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\\& =2cos\left (\frac{\pi}{4}\right ) t | \\& =2cos\left (\frac{\pi}{4}\right ) t | ||
| − | + | \end{align} | |
| + | </math> | ||
---- | ---- | ||
[[CT_Fourier_transform_practice_problems_list|Back to Practice Problems on CT Fourier transform]] | [[CT_Fourier_transform_practice_problems_list|Back to Practice Problems on CT Fourier transform]] | ||
Latest revision as of 11:44, 16 September 2013
Example of Computation of inverse Fourier transform (CT signals)
A practice problem on CT Fourier transform
Specify a Fourier transform $ X(w) $
- $ X(w)=2\pi \delta\left ( w- \frac{\pi}{4}\right )+2\pi \delta\left ( w+ \frac{\pi}{4}\right ) $
Inverse Fourier transform of $ X(w) $
- $ \begin{align} x(t)&=\frac{1}{2\pi}\int_{-\infty}^{\infty}X( \omega)e^{j\omega t}d\omega \\& =\frac{1}{2\pi}\int_{-\infty}^{\infty}2\pi \delta\left ( w- \frac{\pi}{4}\right )e^{j\omega t}d\omega+ \frac{1}{2\pi}\int_{-\infty}^{\infty}2\pi \delta\left ( w+ \frac{\pi}{4}\right )e^{j\omega t}d\omega \\& =\int_{-\infty}^{\infty}\delta\left ( w- \frac{\pi}{4}\right )e^{j\omega t}d\omega+ \int_{-\infty}^{\infty}\delta\left ( w+ \frac{\pi}{4}\right )e^{j\omega t}d\omega \\& =e^{-j\frac{\pi}{4}t}+e^{j\frac{\pi}{4}t} \\& =2cos\left (\frac{\pi}{4}\right ) t \end{align} $
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\end{align}</math>
