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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
ExampleFind the Fourier Transform for the following function
ExampleFind the Fourier Transform for the delta function x(t) = d(t)
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
Method 1 Since and Therefore