(a) Define noise. Where is it most likely to affect the signal?
(b) A broadcast radio transmitter radiates 10 kW when the modulation percentage is 60%. How much of this is carrier power?
(c) What is threshold effect in angle modulation?
(d) Define carrier swing and frequency deviation.
(e) Compare PWM and PPM on at least two points.
(f) In FM, if my is doubled by halving the modulating frequency, what will be the effect on the maximum deviation?
(g) What is modulation index? How is it different for AM and FM?
(h) Which noise is of great importance at high frequencies?
(i) Define information and pulse position modualtion.
(j) Differentiate between NBFM and WBFM.
2.(a) The antenna current of an AM broadcast transmitter modulated to a depth of 40% by an audio sine wave is 11 A. It increases to 12 A as a result of simultaneous modulation by another audio sine wave. What is the modulation index due to this second wave?
(b) What are the disadvantages of SSB-SC with respect to double sideband full carrier?
3. (a) When the modulating frequency in an FM is 400 Hz and the modulating voltage is 2.4 V, the modulation index is 60. Calculate the maximum deviation. What is the modulation index when the modulating frequency is reduced to 250 Hz and the modulating voltage is simultaneously raised to 3.2 V?
(b) Illustrate the block diagram for the detection of SSB-SC signal using phase discrimination method.
4. (a) Explain the detection of FM wave using balanced frequency discrimination.
(b) How is AM generated using square law modulator? Derive expressions.
5. (a) List and discuss the factors influencing
the choice of the intermediate frequency for radio receivers.
(b) Briefly explain the function of each of the blocks in the superheterodyne receiver.
6.Describe the working of a Varactor diode FM modulator and balanced slope detector.
7. (a) If a signal v(t) = 20 sin (2n×106t-10 sin 2n×103t)
represents an FM signal, determine carrier frequency, modulating frequency, modulation index, BW and average power if the load resistance is 50 2. Also write the expression for FM signals if modulating frequency is doubled.
(b) What is fidelity? Explain.
- (a) With a neat diagram, explain the Weaver’s method of SSB generation. State the advantages and disadvan- tages of the method.
(b) Define phase and frequency modulation.
- Write short notes on the following:
(a) Image rejection of the receiver
(b) Pulse amplitude modualtion
BEU Analog communication 2022 Solution = Download
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