Strange EEG data in EDF format

[beerdog]

Hello everyone,

I am loading EEG data in EDF from disk with a simple:

mne.io.read_raw_edf()

However, my raw data looks extremely weird. This is a small section of 2s (Fs=1000) from a random channel. All channels look like this.

I am new to EEG and unsure what to do about it. Does anyone of you have an idea what could cause this? All my data look like this. Could there be something wrong with the way it’s exported?

Thanks in advance and best wishes,
Tim

• MNE version: 0.24.0
• operating system: macOS 12

[cbrnr (Clemens Brunner)]

How did you record your data (which amp, which software, etc.)? On first glance, it looks like the physical range of the signals were too large to store as EDF, but that’s just a guess. Can you try opening the file with EDFbrowser to see if it looks the same?

[beerdog]

Hi Clemens, thanks for your reply!
For the amp, we used a TMS-compatible 24-bit amplifier (NeurOne Tesla with Digital-Out Option, Bittium) connected to an 8-V battery. The software is NeurOne. I think your guess with the signal range was correct!

I will export it in a different format and then try again! Thanks!