Am I recording correct EEG signal?/How can I improve the quality of signal?
Am I recording correct EEG signal?
Hello everyone:)
I’m using 8chan cyton. My projrct involves usin matlab to process the EEG signal, so I have to use export the unfiltered data with CSV file.
I compared the signal from one electrode with the sample EEG data of meditation (same electrode is the sample uses the default positon).
I’m not sure whether the quality of signal is enough (comparing to the sample data)
Additionally, I went through a FFT process and it tells me there was a peak near 50Hz ( which should be power-line interference ), but the power of frequence such as αor θdon't seem clear enough（only small humps, slightluy bigger than zero)_
My questions:
1.Whether I’m recording corret signals or noise only?
2.How can I improve the quality of the signals? ( The electrodes are clean and stick tightly to my scalp, maybe I need a better environment? )
THX for reading my post XD
Raw timeseries of my own (from CSV file)
Raw timeseries from the example data (cut to same length as my data)
FFT plot of my data(power and frequences in Hz)
FFT plot of sample data(power and frequences in Hz)
Comments
https://openbci.com/forum/index.php?p=/discussion/201/large-millivolt-data-values-fbeeg-full-band-eeg
Thank you so much, I applied the bandpass filter and it looks better now.
You still have LOTS of mains noise. In addition to the bandpass, you need to add a notch filter at 60 Hz.
Correction, use whatever mains frequency you have locally. Some of your images show 50 Hz, others show approximately ~ 60 Hz.
Indeed, and I found that I've mistakenly set the sampling rate to be 256Hz (should be 250Hz). The data was recorded when I was tryin to do meditation, it should match with the sample data.
mydata
sampledata（meditation）
The 8th elecrtrode still looks weird, it seems to have huge ringing artifacts or it could be a lose electrode.
I think it's safe to move on now ( I'm just using this as an example to learn how to export the data).
Many thanks!