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<math>x(t)=t^3 e^{-3t} </math>
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[[Category:problem solving]]
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[[Category:ECE301]]
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[[Category:ECE]]
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[[Category:Fourier transform]]
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[[Category:signals and systems]]
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== Example of Computation of Fourier transform of a CT SIGNAL ==
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A [[CT_Fourier_transform_practice_problems_list|practice problem on CT Fourier transform]]
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----
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<math>x(t)=e^{-3t} u(t-3) u(t+3) </math>
  
 
<math>X(w) = \int^{\infty}_{- \infty}x(t)e^{-jwt} dt</math>
 
<math>X(w) = \int^{\infty}_{- \infty}x(t)e^{-jwt} dt</math>
  
<math>= \int^{\infty}_{- \infty} t^3 e^{-3t} e^{-jwt} dt</math>
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<math>= \int^{\infty}_{- \infty} e^{-3t} u(t-3) u(t+3) e^{-jwt} dt</math>
  
<math>= \int^{\infty}_{- \infty} t^3 e^{-(3 + jw)t} dt</math>
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<math>= \int^{3}_{-3} e^{-(3 + jw)t} dt</math>
  
<math>[\frac{1}{3} t^4 \frac{e^{-(3 + jw)t}}{-(3 + jw)}]_{- \infty}^{\infty}</math>
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<math>[\frac{e^{-(3 + jw)t}}{-(3 + jw)}]_{-3}^{3}</math>
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<math>\frac{e^{-(9 + 3jw)}}{-(3 + jw)} - \frac{e^{(9 + 3jw)}}{-(3 + jw)}</math>
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----
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[[CT_Fourier_transform_practice_problems_list|Back to Practice Problems on CT Fourier transform]]

Latest revision as of 11:27, 16 September 2013

Example of Computation of Fourier transform of a CT SIGNAL

A practice problem on CT Fourier transform


$ x(t)=e^{-3t} u(t-3) u(t+3) $

$ X(w) = \int^{\infty}_{- \infty}x(t)e^{-jwt} dt $

$ = \int^{\infty}_{- \infty} e^{-3t} u(t-3) u(t+3) e^{-jwt} dt $

$ = \int^{3}_{-3} e^{-(3 + jw)t} dt $

$ [\frac{e^{-(3 + jw)t}}{-(3 + jw)}]_{-3}^{3} $

$ \frac{e^{-(9 + 3jw)}}{-(3 + jw)} - \frac{e^{(9 + 3jw)}}{-(3 + jw)} $


Back to Practice Problems on CT Fourier transform

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