how to remove scalar factor from text file generated from GUI

hrodriguez

Hi,
I´m trying to analyze data generated from Cyton Daysi hardware (16 channels) in a text file. According to documentation, this hardware implements a gaining factor (24x) by default which is "included" in microVolt value in text file, which has highest values in microVolts like following:

Any clue to manage data without scaling so I can get the real microVolt values. Documentation mentioned a 0.02235 microVolts per count value. How can I apply to data to get real microVolts in session ? Tried band-pass filtering (1-55) but values keep high at delta band.

Thanks in advanced,

Regards,

Hernan

wjcroft

Hi,

A bandpass filter (blocking below .5 Hz) should remove the DC offset you are seeing. All filters have both the cutoff / limits, and a term which controls how sharp the filter is. Which is called 'order' or 'poles' or 'taps'. It is possible your filter is not sharp enough and is still picking up the DC offset. There are also different filter types besides Butterworth,

https://www.google.com/search?q=comparing+DSP+filter+types+butterworth+bessel+elliptic+etc

https://openbci.com/forum/index.php?p=/discussion/201/large-millivolt-data-values-fbeeg-full-band-eeg

William

hrodriguez

Great! Thanks William, I will update my code.