Anna University Chennai - Collection of all important questions for Nov Dec 2016 CS6304 Analog and Digital Communication examinations.

B.E./ B.Tech. DEGREE EXAMINATION Nov Dec 2016

03rd Semester / II Year

Computer Science Engineering

CS6304 Analog and Digital Communication

(Regulation 2013)

Nov Dec 2016 Important Questions

Important 16 Marks Questions (All five units) are listed for CS6304 Analog and Digital Communication subject

1. a. Can you recall the phasor diagram of wideband FM and explain about the bandwidth of FM signal (8)

b. How would you show the difference between phase modulation and frequency modulation. (8)

2. A modulating signal of 2 cos5000t is amplitude modulated over a carrier signal of 5cos20000t

a. What approach would you use to find the modulation index, LSB and VSB frequencies (8)

b. How would you show your understanding of Bandwidth and the ratio of SideBand Power in the Total Power of AM wave (8)

3. a. The first stage of a two stage amplifier has a voltage gain of 10, a 600 Ω input resistor , a 1600 Ω equivalent noise resistance and a 27 kΩ output resistor . For the second stage these values are 25, 81kΩ , 10kΩ and 1 MΩ respectively. What is the equivalent input noise resistance of this two stage amplifier and also what is the noise figure of the amplifier if it is driven by a generator whose output impedance is 50 Ω.

b. How would you show the expression for instantaneous voltage of AM wave? (8)

4. a. How would you explain the nature of SSB spectrum if the modulating signal is m(t)= cos2𝜋.100t + cos2π.2000t and carrier is given by c(t) = cos2π.10000t. (8)

b. Can you recall the relationship between the instantaneous carrier frequency and modulating signal for FM. (8)

5. a. Can you distinguish between modulation index for FM and PM. (4)

b. What is the relationship between modulation index and modulating signal for FM and PM. (12)

6. Can you formulate a theory for amplitude shift keying systems with neat diagram. (16)

7. How would you show your understanding of the operations of Non-coherent and coherent ASK modulators (16)

8. For a BPSK modulator with a Carrier frequency of 70 MHz and an input bit rate of 10 Mbps,

a.What can you say about the maximum and minimum upper and lower side frequencies, draw the output spectrum, (8)

b. How would you summarize the minimum Nyquist bandwidth, and calculate the baud rate (Assume f= 5MHz) (8)

9. Can you identify the bandwidth considerations of 8-PSK system. (16)

10. What approach would you use to explain the principle of

a. FSK transmitter (8)

b. FSK receiver. (8)

11. Estimate the VRC and LRC for the following ASCII encoded message “THE CAT”. Use odd parity for VRC and even parity for LRC (16)

12. a. Interpret the History of Data Communication. (8)

b.Illustrate the Data Communication codes. (8)

13. a.Describe in detail about the Standards Organizations for data communication. (8)

b. State the concept of Data Communication circuits using a basic block diagram. (8)

14. Write about the generation of PAM and it’s demodulation. (16)

15. a.Draw the block diagram of PCM transmitter and receiver and explain. (12)

b.What is ISI? How can it be reduced? (4)

16. Describe how Viterbi procedure is used for decoding convolution codes. (16)

17. Consider a discrete memoryless source with source alphabets S = S0, S1, S2 and their probabilities P0 = ¼, P1 = ¼ , P2 = ¼ . Generate the entropy of the source H(X) & H(X2). Also prove that the entropy of the extended source is equal to n times H(X) i.e., H(X^2) = 2*H(X).

18. Compare the Linear Block Codes and Binary Cyclic Codes in detail. (16)

19. a.Write the Huffman code for a discrete memory less source with probability statistics {0.1,0.1,0.2,0.2,0.4}. (8)

b. Describe the concept of Channel coding theorem.

20. Give main idea of Source Coding Theorem? Explain it with suitable examples.

21. Draw the architecture of GSM system and explain the function of each block. (16)

22. a. Report the channel assignment strategies. (8)

b. Show the concept of Handoff in cellular communication (8)

23. a . Explain the operation of CDMA multiplexing system. (10)

b. Identify the advantages of CDMA over TDMA multiple access schemes. (6)

24. Describe the concept of cellular topology and cell fundamentals with examples. (16)

25. a.Point out Direct Broadcast Satellite. (8)

b.List the functionality of Bluetooth. (8)

B.E./ B.Tech. DEGREE EXAMINATION Nov Dec 2016

03rd Semester / II Year

Computer Science Engineering

CS6304 Analog and Digital Communication

(Regulation 2013)

Nov Dec 2016 Important Questions

Important 16 Marks Questions (All five units) are listed for CS6304 Analog and Digital Communication subject

1. a. Can you recall the phasor diagram of wideband FM and explain about the bandwidth of FM signal (8)

b. How would you show the difference between phase modulation and frequency modulation. (8)

2. A modulating signal of 2 cos5000t is amplitude modulated over a carrier signal of 5cos20000t

a. What approach would you use to find the modulation index, LSB and VSB frequencies (8)

b. How would you show your understanding of Bandwidth and the ratio of SideBand Power in the Total Power of AM wave (8)

3. a. The first stage of a two stage amplifier has a voltage gain of 10, a 600 Ω input resistor , a 1600 Ω equivalent noise resistance and a 27 kΩ output resistor . For the second stage these values are 25, 81kΩ , 10kΩ and 1 MΩ respectively. What is the equivalent input noise resistance of this two stage amplifier and also what is the noise figure of the amplifier if it is driven by a generator whose output impedance is 50 Ω.

b. How would you show the expression for instantaneous voltage of AM wave? (8)

4. a. How would you explain the nature of SSB spectrum if the modulating signal is m(t)= cos2𝜋.100t + cos2π.2000t and carrier is given by c(t) = cos2π.10000t. (8)

b. Can you recall the relationship between the instantaneous carrier frequency and modulating signal for FM. (8)

5. a. Can you distinguish between modulation index for FM and PM. (4)

b. What is the relationship between modulation index and modulating signal for FM and PM. (12)

6. Can you formulate a theory for amplitude shift keying systems with neat diagram. (16)

7. How would you show your understanding of the operations of Non-coherent and coherent ASK modulators (16)

8. For a BPSK modulator with a Carrier frequency of 70 MHz and an input bit rate of 10 Mbps,

a.What can you say about the maximum and minimum upper and lower side frequencies, draw the output spectrum, (8)

b. How would you summarize the minimum Nyquist bandwidth, and calculate the baud rate (Assume f= 5MHz) (8)

9. Can you identify the bandwidth considerations of 8-PSK system. (16)

10. What approach would you use to explain the principle of

a. FSK transmitter (8)

b. FSK receiver. (8)

11. Estimate the VRC and LRC for the following ASCII encoded message “THE CAT”. Use odd parity for VRC and even parity for LRC (16)

12. a. Interpret the History of Data Communication. (8)

b.Illustrate the Data Communication codes. (8)

13. a.Describe in detail about the Standards Organizations for data communication. (8)

b. State the concept of Data Communication circuits using a basic block diagram. (8)

14. Write about the generation of PAM and it’s demodulation. (16)

15. a.Draw the block diagram of PCM transmitter and receiver and explain. (12)

b.What is ISI? How can it be reduced? (4)

16. Describe how Viterbi procedure is used for decoding convolution codes. (16)

17. Consider a discrete memoryless source with source alphabets S = S0, S1, S2 and their probabilities P0 = ¼, P1 = ¼ , P2 = ¼ . Generate the entropy of the source H(X) & H(X2). Also prove that the entropy of the extended source is equal to n times H(X) i.e., H(X^2) = 2*H(X).

18. Compare the Linear Block Codes and Binary Cyclic Codes in detail. (16)

19. a.Write the Huffman code for a discrete memory less source with probability statistics {0.1,0.1,0.2,0.2,0.4}. (8)

b. Describe the concept of Channel coding theorem.

20. Give main idea of Source Coding Theorem? Explain it with suitable examples.

21. Draw the architecture of GSM system and explain the function of each block. (16)

22. a. Report the channel assignment strategies. (8)

b. Show the concept of Handoff in cellular communication (8)

23. a . Explain the operation of CDMA multiplexing system. (10)

b. Identify the advantages of CDMA over TDMA multiple access schemes. (6)

24. Describe the concept of cellular topology and cell fundamentals with examples. (16)

25. a.Point out Direct Broadcast Satellite. (8)

b.List the functionality of Bluetooth. (8)

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