EC2311 Communication Engineering Question Bank : valliammai.co.in

Name of the College : Valliammai Engineering College
Subject : Communication Engineering
Website : valliammai.co.in
Document Type : Question Bank

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Valliammai Communication Engineering Question Paper

UNIT I

ANALOG COMMUNICATION
PART- A
Important Questions :
1. Define amplitude Modulation and draw the frequency spectrum of Amplitude modulated signal
2. A 500W carrier is AM modulated to a depth of 75%. Calculate the total power of the modulated wave.

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3. Define sensitivity.
4. Define frequency modulation.
5. A 500W carrier is AM modulated to a depth of 70%. Calculate the total power of the modulated form DSBSC of AM.
6. Define Modulation index and percent modulation for an AM wave.
7. Define Low level Modulation and High level Modulation.
8. What is AM wave envelope?
9. What are the disadvantages of conventional (or) double side band full carrier system?
10. AM transmitter radiates 9 kW with the unmodulated carrier and 10.125 kW when the carrier is modulated. Calculate the modulation index.

11. Define AM Vestigial sideband.
12. What are the advantages and disadvantages of single sideband transmission?
13. Define Double sideband suppressed carrier AM?
14. Define frequency deviation.
15. State Carson rule.
16. Mention the advantages and disadvantages of FM.
17. What is the modulation index of FM?
18. 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.
19. Write down the basic principle used in superheterdyne receivers?
20. Draw a pre-emphasis circuit.

PART- B
Important Questions
1. (i)Explain the generation of frequency modulated signal using reactance modulation scheme with neat diagram.
(ii)Describe the relationship between FM and PM.
2. (i)Compare wideband andv narrow band FM system.
(ii)How does the phase shift method efficiently suppress the unwanted side band? explain with diagram.
3. (i)With a neat sketch diagram,explain the operation of Armstrong frequency modulation system.
(ii) Illustrate the operation of VSB transmission.
4. (i)Derive an expression for AM wave and its power relation.
(ii) What are the advantages of single sideband modulation technique?explain any one method of SSB generation.
5. (i)Derive an expression for the narroband FM wave.
(ii)Explain the Armstrong method of FM generation.
6. What are the relative merits of high levels modulation and low level modulation in AM transmission? The anode dissipation of a class C power amplifier is 944 Watta when modulation depth is 60% , the efficiency of a power amplifiers is 60%,while that the modulator is 25%.find
(i) Carrier power and modulator tube dissipation when modulation depth is 100%
(ii) AF output and rating of the modulation value to affect 100% modulation
(iii)Overall efficiency at 60% modulation depth
7. Explain in detail Armstrong method of FM generation and compare NBFM and WBFM.
8. Discuss the coherent detection of DSB – sc modulated wave with a block diagram of detector and explain.

UNIT II

DIGITAL COMMUNICATION
PART- A
Important Questions
1. What are the elements of Digital Communication systems?
2. What is Pulse Width modulation?
3. How does the phase of the carrier vary for the message m(n) = {1,0,1,1,0,1)
4. Define Slope overload noise. How it is reduced?
5. Specify Nyquist rate of signal f(t) = sin (200t)
6. Draw a pulse position modulated wave.
7. How is PPM obtained from PWM?
8. Write the primary difference between QPSK and MSK systems.
9. What are the different pulse modulation techniques? Discuss their advantages
10. What is meant by the term aliasing?
11. State the applications of FSK
12. Define quantization error?
13. Explain adaptive delta modulation.
14. Define dynamic range.
15. Define ASK, PSK and FSK?
16. Define granular noise. How it is reduced.
17. What is OOK?
18. What is the Nyquist sampling rate? Find nyquist rate for the signal f(t) =sin(200pt)
19. Define PCM and PPM.
20. Define QAM. PAM

PART- B
Important Questions
1. With a neat block diagram explain the PAM modulation and demodulation process and derive an expression for PAM wave and depth of modulation.
2. (i)Explain working principle of ASK modulator and detector with neat diagram.
(ii)Draw ASK,FSK,PSK signal to transmit the data stream 1111000111.
3. (i)With neat sketch explain the generation of delta modulated sinal and derive the expression for SNR.
(ii)State the drawbacks of DM and suggest a method to overcome it.
4. Explain the QPSK modulation scheme with its constellation diagram.
5. Briefly describe the concept of QAM and draw the constellation diagram of 16 QAM.
6. How does ADM differ from DM?support from your answer with block diagram and waveforms.
7. (i)What is DPSK?discuss its operation with the required diagrams. (ii)Compare PCM and DPCM techniques.
8. (i)State and prove sampling theorem. (ii)Explain the generation of PWM and PPM waves.
9. (i)Compare PCM and DM. (ii)Explain the concept of BPSK and QPSK techniques in data communication.
10. What is meant by quantization ?explain in detail DPCM communication system.
11. Discuss the advantages of digital communications and explain QPSK and QAM techniques with neat diagram.
12. Explain the functioning of a FSK digital transmitter and receiver with relevant diagrams.