megs05
Newbie level 1
Hi,
I am referring to the paper "Half Band IIR Filter Design using MATLAB" by Lutovac and Mili, to design an IIR HB filter, but I am not getting the results as expected.
An example in the paper:
Fp = .22;
Fs = 0.5 - Fp;
Rp = 0.01;
As = 46;
if(-10*log10(1-(10^(-Rp/10)))>As)
HBAs = -10*log10(1-(10^(-Rp/10)));
else
HBAs = As;
end
HBRp = 10*log10(1+(1/((10^(HBAs/10))-1)));
Order = ellipord(2*Fp, 2*Fs, HBRp, HBAs);
[z,p,k] = ellip(Order+1,HBRp,HBAs,2*Fp);
zplane(zl,pl)
the poles which should be on imag axis (as per HB property) are not all on imag axis and hence they can not be realized as a sum of two all pass filters (equation 5 in the paper). Can some one tell me if this is expected? and if yes then how can I get the filter to be a sum of two all pass filters?
Thanks,
I am referring to the paper "Half Band IIR Filter Design using MATLAB" by Lutovac and Mili, to design an IIR HB filter, but I am not getting the results as expected.
An example in the paper:
Fp = .22;
Fs = 0.5 - Fp;
Rp = 0.01;
As = 46;
if(-10*log10(1-(10^(-Rp/10)))>As)
HBAs = -10*log10(1-(10^(-Rp/10)));
else
HBAs = As;
end
HBRp = 10*log10(1+(1/((10^(HBAs/10))-1)));
Order = ellipord(2*Fp, 2*Fs, HBRp, HBAs);
[z,p,k] = ellip(Order+1,HBRp,HBAs,2*Fp);
zplane(zl,pl)
the poles which should be on imag axis (as per HB property) are not all on imag axis and hence they can not be realized as a sum of two all pass filters (equation 5 in the paper). Can some one tell me if this is expected? and if yes then how can I get the filter to be a sum of two all pass filters?
Thanks,