Question Paper: Analog Communication Question Paper - December 2016 - Electronics and Telecom Engineering (Semester 5) - Mumbai University (MU)
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## Analog Communication - December 2016

### MU Electronics and Telecom Engineering (Semester 5)

Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

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

1(a) Justify why FM is more immune to noise. 5 marks

1(b) Define noise factor and noise figure. 5 marks

1(c) What is Pre-emphasis? Why is it used? Sketch and explain pre-emphasis circuit. 5 marks

1(d) what is quantization? Explain types of quantization. 5 marks

1(e) Hwy AGC is required in receivers? Differentiate between simple AGC and Delayed AGC. 5 marks

2(a) With neat block diagram explain filter method of SSB generation. State its drawbacks. 5 marks

2(b) Explain practical diode detector with delayed AGC. 5 marks

3(a) The antenna current of AM broadcast transmitter modulated to the depth of 40% by an audio sine wave is 11 Ampere. It increases to 12 Ampere as a result of simultaneous modualtionby another audio sinewave. What is the modulation index due to this second wave? 5 marks

3(b) Derive mathematical expression for FM wave and its modulation index. 5 marks

4(a) Explain the operation of Foster seely discriminator with the help of circuit diagram and phasor diagram. 5 marks

4(b) If a broad superjetrodyne receiver having no RF amplifier, the loaded Q of the antenna coupling circuit ( at the input to the mixer) is 100.
i) if the intermidate frequency is 455kHz, calculate the image frequency and its rejection at 1000kHz and 25 Mhz.
ii) In order to make the image frequency rejection of the receivers as good at 25MHz as it was at 1000kHz, calculate the loaded Q which an RF amplifier for this receiver would have.
5 marks

5(a) State and prove theorem for low pass band imited signal. 5 marks

5(b) With the help of block diagram and waveform explain generation and detection of Pulse Width Modulation. 5 marks