Daffodil International University
Department of Computer Science and Engineering
Faculty of Science & Information Technology
Mid Term Examination, Fall 2020 @ DIU Blended Learning Center Course Code: CSE411, Course Title: Communication Engineering
Level: 4 Term: 1 Section: O-1(EVE), O2(EVE) Instructor: ASMFH Modality: Open Book Exam Date: Saturday 7 November, 2020 Time: 07:00-011:00pm
Four hours (4:00) to support online open/case study based assessment Marks: 25 Directions:
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Students need to go through the CASE STUDY shown in this exam paper.
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Analyze and answer specific section based on your own thinking and work.
Q1. a. Assume that a voice channel occupies a five times the bandwidth of the highest digit in the last five digits of your ID. We need to combine five voice channels into a link with a sufficient bandwidth, from 225 KHz to 525 kHz. Show the configuration, using the frequency domain.
Assume there is guard band of 3 KHZ between each channel.
[N.B.: If the ID is 181-15-10591, consider last 5 digits 10591. The highest digit is 9.
Find the bandwidth]
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b. Explain two real life applications of guard band in communication industry. 2 Q2 a. Create 7 numbers from your official name as instructed below. Prove that the data has been
sent without any error using checksum mechanism.
[N.B: Suppose your name is Rashed Haque. Take the first seven letters (R, A, S, H, E, D, H).
Find the numbers by indexing as A=1, B=2, C=3, D=4… Y=25, Z=26]
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b. Consider the last 3 digits of your ID number as the frequency (Hz) of transmission.
I. If the peak amplitude is 15V then draw the transmission wave in time domain.
II. If the peak amplitude is 15V then draw the transmission wave in frequency domain.
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Q3. Consider the last 5 digits of your ID. Convert the number into binary for considering data.
Draw the signals using following line coding schemes:
a) NRZ-I
b) Differential Manchester c) Pseudo ternary
d) Alternate Mark Inversion(AMI)
[N.B.: If id is 181-15-11111, consider last 5 digits 11111.
The binary of (11111)10 = (10101101100111)2. Now apply the line coding schemes in this data]
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