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## Anna University questions - CS2204 / CS36 / EC1207 / 080230008 / 10144 / CS305 Analog and Digital Communication April May 2015, Computer Science and Engineering (CSE), Third Semester, Regulation 2008 and 2010

Exam
B.E/B.Tech. (Full Time) DEGREE END SEMESTER EXAMINATIONS
April May 2015
Subject Code

Subject Name

## Analog and Digital Communication

Branch
Computer Science and Engineering
Semester
Third Semester
Regulation
2008/2010

B.E / B.Tech. (Full Time) DEGREE END SEMESTER EXAMINATIONS, APRIL / MAY 2015
Computer Science and Engineering
Third Semester
CS2204 / CS36 / EC1207 / 080230008 / 10144 / CS305 ANALOG AND DIGITAL COMMUNICATION
(Regulations 2008/2010)
Time : 3 Hours                      Answer A L L Questions                Max. Marks 100
PART-A (10 x 2 = 20 Marks)

1. Define repetition rate of the AM envelope.
2. Define frequency deviation and phase deviation.
3. Define information capacity.
4. Compare PSK and QAM.
5. Define companding.
6. Define slope overload and granular noise.
7. Contrast Connection oriented and connectionless protocols.
8. Define Baudot code.
9. What do you mean by Pseudo noise sequence?

Part-B (5* 16 = 80 Marks)

11. (a) (i) Describe the basic operation of the AM modulator and explain the phase representation of an AM modulated wave. (8)
(ii) Discuss the relationship between phase deviation and modulation index and frequency deviation and percent modulation. (8)
Or
(b) (i) One input to a conventional AM modulator is 100 KHz carrier with an amplitude of 20 Vp. The second input is 10 KHz modulating signal that is of sufficient amplitude to cause a change in the outpսt wave of ± 6.5 Vp. Determine :
(1) Upper and lower side frequencies
(2) Modulation coefficient and percent modulation
(3) Maximum and Minimum amplitudes of the envelope
(4) Expression for the modulated wave and
(5) Draw the output p? (8)
(ii) Discuss the frequency analysis and bandwidth requirements of angle modulated waves. (8)

12. (a) (i) Discuss the following: (8)
(1) Frequency Shift Keying (FSK) basic principles
(2) FSK Modulator
(3) FSK demodulator
(ii) Describe QAM Transmitter and Receiver with neat sketch. (8)
Or
(b) (i) Describe FSK Transmitter and Receiver with neat sketch. (8)
(ii) Discuss the following terminologies: (8)
(1) Bandwidth efficiency
(2) Carrier recovery
(3) Squaring loop
(4) Costas loop

13. (a) Describe Delta modulation PCM and Adaptive Delta Modulation PCM and compare it. (16)
Or
(b) With neat sketch explain the simplex PCM transmission system and PCM sampling. (16)

14. (a) (i) Discuss the following error correcting methods: (8)
(1) Retransmission,
(2) Forward Error Correction.
(ii) Describe data communication hardware with neat sketch. (8)
Or
(b) (i) Discuss the following error detection techniques:
(1) Redundancy Checking
(2) Checksum
(3) Cyclic redundancy Checking (8)
(ii) Discuss different data communication modems. (8)

15. (a) Discuss and compare CDMA and TDMA in wireless Communication Systems. (16)
Or
(b) Explain Direct Sequence Spread Spectrum with Coherent Binary PSK. (16)

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