END TERM EXAMINATION
FOURTH SEMESTER BTech
Subject Code: ETCS-208
Subject: Communication Systems
Time: 3 Hrs M.M: 75
Note: Attempt any five questions. Question 1 is compulsory. Select one question from each unit.
Question 1: (5×5 = 25)
(a) Derive an expression for single tone amplitude modulated wave.
(b) What is Carson's rule? Define modulation index for FM.
(c) State and prove sampling theorem in time domain.
(d) Differentiate DPSK and QPSK techniques?
(e) List the steps for determining all the code words for a Linear Block Code.
Question 2: With the help of a block diagram explain communication system model. List the advantages and disadvantages of Digital Communication. (12.5)
Question 3: What is Double side-band suppressed carrier system? Discuss two types of a product modulator. (12.5)
Question 4: Derive an expression for a single tone narrow band frequency modulated wave. List the differences between narrowband FM and wideband FM. (12.5)
Question 5: What is meant by 'Noise' in communication system? Explain the following terms (12.5)
ⅰ Signal to Noise Ratio
ⅱ Noise Figure
ⅲ Noise Temperature
Question 6: What is PAM? With the help of sample and hold circuit explain its working principle. List some drawbacks of PAM signal. (12.5)
Question 7: Compare delta modulation (DM), Adaptive delta modulation (ADM) and Pulse Code Modulation techniques. (12.5)
Question 8: Draw the block diagram of QPSK system and explain its working. Write and draw the power spectral density of QPSK signals. (12.5)
Question 9: Define the following terms. (12.5)
(a) Code Word
(b) Block Length
(c) Channel Data Rate
(d) Code Vectors