From: Jim Meissner (jpmeissner_at_mindspring.com)
Date: 2001-12-23 16:25:52
Dear Jim Peters:
> Also, there are much better ways of getting the data from the EEG to
> the computer via the sound card line-in than this, for instance using
> amplitude-modulation of a carrier.
Actually an FM modulated carrier is much less prone to noise and interference. I built a wireless EEG setup using a baseball cap with electrodes mounted on the sweatband and the amplifier and transmitter on the top of the head inside the cap. The power was 4 AA batteries. It was possible to do biofeedback listening to your brain on the FM stereo.
I am still unpacking from my move and I just found this toy. I could put the schematic on the web page if anyone is interested.
Juergen P. (Jim) Meissner
Check out my Website at www.MeissnerResearch.com
Read about the benefits of the Brain State Synchronizer sounds for improving your life and health.
----- Original Message -----
From: Jim Peters
To: buildcheapeeg_at_yahoogroups.com
Sent: Sunday, December 23, 2001 7:04 AM
Subject: Re: [buildcheapeeg] Re: modularEEG input stage prototype ... Some Ideas/Jim cont.
JimmyB_101 wrote:
> --- In buildcheapeeg_at_yahoogroups.com, Jim Peters <jim_at_uazu.net> wrote:
>
> >
> > What I'm finding so far is that what I want to do, e.g. shift a
> 256Hz
> > sampled signal up 8 octaves, has been implemented in theory many
> > times, but the detail makes these solutions completely inappropriate
> > for our particular application.
> >
> > (An 8-octave shift (256x) would map 0.2Hz to 51Hz, and 40Hz to
> 10kHz.
> > This seems a fairly good mapping of interesting brain-wave
> frequencies
> > to the audible range, although other shifts than 8-octave should
> also
> > be possible from the same code. I'd like to keep with whole
> octaves,
> > so that the frequencies have a clear relation to the original
> > frequencies, in case that matters).
> >
>
> for one thing, this would seem to bring the possibility of using
> a sound card for A>D back into the picture.
Actually, I was planning on running this on the host computer, not on
the EEG board. You'd need a fairly powerful processor to do this on
the board (206MHz StrongARM?), unless someone can find a *much* more
efficient algorithm.
Also, there are much better ways of getting the data from the EEG to
the computer via the sound card line-in than this, for instance using
amplitude-modulation of a carrier. Because of the nature of a
pitch-shifter, this isn't a nice simple operation, so there will
always be some level of compromise and error. For recording the data,
I would personally prefer a more direct and unprocessed input, such as
a serial, IRDA or USB connection, or an amplitude-modulated carrier to
the soundcard line-in.
Jim
-- Jim Peters (_)/=\~/_(_) Uazú (_) /=\ ~/_ (_) jim@ (_) /=\ ~/_ (_) www. uazu.net (_) ____ /=\ ____ ~/_ ____ (_) uazu.netYahoo! Groups Sponsor ADVERTISEMENT
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