Seat Number King Mongkut’s University of Technology Thonburi Final Examination Semester 2 -- Academic Year 2015 Subject: EIE 467 Digital Communications For: Electrical Communication and Electronic Engineering, 3 rd Yr (Inter. Program) Exam Date: Tuesday May 10, 2016 Time: 9.00am-12.00pm Instructions:- 1. This exam consists of 5 problems with a total of 24 pages, including the cover. 2. This exam is closed-book. 3. You are not allowed to use a written A4 note for this exam. 4. Answer each problem on the exam itself. 5. A calculator compiling with the university rule is allowed. 6. A dictionary is not allowed. 7. Do not bring any exam papers and answer sheets outside the exam room. 8. The exam has no correction. If you think that you find a mistake, explain it for a possibility of a partial credit. 9. Open Minds … No Cheating! GOOD LUCK!!! Remarks:- • Raise your hand when you finish the exam to ask for a permission to leave the exam room. • Students who fail to follow the exam instruction might eventually result in a failure of the class or may receive the highest punishment within university rules. • Carefully read the entire exam before you start to solve problems. Before jumping into the mathematics, think about what the question is asking. Investing a few minutes of thought may allow you to avoid twenty minutes of needless calculation! Question No. 1 2 3 4 5 TOTAL Full Score 22 25 16 23 14 100 Graded Score Name ______________________________________________Student ID___________________ This examination is designed by Watcharapan Suwansantisuk; Tel: 9069 This examination has been approved by the committees of the ENE department. _____________________________________ (Asst. Prof. Suwat Pattaramalai, Ph.D.) Acting Head of Electronic and Telecommunication Engineering Department Name ................................................ Student ID 560705038 ...... Seat Number ............ Problem 1: Pulse amplitude modulation (PAM) [22 points] modulator signal encoder pass filter signal decoder ideal low− baseband to passband passband to baseband demodulator baseband baseband 110 u(t) 2 cos(2πfct) x(t) cos(2πfct) g(t) v(t) A PAM modulator is connected directly to a PAM demodulator through a noiseless channel, as shown in the above figure. The binary input b 0 b 1 b 2 is 110 The amplification factor is a = 5. The symbol interval is T = 2 sec, and the pulse is the square root of raised cosine filter with the roll-off factor α =0.4. The carrier frequency is f c =0.5 Hz. Fill in the blanks below. You do not need to justify your answer (2 points each). (a) The output from the signal encoder is . (b) The output from the baseband demodulator is . (c) The output from the signal decoder is . 2
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Seat Number Problem 1: Pulse amplitude modulation (PAM)webstaff.kmutt.ac.th/~watcharapan.suw/class/EIE-467/exam/AY2558... · Seat Number Problem 1: Pulse amplitude modulation (PAM)
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Seat Number
King Mongkut’s University of Technology Thonburi Final Examination
Semester 2 -- Academic Year 2015
Subject: EIE 467 Digital Communications For: Electrical Communication and Electronic Engineering, 3rd Yr (Inter. Program) Exam Date: Tuesday May 10, 2016 Time: 9.00am-12.00pm Instructions:-
1. This exam consists of 5 problems with a total of 24 pages, including the cover. 2. This exam is closed-book. 3. You are not allowed to use a written A4 note for this exam. 4. Answer each problem on the exam itself. 5. A calculator compiling with the university rule is allowed. 6. A dictionary is not allowed. 7. Do not bring any exam papers and answer sheets outside the exam room. 8. The exam has no correction. If you think that you find a mistake, explain it for a possibility
of a partial credit. 9. Open Minds … No Cheating! GOOD LUCK!!!
Remarks:- • Raise your hand when you finish the exam to ask for a permission to leave the exam
room.
• Students who fail to follow the exam instruction might eventually result in a failure of the class or may receive the highest punishment within university rules.
• Carefully read the entire exam before you start to solve problems. Before jumping into the mathematics, think about what the question is asking. Investing a few minutes of thought may allow you to avoid twenty minutes of needless calculation!
Question No. 1 2 3 4 5 TOTAL
Full Score 22 25 16 23 14 100
Graded Score
Name ______________________________________________Student ID___________________
This examination is designed by Watcharapan Suwansantisuk; Tel: 9069
This examination has been approved by the committees of the ENE department.
_____________________________________ (Asst. Prof. Suwat Pattaramalai, Ph.D.)
Acting Head of Electronic and Telecommunication Engineering Department