Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Winter 5th Sem 3151104 Analog And Digital Communication Previous Question Paper
Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER?V (NEW) EXAMINATION ? WINTER 2020
Subject Code:3151104 Date:01/02/2021
Subject Name:Analog and Digital Communication
Time:10:30 AM TO 12:30 PM Total Marks: 56
Instructions:
1. Attempt any FOUR questions out of EIGHT questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Draw the detailed Block Diagram of Communication
03
System.
(b) Why is Modulation required in Communication? Discuss
04
in detail.
(c) (i) Discuss Channel Capacity relative to Channel
04
Bandwidth and Signal Power.
(ii) Discuss the Trade off between Bandwidth and SNR.
03
Q.2 (a) Compare Analog and Digital Communication.
03
(b) A certain transmitter radiates 9kW with the carrier
04
unmodulated and 10.125kW when the carrier is
sinusoidally modulated. Calculate the modulation index.
If another sine wave is simultaneously transmitted with
modulation index 0.4, determine the total radiated power.
(c) Derive expression of Total transmission bandwidth
07
required for DSBSC and SSB in terms of modulating
signal frequency. Make suitable comment for bandwidth
efficient Amplitude Modulation.
Q.3 (a) Compare Amplitude Modulation and Angle Modulation.
03
(b) Given modulating bit stream is 10010011. Draw the
04
ASK,FSK and BPSK signals. Also draw the waveforms
for carrier and modulating bit stream.
(c) Draw and explain every block in Superheterodyne
07
receivers.
Q.4 (a) Enlist various methods of FM generation. Explain any
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one of them.
(b) Explain QPSK modulator with schematic diagram.
04
(c) Explain Preemphasis and Deemphasis in FM
07
broadcasting with block diagram , filter circuits and
frequency response.
Q.5 (a) Draw the detailed block diagram of PCM.
03
(b) Calculate the bit rate for T1 carrier system.
04
(c) Explain DPCM with block diagram.
03
With mathematical analysis prove that SQNR is
04
improved in DPCM as compared to PCM.
Q.6 (a) State `Sampling Theorem'. Discuss Nyquist Rate of
03
1
sampling.
(b) A message signal x(t) band limited to 3 KHz is sampled
04
at a rate 33.34 % higher than the Nyquist rate. Calculate
the sampling rate. The maximum acceptable error in the
sample amplitude (the maximum quantization error) is
0.5% of the peak amplitude mp . The quantized samples
are binary coded. Find the bit rate. Find the minimum
bandwidth of a channel required to transmit the coded
binary signal. If 24 such signals are time division
multiplexed, determine the maximum transmission
bandwidth required to transmit the multiplexed signal.
(c) Explain `Slope Overload' with diagram.
04
Derive the condition to avoid slope overload considering
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x(t)=A cos(m t) as input signal, as step size and Ts as
sampling interval.
Q.7 (a) Enlist the properties of Line Codes.
03
(b) Explain how to read an eye diagram.
04
(c) Explain Data Scrambling with suitable example.
07
Q.8 (a) Give the full forms of (i) ISI (ii) PSD (iii) AMI
03
(b) Draw the signals for Unipolar NRZ, Unipolar RZ, Polar
04
NRZ, Polar RZ for 10100111 data.
(c) Explain Clock Recovery in PCM system.
07
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This post was last modified on 04 March 2021