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EE 207 Dr. Adil Balghonaim. Chapter 4 The Fourier Transform. Let x p (t) be a periodical wave, then expanding the periodical function. Rewriting x p (t) and X n. Fourier Transform Pairs. Fourier Transform Pairs. Fourier Transform Pairs. Finding the Fourier Transform.
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EE 207 Dr. Adil Balghonaim Chapter 4 The Fourier Transform
Let xp(t) bea periodical wave, then expanding the periodical function Rewriting xp(t) and Xn
Example 4-1 Find the Fourier Transform for the following function
Properties of the Fourier Transform 1-Linearity Proof
2-Time-Scaling (compressing or expanding) Let Then Proof Change of variable
Now Let Change of variable Since
3-Time-Shifting Proof
Example Find the Fourier Transform of the pulse function Solution From previous Example
4-Time Transformation Proof
6- The convolution Theorem Convolution in Time Multiplication in Frequency Proof
Now substitute x2(t-l) ( as the inverse Fourier Transform) in the convolution integral
The multiplication Theorem Proof Similar to the convolution theorem , left as an exercise Applying the multiplication Theorem
Find the Fourier Transform of following Solution Since
6-Frequency Shifting Proof
Since and Therefore
7-Integration Example Find the Fourier Transform of the unit step function u(t)