Scicos Block
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Gaussian filter block

Contents

• Gaussian filter block
  • Palette
  • Description
  • Dialog box
  • Default properties
  • Interfacing function
  • Computational function
  • See also
  • Authors

Palette

• Filter - Digital filters palette

Description

The impulse response of that filter is given by :

$$\begin{eqnarray} h\left(t\right)&=&B\sqrt{\frac{2\pi }{\ln \left(2\right)}}\exp... ...ight)}\left(\frac{B\pi t}{T_{\rm s}}\right)^{2}\right), \nonumber \end{eqnarray}$$

with B (or symbol period per band product BT) the only parameter.

The transfert function of that filter is :

$$\begin{eqnarray} H\left(f\right)&=&\exp\left(-\frac{\ln\left(2\right)}{2 B^{2}}f^{2}\right).\nonumber \end{eqnarray}$$

Figure : Impulse response and transfert function of a Gaussian Filter for $BT=0.7$ and $BT=0.9$.

Dialog box

• Size of input vectors
  Vector of integers. Set the size of the input vectors. Each integer entry defines a filter.
  For a "scalar-based" mode, use size(s) =1.
  For a "vector-based" mode, use size(s) greater than 1.
  Properties : Type 'vec' of size -1.

• Samples per symbol
  Vector of integers. Define the number of samples per symbol.
  Properties : Type 'vec' of size -1.

• BT Factor
  Vector of real. Define the factor BT for each filter.
  Properties : Type 'vec' of size -1.

• Length of impulse response
  Vector of integers. Set the number of coefficients of the Gaussian impulse response.
  Properties : Type 'vec' of size -1.

• Filter Gain
  Vector of real. The output gain of the filter.
  Properties : Type 'vec' of size -1.

• Inherit (no:0, yes:1)
  Integer. Herits events by its regular input ports (disable the event input port).
  Properties : Type 'vec' of size 1.

• Plot impulse response (0:no or winid)
  Integer. Plot impulse response in a graphic window. The value of this parameter set the window Id of the graphic.
  Properties : Type 'vec' of size 1.

Default properties

• always active: no
• direct-feedthrough: yes
• zero-crossing: no
• mode: no
• regular inputs:
  - port 1 : size [1,1] / type 1
  
• regular outputs:
  - port 1 : size [1,1] / type 1
  
• number/sizes of activation inputs: 1
• number/sizes of activation outputs: 0
• continuous-time state: no
• discrete-time state: no
• object discrete-time state: no
• name of computational function: com_filter

Interfacing function

• MODNUMCOS/macros/scicos_blocks/Filter/GAUSSF_c.sci [view code]

Computational function

• MODNUMCOS/routines/filter/com_filter.c (Type 4) [view code]

See also

• SRRCF_c - Square Raised Root Cosine filter block (Scicos Block)
• RCF_c - Raised Cosine filter block (Scicos Block)

Authors

A. Layec