Mumbai University Previous year question papers
IV Sem ETC-Examination Dec 2012
Principles of Communication
N.H. : (1) Question No. 1 is compulsory.
(2) Attempt any four questions out of remaining six questions.
(3) Assume suitable data if required.
1.Answer the following: (any four) 20
(a) Explain why FM is more immune to noise
(b) What is aliasing? How can it be prevented ?
(c) Define Noise factor and Noise figure.
(d) Explain FM noise triangle.
(e) What is the difference between noise and interference? Explain different types of noise.
2. (a) Derive equation for total transmitted power, total side band power and single side band power for AM wave and draw freq. spectrum for DSBFC.
(b) The antenna current of AM broadcast t(8?smitt~r modulated to the depth of 40% by an audio sine wave is 11Ampere. It iricreases-to 12 Ampere as a result of simultaneous modulation by another audio sinewave. What is the modulation index due to this second wave?
3. (a) Draw and explain Delta modulatiqn transmitter and receiver. What is slope overload distortion?
(b) Explain the following terms –
(iv) DQUbie spottiilg-
4. (a) State and prove sampling theorem.
(b) Define FM and derive equation of FM wave. 10
5. (a) Derive the Friss formula for calculations of total noise figure for two amplifiers connected in cascade.
(b) Explain the operation of Foster seely discriminator with the help of circuit diagram and phasor diagram.
6. (a) Explain generation and demodulation of PAM signal with the-help of suitable diagrams.
(b) Draw a neat block diagram of differential pulse code modulation transmitter and receiver and explain thy same.
7. Write short notes on the following :- 20
(a) Pre-emphasis and Deemphasis
(b) Primary causes ofISI
(c) Adaptive delta modulation