I used systemIdentification to calculate the transfer function of my filter (see first figure) and then saved the idtf variable (attached). However, when I load the idtf variable and use freqz to plot the frequency response it looks very different (see second figure).
%number of frequencies
n = 50000;%sampling frequency
f_sample = 2e8; %Hz
%transfer function numerator
b = [9.875702215802889e+04,6.459317537238607e+09];%transfer function denominator
a = [1,1.844463395715939e+05,5.691593683410083e+09];%calculate tranfer function response
[h_calc, w_calc] = freqz(b,a,n,f_sample);%plot transfer function
figure(3)plot(w_calc,h_calc)set(gca,'XScale','log')set(gca,'YScale','log')xlabel('Frequency (Hz)')ylabel('Filter Response')
Best Answer