Problems configuring the bias
sumedhkaulgud
Bangalore, India
in Cyton
Hi,
I just bought a new OpenBCI V3 32 bit module and I have been trying to collect some ECG data. I am using the first four channels with a common reference at SRB2. However in all my readings I am getting a high level on common-mode noise @ 50Hz. It is at such high levels that it almost completely masks my ECG peaks. I tried to configure the bias drive in order to remove the common mode noise as suggested by the datasheet but it doesn't seem to be working properly. I am measuring the bias signal on channel 5 and it is essentially saturating at -2.4 V with some marginal flickering.
This is the channel data raw and after filtering for 50 Hz and all its harmonics. As you can see the common mode noise is very high and even after filtering a large residual noise remains.
This is the Bias measurement that I did on channel 5. It is almost saturated to 2.5 V.
Ideally the bias should be driving back the inverse of the common mode noise back into the body to cancel it out. However it is not working the way it is supposed to here. I have tied multiple configurations of the bias but I'm still getting the same problem. I have even tried changing the place I sit and take my readings from but there is no significant drop in the noise levels. Can some one please explain how I can solve this problem.
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