Unexpected PPG Signal Output from Empatica EDF File using MNE

[IsraaMoustafa]

Hi everyone!

I'm working with an Empatica .edf file and trying to extract the PPG:wrist signal using the MNE library. However, when I load the data, the extracted signal mostly consists of values around 1 and -1, which doesn’t look like a valid PPG waveform.

Here’s a plot of what I’m seeing:

I expected to see a smooth pulsatile waveform, but instead, it looks more like a square wave oscillating between 1 and -1.
Has anyone else encountered this? Any ideas on what might be happening or how to properly extract the PPG signal? Any help would be greatly appreciated! 😊

Thanks in advance!