Hi Ryan, I still have not resolved the issue...I replaced the square waves with sine waves, and the same problem persists -- the bias signal formed from averaging individual channels contains frequency components of all the input channels and therefore each recorded channel gets injected with the other channels' frequency components. It is not clear to me how impedance mismatch in each channel can solve this. Although if both channels are contaminated with common mode noise, say 60Hz power line, the 60Hz noise will be subtracted from the input channels. So far, my conclusion about the RLD is that it indeed removes common mode noise, but mixes the differential mode...I'm thinking one possible solution is to set the bandwidth of the bias amplifier to below the EEG signals of interest (say below 1Hz). But this approach would not be able to filter out high frequency common mode noise (which may not matter too much since EEG bandwidth is limited to below 50Hz). Any suggestions?
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