I want to filter real acceleration data. I have to remove the very low frequencies <1Hz that are dominating my frequency plot. I have designed a HighPass Butterworth IIR Filter usign designfilt, but I don't understand the meaning of stopband and passband attenuation. I know that attenuation at cuttoff is 3db, but how can I calculate the passband and stopband attenuation if I have defined the bandpass frequency and cutoff frequency.
My way of defining the Astop and Apass until now was by guessing, but I guess this is not the correct way of defining these. I would like to know how they can be calculated properly?
This is the PSD of raw acceleration data.
This is the PSD of the filtered data.
Also, this is the code I have used to define the filter
Fs = 5000;
Nf = 1;
Fpass = 1000;
Fstop = 0.6;
Apass = 1;
Astop = 10;
HighPassIIRButterworth = designfilt('highpassiir','PassbandFrequency',Fpass,...
'StopbandFrequency',Fstop,'PassbandRipple',Apass,'StopbandAttenuation',...
Astop,'SampleRate',Fs,'DesignMethod','butter');
fvtool(HighPassIIRButterworth)
