modular eeg work report

From: Chris (e9300298_at_student.tuwien.ac.at)
Date: 2002-07-10 15:29:45


Hi all members of the openEEG - Projekt !

This is my fisrt hello to the group, my name is Chris, i'm from Austria
(Vienna). I like working with the possibilities of biofeedback for a
several years now, I built some installations (like a brain-driven
car-racing-game, or the ironic 'brain-washing machine', which translates
brainwaves into washing-sounds) to bring this technology more to the
public. My engeneering comes more from the software-side, I have to
describe my knowledge about amplifier-hardware as 'tiny'. I found the
openEEG-project and the mailinglist about 3 months ago, searching for an
eeg-concept that I could build with my home-grown hardware-skills. ..
that was really a happy click!!
I decided to manufacure the modular-eeg - design by Jörg, it seemed
optimal for my needs and there was best documentation for this project
at that time (april).
After the downloads (eagle-cad, avr-gcc, SP12), printouts, PCB,
orderings (I got most of the parts here in vienna, 1 capacitor 0,3u and
4 'Spulen' 0,22uH have slightly different values) I am finished with my
first two boards now - and they work :-)
I used Jörg's firmware version from 8/2000 that comes with the download
of RS232-EEG. I had to do some minor changes to get it working. (there
was a compile-error at uart.c, maybe only at my version of avr-gcc).
I have problems with 50-Hz humm (I can reject it to an amount that I
actually see brainwaves only when i connect myself to GND, can somebody
help here ?
I also get this noise when I use battery-power. Could shielding of the
Electrode-cables help ? I don't fully understand the concept of the
right-leg-driver - is it ok when i use the average-signal from the
earlobes ?)

I ordered two (expensive) bluetooth-modules to test this possibility for
wireless transmission. (I hope bluetooth becomes more affordable, I use
it for my prototype because a SPP-module should be easy to apply. It has
a range of max. 15 m)
the two ModularEEG-boards now sit in a plexi-box with 4 buttons for
control-inputs for the software, 1 LED (indicates data transmission), 1
battery-pack, and I hope soon the bluetooth -module. the box could be
mounted at the belt or weared on the chest.)

I wrote my first test-applikation in delphi2, win32. I do not have linux
installed, but the openEEG-project is yet another reason to do. I hope
I'll get that in the next month or so. Does someone have some tips on
whats useful (what distribution, C-Compiler, sound- or open-gl - libs) ?

I love the openness of the design of Dave's Biosensory-Library and would
like to contribute where I can. I think about ways for a bio-triggerd
environment using 3d-graphics and various sounds for some time now - for
me the things get more realistic yet. Personally, I would like to have a
proper sound and graphic - output better today than tomorrow, but in our
case a step-by step development seems to be the best.
Are there some low-level tools, classes or dll's, that programmers can
use ?
A stream-oriented design like Dave points out on his homepage looks good
to me.

Best Regards,
Chris.



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