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

a = filtfilt(d1,deriv1);

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

  • $\begingroup$ Hi! These are MATLAB functions right? It's better if you clarify. $\endgroup$
    – Fat32
    Commented Mar 16, 2017 at 11:08

1 Answer 1


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.


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