Stubborn Artifact noise --> GUI resource allocation

MitchMMitchM Appleton, WI, USA
edited July 2018 in OpenBCI_GUI
Sorry if this is the wrong place, i was debating if this was a OpenBCI GUI issue or a Electrode issue, but looking at other posts i thought id try out here first.

I have the latest Cyton Board (eventually want to get the dasiy but I'm limited in funding) and i am using the Gold Cup Electrodes. (8 for the eeg, one for reference, one for ground, what could be better... or so i thought) 

I tried hooking up the SRB2 and Bias in a few different configurations  (Reference + Bias) A1 + A2, A1 + Cz, A2 + Cz, Cz + A1, Cz + A2 all keep giving me a constant spike & pulse that lines up with heart rate, but this is my first time seeing eeg readings like this, perhaps my brain does randomly spike on all brainwaves like a rather slow techno beat.  playing around with the OpenBCI GUI settings for each channel for things like PGA Gain, Input Type, Bias and is SRB2 on or off seems to not yield any any different results besides wayyy to much noise or nothing at all. I had a though that i might need to use the SRB1 pin as well but the images for electrode placement on have one head reference, but you could argue A1+A2+Cz is enough, but then the electrodes don't come in packs of 11, just 10, so there must be a way to get rid of this stupid nose (glad i'm alive though) as its keeping me from getting to next steps or anything meaningful.

below are pictures i took with me phone of the electrode placement on my head (the best I could) and what the OpenBCI was doing. and help with this as far as electrode placment, or how to actually clean up this info (if its in a tutorial, the google cannot seem to find it with my key words and the tutorials that are out for this site dont use all 8 and mention the SRB1 but assumes the google can find "Documentation" and provides no link. (tutorial with missing info: http://docs.openbci.com/Tutorials/01-Cyton_Getting Started_Guide#cyton-getting-started-guide-v-connect-yourself-to-openbci-3-connect-your-electrodes-to-your-head-and-body)

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Edit... huh seems my methods of image uploads are not friendly with this forum so i have uploaded them here https://1drv.ms/f/s!AiutdRJAvNiliLcfQNfexzg4DdG-cg




Comments

  • wjcroftwjcroft Mount Shasta, CA
    MItch, hi.

    What happens when you  go through each step of the Cyton tutorial? Do you get the expected ECG, EMG, EEG?


    The images you show with noise show the identical noise pulse on all 8 channels. Usually this indicates something common with all 8 channels, such as noise on the SRB2 common reference. But possibly could also be noise from electromagnetics in your immediate area. Have you tried this test from a different computer / different location? Avoid all EMF generating equipment such as phones, routers, wall warts, extension cords, power supplies, near you.

    What paste are you using?

    SRB2 is the default reference and is the pin closest to the board. SRB1 is the pin farthest from board and IS NOT the default. In general use the pins closest to board, or as directed by the tutorial.

    Regards,

    William

  • MitchMMitchM Appleton, WI, USA
    William, 

    I actually figured out what was going on, and its not at all what thought (see Issue #349 In GitHub). I noticed that the configuration of widgets I was using on my laptop running the GUI would "lag" or stop reporting for 1-2 seconds" and during that time it would cause those spikes. When I stopped using the widget "Head Plot" The artifact noise went away completely. there is still a slight delay every 5-7 seconds (depends on what the "window" drop down is selected as) but not enough to cause it to generate that artifact. also no matter what Vert scale setting I use it also seems to not like that and my plot graph will randomly reset its self (span of 0 reading to the left of the spike, a spike as if I turned the device on, then expected signal to the right of spike) I have duplicated the clean/expected results multiple days (today as well) and I actually put a phone charging over the electrodes and cables and did not get any noticeable spiking.

       I am using the Ten 20 paste, since the electrodes that are used with the headset are not sold separately and the site recommends against the other offed electrodes for EEG readings with the Cyton. I got set up using http://docs.openbci.com/Tutorials/01-Cyton_Getting%20Started_Guide and installing the program for windows based on what the docs and guides say (Program file folder location, run both the HUB and GUI as administrator, etc) Also cant get the WIFI shield to work, but that's a different set of issues that i will create a different topic about (support email cc'ed the creator of the wifi shield in my email to them)
  • wjcroftwjcroft Mount Shasta, CA
    Mitch, nice detective work. And thanks for logging the issue on Github.

  • MitchMMitchM Appleton, WI, USA
    I only found it after a few hours of googling with no success and trying to think about what else might be causing the noise with the device. Multimeetering the lines were all as expected so i just stared at the graph, saw a lag, so started playing around from there....  I also found I have better results with the following set up... though do not fully understand why since all the guides seem to hint that its not necessary for EEG readings from the board, but never go into why you WOULD want to use it.... http://eeghacker.blogspot.com/2014/04/openbci-measuring-electrode-impedance.html was the inspiration to try it. 

    SRB2 (lower pin?) connected to Cz on the head,
    BIAS (Lower pin) connected to A2,
    SRB1 (Upper pin?) connected to A1 and enabled via the "Hardware Settings" button 
    Imput type set to "Normal" 
    PGA Gain x24

    see Screenshot of "Expected" output to see what I am getting now with this configuration.
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