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| − | <span style="color:green"> I suggest putting a link next to each formula explaining how to obtain it from the formula in terms of <math>\omega</math>. Also, I would not use the "mathcal" (curly) font for the transform variable, just a capital letter instead. </span> --[[User:Mboutin|Mboutin]] 08:52, 3 September 2010 (UTC) | + | *<span style="color:green"> I suggest putting a link next to each formula explaining how to obtain it from the formula in terms of <math>\omega</math>. Also, I would not use the "mathcal" (curly) font for the transform variable, just a capital letter instead. </span> --[[User:Mboutin|Mboutin]] 08:52, 3 September 2010 (UTC). |
| + | **<span style="color:green"> Fixed the X(f) notation </span> -[[User:sbiddand|Sbiddand]] | ||
{| | {| | ||
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|- | |- | ||
| align="right" style="padding-right: 1em;" | CT Fourier Transform | | align="right" style="padding-right: 1em;" | CT Fourier Transform | ||
| − | | <math> | + | | <math>X(f)=\mathcal{F}(x(t))=\int_{-\infty}^{\infty} x(t) e^{-i2\pi ft} dt</math> |
|- | |- | ||
| align="right" style="padding-right: 1em;" | Inverse DT Fourier Transform | | align="right" style="padding-right: 1em;" | Inverse DT Fourier Transform | ||
| − | | <math>\, x(t)=\mathcal{F}^{-1}( | + | | <math>\, x(t)=\mathcal{F}^{-1}(X(f))=\int_{-\infty}^{\infty}X(f)e^{i2\pi ft} df \,</math> |
|} | |} | ||
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| <span class="texhtml">''x''(''t'')</span> | | <span class="texhtml">''x''(''t'')</span> | ||
| <math>\longrightarrow</math> | | <math>\longrightarrow</math> | ||
| − | | <math> | + | | <math> X(f) </math> |
|- | |- | ||
| align="right" style="padding-right: 1em;" | CTFT of a unit impulse | | align="right" style="padding-right: 1em;" | CTFT of a unit impulse | ||
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| <span class="texhtml">''x''(''t'')</span> | | <span class="texhtml">''x''(''t'')</span> | ||
| <math>\longrightarrow</math> | | <math>\longrightarrow</math> | ||
| − | | <math> | + | | <math> X(f) </math> |
|- | |- | ||
| align="right" style="padding-right: 1em;" | multiplication property | | align="right" style="padding-right: 1em;" | multiplication property | ||
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|- | |- | ||
| align="right" style="padding-right: 1em;" | Parseval's relation | | align="right" style="padding-right: 1em;" | Parseval's relation | ||
| − | | <math>\int_{-\infty}^{\infty} |x(t)|^2 dt = \int_{-\infty}^{\infty} | | + | | <math>\int_{-\infty}^{\infty} |x(t)|^2 dt = \int_{-\infty}^{\infty} |X(f)|^2 df</math> |
|} | |} | ||
Revision as of 18:30, 6 September 2010
- I suggest putting a link next to each formula explaining how to obtain it from the formula in terms of $ \omega $. Also, I would not use the "mathcal" (curly) font for the transform variable, just a capital letter instead. --Mboutin 08:52, 3 September 2010 (UTC).
- Fixed the X(f) notation -Sbiddand
| CT Fourier Transform Pairs and Properties (frequency f in hertz per time unit) (info) | |
|---|---|
| Definition CT Fourier Transform and its Inverse | |
| CT Fourier Transform | $ X(f)=\mathcal{F}(x(t))=\int_{-\infty}^{\infty} x(t) e^{-i2\pi ft} dt $ |
| Inverse DT Fourier Transform | $ \, x(t)=\mathcal{F}^{-1}(X(f))=\int_{-\infty}^{\infty}X(f)e^{i2\pi ft} df \, $ |
| CT Fourier Transform Pairs | ||||
|---|---|---|---|---|
| x(t) | $ \longrightarrow $ | $ X(f) $ | ||
| CTFT of a unit impulse | $ \delta (t)\ $ | $ 1 \! \ $ | ||
| CTFT of a shifted unit impulse | $ \delta (t-t_0)\ $ | $ e^{-i2\pi ft_0} $ | ||
| CTFT of a complex exponential | $ e^{iw_0t} $ | $ \delta (f - \frac{\omega_0}{2\pi}) \ $ | ||
| $ e^{-at}u(t)\ $, where $ a\in {\mathbb R}, a>0 $ | $ \frac{1}{a+i2\pi f} $ | |||
| $ te^{-at}u(t)\ $, where $ a\in {\mathbb R}, a>0 $ | $ \left( \frac{1}{a+i2\pi f}\right)^2 $ | |||
| CTFT of a cosine | $ \cos(\omega_0 t) \ $ | $ \frac{1}{2} \left[\delta (f - \frac{\omega_0}{2\pi}) + \delta (f + \frac{\omega_0}{2\pi})\right] \ $ | ||
| CTFT of a sine | $ sin(\omega_0 t) \ $ | $ \frac{1}{2i} \left[\delta (f - \frac{\omega_0}{2\pi}) - \delta (f + \frac{\omega_0}{2\pi})\right] $ | ||
| CTFT of a rect | $ \left\{\begin{array}{ll}1, & \text{ if }|t|<T,\\ 0, & \text{else.}\end{array} \right. \ $ | $ \frac{\sin \left(2\pi Tf \right)}{\pi f} \ $ | ||
| CTFT of a sinc | $ \frac{2 \sin \left( W t \right)}{\pi t } \ $ | $ \left\{\begin{array}{ll}1, & \text{ if }|f| <\frac{W}{2\pi},\\ 0, & \text{else.}\end{array} \right. \ $ | ||
| CTFT of a periodic function | $ \sum^{\infty}_{k=-\infty} a_{k}e^{ikw_{0}t} $ | $ \sum^{\infty}_{k=-\infty}a_{k}\delta(f-\frac{kw_{0}}{2\pi}) \ $ | ||
| CTFT of an impulse train | $ \sum^{\infty}_{n=-\infty} \delta(t-nT) \ $ | $ \frac{1}{T}\sum^{\infty}_{k=-\infty}\delta(f-\frac{k}{T}) \ $ | ||
| CT Fourier Transform Properties | |||
|---|---|---|---|
| x(t) | $ \longrightarrow $ | $ X(f) $ | |
| multiplication property | $ x(t)y(t) \ $ | $ X(f)*Y(f) =\int_{-\infty}^{\infty} X(\theta)Y(f-\theta)d\theta $ | |
| convolution property | $ x(t)*y(t) \! $ | $ X(f)Y(f) \! $ | |
| time reversal | $ \ x(-t) $ | $ \ X(-f) $ | |
| Other CT Fourier Transform Properties | |
|---|---|
| Parseval's relation | $ \int_{-\infty}^{\infty} |x(t)|^2 dt = \int_{-\infty}^{\infty} |X(f)|^2 df $ |
