EC 09 404/PTEC 09 403-ANALOG COMMUNICATION APRIL 2013 (2009 Scheme)

SUBJECT - ANALOG COMMUNICATION

CODE -  09 404/09 403

SEMESTER - FOURTH

BRANCH - EC/PTEC

UNIVERSITY - CALICUT

YEAR - 2013

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Part A

Answer all questions.

1. What is the significance of Power spectral density ?

2. Draw the phasor representation of an AM wave.

3. Define frequency deviation.

4. What is an Image frequency ?

5. Define effective noise temperature.

(5x2=10 marks)

Part B

Answer any four questions.

6. Write a note on Ergodic processes.

7. A modulating signal Vm= 25 cos 2pi(1x10^3)t is used to amplitude modulate the carrier signal Vc=50cos 2pi(25x10^3)t. Find the lower and upper side frequencies, modulation Index and efficienty of the modulated wave.

8. State and explain Carson's Rule.

9. What is a varactor diode ? How it is used to generate the FM wave ?

10. The Q factor a preselectro receiver is 100. Find the Image frequency and its rejection ratio for a tuning of 1155 kHz.

11. Write a note on :

    (a) Thermal noise and

    (b) Flicker noise.

(4x5=20 marks)

Part C

12. (a) Discuss in detail about the Random Variables and its significance in communication.

Or

    (b) Discuss in detail about auto correlation and cross correlation.

13. (a) Derive an expression for the AM wave, its power relation and efficieny.

Or

    (b) Derive an expression for the output signal to noise ratio of a DSB-SC receiver using Coherent detection.

14. (a) Explain the operation of a Double conversion receiver.

Or

    (b) Draw the block diagram of a Phase Locked Loop and explain the Fm demodulation process using PLL.

15. (a) Explain the various sources of noises.

Or

    (b) Derive an expression for the output signal to Noise ratio of an FM receiver.

(4x10 = 40 marks)

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