Principles of Analog & Digital Comm. - May 2015

Information Technology (Semester 3)

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 four:

1 (a) What is convolution of signals?(5 marks) 1 (b) Explain noise factor?(5 marks) 1 (c) Define selectivity?(5 marks) 1 (d) What is Inter symbol Interference?(5 marks) 1 (e) What is Bit rate and Baud rate?(5 marks) 2 (a) Explain digital communication system in details?(6 marks) 2 (b) What are types of Internal Noise?(6 marks) 2 (c) What is mean by signal to noise ratio? Discuss the importance of SNR in radio receiver?(8 marks) 3 (a) Obtain the Fourier transform of a sine wave having frequency of f_s and peak amplitude of unity. Also plot its frequency spectrum?(10 marks) 3 (b) A sinusoidal carrier has amplitude of 20V and frequency 30 Khz. It is amplitude modulated by sinusoidal voltage of amplitude 3V and frequency 2KHz. Modulated voltage is developed across a 50Ω resistance.
i) Write the equation for modulated wave
ii) Plot the modulated wave showing maxima and minima of waveform
iii) Determine the modulation index
iv) Draw the spectrum of modulated wave?(10 marks) 4 (a) Explain generation of FM by Armstrong method?(10 marks) 4 (b) What is pulse position modulation (PPM)? Explain modulation and demodulation technique used for ppm?(10 marks) 5 (a) A Band pass signal has spectral range that extends from 30KHz to 75 Khz. Find the sampling frequency?(10 marks) 5 (b) Explain in detail generation of any method used in AM?(10 marks)

Write short notes on (any four):

6 (a) Friiss Formula(5 marks) 6 (b) Noise Bandwidth(5 marks) 6 (c) Balanced Modulator(5 marks) 6 (d) Pre-emphasis and De-emphasis(5 marks) 6 (e) Ratio Detector(5 marks)