Analog Communication - May 2014

Electronics & Telecomm. (Semester 5)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks.

Answer the following :

1 (a) What is Quantization? Explain types of quantization(5 marks) 1 (b) AM is the waste of power and bandwidth. Justify the statement(5 marks) 1 (c) Explain why FM is more immune to noise(5 marks) 1 (d) Explain double spotting in radio receivers(5 marks) 2 (a) State advantages of SSB over DSB. Explain any one method generate SSB (10 marks) 2 (b) Explain the following with reference o radio receivers :-
(i) Sensitivity (ii) Fidelity
(iii) Selectivity (iv) Dynamic Range
(10 marks) 3 (a) Derive Mathematical expression for FM wave and its modulation index(10 marks) 3 (b) One input to a conventional AM modulator is 500 KHz carrier eith amplitude of 20 Vp. The second input is 10 KHz modulation signal that is of sufficeint amplitude to cause a change in output wave of ± 7.5 Vp. Determine :
(i) Upper and lower sideband frequencies.
(ii) Modulation co-efficient and percentage modulation
(iii) Expression of modulated wave
(iv) Draw output spectrum
(v) Sketch output envelope(10 marks) 4 (a) Explain indirect method of FM generation(10 marks) 4 (b) With the help of neat circuit diagram explain the generation and detection of Pulse Position Modulation (PPM) signal(10 marks) 5 (a) What are the drawbacks of delta modulation? How adaptive delta modulation solve these problem?(10 marks) 5 (b) State and prove sampling theorem for low pass signal(10 marks) 6 (a) Draw the following data waveform for the bit stream 11010010 :
(i) Unipolar NRZ
(ii) Bipolar RZ
(iii) Bipolar NRZ
(iv) Bipolar RZ-AMI
(v) Unipolar RZ (10 marks) 6 (b) Draw the block diagram of Pulse code modulation and explain each block(10 marks)

Answer the following (any four) :-

7 (a) Automatic Gain Control (5 marks) 7 (b) Pre-emphasis and De-emphasis(5 marks) 7 (c) Squetch Circuit(5 marks) 7 (d) Comparison of Narrowband and Wideband FM(5 marks) 7 (e) Adjacent channel and co-channel Interface(5 marks)