access techniques that

are used in wireless communications. What

difference is taken into account here as the channel

is now wireless? (15)

BTL 6 Creating

UNIT V SATELLITE, OPTICAL FIBER – POWERLINE, SCADA

Orbits : types of satellites : frequency used link establishment, MA techniques used

in satellite communication, earth station; aperture actuators used in satellite –

Intelsat and Insat: fibers – types: sources, detectors used, digital filters, optical link:

power line carrier communications: SCADA

PART A

Q.No Questions BT

Level

Competence

1. What are the essential components of a satellite

system? BTL 1 Remembering

2. State snells law. Give the significance in optics. BTL 1 Remembering

3. Explain about SCADA. BTL 1 Remembering

4. What are the types of optical fiber available? BTL 1 Remembering

5. Expand and define EIRP. BTL 1 Remembering

6. Define geosynchronous satellite. BTL 1 Remembering

7. Write the difference between optical fiber cable and

RF cable BTL 2 Understanding

8. Compare the advantages and disadvantages of

geosynchronous satellite BTL 2 Understanding

9. Distinguish between single mode and multimode

fibers BTL 2 Understanding

10. Give the primary advantages of optical fiber systems BTL 2 Understanding

11. Calculate the critical angle of a fiber with n1=

1.4917and n2 =1.4894. BTL 3 Applying

12. Illustrate the applications of geostationary satellite BTL 3 Applying

13. Specify uplink and downlink frequency for satellite

communication BTL 3 Applying

14. Analyze the differences between LASER and LED BTL 4 Analyzing


15. Point out the types of sources and detectors in optical

communication systems. BTL 4 Analyzing

16. Explain the multiple access technique in satellite BTL 4 Analyzing

17. Explain apogee and perigee BTL 5 Evaluating

18. Estimate the acceptance cone angle for an optical fibre

with core and cladding refractive index of n1=1.48 and

n2=1.46 respectively.

BTL 5 Evaluating

19. Formulate the expression for the term numerical

aperture BTL 6 Creating

20. Write the expression of path loss L of satellite

communication system in dB. BTL 6 Creating

PART –B (13 Marks)

1. (i) Describe the principle of operation of power line carrier communication-SCADA. (7)

(ii) Explain various types of losses in optical fibre. (6)

BTL 1 Remembering

2. Explain various light generating and detecting systems

in a fibre optic communication. (13) BTL 1 Remembering

3. (i) Illustrate Kepler’s law and how they relate to

satellite communication. (7)

(ii) Illustrate the significance of satellite link budgets

and how they are calculated. (6)

BTL 1 Remembering

4. (i)Identify the various blocks and its functionalities of a fibre optic communication system. (8)

(ii)State advantages of Fiber optic communication. (5)

BTL 1 Remembering

5. Classify the multiple access techniques in satellite

Communication. (13) BTL 2 Understanding

6. (i) Explain with the block diagram of a satellite earth

station. (7)

(ii) Explain in detail about the aperture actuators used

in satellites. (6)

BTL 2 Understanding

7. Write short notes on

(i) Satellite Sub system. (5) (ii) Satellite frequency allocation and reuse

concept. (5) (iii) Digital filters. (3)

BTL 2 Understanding

8. Estimate the uplink and downlink model of satellite

communication system. (13) BTL 3 Applying

9. (i) Explain the principle of light propagation in fibre

along with NA. (8)

(ii)What is dispersion? Explain various types of

dispersion in fibres. (5)

BTL 3 Applying

10. Explain the concept of geostationary earth orbit, its

advantages, limitations and applications. (13) BTL 4 Analysing


11. (i) Define index profile for the optical fibre and explain

various types of fibre (8)

(ii) Draw the block diagram and explain optical fibre link budget. (5)

BTL 4 Analysing

12. (i) Elaborate the concept of geostationary satellite and

brief about INTELSAT and INSAT. (7)

(ii) Explain briefly the modulation techniques for

satellite links. (6)

BTL 4 Analysing

13. A multimode step index fibre with a core refractive

index of 1.4917, core diameter of 60 um and

normalized frequency =12 at wavelength of 1.3um.

Calculate NA, relative index difference, critical angle

and total number of guided modes. (13)

BTL 5 Evaluating

14. (i) What are the modes of operation suggested in

optical fibres? How are optical fibres classified

according to this? Discuss elaborately. (9)

(ii) The numerical aperture NA for a fibre is 0.352 and

it has a core diameter of 50um and used at light of

wavelength of 0.8um. Determine the V-number,

number of modes in step index and graded index fibre

(where alpha is 2). (4)

BTL 6 Creating


1. i) Summarize in detail, a satellite communication

system. Also list out typical frequency spectrum used

in this communication. What is the relation between

the uplink frequency and the downlink frequency in a

satellite link? Which one is higher? Why? (10)

ii) Describe the technique of SCADA. (5)

BTL 5 Evaluating

2. Draw the block diagram of satellite communication

system and derive the link equations. (15) BTL 6 Creating

3. Briefly elaborate about optical sources such as LED

and Laser Diode. (15) BTL 5 Evaluating

4. I

)

i) Discuss about a fiber optic communication system.

State the major merits of an optical fiber systems. If

there are so many compelling reasons for opting this

type of communication, why is it not used

everywhere? (10)

ii) Formulate the optical fibers based on the material

used and profile structure. (5)

BTL 6 Creating

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VALLIAMMAI ENGINEERING COLLEGE Semester/EC6651...4. i) Draw the block diagram for generation and...

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