MATLAB: How to remove the noise from EEG signal

fit ring eeg data

How can I remove the noise from row EEG signal?
I have used notch filter but it still does not like EEG signal?
Can some one hlep?

Best Answer

Your signal contains a 50Hz noise and you want to extract the signal inside the band from 35Hz to 50Hz. This must fail for obvious reasons, because the noise peak is inside the wanted signal.
In addition you might get strange interference effects, if you apply two filters. What about extracting the signal by a bandpass filter from 35Hz to 45Hz (or 49Hz, if you use a higher order) directly? Then the 50Hz signal is cut off implicitly. And the same works for 4-7Hz also.
Of course you cannot get a very smooth looking EEG signal except if you apply a brute filtering. But if you do so, this is not a clean measurement anymore. Be aware that a signal, which consists of different frequencies from the band 35-50Hz with different amplitudes, which vary over the time, must look "noisy".
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