Analog Communication - Dec 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.

Solve any Five:

1 (a) Modulation index for AM should be less than one. Justify/Contradict.(4 marks) 1 (b) Distinguish between narrow band FM and wideband FM.(4 marks) 1 (c) Define noise figure and signal to noise ratio.(4 marks) 1 (d) Explain double spotting with reference to radio receiver.(4 marks) 1 (e) Explain aliasing error and aperture effect.(4 marks) 1 (f) List the application of pulse communication.(4 marks) 2 (a) Explain low level and high level modulation techniques with the help of diagram.(10 marks) 2 (b) Explain Partical diode detector with delayed AGC in detail.(10 marks) 3 (a) Explain the principle and working of transistor direct PM Modulator.(10 marks) 3 (b) With suitable diagram, explain the working of stabilized reactance modulator.(10 marks) 4 (a) Explain independent sideband receive in detail.(10 marks) 4 (b) For a receiver with IF and RF frequencies of 455 KHz and 900 KHz respectively Determine:
i) The Local Oscillator frequency
ii) Image frequency
iii) Image rejection ratio for a pre-selector Q of 80.(10 marks) 5 (a) Explain Pulse Code Modulator and demodulator using neat diagram.(10 marks) 5 (b) What are the drawbacks of delta modulation. Explain the method to overcome these drawbacks.(10 marks) 6 (a) Draw the FDM system to combine three voice channels. Each voice channel occupies a bandwidth of 4 KHz. The common voice channel has a bandwidth of 12 KHz from 100 KHz to 112 Khz.(10 marks) 6 (b) Classify and explain different types of noise affecting communication.(10 marks)