Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 6th Sem Old 161001 Digital Communication Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? VI (Old) EXAMINATION ? WINTER 2019
Subject Code: 161001 Date: 11/12/2019
Subject Name: Digital Communication
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Explain the advantages of digital communication over
analog communication.
07
(b)
What is a line code?
Describe the desirable properties of line codes
07
Q.2 (a) Draw neat diagram of delta modulator, delta demodulator,
input waveform, output waveform and error waveform.
Define slope overload and write the condition to avoid
lope overload in delta modulation.
07
(b) Derive an equation of signal-to noise ratio for a uniform
quantizer.
07
OR
(b) State Nyquist sampling theorem. Write the condition and
name of the circuit to avoid aliasing. Discuss the
applications of sampling theorem.
07
Q.3 (a) Explain HDB3 signaling with an example. Draw it PSD. 07
(b) What is a regenerative repeater?
Draw its block diagram and state the function of each
block in 2-3 sentences.
07
OR
Q.3 (a) Draw neat waveforms of data, carrier and modulated
signals for ASK, FSK and PSK modulations. What is the
difference in PSDs of ASK and PSK.
07
(b) State the Nyquist criterion for zero ISI. Draw time and
frequency domain waveforms for the pulse that satisfies
this criterion. Define roll-off factor.
07
Q.4 (a) Define the following mathematically with reference to
probability and random variables:
Conditional probability, joint probability, CDF, PDF,
Statistical mean, variance, correlation.
07
(b) State and explain central limit theorem. 07
OR
Q.4 (a) Find the mean square value of quantization error in PCM
considering uniform random variable approach
07
(b) Give mathematical expression of Gaussian PDF and CDF.
Also, draw the curves for the CDF and PDF of Gaussian
random variable. Define Q function and express the
probability that Gaussian random variable is greater than
some value x in terms of Q function.
07
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Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? VI (Old) EXAMINATION ? WINTER 2019
Subject Code: 161001 Date: 11/12/2019
Subject Name: Digital Communication
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Explain the advantages of digital communication over
analog communication.
07
(b)
What is a line code?
Describe the desirable properties of line codes
07
Q.2 (a) Draw neat diagram of delta modulator, delta demodulator,
input waveform, output waveform and error waveform.
Define slope overload and write the condition to avoid
lope overload in delta modulation.
07
(b) Derive an equation of signal-to noise ratio for a uniform
quantizer.
07
OR
(b) State Nyquist sampling theorem. Write the condition and
name of the circuit to avoid aliasing. Discuss the
applications of sampling theorem.
07
Q.3 (a) Explain HDB3 signaling with an example. Draw it PSD. 07
(b) What is a regenerative repeater?
Draw its block diagram and state the function of each
block in 2-3 sentences.
07
OR
Q.3 (a) Draw neat waveforms of data, carrier and modulated
signals for ASK, FSK and PSK modulations. What is the
difference in PSDs of ASK and PSK.
07
(b) State the Nyquist criterion for zero ISI. Draw time and
frequency domain waveforms for the pulse that satisfies
this criterion. Define roll-off factor.
07
Q.4 (a) Define the following mathematically with reference to
probability and random variables:
Conditional probability, joint probability, CDF, PDF,
Statistical mean, variance, correlation.
07
(b) State and explain central limit theorem. 07
OR
Q.4 (a) Find the mean square value of quantization error in PCM
considering uniform random variable approach
07
(b) Give mathematical expression of Gaussian PDF and CDF.
Also, draw the curves for the CDF and PDF of Gaussian
random variable. Define Q function and express the
probability that Gaussian random variable is greater than
some value x in terms of Q function.
07
2
Q.5 (a) Define information and derive and expression for channel
capacity of a Binary Symmetric Channel.
07
(b) Define following with reference to error detecting and
correcting codes:
Code efficiency, Hamming bound, perfect code, generator
polynomial, interlaced code, code tree, burst error-
detecting/correcting code.
07
OR
Q.5 (a) Design an optimum binary receiver and compute error
probability for 16-QAM system. Assume all messages are
equi-probable and AWGN channel.
07
(b) Explain the coherent detection of ASK signal with neat
diagram, waveforms and relevant expressions.
07
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This post was last modified on 20 February 2020