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# EC6402 Question Bank Communication Theory

EC6402 Question Bank Communication Theory Regulation 2013 Anna University free download. Communication Theory Question Bank free download.

## Sample Question Bank:

1. Compare AM, DSB-SC, SSB and VSB wave?

2. Define modulation index of AM signal..

3. Compare Frequency and Phase modulation.

4. Convert NBFM to WBFM?

5. Define noise figure.

6. Define Thermal noise.

7. Define Figure of merit.

8. Define pre-emphasis and de-emphasis

9. What is channel redundancy?

10. State Shannon‘s theorem

11. ((i) Explain Frequency Translation. (8)
(ii) Derive the equation of an AM wave. Also draw the modulated AM wave for various modulation index. (8)
OR
(b(i) Explain the generation of SSB signal. (10)
(ii) Show that an AM can be recovered, irrespective of value of % modulation by using synchronous detection technique. (6)

12 (a) (Draw the circuit diagram of Foster-Seeley discriminator and explain its working. (16)
OR
(b) (i) Explain the Armstrong method for generation of FM signal with block diagram. (10)
(ii) A modulating signal 5cos (2π15*1000t) angle modulates a carrier Acosωt. Find the modulation index & bandwidth for FM system & determine the change in bandwidth & modulation index for FM if fm is reduced by 5 KHz. (6)

13. (a) Derive the effective noise temperature of a cascade amplifier. Explain how the various noises are generated and the method of representing them. (16)
OR
(b) Discuss the following:
i) noise equivalent bandwidth (4)
ii) narrow band noise (4)
iii) noise temperature (4)
iv) noise spectral density (4)

14. (a) Explain the working of AM & FM Superheterodyne receivers with its parameters. (16)
OR
(b) Derive the expression for output signal to noise for a DSB-SC receiver using coherent detection. (16)

 Subject Name Communication Theory Subject Code EC6402 Regulation 2013