From: jiva_at_humboldt1.com
Date: 2001-04-29 00:55:21
--- In buildcheapeeg_at_yahoogroups.com, "Rob Sacks" <editor_at_realization.org> wrote:
> Actually, let me ask you to back up a little,
> because maybe I missed the point. What functions
> would be done on the sound card?
>
Thought about it some more and here's what
the soundcard angle might accomplish:
1) the outboard hardware is reduced to a pre-amp,
possibly a low- pass filter to reject 50/60hz, a place to
plug in electrodes and send out line level analog
data to the sound card, maybe user isolation.
The complexity, size, cost of the 'black box' is
cut by what? a factor of 10?
2) the soundcard provides the smarts and does the A>D
conversion. The 'driver' software is a module that could
be incorporated into an app like yours or it might emulate
a serial port if need be and send the data that way.
3) issues:
* Soundcards don't have a frequency response to near 0 hz.
I don't know if it is possible to overcome this with some clever
scheme. Someone who wrote me earlier on this topic thought
it was possible that this was an issue with the design of the
card's input section rather than a limitation of the chipset.
I didn't understand Joerg's soundcard scheme but I think
it required the 'black box' still be smart and prep the data
for the card.
* As Moritz points out, isolating the user from the computer is
harder to do.
Radio Shack has simple Infrared "voice communicator" and
"analog data transmission system" projects in their project
books. I don't know if that sort of thing would meet the
data transmission requirements or not.
I know little about any of these areas ... enough to get in
trouble but not know what I'm talking about. However,
I thought I'd stir the pot and see if the folks who do know
might come up with a working solution. If this could work
it would make for a very inexpensive system.
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:29 BST