I'm applying the next bandpass filter to the data of an impulse response coming from .wav; it fades data below 10 Hz and above 400 Hz:
d = fdesign.bandpass('N,Fst1,Fp1,Fp2,Fst2,C',... 117,9.99,10,400,400.01,10000); d.Stopband1Constrained = true; d.Astop1 = 60; d.Stopband2Constrained = true; d.Astop2 = 60; Hd = design(d,'equiripple'); % Passband type h = fvtool(Hd); % Filter design plot
As you can see, magnitude order is notoriously smaller in the bottom plot than the top one in this second plot. Considering the first picture, at least for around 200 Hz resulting amplitude might be almost equal to the original one but it doesn't happen (regardless of the amplitude increase after 300 Hz).
Is something missing in my design that causes this differences? Do I have to do any normalization to get an amplitude after filtering similar to the original one? Using 117 as filter's order is the best option to minimize fading. Thank you in advance for you help.