From: Doug Sutherland (wearable_at_earthlink.net)
Date: 2001-12-18 05:26:17
Hi Yaniv,
> i guess were talking about modular eeg <snip>
> this design's intetion is to be a modular design, so
> you can add more channels up to 6 channels, and part
> of them could be emg, ecg, etc, at only the cost of
> a card. so this design is superior to any 2 channel
> device on the market, so you get more, i might say
> much more for your money.
I didn't realize that ModularEEG was intended to be
expandable like this. Are you saying that the digital
board is capable of supporting multiple amp boards?
Is it set up for that now? It appears that six ADC
pins are already used. Are you sure there is enough
ADC ports to support two more amp boards?
I like the idea of modularity, and I eventually do
want a system which includes ecg,emg,gsr, and temp.
I'm not sure that adding more of these same amp
boards is the right approach though. Looking at some
others that do multi-signals ...
WaveRider Jr has 2 EEG channels and an extra GSR
channel. There is no need for all of that fancy
circuitry for GSR. If we want to support GSR then
it probably makes sense to add a simple GSR circuit.
http://www.dynamind.com/waveriderjr.htm
WaveRider Pro has 4 channels which can support EEG,
ECG, or EMG, plus the extra GSR channel.
http://www.dynamind.com/waveriderpro.htm
Procomp has 8 channels. There are two channels for
0-40Hz (EEG) and 6 channels for 0-5Hz. It appears
that the sampling rate can be set separately for
the 0-40Hz and 0-5Hz channels (20-256 samples/sec).
They have EMG, BVP (heart reate), GSR, temp, and
respiration sensors that work with their unit.
Presumably there is different circuitry for the
0-40Hz and 0-5Hz channels.
http://www.cardiopro.com/prospec.htm
Cyberlink has three channels: EEG, EOG, and EMG.
http://www.brainfingers.com/cyberlink.htm
It may make some sense to have a different amp
board for adding other signals. Rather than
adding more of the same amp board, perhaps it
would make more sense to have one different
add-on board with support for GSR and temp plus
maybe 4 other channels for EMG and other signals.
It seems that different circuitry could be used
for these. It would be cool if there were two
connectors on the digital board, one for the
2-channel EEG amp and another for the 6-channel
GSR, temp, and 2 or 4 multi-purpose channels.
I think this would be better than adding more
of the same amp board. I wonder if the uC is
fast and capable enough to handle all of this.
Would a second uC be needed to handle the ADC?
Can we sample all of these signals fast enough?
I don't think we want to have multiple digital
boards with multiple connections to the PC.
-- Doug
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