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{|
 
{|
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! colspan="2" style="background: #e4bc7e; font-size: 110%;" | Discrete-time Fourier Transform Pairs and Properties
+
|-
 +
! colspan="2" style="background: #e4bc7e; font-size: 110%;" | Discrete-time Fourier Transform Pairs and Properties
 
|-
 
|-
 
! colspan="2" style="background: #eee;" | DT Fourier transform and its Inverse
 
! colspan="2" style="background: #eee;" | DT Fourier transform and its Inverse
 
|-
 
|-
−
| align="right" style="padding-right: 1em;" | DT Fourier Transform || <math>\,\mathcal{X}(\omega)=\mathcal{F}(x[n])=\sum_{n=-\infty}^{\infty}x[n]e^{-j\omega n}\,</math>
+
| align="right" style="padding-right: 1em;" | DT Fourier Transform  
−
|-  
+
| <math>\,\mathcal{X}(\omega)=\mathcal{F}(x[n])=\sum_{n=-\infty}^{\infty}x[n]e^{-j\omega n}\,</math>
−
| align="right" style="padding-right: 1em;" | Inverse DT Fourier Transform || <math>\,x[n]=\mathcal{F}^{-1}(\mathcal{X}(\omega))=\frac{1}{2\pi} \int_{0}^{2\pi}\mathcal{X}(\omega)e^{j\omega n} d \omega\,</math>
+
|-
 +
| align="right" style="padding-right: 1em;" | Inverse DT Fourier Transform  
 +
| <math>\,x[n]=\mathcal{F}^{-1}(\mathcal{X}(\omega))=\frac{1}{2\pi} \int_{0}^{2\pi}\mathcal{X}(\omega)e^{j\omega n} d \omega\,</math>
 
|}
 
|}
 +
 
{|
 
{|
 
|-
 
|-
 +
! colspan="4" style="background: #eee;" |
 
! colspan="4" style="background: #eee;" | DT Fourier Transform Pairs
 
! colspan="4" style="background: #eee;" | DT Fourier Transform Pairs
−
|-
 
−
| align="right" style="padding-right: 1em;" |  || <math> x[n] \ </math> || <math>\longrightarrow</math>|| <math> \mathcal{X}(\omega) \ </math>
 
−
|-
 
−
| align="right" style="padding-right: 1em;" | DTFT of a complex exponential || <math>e^{jw_0n} \ </math> || || <math>\pi\sum_{l=-\infty}^{+\infty}\delta(w-w_0-2\pi l) \ </math>
 
−
|-
 
−
| align="right" style="padding-right: 1em;" | ([[DTFT_rectangular_window|info]]) DTFT of a rectangular window || <math>w[n]= \ </math> || || add formula here
 
−
|-
 
−
| align="right" style="padding-right: 1em;" |  || <math>a^{n} u[n],  |a|<1 \ </math> || ||<math>\frac{1}{1-ae^{-j\omega}} \ </math>
 
 
|-
 
|-
−
| align="right" style="padding-right: 1em;" | || <math>(n+1)a^{n} u[n],  |a|<1 \ </math> || ||<math>\frac{1}{(1-ae^{-j\omega})^2} \ </math>
+
| align="right" style="padding-right: 1em;" |  
 +
| align="right" style="padding-right: 1em;" |
 +
| <math> x[n] \ </math>
 +
| <math>\longrightarrow</math>
 +
| <math> \mathcal{X}(\omega) \ </math>
 
|-
 
|-
−
| align="right" style="padding-right: 1em;" | || <math>\sin\left(\omega _0 n\right) u[n] \ </math> || ||<math>\frac{1}{2j}\left( \frac{1}{1-e^{-j(\omega -\omega _0)}}-\frac{1}{1-e^{-j(\omega +\omega _0)}}\right)</math>
+
| align="right" style="padding-right: 1em;" |  
 +
| align="right" style="padding-right: 1em;" | DTFT of a complex exponential
 +
| <math>e^{jw_0n} \ </math>  
 +
|  
 +
| <math>\pi\sum_{l=-\infty}^{+\infty}\delta(w-w_0-2\pi l) \ </math>
 
|-
 
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" | ([[DTFT rectangular window|info]]) DTFT of a rectangular window
 +
| <math>w[n]= \ </math>
 +
|
 +
| add formula here
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" |
 +
| <math>a^{n} u[n],  |a|<1 \ </math>
 +
|
 +
| <math>\frac{1}{1-ae^{-j\omega}} \ </math>
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" |
 +
| <math>(n+1)a^{n} u[n],  |a|<1 \ </math>
 +
|
 +
| <math>\frac{1}{(1-ae^{-j\omega})^2} \ </math>
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" |
 +
| <math>\sin\left(\omega _0 n\right) u[n] \ </math>
 +
|
 +
| <math>\frac{1}{2j}\left( \frac{1}{1-e^{-j(\omega -\omega _0)}}-\frac{1}{1-e^{-j(\omega +\omega _0)}}\right)</math>
 
|}
 
|}
  
 
{|
 
{|
 
|-
 
|-
 +
! colspan="4" style="background: #eee;" |
 
! colspan="4" style="background: #eee;" | DT Fourier Transform Properties
 
! colspan="4" style="background: #eee;" | DT Fourier Transform Properties
−
|-
 
−
| align="right" style="padding-right: 1em;" |  || <math>x[n] \ </math> || <math>\longrightarrow</math>|| <math> \mathcal{X}(\omega) \ </math>
 
−
|-
 
−
| align="right" style="padding-right: 1em;" | multiplication property|| <math>x[n]y[n] \ </math> || || <math>\frac{1}{2\pi} \int_{2\pi} X(\theta)Y(\omega-\theta)d\theta</math>
 
−
|-
 
−
| align="right" style="padding-right: 1em;" |  convolution property || <math>x[n]*y[n] \!</math> || ||<math> X(\omega)Y(\omega) \!</math>
 
 
|-
 
|-
−
| align="right" style="padding-right: 1em;" | time reversal ||<math>\ x[-n] </math> || ||<math>\ X(-\omega)</math>
+
| align="right" style="padding-right: 1em;" |  
 +
| align="right" style="padding-right: 1em;" |
 +
| <math>x[n] \ </math>  
 +
| <math>\longrightarrow</math>
 +
| <math> \mathcal{X}(\omega) \ </math>
 
|-
 
|-
−
| align="right" style="padding-right: 1em;" | Differentiation in frequency ||<math>\ nx[n] </math> || ||<math>\ j\frac{d}{d\omega}X(\omega)</math>
+
| align="right" style="padding-right: 1em;" |  
 +
| align="right" style="padding-right: 1em;" | multiplication property
 +
| <math>x[n]y[n] \ </math>  
 +
|  
 +
| <math>\frac{1}{2\pi} \int_{2\pi} X(\theta)Y(\omega-\theta)d\theta</math>
 
|-
 
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" | convolution property
 +
| <math>x[n]*y[n] \!</math>
 +
|
 +
| <math> X(\omega)Y(\omega) \!</math>
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" | time reversal
 +
| <math>\ x[-n] </math>
 +
|
 +
| <math>\ X(-\omega)</math>
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" | Differentiation in frequency
 +
| <math>\ nx[n] </math>
 +
|
 +
| <math>\ j\frac{d}{d\omega}X(\omega)</math>
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" | Linearity
 +
| <math>ax[n]+by[n]</math>
 +
|
 +
| <math>aX(\omega)+bY(\omega)</math>
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" | Time Shifting
 +
| <math>x[n-n_0]</math>
 +
|
 +
| <math>e^{-j\omega n_0}X(\omega)</math>
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" | Frequency Shifting
 +
| <math>e^{j\omega_0 n}x[n]</math>
 +
|
 +
| <math>X(\omega-\omega_0)</math>
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" | Conjugation
 +
| <math>x^{*}[n]</math>
 +
|
 +
| <math>X^{*}(-\omega)</math>
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" | Time Expansion
 +
| <math>x_(k) [n]=\left\{\begin{array}{ll}x[n/k], &  \text{ if n = multiple of k},\\ 0, & \text{else.}\end{array} \right.</math>
 +
|
 +
| <math>X(k\omega)</math>
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" | Differentiating in Time
 +
| <math>x[n]-x[n-1]</math>
 +
|
 +
| <math>(1-e^{-j\omega})X(\omega)</math>
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" | Accumulation
 +
| <math>\sum^{n}_{k=-\infty} x[k]</math>
 +
|
 +
| <math>\frac{1}{1-e^{-j\omega}X(\omega)</math>
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" | Symmetry
 +
| x[n] real and even
 +
|
 +
| <math>X(\omega)</math>&nbsp;real and even
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" |
 +
| x[n] real and odd
 +
|
 +
| <math>X(\omega)</math>&nbsp;purely imaginary and odd
 +
|-
 +
| align="right" style="padding-right: 1em;" |
 +
| align="right" style="padding-right: 1em;" |
 +
|
 +
|
 +
|
 
|}
 
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|-
 
! colspan="2" style="background: #eee;" | Other DT Fourier Transform Properties
 
! colspan="2" style="background: #eee;" | Other DT Fourier Transform Properties
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|-  
+
|-
−
| align="right" style="padding-right: 1em;" | Parseval's relation || <math>\frac {1}{N} \sum_{n=-\infty}^{\infty}\left| x[n] \right|^2 = </math>
+
| align="right" style="padding-right: 1em;" | Parseval's relation  
 +
| <math>\frac {1}{N} \sum_{n=-\infty}^{\infty}\left| x[n] \right|^2 = </math>
 
|}
 
|}
 +
 
----
 
----
−
[[Collective_Table_of_Formulas|Back to Collective Table]]  
+
 
 +
[[Collective Table of Formulas|Back to Collective Table]]  
 +
 
 
[[Category:Formulas]]
 
[[Category:Formulas]]

Revision as of 13:10, 10 April 2011

Discrete-time Fourier Transform Pairs and Properties
DT Fourier transform and its Inverse
DT Fourier Transform $ \,\mathcal{X}(\omega)=\mathcal{F}(x[n])=\sum_{n=-\infty}^{\infty}x[n]e^{-j\omega n}\, $
Inverse DT Fourier Transform $ \,x[n]=\mathcal{F}^{-1}(\mathcal{X}(\omega))=\frac{1}{2\pi} \int_{0}^{2\pi}\mathcal{X}(\omega)e^{j\omega n} d \omega\, $
DT Fourier Transform Pairs
$ x[n] \ $ $ \longrightarrow $ $ \mathcal{X}(\omega) \ $
DTFT of a complex exponential $ e^{jw_0n} \ $ $ \pi\sum_{l=-\infty}^{+\infty}\delta(w-w_0-2\pi l) \ $
(info) DTFT of a rectangular window $ w[n]= \ $ add formula here
$ a^{n} u[n], |a|<1 \ $ $ \frac{1}{1-ae^{-j\omega}} \ $
$ (n+1)a^{n} u[n], |a|<1 \ $ $ \frac{1}{(1-ae^{-j\omega})^2} \ $
$ \sin\left(\omega _0 n\right) u[n] \ $ $ \frac{1}{2j}\left( \frac{1}{1-e^{-j(\omega -\omega _0)}}-\frac{1}{1-e^{-j(\omega +\omega _0)}}\right) $
DT Fourier Transform Properties
$ x[n] \ $ $ \longrightarrow $ $ \mathcal{X}(\omega) \ $
multiplication property $ x[n]y[n] \ $ $ \frac{1}{2\pi} \int_{2\pi} X(\theta)Y(\omega-\theta)d\theta $
convolution property $ x[n]*y[n] \! $ $ X(\omega)Y(\omega) \! $
time reversal $ \ x[-n] $ $ \ X(-\omega) $
Differentiation in frequency $ \ nx[n] $ $ \ j\frac{d}{d\omega}X(\omega) $
Linearity $ ax[n]+by[n] $ $ aX(\omega)+bY(\omega) $
Time Shifting $ x[n-n_0] $ $ e^{-j\omega n_0}X(\omega) $
Frequency Shifting $ e^{j\omega_0 n}x[n] $ $ X(\omega-\omega_0) $
Conjugation $ x^{*}[n] $ $ X^{*}(-\omega) $
Time Expansion $ x_(k) [n]=\left\{\begin{array}{ll}x[n/k], & \text{ if n = multiple of k},\\ 0, & \text{else.}\end{array} \right. $ $ X(k\omega) $
Differentiating in Time $ x[n]-x[n-1] $ $ (1-e^{-j\omega})X(\omega) $
Accumulation $ \sum^{n}_{k=-\infty} x[k] $ $ \frac{1}{1-e^{-j\omega}X(\omega) $
Symmetry x[n] real and even $ X(\omega) $ real and even
x[n] real and odd $ X(\omega) $ purely imaginary and odd
Other DT Fourier Transform Properties
Parseval's relation $ \frac {1}{N} \sum_{n=-\infty}^{\infty}\left| x[n] \right|^2 = $

Back to Collective Table

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Alumni Liaison

Ph.D. 2007, working on developing cool imaging technologies for digital cameras, camera phones, and video surveillance cameras.

Buyue Zhang