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Chapter 6: Continuous-time Fourier Methods Dr. Kalyana Veluvolu Example 1 (Find the Fourier Series Pair) 1
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Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Jan 13, 2020

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Page 1: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Example 1 (Find the Fourier Series Pair)

1

Page 2: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Example 2

2

Find the Fourier Series pair for the periodic function defined in one period

Page 3: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Example 2 Cond…

3

Page 4: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Example 3

4

Page 5: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Example 3 Cond..

5

Page 6: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Example 3 Cond..

6

Page 7: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Example 4

7

Page 8: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Example 5

8

Page 9: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Fourier Transform Properties

9

Page 10: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Fourier Transform Properties

10

Page 11: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Example 6 - CTFT

11

rect(t) sinc(f)F

Linearity 25 rect(t) 25 sinc(f)F

Time Scaling 25 rect(t/10) 250 sinc(10f)F

Time Shifting 25 rect((t-4)/10) 250 sinc(10f)F 8j fe

Find CTFT of x(t)= 25 rect((t-4)/10)

We can find the CTFT of the unit rectangle function

in the table of Fourier Transforms

Page 12: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Example 7 - CTFT

12

Page 13: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

If x(t)= 10 Sin(t) find

(a) The CTFT of x(t) ; b) The CTFT of x(2(t-1));

c) The CTFT of x(2t-1)

Better to use radian-frequency form of CTFT

Example 8 - CTFT

13

a)

Page 14: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu

Example 8 – CTFT contd..

14

b) The CTFT of x(2(t-1));

Page 15: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu 15

Example 8 – CTFT contd..

c) The CTFT of x(2t-1);

Page 16: Chapter 6: Continuous-time Fourier Methods Example 1 (Find the Fourier …ncbs.knu.ac.kr/Teaching/SS_Files/SS_Chapter6-Problems.pdf · 2017-11-22 · Chapter 6: Continuous-time Fourier

Chapter 6: Continuous-time Fourier Methods

Dr. Kalyana Veluvolu 16

Example 9 – CTFT