Analog Communication - May 2014

Electronics & Telecom Engineering (Semester 4)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.

Answer any one question from Q1 and Q2

1 (a) Explain the phase shift method for generating SSB-SC. State its advantages and disadvantages.(6 marks) 1 (b) Differentiate between NBFM and WBFM.(6 marks) 2 (a) Compare between DSB-FC, DSB-SC, and SSB-SC.(6 marks) 2 (b) An angle modulated wave with a carrier frequency ω_c=2πX10^-5 is defined by the equation, φ_EM(t)=10 cos (ω_c t+5 sin 2000 π t). Find.
i) Power of the modulated signal
ii) Frequency deviation
iii) bandwidth(6 marks)

Answer any one question from Q3 and Q4

3 (a) Explain FM detection using PLL.(6 marks) 3 (b) Three resistors of 10 KΩ, 22KΩ and 33 KΩ are at room temperature (27°C). For a bandwidth of 100 kHz. Calculate the thermal noise voltage generated by:
i) Each resistor
ii) Three Resistors in series
iii) Three Resistors in parallel(6 marks) 4 (a) Explain how a diode can be used to detect an AM signal. What are the different types of distortions that occur in a typical diode detector circuit?(6 marks) 4 (b) Derive the Friss's formula for Noise Factor of amplifiers in cascade.(6 marks)

Answer any one question from Q5 and Q6

5 (a) Explain the performance of Baseband system in presence of noise.(7 marks) 5 (b) Explain threshold in angle modulation.(6 marks) 6 (a) Explain the performance of AM in presence of noise.(8 marks) 6 (b) With the help of mathematical expression explain which is superior PM/FM?(5 marks)

Answer any one question from Q7 and Q8

7 (a) Explain band Limited and time limited signal.(6 marks) 7 (b) What is Nyquist criterion? State sampling theorem in time domain. Draw the spectrum showing aliasing and guard band.(7 marks) 8 (a) Compare between PAM, PWM and PPM.(6 marks) 8 (b) With the help of block diagram, explain transmitter and receiver of pulse code modulation.(7 marks)