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  • Committer: Bazaar Package Importer
  • Author(s): Torsten Werner
  • Date: 2002-03-21 16:57:43 UTC
  • Revision ID: james.westby@ubuntu.com-20020321165743-e9mv12c1tb1plztg
Tags: upstream-2.6
Import upstream version 2.6

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man/signal/yulewalk.cat
 
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yulewalk          Scilab Group          Scilab Function            yulewalk
 
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NAME
 
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   yulewalk -  least-square filter design
 
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CALLING SEQUENCE
 
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 Hz = yulewalk(N,frq,mag) 
 
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PARAMETERS
 
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 N          : integer (order of desired filter)
 
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 frq        : real row vector (non-decreasing order), frequencies.
 
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 mag        : non negative real row vector (same size as frq), desired
 
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            magnitudes.
 
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 Hz         : filter B(z)/A(z)
 
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DESCRIPTION
 
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   Hz = yulewalk(N,frq,mag) finds the N-th order iir filter
 
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                   n-1         n-2            
 
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       B(z)   b(1)z     + b(2)z    + .... + b(n)
 
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 H(z)= ---- = ---------------------------------
 
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                 n-1       n-2
 
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       A(z)    z   + a(2)z    + .... + a(n)
 
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   which matches the magnitude frequency response given by vectors frq and
 
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  mag. Vectors frq and mag specify the frequency and magnitude of the
 
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  desired frequency response. The frequencies in frq must be between 0.0
 
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  and 1.0, with 1.0 corresponding to half the sample rate. They must be in
 
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  increasing order and start with 0.0 and end with 1.0. 
 
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EXAMPLE
 
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 f=[0,0.4,0.4,0.6,0.6,1];H=[0,0,1,1,0,0];Hz=yulewalk(8,f,H);
 
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 fs=1000;fhz = f*fs/2;  
 
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 xbasc(0);xset('window',0);plot2d(fhz',H');
 
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 xtitle('Desired Frequency Response (Magnitude)')
 
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 [frq,repf]=repfreq(Hz,0:0.001:0.5);
 
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 xbasc(1);xset('window',1);plot2d(fs*frq',abs(repf'));
 
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 xtitle('Obtained Frequency Response (Magnitude)')
 
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