Sample question papers Mumbai University IT 4th Sem Principles of Communication Engineering
Sample question papers Mumbai University
IT 4th Sem Principles of Communication Engineering
N.B.(1) Question NO.1 is compulsory.
(2) Attempt in all five question.
(3) All questions carry equal marks.
(4) Assume the , data if necessary.
1. (a) What do you mean by flywheel effect?
(b) Explain the relationship between FM and PM
(c) Compare ground wave propagation with space wave propagation.
.(d) What do you mean by double spotting?
2. (a) Explain with circuit diagram, collector modulated class C transistor ~mplifier. What 10
are the advantages of collector modulation over base modulation.
. (b) A 5 kW unmodulated carrier is simultaneously modulated by two audio signals 10
with modulations index 80% and 50%. Find the transmitted power and effective
modulation index. Also find the antenna current with and without modulating
signal’ assuming antenna resistance of 50 Os.
3. (a) Draw the block diagram of a phase cancellation SSB generation and explain how 10
the carrier and unwanted sideband are suppressed. What change is necessary
to suppress the other sideband?
(b) Sketch the circuit of a practical diode detector and explain its working. What is 10
negative peak clipping? Calculate the maximum modulation index that the above
detector can tolerate without causing negative peak clipping.
.4. (a) Explain with circuit diagram, the ratio detector used to demodulated FM. Why 10
ratio detector is preferred over Faster-Seeley detector for FM demodulation?
(b) Derive an expression for frequency modulated waveform. 6
(c) A modulating signal 5 cos 27t 15 x 103t, angle modulates a carrier A cQs wet 4
with deviation 75 kHz. Find the modulation index and bandwidth for FM. –
5. (a) What do you mean by superhetrodyne receiver? Explain its working with .neat 10
(b) A superhetrodyne receiver having a RF amplifier and an IF of 455 kHz is tuned 10
to 15 MHz. Calculate the Q of the RF amplifier and mixer input circuits, both
being the same, if the receiver’s image rejection is to be 120.
6. (a) Explain the structure of ionosphere with neat diagram.
(b) What do you mean by TOM. Compare TOMwith FDM.
7. (a) What are the various pulse modulation techniques? Give one method for the 10
generation of PAM.
(b) Draw neat block diagram of Delta modulator and explain its working. What are 10
the drawbacks of Delta modulator and how are they overcome by ADM.