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G.NARAYANAMMA INSTITUTE OF TECHNOLOGY & SCIENCE ( FOR WOMEN)

(AUTONOMOUS)

II B.Tech, II-Sem Examinations 2013

SUBJ ECT: PRINCIPLES OF COMMUNICATIONS MAX.MARK S: 75

TIME: 3 Hrs DATE:

____________________________________________________________________________MODEL PAPER-I

Note: i. The question paper comprises of Part A & Part B

ii. Part A is compulsory and all questions should be answered at one place

iii. Questions 1 5 carry 1 mark each and 6 to 10 carry 2 marks each in part A

iv. Part B has 8 questions. Answer any 5 questions and each question carry 12 marks.

PART A (15 MARK S)

Answer all questions (5 1 =5M)

1. ____________ is a process in which analog signal is converted into a corresponding

sequence of samples that are uniformly spaced in time.

2. Fourier transform of a unit impulse function is __________________

3. Aliasing occurs, when the Nyquist rate is _________________________.

4. The main advantage of TDM over FDM is that ________.

5. The advantage of cyclic code is ______________.

(5 2 =10M)

6. What is the transmission bandwidth of a PAM/TDMchannel?

7. What is aperture effect? How it can be reduced?

8. Give the applications of Hilbert transform.

9. Define the information rate?

10. What are the types of error control methods?

PART B (60 MARK S)

Answer any five Questions

1. (a) What are the types of communications? Explain.(b) Define noise. Where is it most likely to affect the signal? [6+6] M

2. (a) A voltage v(t) = 200 sin ct (1+0.4sin mt) is applied to a resistor of 100 ohms. Find the

carrier frequency, modulating frequency, modulation index and power dissipated by each of

the frequency components present in the voltage v.

(b) Explain the Synchronous Detection in DSB-SC demodulation process with block diagram.

[6+6]M

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3. a) Explain about parameter variation method (direct method) for FM generation.

b) Explain the generation of PM using FM. [6+6]M

4. (a) Describe different types of signaling formats with neat sketches.

(b) Explain the features of Flat top Sampling and Aperture effect. [6+6]M

5. (a) What do you understand by PCM? How quantizing and coding are done?

(b) What is aliasing effect and aperture effect. How these effects can be overcome. [6+6]M

6. (a) Differentiate BPSK & QPSK

(b) Definei. Baud Rateii. Matched Filteriii. Band width efficiency.iv. SNR. [6+6]M

7. Write short notes on: [12] M

(a) Entropy(b) Redundancy(c) Hartley-Shannon Law(d) Channel capacity.

8. For a (6,3) linear black code, the parity check matrix is H=

For all the possible data words, find the corresponding code words. [12]M