Engineering BE Electronics and Computer Science Sem 4 May 2019 2019 Principle Of Communication Engineering Question Paper - Mumbai University | munotes

Questions asked in this paper

1. Q2 attempt any 3 questions from the remaining five questions
2. Q1 Answer any 4 questions: 20 marks
   • a) neat circuit diagram and waveforms, explain the working of envelope detector What are its merits and demerits?
   • b) Explain double spotting. How it can be overcome in AM receivers?
   • c) Define the following terms with respect to Radio Receivers :
   • d) tone FM signal is given by erm (t) = 20 Cos (16 t + 25 Sin t) Find the modulation index, modulating frequency, deviation, carrier frequency and power in the FM signal
   • e) | What is Coherent detection? Explain the method of Coherent detection of SSB-SC AnAM signal is produced by modulating a carrier signal with peak voltage of 1OV and (6) frequency of 100KHz by a sinusoidal signal of amplitude 4V and frequency
   • a) modulation index and Write its mathematical expression
   • b) of AM and sketch its two sided spectrum
   • c) power of the modulated wave developed across load resistance, =50 Q and power content in each sideband and carrier
   • b) What are the methods employed for generation of SSB? Explain the third method of SSB_ generation with its advantages and disadvantages Prove that Balanced modulator circuit (diode based BJT based) can generate a DSB- (6) 8
3. Q3 Explain the Armstrong method of FM generation. Compare WBFM signal with the modulation index and the bandwidth for FM system 6 marks
   • (1) Determine the change in the BW and modulation index for FM , if modulating
   • (ii) find bandwidth and modulation index ,if amplitude is reduced to half Paper Subject Code: 40905 Principles of Communication Engineering
   • c) Draw and explain the transmitter and receiver of Linear Delta modulation. What is by slope overload distortion? Explain How it can be eliminated? Explain how Foster- Seelay discriminator can be used for FM detection. List its merits 6
   • b) Draw the functional block diagram of Super-heterodyne receiver with waveforms at the — output of each block. Explain the functions of each block 8
   • c) What is image frequency and its significance? A super-heterodyne tuned a signal of 1100 KHz frequency with the local oscillator frequency being 1555 KHz? What is the image frequency? What will be the image Frequency rejection ratio the tuned circuit of mixer stage has a loaded Q of 60? 6
4. Q5 a) With the help of a neat block diagram explain the generation and detection ofa PWM _ signal. With relevant waveforms, explain how a PPM signal can be generated from a 10 marks
   • b) State and Prove Sampling theorem for low pass signals. Draw the spectrum of sampled signal for fs > 2W., fs = 2W. What is Aliasing error? How can you overcome 10
5. Q6 Write short notes : any four 20 marks
   • a) Block diagram of PCM transmitter and receiver
   • b) system
   • c) Noise triangle and its significance Block diagram of TRF receiver: its merits and demerits Pre emphasis and de-emphasis circuits

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