Dear all,
I would like to begin with the appropriate newbie disclaimer: I very much depend on step-by-step instructions (like the excellent "Getting Started" section) and feel a bit lost when I encounter a problem on my own. Expect stupid questions from me! Thank you!
So, I bought a Cyton two years ago for an EEG-project, did a basic set up back then and, as far as I remember, everything went fine. Only that the project wasn't our highest priority, was post-poned several times and we finally rebooted some weeks ago; meanwhile, Cyton was not in use.
Now, I downloaded the newest version of the OpenBCI software and updated firmwares of the dongle and the Cyton board to the current versions.
Again, I walked through the Getting Started section, but this time, I have an oddly strong constant noise on all electrodes. The following image is with no electrodes attached:
![No_electrodes.png]()
So channel 1 shows a constant 1 Hz-signal and all the other channels are just caotic. Note that scaling is set to 'auto' because signal strength goes far beyond the available scales. Impedances are also in the 10s of thousands.
I nevertheless proceeded to set up an arrangement for polysomnography:
(SRB2: right mastoid, N1P: outer corner of the right eye, N2P: outer corner of the left eye, N3P: left frontal, N4P left parietal, N5P: left occipital, N6P: left chin, N6P2: clavicule, N7P: empty, N8P: chest; BIAS: empty, AGND: left mastoid).
![connected.png]()
But besides getting a decent EKG on chanel 8, there was little change. And the EKG might also disappear with any handling of software or hardware. But overall, detaching or reattaching electrodes made no notable difference, be it ground, reference or any of the others. I think I used a sufficient amount of contact gel, but that didn't improve impedances. Channel 1 looks a bit more organic, but that's just by filtering, and it is not synchronous to heart beat, even though it might appear so on first glance.
One last curiosity I want to point out is that when I silence a channel, it will actually be the subsequent channel that goes flat.
![Silent_6.png]()
Here, I turned off channel 5 (yellow), as you can see by the greyed number 5; it is however channel 6 that goes silent; it might eventually come back.
As for trouble-shooting, I didn't know what to do beyond checking the electrodes themselves (which seem fine) and reinstalling the software and re-uploading the firmware. So I'm stuck - and would be happy about any suggestions!
Thanks in advance,
Derek
