Principles of Analog & Digital Comm. - May 2014

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. 1 (a) Explain friiss transmission formula.(5 marks) 1 (b) What are the energy signal and power signals.(5 marks) 1 (c) Explain Ask system.(5 marks) 1 (d) Compare pcm and Delta modulation.(5 marks) 2 (a) Explain the operating principle, working of transmitter and receiver of BPSK system.(10 marks) 2 (b) An amplitude modulated ware form has a form
Xc(t)=10 (1+0.6 Cos2000?t+0.4 Cos400?t)Cos2000?t)
(i) Sketch the amplitude spectrum of Xc(t)
(ii) Find the power content of each spectral component including currier.
(iii) Find total power and sideband power.
(iv) What is modulation index.(10 marks) 3 (a) What is meant by sensitivity of a radio receiver and How it is improved.(10 marks) 3 (b) Find the mathematical expression of FM signal.(10 marks) 4 (a) State and prove the sampling theorem for low pass and limited dignal. Explain aliasing error.(10 marks) 4 (b) Explain the working of foster seeley discriminator with neat ckt diagram and phasor diagram.(10 marks) 5 (a) What is meant by sensitivity of a radio receiver and How it is improved.(10 marks) 5 (b) What are the advantage of QPSK system.(5 marks) 5 (c) Compare analog and digital communication system.(5 marks) 6 (a) What are advantage and dis-advantage of digital communication also draw block diagram of pcm and explain it.(10 marks) 6 (b) Explain the following in relation of radio receiver
(i) Selectivity
(ii) Sensitivity
(iii) Double spotting.(10 marks)