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
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