Difference between revisions of "HW5.3 I-Cheng Chen ECE301Fall2008mboutin" - Rhea

Revision as of 12:43, 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 ---- [[CT_Fourier_transform_practice_problems_list|Back to Practice Problems on CT Fourier transform]] \end{align} $