DR.
BABASAHEB AMBEDKAR TECHNOLOGICAL UNIVERSITY, LONERE
Supplementary Winter Examination – 2024
Course: B. Tech
Branch : Electronics & Telecommunication Engineering and Allied
Subject Code & Name: Digital Communication/ BTETC602 Semester : VI
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Max Marks: 60 Date: 20/12/2024 Duration: 3 Hr.
Instructions to the Students:
1. Each question carries 12 marks.
2. Question No. 1 will be compulsory and include objective-type questions.
3. Candidates are required to attempt any four questions from Question No. 2 to Question No. 6.
4. The level of question/expected answer as per OBE or the Course Outcome (CO) on which the
question is based is mentioned in ( ) in front of the question.
5. Use of non-programmable scientific calculators is allowed.
6. Assume suitable data wherever necessary and mention it clearly.
(Level/CO) Marks
Q. 1 Objective type questions. (Compulsory Question) 12
1 What is necessary for digital communication? CO1 1
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a. Precision b. Frame c. Character d. All of the
timing synchronization synchronization mentioned
2 What are the disadvantages of digital communication? CO3 1
a. Needs more b. Is more c. Needs more d. None of the
bandwidth complex bandwidth & Is mentioned
more complex
3 Synchronization available in digital communication are CO3 1
a. Symbol b. Frame c. Carrier d. All of the
synchronization synchronization synchronization mentioned
4 Analog to digital conversion includes CO3 1
a. Sampling b. Quantization c. Sampling & d. None of the
Quantization mentioned
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5 The method in which the tail of one pulse smears into adjacent symbol CO2 1
interval is called as
a. Intersymbol b. Interbit c. Interchannel d. None of the
interference interference interference mentioned
6 Random process is a function of ______ CO1 1
a. Random b. Random c. Random d. None of the
event and time event and event and real mentioned
frequency number
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7 Matched filter technique is used to 1
a. Increase SNR b. Decrease c. SNR is not d. None of the
SNR affected mentioned
8 What is the advantage of using matched filter detection? CO1 1
a. Rapid b. c. High d. Low power
increase in Simultaneous accuracy consumption
processing gain detection
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9 FSK reception uses CO2 1
a. Correlation b. PLL c. Correlation d. None of the
receiver receiver & PLL mentioned
10 QAM uses ______ as the dimensions. CO1 1
a. In phase b. Quadrature c. In phase & d. None of the
Quadrature mentioned
11 The properties used for pseudorandom sequence are CO4 1
a. Balance b. Run c. Correlation d. All of the
mentioned
12 The sequences produced by shift register depends on CO4 1
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a. Number of b. Feedback tap c. Initial d. All of the
stages connections conditions mentioned
Q. 2 Solve the following. 12
A) With a neat block diagram explain the Adaptive Delta Modulation CO3 6
transmitter and receiver with waveforms.
B) An analog signal is sampled, quantized and encoded into a binary PCM CO3 6
wave. The sampling frequency is fs=8kHz and number of
representation levels are 64. The PCM signal is transmitted over a
baseband channel using discrete pulse amplitude modulation.
Determine the minimum bandwidth of PCM system if each pulse
takes, a) 2 amplitude levels, b) 4 amplitude levels or (c) 8 amplitude
levels.
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Q.3 Solve the following. 12
A) Draw the following line code formats for bit stream: 11001001 CO2 6
i. Unipolar RZ and NRZ
ii. Polar RZ and NRZ
iii. Bipolar NRZ (AMI)
iv. Split phase Manchester
v. Polar Quaternary NRZ
B) Derive an expression for maximum signal to quantization noise ratio CO1 6
for linear quantization.
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Q. 4 Solve Any Two of the following. 12
A) Write a note on Wide-sense stationary process. CO1 6
B) Give the classification of Random processes. Explain in detail. CO1 6
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C) Prove the following autocorrelation properties. CO1/CO2 6
i. R(t) is an even function of τ.
ii. R(t) is maximum at τ=0.
Q.5 Solve Any Two of the following. 12
A) Describe the generation and detection of coherent QPSK. CO2 6
B) Compare all the digital modulation techniques. CO3 6
C) Describe the concept of continuous AWGN channel into a vector CO4 6
channel.
Q. 6 Solve Any Two of the following. 12
A) Define PN sequence. Explain the generation of maximum length CO3/ CO4 6
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sequences along with its properties.
B) Write a note on Personal communication system. CO1/CO2 6
C) Write a note on wireless telephone system. CO1/CO2 6
*** End ***
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