Daisy recording looks odd
hello, we have a Cyton+daisy board and we use OpenBCI GUI.
The signals look good live but the recorded csv seems messed up.
Looking at the files we note that there's a nonsense alternating pattern in the numbers,
on even sample indexes we have
-134420.1725030151, -133356.38592915368, -138674.9388188051, -144263.63489194334, -173778.35348586482.... -138841.7722394195, -133360.85627804475, -135149.77814552526
on odd samples we have
-1367.1668013533117, -3025.3980190036323, 7492.416500141204, 0.0, 0.0, 0.0, 0.0, 0.0....
Sporadically we are able to record a pseudo-correct signal (without the alternating pattern) but, once plotted in Matlab, the signal does not resemble an EEG at all (totally different from what I see live on OpenBCI screen).
Any help?
m.
Comments
Magrini, hi.
This is an unusual behavior. I've not quite seen this pattern of abnormal samples. Are you sure your Daisy is securely plugged into the mainboard Cyton? If the inter-board connection is marginal, that might explain it. Although you say the GUI view is always correct, which means the GUI is seeing all 16 channels correctly.
I think you are aware that the large microvolts values are because of the DC offset, and are removed by appropriate filtering. GUI does this automatically for the display, but CSV recording file is raw and unfiltered.
https://openbci.com/forum/index.php?p=/discussion/201/large-millivolt-data-values-fbeeg-full-band-eeg
Regards, William
I also suggest you email (contact at openbci.com) and explain your situation, referencing this Forum thread with a link.
yes, you're right. when I remove the daisy, using only the first 8 channels that weird pattern disappears.
yes sure, even if with the same butterworth filters I still saw large jumps in the signals, when using the daisy (probably related to the marginal inter-board connection).
thanks
m.