[Eeglablist] 16 Hz artifact with lower harmonics in data

[Malte Anders]

Hi Bene,

Thank you very much!

Someone already mentioned the 16 2/3 Hz thing with trains to me via private
Email, but your blog post sheds some more light onto this. Indeed, the
measurement is taking place in Germany, in some basement at TU Munich... I
need to have a look at this next week.

My idea is to connect an Open BCI for troubleshooting, which can be run
from 4 x 1.5 Volt AA Batteries. In that case we would eliminate any
external artifacts that are induced via the grounding circuit.

Best wishes!
Malte

Benedikt V. Ehinger <science at benediktehinger.de> schrieb am Do., 31. März
2022, 21:25:

> Hi!
> We observed this with a railway line (important: in Germany) nearby:
> https://urldefense.proofpoint.com/v2/url?u=https-3A__benediktehinger.de_blog_science_trains-2Dand-2Deeg_&d=DwIFaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=e6pZJC_XEDiwU7oAh8oG3hkF2MrfOHh2eni06_FGdgEvmT5Qcv5j9FM8RxQ80SdH&s=RECakigl7u0Nl4lJBABntcKX-5agXzdxePZ9ayIC_q4&e= . Note that 16
> 2/3 is exactly 50Hz divided by 3. Hope that helps already :-)
> Cheers, Bene
>
> Am 31.03.2022 um 12:20 schrieb Malte Anders:
> > Dear all,
> >
> > We are currently trying to record EEGs on the open brain of certain
> animals
> > - so no "standard" human recordings. The gold electrodes are placed
> > directly on the brain, without any conductive gel applied.
> >
> > We are encountering a strange ~16 Hz artifact, with harmonics around
> ~10.x
> > Hz and ~5.x Hz, see these images:
> >
> https://urldefense.proofpoint.com/v2/url?u=https-3A__ibb.co_NKMcrf0&d=DwIBaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=c88_VOjmnuVwvN-A41WN_LrcUXdxqhHwgozv6g_vBGXNTPB1AS0LrJkqDp8M8B44&s=E8I2mkOB0AmaOPUEUXwPZvKu-BkYWuzhow82gl11YCg&e=
> >
> https://urldefense.proofpoint.com/v2/url?u=https-3A__ibb.co_Z8zkCpp&d=DwIBaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=c88_VOjmnuVwvN-A41WN_LrcUXdxqhHwgozv6g_vBGXNTPB1AS0LrJkqDp8M8B44&s=haiZvyK3aT-jVpA4wpHVfjQQrPRs1O0cx88EnN9NitE&e=
> >
> > Anybody ever saw artifacts in these frequency ranges? I am trying to
> narrow
> > down if those artifacts stem from our recording setup itself (maybe bad
> > impedance between the brain and the measuring electrode?), or from any
> > other external hardware in our recording setup.
> >
> > Any help is much appreciated!
> > Malte
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