Analog Communication - Dec 2012

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 : (Any Four )

1 (a) Explain why FM is more immune to noise(5 marks) 1 (b) What is aliasing? How can it be prevented?(5 marks) 1 (c) Define Noise fator and Noise figure(5 marks) 1 (d) Explain FM noise triangle(5 marks) 1 (e) What is the difference between noise and inteference? Explain different types of noise(5 marks) 2 (a) Derive equation for total transmitted power, total side band power ans single side band power for AM wave and draw frequency spectrum for DSBFC(10 marks) 2 (b) The antena current of AM broadcast transmitter modulated to the depth of 40% by an audio sine wave is 11 Ampere. It increases to 12 Ampere as a result of simultaneous modulation by another audio sinewave. What is the modulation index due to this second wave?(10 marks) 3 (a) Draw and explain Delta modulation transmitter and receiver. What is slop overload distortion?(10 marks) 3 (b) Explain the following terms-
(i) Selectivity
(ii) Fidelity
(iii) Sensitivity
(iv) Double spotting
(v) Quantization(10 marks) 4 (a) State and prove sampling theorem (10 marks) 4 (b) Define FM and derive equation of FM wave(10 marks) 5 (a) Derive the Friss formula for calculations of total noise figure for two amplifiers connected in cascade(10 marks) 5 (b) Explain the operation of Foster seely discriminator with the help of circuit diagram and phasor diagram(10 marks) 6 (a) Explain generation and demodulation of PAM signal with the help of suitable diagrams.(10 marks) 6 (b) Draw a neat block diagram of differentiat pulse code modulation transmitter and receiver and explain the same.(10 marks)

Explain short note on the following :-

7 (a) Pre-emphasis and Deemphasis(5 marks) 7 (b) Primary causes of ISI (5 marks) 7 (c) Adaptive delta modulation (5 marks) 7 (d) AGC(5 marks)