Fundamentals of Communication Engg - May 2012

Electronics Engineering (Semester 4)

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) A 400 watts carrier is modulated to a depth of 75%. Find the total power in the amplitude modulated wave. Assume modulated signal to be a sinusoidal one.(5 marks) 1 (b) The bit sequence 1011101011 is to be transmitted using following formats:
(i) Unipolar RZ
(ii) Unipolar NRZ
(iii) Bipolar RZ
(iv) Bipolar NRZ
(v) Split - phase manchester
Draw all the waveforms.(5 marks) 1 (c) Describe the significance of FM noise triangle.(5 marks) 1 (d) Explain in brief frequency division multiplexing.(5 marks) 2 (a) Define the following propagation terms:
(i) Critical frequency and critical angle
(ii) virtual height
(iii) MUF
(iv) Skip distance and Skip zone
(v) Free - space path loss(10 marks) 2 (b) A reciever connected to an antenna whose resistance is 50?. Calculate the reciever's noise figure in decibles and its equivalent noise temperature.(5 marks) 2 (c) Explain the difference between correlated and uncorrelated noise.(5 marks) 3 (a) Draw and explain the block diagram of an ISB transmitter.(10 marks) 3 (b) Draw and explain the 'Third method' of SSB generation. That uses the balance mmodulator to suppress the carrier.(10 marks) 4 (a) If the signal V(t) = 20sin(6.2810⁶t+10sin6.2810³t) represents a phase modulated signal, determine:
(i) Carrier frequency
(ii) Modulating frequency
(iii) Modulating index
(iv) Peak phase deviation(5 marks) 4 (b) Describe the difference between FM and AM reciever, bearing in mind the different frequency ranges and bandwidths over which they operate.(5 marks) 4 (c) Explain the operation of balanced slope detector, using a circuit diagram and response characteristics.(10 marks) 5 (a) Draw the block diagram of an AM superheterodyne reciever and describe its operation and the primary function of each stage.(10 marks) 5 (b) Describe the important parameters of radio reciever.(10 marks) 6 (a) State and prove sampling theorem in time domain.(10 marks) 6 (b) For a PAM transmission of voice signal having maximum frequency equal to F_m=3KHz, calculate the transmission bandwidth. It is given that the sampling frequency F_s=8KHz and the pulse duration t=0.1Ts.(10 marks) 7 (a) What is the slope overload distortion and granular noise in delta moduation? How is it removed in ADM?(10 marks) 7 (b) With the help of a neat diagram explain the transmitter and reciever of pulse code modulation.(10 marks)