Principles of Analog & Digital Comm. Question Paper - May 17 - Information Technology (Semester 3)

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Principle of Communications - May 17

Information Technology (Semester 3)

Total marks: 80
Total time: 3 Hours INSTRUCTIONS
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Draw neat diagrams wherever necessary.

Solve any four question from Q.1(a, b, c, d, e)

1(a) Compare analog and digital communication system.

5 marks 00

1(b) Define modulation. Explain and Justify any two need of modulation.

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1(c) Explain in brief Pre-emphasis and De-emphasis in FM.

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1(d) Explain in brief the process of quantization.

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1(e) What is line coding. Draw the NRZ and Manchester signal for the following binary signal 10111010.

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2(a) Explain the term thermal noise. Prove that the noise voltage Vn√4kTBRVn4kTBR V_{n}\sqrt{4kTBR} / For electronic device operating at a temperature of 17°C with a bandwidth of 10 KHz, determine
1. Thermaol noise power in dBm. 2. RMS noise volatage for a 100Ω internal resistance and a 100Ω load resistance.

5 marks 00

2(b) State and prove time scaling property of Fourier transd 01m. Determine the Fourier transform for a rectangular pulse of amplitude 'A' and time period 'T' is from-T/2 to T/2

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3(a) An AM signal appears across a 50Ω load and has the following equation [v(t)= 12(1+sin12.566×10³t) sin 18.85×10⁶t volts br> i) Sketch the envelope of this signal in time domain.
ii) Calculate modulation index, sideband frequencies, total power and bandwidth.

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3(b) What are the limitations of 'TRF' receiver. Explain how these limitations are avoided using super heterodyne receiver.

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4(a) With the help of neat circuit diagram explain the working of Ratio detector.

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4(b) What is multiplexing in communication system. Draw and explain in brief the transmitter and receiver of FDM.

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5(a) State and prove sampling theorem for how pass band limited signal. Explain aliasing error.

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5(b) What are the various pulse modulation techniques? Explain how PPM is obtained from PWM.

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6(a) Explain in brief the generation and detection of Delta modulation.

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6(b) Explain the generation and detection of ASK signal with block diagram and waveforms.

5 marks 00

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