Dear support team,
we have recently started recording with our 64 channel system (it was previously used for a couple of months by another researcher in our group). With average reference the signal looks ok, however, with linked earlobes, the B-block channels look much noisier (i.e. high frequency noise) than the A-block channels. We have two A blocks and two B blocks and the problem occurs with all A/B combinations (though there may be some difference in strength of noise). When we put the electrodes in salt water, channels seem comparable, yet an FFT suggests that there is more 50 Hz power in the B-channels. Do you have any idea, what this could mean and how it could be solved?
Thank you very much in advance,
Erik
Thank you Coen,
this has improved the recording. In addition, we have played around with different external electrodes and believe that the recording is improved, when we use external electrodes (as a reference) that are about as old as the EEG-electrodes.
Best Erik