(New page: {| | align="left" style="padding-left: 0em;" | CTFT of a sinc |- | <math> X(f)=\mathcal{X}(2\pi f)=\left\{\begin{array}{ll}1, & \text{ if }|f| <\frac{W}{2\pi},\\ 0, & \text{else.}\end{a...) |
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− | + | =How to obtain the CTFT of a sinc in terms of f in hertz (from the formula in terms of <math>\omega</math>) = | |
− | + | ||
− | + | Recall: | |
− | | <math> X(f)=\mathcal{X}(2\pi f)=\left\{\begin{array}{ll}1, & \text{ if }|f| <\frac{W}{2\pi},\\ 0, & \text{else.}\end{array} \right. \ </math> | + | |
− | + | <math>x(t)=\frac{2 \sin \left( W t \right)}{\pi t }</math> | |
− | | | + | |
+ | <math>\mathcal{X}(\omega)=\left\{\begin{array}{ll}1, & \text{ if }|\omega| <W,\\ 0, & \text{else.}\end{array} \right.</math> | ||
+ | |||
+ | To obtain X(f), use the substitution | ||
+ | |||
+ | <math>\omega= 2 \pi f </math>. | ||
+ | |||
+ | More specifically | ||
+ | |||
+ | <math> X(f)=\mathcal{X}(2\pi f)=\left\{\begin{array}{ll}1, & \text{ if }|f| <\frac{W}{2\pi},\\ 0, & \text{else.}\end{array} \right. \ </math> | ||
+ | |||
+ | ---- | ||
+ | [[ECE438_HW1_Solution|Back to Table]] |
Latest revision as of 10:59, 15 September 2010
How to obtain the CTFT of a sinc in terms of f in hertz (from the formula in terms of $ \omega $)
Recall:
$ x(t)=\frac{2 \sin \left( W t \right)}{\pi t } $
$ \mathcal{X}(\omega)=\left\{\begin{array}{ll}1, & \text{ if }|\omega| <W,\\ 0, & \text{else.}\end{array} \right. $
To obtain X(f), use the substitution
$ \omega= 2 \pi f $.
More specifically
$ X(f)=\mathcal{X}(2\pi f)=\left\{\begin{array}{ll}1, & \text{ if }|f| <\frac{W}{2\pi},\\ 0, & \text{else.}\end{array} \right. \ $