How to plot the RAW EEG for the complete duration of the recording?

vaibhav2912vaibhav2912
edited October 2016 in General Discussion
Hello all,

I have recorded 60 seconds of EEG data using OpenBCI board. I want to know how can I plot the RAW EEG data for the complete duration of the recording in a single file. In OpenBCI GUI I can see the data for the duration of 5 seconds only. Is there a way to plot the full 60 seconds of RAW EEG data?

Thank You,
Vaibhav

Comments

  • wjcroftwjcroft Mount Shasta, CA
    Vaibhav,

    Have you looked at EEGrunt or EDFBrowser? The latter would require that you filter out the DC component so your plots are centered.


  • vaibhav2912vaibhav2912
    @wjcroft

    I am already using EEGrunt for generating spectrograms but how do I get RAW EEG data from it?
  • wjcroftwjcroft Mount Shasta, CA
    Let's include Isa @brain, EEGrunt author. I believe it has mulitple plotting functions built into it.

  • vaibhav2912vaibhav2912
    Thanks @wjcroft.
    I have limited knowledge about python. If someone can guide me on how to do it then I can get it done I guess.
  • wjcroftwjcroft Mount Shasta, CA
    Have you experimented with EDFBrowser? You would need to use the menu options to first filter the signal with a bandpass or highpass filter to drop off DC component below say .5 hz. Otherwise EDFBrowser has tons of features and you can zoom and pan around your entire session, no matter how long, even hours.

    http://openbci.com/community/ascii-to-edf-format-converter/

    I'm not quite sure why she used the Matlab script there; you could drop the header comments and sample counter with a text editor or Excel. EDFBrowser has built in filtering and CSV conversion features.

  • vaibhav2912vaibhav2912
    I have installed EDF browser now. I can't figure out how to convert .txt files generated by the OpenBCI to the EDF format.
  • wjcroftwjcroft Mount Shasta, CA
    Did you read the previous link? Also see,

    http://www.teuniz.net/edfbrowser/EDFbrowser manual.html#ASCII_to_EDF_converter

    http://openbci.com/forum/index.php?p=/search&Search=edfbrowser

  • vaibhav2912vaibhav2912
    @wjcroft ;
    I got it to work in EDF browser. Thanx a lot for your help
  • brainbrain Canada
    edited October 2016
    @vaibhav2912 I didn’t get an email notification from @wjcroft's @mention, and it looks like you’ve got it working with EDF viewer. However, if you’re interested, it’s pretty easy to plot a whole session with EEGrunt, using the `EEG.signalplot()` function. It sounds like you already have EEGrunt up and running; the signalplot function is called in the demo scripts (analyze_channel.py and analyze_data.py). However, you’ll need to zoom in on the plot to be able to make anything out: it’s scaled to fit the maximum and minimum values over the whole session, and there are often wild spikes when the OpenBCI starts streaming data.

    Below are screenshots of what it looks like with the EEGrunt sample data. Zoomed out, it just looks like a slightly wiggly line — hardly even recognizable as an EEG signal:

    image

    …but zoomed in, we see a nice EEG signal (you can use the tools in PyPlots’s plot viewer to scroll around and zoom in and out):

    image
  • vaibhav2912vaibhav2912
    edited October 2016
    @brain Thanks a lot for the help.

    These plots are generated every time I analyze recorded signal file to see the spectrograms but it never occurred to me that this is the RAW EEG signal cause it was zoomed out so much that its hard to recognize as the EEG signal. I think till today I just concentrated on the spectrograms that's why I missed this.

    This is very easy and looks crisp clean.

    This makes my task so much simpler. I don't have to fire up another program and convert the file to EDF format and then analyze it. 

    Thanks a lot for pointing this out. 
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