Filtering certain frequencies from EEG signal

I have an EEG data in .continuous format. I have codes to open the data file and plot it. Now I want to filter out signal with frequencies from 3Hz to 12Hz. I have used 2nd order butterworth filter but that removes the important peaks too. I have even tried doing it using EEGLAB toolbox but I cannot open my .continuous file in EEGLAB (error as shown in the picture). I have installed FIELDTRIP and tried again, it doesn't work. Could someone point out the possible things that I can do to solve my problem?

Thanks in advance.

Answer 1

[Kaashyap Pappu]

You could try to increase the filter order or vary the passband ripple values to see if there is an improvement in the result.

A similar question has been addressed here that could be of some help. Alternatively, the Filter Designer App could also be of use to verify the magnitude and phase responses of the filter designed.

Hope this helps!

[Sparsha Kumari]

Many thanks! I will try that out.