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Aide Scilab >> Traitement du Signal > fsfirlin

fsfirlin

design of FIR, linear phase filters, frequency sampling technique

Calling Sequence

[hst]=fsfirlin(hd,flag)

Arguments

hd

vector of desired frequency response samples

flag

is equal to 1 or 2, according to the choice of type 1 or type 2 design

hst

vector giving the approximated continuous response on a dense grid of frequencies

Description

function for the design of FIR, linear phase filters using the frequency sampling technique

Examples

//
//Example of how to use the fsfirlin macro for the design 
//of an FIR filter by a frequency sampling technique.
//
//Two filters are designed : the first (response hst1) with 
//abrupt transitions from 0 to 1 between passbands and stop 
//bands; the second (response hst2) with one sample in each 
//transition band (amplitude 0.5) for smoothing.
//
hd=[zeros(1,15) ones(1,10) zeros(1,39)];//desired samples
hst1=fsfirlin(hd,1);//filter with no sample in the transition
hd(15)=.5;hd(26)=.5;//samples in the transition bands
hst2=fsfirlin(hd,1);//corresponding filter
pas=1/prod(size(hst1))*.5;
fg=0:pas:.5;//normalized frequencies grid
plot2d([1 1].*.fg(1:257)',[hst1' hst2']);

// 2nd example
hd=[0*ones(1,15) ones(1,10) 0*ones(1,39)];//desired samples
hst1=fsfirlin(hd,1);//filter with no sample in the transition
hd(15)=.5;hd(26)=.5;//samples in the transition bands
hst2=fsfirlin(hd,1);//corresponding filter
pas=1/prod(size(hst1))*.5;
fg=0:pas:.5;//normalized frequencies grid
n=prod(size(hst1))
plot(fg(1:n),hst1);
plot2d(fg(1:n)',hst2',[3],"000");

See Also

  • ffilt — coefficients of FIR low-pass
  • wfir — linear-phase FIR filters

Authors

G. Le Vey

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Copyright (c) 1989-2007 (ENPC)
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Last updated:
Wed Oct 05 12:10:56 CEST 2011