From: Joerg Hansmann (info_at_jhansmann.de)
Date: 2001-06-29 17:18:31
Hi,
----- Original Message -----
From: Lovass Laszlo <prochess_at_e...>
To: <buildcheapeeg_at_yahoogroups.com>
Sent: Friday, June 29, 2001 11:11 AM
Subject: [buildcheapeeg] bandwith idea
> Hi,
>
> An idea has crossed my mind: what if using a rate of 256 samples/sec
That is in fact the sample rate of the RS232EEG01..03
> and a
> freq band DC to 100 Hz (lowpass point here)
The RS232EEGanalog03 uses a 75 Hz 5th order lowpass.
In reality you cannot use 1/2 sample frequency as the upper
cutoff-frequency of the low-pass, because it has a limited roll-off.
> and also using a reference
> channel for detecting noises (like muscle impulses, radio freq, 50/60 Hz
> buzz, etc.)
Where exactly should the reference channel be connected to ?
To a resistor ?
To the body ?
> and subtract it in the amplifier section.
You can only compensate errors, if you can measure them exactly.
So the question is: How and where do you want to measure the
error-voltages ?
> The possible advantages: getting rid of phase and amplitude distorsion,
> possible use of gamma and even higher brainwaves (cf. 35-45 Hz brainwave
> research of visual observations, etc.).
>
...
Regards,
Joerg
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