[Eeglablist] EEGs in mobile/portable office trailers

[Makoto Miyakoshi]

Hi Ingmar, Robert, and Michael,

Here is an interesting technical report for you.
https://urldefense.com/v3/__https://www.amazon.com/gp/customer-reviews/R2EOHOXO4AKND0/ref=cm_cr_arp_d_rvw_ttl?ie=UTF8&ASIN=B078T2R64C__;!!Mih3wA!G2616J0-2v0nQamGLx1JrYgXH6nJyOXV0tXlwQ1Ulno8rHQEBkEEsyH30-tjBedwHnlRjXVdjyWGIhS4Gs0gNz_M24k$ 
It's interesting that Robert mentioned about a radio. This report says the
same thing.

Ingmar, the EEG's frequency range is in the 'extremely low frequency' range.
https://urldefense.com/v3/__https://www.rfcafe.com/references/electrical/freq-bands.htm__;!!Mih3wA!G2616J0-2v0nQamGLx1JrYgXH6nJyOXV0tXlwQ1Ulno8rHQEBkEEsyH30-tjBedwHnlRjXVdjyWGIhS4Gs0giRkRFKA$ 
Thanks to its extreme lowness and sensitivity properties, EEG signals are
usually not disturbed very much by external noise sources.
Practically, only line noise is an issue. This is why 'From shield to
field' was possible for MoBI conditions. You can't do the same with MEG!

To reduce line noise (and any external ones), it is important for your EEG
recorder to have a 'Driven Right Leg' circuit (i.e. 'DRL' channel/electrode)
https://urldefense.com/v3/__https://en.wikipedia.org/wiki/Driven_right_leg_circuit__;!!Mih3wA!G2616J0-2v0nQamGLx1JrYgXH6nJyOXV0tXlwQ1Ulno8rHQEBkEEsyH30-tjBedwHnlRjXVdjyWGIhS4Gs0gXpGD_po$ 

I make the following report available for you for your info in case you
find them helpful. I did these works a few months ago.

https://urldefense.com/v3/__https://drive.google.com/file/d/1BkYxyt-O_M8bFPpCX1KYZZXp_YO7YAsZ/view?usp=sharing__;!!Mih3wA!G2616J0-2v0nQamGLx1JrYgXH6nJyOXV0tXlwQ1Ulno8rHQEBkEEsyH30-tjBedwHnlRjXVdjyWGIhS4Gs0ghPJJAr4$ 
https://urldefense.com/v3/__https://drive.google.com/file/d/1heBEru1mQKnx0AGw39bZUAtLmAGsgvUZ/view?usp=sharing__;!!Mih3wA!G2616J0-2v0nQamGLx1JrYgXH6nJyOXV0tXlwQ1Ulno8rHQEBkEEsyH30-tjBedwHnlRjXVdjyWGIhS4Gs0gZx53_c0$ 
Makoto

On Tue, Jun 27, 2023 at 5:19 PM Dr. Michael Villanueva via eeglablist <
eeglablist at sccn.ucsd.edu> wrote:

> Hello Ingmar
> I have substantial field experience (remote and urban) with
> mobile/portable EEG devices in different parts of the world under harsh
> conditions.
>
> Some locations were noisy with 60 Hz, and sometimes a poor (or bad) ground
> was in the mix. However, a Trifield meter helped us understand the severity
> of a problem. What we found much worse was fluctuating air conditioning. In
> locations that were exceptionally hot and humid, it would take the human
> body a while to adapt to the change in temperature in the mobile unit. We
> had EEG recordings that showed steep, undulating waves across all channels
> due to skin pores that would open and close to control sweating. The
> microscopic ebbing and flowing of sweat alters the EEG. Finally, in some
> places, it proved impossible to prevent outside noise. We would get an
> unexpected muscle and audio orientation to sudden noises that regularly
> passed through the corrugated walls.
>
> For us, in order of frequency occurrence:
> 1. Audio noise from outside the unit that evoked an audio potential.
> 2. Sweat-induced artifact.
> 3. Poor grounding of the unit's electrical system. However, I do not
> understand electricity, so what we call lousy grounding might have been
> something else. I can say that the EEG would show a very peculiar jittery
> square wave morphology. Nonetheless, preprocessing resolved most of the
> problems, and ASR benefited the sweat artifact.
>
> Michael
>
> -----Original Message-----
> From: eeglablist <eeglablist-bounces at sccn.ucsd.edu> On Behalf Of Ingmar
> Brilmayer via eeglablist
> Sent: Tuesday, June 27, 2023 1:56 AM
> To: eeglablist at sccn.ucsd.edu
> Subject: [Eeglablist] EEGs in mobile/portable office trailers
>
> Dear list,
>
> I wanted to ask if anyone has experience with measuring EEGs in
> mobile/portable office trailers. Our laboratory spaces are being renovated
> and/or moved to another building, and we are currently thinking about how
> to manage the (as we assume quite long) transition period. Do you think
> there could be any issues with interference or similar problems? After all,
> such containers are typically made of metal and the wiring might also be,
> say, "improvised" compared to our lab building. Also, with trams and trains
> in the city, we thought that this "container solution" might, all in all,
> be potentially problematic. Thank you in advance for your expertise!
>
> Ingmar
>
> _______________________________________________
> Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> To unsubscribe, send an empty email to
> eeglablist-unsubscribe at sccn.ucsd.edu
> For digest mode, send an email with the subject "set digest mime" to
> eeglablist-request at sccn.ucsd.edu
> _______________________________________________
> Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> To unsubscribe, send an empty email to
> eeglablist-unsubscribe at sccn.ucsd.edu
> For digest mode, send an email with the subject "set digest mime" to
> eeglablist-request at sccn.ucsd.edu
>