ECG in matlab gives me nonsensical signal

mecapi · April 2019

Hello. I'm trying to view an ECG signal in matlab.

While i was reading the signal in the OpenBci app, i got a normal signal that looked like the 3rd image. However, when i plot the signal from the txt file in matlab and filter at 50Hz , i get the 1rs (not filtered ) and 2nd (filtered) image. Do i need a special algorithm ?

Billh · April 2019

The scaling looks odd-- what are the X axis and Y axis units?

wjcroft · April 2019

Mecapi, and Bill, hi.

The top graph, with slowly rising microvolts in the 12,000 to 18,000 microvolts range (12 to 18 millivolts), looks like a DC offset,

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

And both top graphs look like you have lots of mains noise. Have you tried a simple bandpass, from say .5 Hz to 40 Hz? You mention you filtered 50Hz with Matlab, but what kind of filter? It's not enough. You could do both a bandpass and a notch at 50Hz.

Regards,

William

ECG in matlab gives me nonsensical signal

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