Python serial, large sample data values?

andrew_MXandrew_MX Shandong University
edited October 2018 in Software
Hello!
I am doing my own program using the OpenBci Board，and I want to desing a GUI for further test.

I use the python serial and pyqt5 for design , but the data format that I get seems not good. 

In GUI of processing,the EEG result comes to about 10mV - 200mV, but the result of my hardware always comes to about 18000,-183750mV,like this. I have use the same way to decode the 33 byte of the serial ,250 packet per second.

I want to ask whether there is some conversion formula? The read_data module is drawing lessons from the cyton.py. And I have also use the scale_fac_uVolts_per_count which is about 0.022351.


I need you help!

Comments

  • wjcroftwjcroft Mount Shasta, CA
    Andrew, hi.

    "In GUI of processing,the EEG result comes to about 10mV - 200mV". The abbreviation for microvolts is uV. Millivolts is mV. Normal 1-40Hz EEG is in the uV range. So yes, the GUI shows generally less than 200uV.

    "but the result of my hardware always comes to about 18000,-183750mV"

    This is the DC offset. See this thread,


    Regards,

    William

  • andrew_MXandrew_MX Shandong University
    Thank you for your reply, William.

    And I think whether there is self-contained filters in the OpenBci board. And in the GUI of processing, there seems 5 filters chioces(None,1-50Hz，7-13Hz)and so on .
    Are they real time filter which each compute 1 point data and add to the display_buff , or compute a buffer data(maybe 512 points) and then copy them to the display_buff?
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