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Discussion Groups | Matlab DSP | strange result for filter design
Technical discussion about Matlab and issues related to Digital Signal Processing.
strange result for filter design - Moshe Malkin - Jan 6 2:24:00 2003
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Hello,
The following code fails completely. Instead of producing the requested filter it returns the filter coefficients as all zeros. Here's the code: % design narrowband filter f = [0.444 0.49 0.51 0.556 ]; a = [0 1 0]; dev = [0.0316 0.05 0.0316]; % estimate order using remezord [n,fo,ao,w] = remezord(f,a,dev) % get filter coefficients b = remez(n,fo,ao,w); % ERROR: the b vector is all zeros. % How is this possible? thanks |
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Re: strange result for filter design - Jeff Brower - Jan 6 15:02:00 2003
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Moshe Malkin- What is the order of the filter returned by remezord? Jeff Brower Signalogic > The following code fails completely. > Instead of producing the requested filter > it returns the filter coefficients as all zeros. > > Here's the code: > > % design narrowband filter > f = [0.444 0.49 0.51 0.556 ]; > a = [0 1 0]; > dev = [0.0316 0.05 0.0316]; > % estimate order using remezord > [n,fo,ao,w] = remezord(f,a,dev) > % get filter coefficients > b = remez(n,fo,ao,w); > > % ERROR: the b vector is all zeros. > % How is this possible? > thanks |
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Re: strange result for filter design - c r - Jan 6 15:17:00 2003
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Moshe, what are you design specifications? I think you may have normalized incorrectly, or set up vector dev incorrectly. You might check that, for some stupid reason every filter design program in matlab is different! It annoys me that they did not standardized this aspect of Matlab, it has caused me much headache. Let me know, and I will see what I can do. The following is some sample code I programmed a while ago using the remez exchange algy. You might be able to apply this to help trouble shoot your problem Fs = 48e3 fp1 = 80 fs1 = 70 fp2 = 160 fs2 = 200 fp = [fp1/(Fs) fp2/(Fs)]; %Passband edge frequencies fs = [fs1/Fs fs2/Fs];%Stopband edge frequencies ws = 70; %Stopband attenuation wp = .02; %Passband attenuation %Application of the remez algorithm %Calculate ripple specs in decimal form, see page 725 of Ambardar handout %Eq. 20.9 and 20.10 epb = 10^(wp/20); esb = 10^ (-ws/20); dp = (epb - 1)/(epb + 1) ds = (1 + dp)*esb D = [ds dp ds]; %Deviation vector for remezord [N,fo,mo,w] = remezord( [fs(1) fp(1) fp(2) fs(2)], [0,1,0],D,1) N = 2*floor(N/2 + 1/2); %This assures that N is an even number hz = remez(N,fo,mo,w); Moshe Malkin <> wrote:Hello, The following code fails completely. Instead of producing the requested filter it returns the filter coefficients as all zeros. Here's the code: % design narrowband filter f = [0.444 0.49 0.51 0.556 ]; a = [0 1 0]; dev = [0.0316 0.05 0.0316]; % estimate order using remezord [n,fo,ao,w] = remezord(f,a,dev) % get filter coefficients b = remez(n,fo,ao,w); % ERROR: the b vector is all zeros. % How is this possible? thanks Yahoo! Groups SponsorADVERTISEMENT _____________________________________ /groups.php3 Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. --------------------------------- |
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Re: strange result for filter design - navaneetha krishnan - Jan 6 15:47:00 2003
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Hi, That appears to be a bug in remez. See http://www.mathworks.com/support/solutions/data/31015.shtml Navan --- Moshe Malkin <> wrote: > Hello, > The following code fails completely. > Instead of producing the requested filter > it returns the filter coefficients as all zeros. > > Here's the code: > > % design narrowband filter > f = [0.444 0.49 0.51 0.556 ]; > a = [0 1 0]; > dev = [0.0316 0.05 0.0316]; > % estimate order using remezord > [n,fo,ao,w] = remezord(f,a,dev) > % get filter coefficients > b = remez(n,fo,ao,w); > > % ERROR: the b vector is all zeros. > % How is this possible? > thanks __________________________________________________ |
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Re: strange result for filter design - Priyank Saxena - Jan 7 10:27:00 2003
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thats right. I'm using Matlab version 5.2 and the code runs absolutely fine. the output of the code is attached. -priyank --- navaneetha krishnan <> wrote: > Hi, > > That appears to be a bug in remez. > > See > http://www.mathworks.com/support/solutions/data/31015.shtml > > Navan > > --- Moshe Malkin <> wrote: > > Hello, > > > > > > The following code fails completely. > > Instead of producing the requested filter > > it returns the filter coefficients as all zeros. > > > > Here's the code: > > > > % design narrowband filter > > f = [0.444 0.49 0.51 0.556 ]; > > a = [0 1 0]; > > dev = [0.0316 0.05 0.0316]; > > % estimate order using remezord > > [n,fo,ao,w] = remezord(f,a,dev) > > % get filter coefficients > > b = remez(n,fo,ao,w); > > > > % ERROR: the b vector is all zeros. > > % How is this possible? > > > > > > thanks > __________________________________________________ __________________________________________________ | |||
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