Recorded data format and processing

ShawnShawn Chicago
in Software

Hi,
I am learning about dealing with the data collected from 16 channels Cyton + Daisy board. Just wondering if the collected TXT and CSV files are raw? Or already processed by openbci GUI.
Besides, since I am more familiar with R, so is there any tips or doc about how to process collected data with R? There are not many resources regarding this online.
Any help would be really appreciated!
Best,
Shawn

Comments

  • wjcroftwjcroft Mount Shasta, CA

    Shawn, hi.

    CSV files are raw. Usually you want to apply some type of filter, such as a bandpass from say .5 Hz to 45 Hz. Also recommended is a notch filter at your mains frequency, which is 60 Hz in the US.

    https://cran.r-project.org/web/packages/gsignal/vignettes/gsignal.html

    William

  • ShawnShawn Chicago

    Hi William,
    Thank you for your reply, how about the txt files? Since the CSV files don't have headers for each column.

  • wjcroftwjcroft Mount Shasta, CA

    https://docs.openbci.com/Software/OpenBCISoftware/GUIDocs/#exported-data

  • ShawnShawn Chicago

    @wjcroft, Hi William, I am using the 10-20 system with a cyton-daisy board. When we collect data, there are both BIAS and Reference channels connected. But does OpenBCI GUI save the BIAS and Reference data? If not, how should I set up a reference channel in third-party software like MatLab(EEGLab)?

  • wjcroftwjcroft Mount Shasta, CA

    'Bias' is the same as 'Ground' on other EEG amps. All EEG is 'differential' (subtracted) voltage, measured between the channel in question and the 'reference' / (SRB2 on Cyton) lead. There is no separate reference channel on Cyton.

  • ShawnShawn Chicago

    @wjcroft said:
    'Bias' is the same as 'Ground' on other EEG amps. All EEG is 'differential' (subtracted) voltage, measured between the channel in question and the 'reference' / (SRB2 on Cyton) lead. There is no separate reference channel on Cyton.

    So the data saved is already referenced? We don't need to re-reference or just apply 0-reference in such case, is that correct?

  • wjcroftwjcroft Mount Shasta, CA

    Correct, already has the single reference location you have chosen. You can re-reference if you want, not needed. Zero reference is a different type of re-reference.

    https://eeglab.org/tutorials/05_Preprocess/rereferencing.html

  • ShawnShawn Chicago

    @wjcroft said:
    Correct, already has the single reference location you have chosen. You can re-reference if you want, not needed. Zero reference is a different type of re-reference.

    https://eeglab.org/tutorials/05_Preprocess/rereferencing.html

    Many thanks!

  • ShawnShawn Chicago

    Hi, I have another question, how could I add markers at some specific time points to the data stream? Or is there another way to create a separate file with marker info and merge it with the data from OpenBCI GUI? Thanks

  • wjcroftwjcroft Mount Shasta, CA

    Shawn, hi.

    The best approach and most accurate with Cyton, is to use the 'external trigger' inputs.

    https://docs.openbci.com/Cyton/CytonExternal/

    William

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