Principles Of Communication Question Paper for Anna Univ IT Department

Third Semester 
Information Technology 
(Regulation 2008) 
Time : Three hours Maximum : 100 Marks 
Answer ALL Questions 
PART A — (10 × 2 = 20 Marks) 
1. Define amplitude modulation. 
2. What is modulation index? 
3. Why is ASK called as ON-OFF keying? 
4. What are the differences between QASK and QPSK? 
5. Define sampling rate? 
6. What is ISI? 
7. Define Pseudonoise sequence? 
8. What are the different types of multiple access techniques? 
9. Define Kepler’s three laws of planetary motions. 
10. What are the losses encountered by optical fiber? 

PART B — (5 × 16 = 80 Marks) 

11. (a) (i) Write short notes on : 
 (1) AM voltage distribution. (4) 
 (2) AM power distribution. (4) 
 (ii) An audio frequency signal 10 sin 2π ×500t is used to amplitude 
modulate a carrier of 50 t sin 2π ×10 . Calculate 
 (1) Modulation index (2) 
 (2) Side band frequencies (2) 
 (3) BW required (2) 
 (4) Total power delivered to the load of 600 Ω. (2) 
(b) (i) Compare FM and AM. (12) 
 (ii) The phase deviation constant in a phase modulation system is 
K = 0.01 rad/v. Calculate the maximum phase deviation when a 
modulating signal of 10 V is applied? (4) 
12. (a) (i) Explain the principle of FSK transmitter and receiver. (10) 
 (ii) Write short notes on the spectrum and bandwidth of FSK. (6) 
(b) (i) Compare the various types of digital modulation techniques. (8) 
 (ii) Explain the eyepattern in base band digital transmission with a 
neat diagram. (8) 
13. (a) (i) Explain the elements of PCM system with a neat block diagram. (12) 
 (ii) What is companding? (4) 
(b) (i) Find the signal amplitude for minimum quantization error in a 
delta modulation system if step size is 1 volt having repetition 
period 1 ms. The information signal operates at 100 Hz. (4) 
 (ii) Describe the operation of DPCM system with a relevant diagram.(12) 
14. (a) (i) Write a short note on frequency hop spread spectrum. (10) 
 (ii) Explain the applications of spread spectrum techniques. (6) 
(b) (i) Give a detail account of the different types of multiple access 
techniques. (10) 
 (ii) Compare TDMA and CDMA. (6) 
15. (a) (i) Discuss briefly the basic satellite communication system. (8) 
 (ii) Write short notes on the LEO and GEO orbits. (8) 
(b) Enumerate the elements of an optical fiber transmission link. (16) 

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