Low pass FIR filter for EEG signal

I'm trying to do Analysis of EEG Signal for the Detection of epileptic seizure so in the pre-processing of the EEG signal I use a low pass FIR filter

d1=designfilt('lowpassfir','PassbandFrequency',0.15,'StopbandFrequency',0.2,'PassbandRipple',3,'StopbandAttenuation',60,'DesignMethod','equiripple');
a = filtfilt(d1,deriv1);


I want to know if the values above for PassbandFrequency and StopbandFrequency are right.

• Hi! These are MATLAB functions right? It's better if you clarify. Commented Mar 16, 2017 at 11:08

Assuming MATLAB functions to be used, passband frequency 0.15 means $\omega_p = 0.15 \pi$ whereas stopband frequency 0.2 means $\omega_s = 0.2 \pi$ and since $\omega_s > \omega_p$ these settings qualify for a proper lowpass filter.

Also passband ripple being $3dB$ and stopband attenuation being $60 dB$ are valid choices (although more exact specifications requires the knowledge application requirements)

The equiripple option designs a filter in which the designed filter magnitude error is distributed accross the pass and/or stop bands in equal amounts so as to reduce the filter length to a minimum while still meeting the maximum of the allowed peak error criteria.