Re: [buildcheapeeg] RF EEG interface

From: Doug Sutherland (wearable_at_earthlink.net)
Date: 2001-12-07 12:14:15


Jim,

I'm wondering if perhaps this is the wrong place to discuss
these things, since they aren't really related to OpenEEG.
I'm considering starting a new yahoogroup for discussion
of generic bioengineering-hacking topics like home brew
eeg/ecg/emg/gsr/etc and also computer-interfacing topics
like eeg-based computer control. It seems like we might be
stepping out of bounds for this group. I kind of felt the
same way talking about eeg hacking on mind-l, that group is
really for mind machine talk.

> I am now thinking about is using two FM transmitters
> and two receivers with a very slow AFC. Or one of these
> new SAW oscillators.

Abacom has 433Mhz AM transmitter/receiver pairs with
SAW resonators. They have a range of FM stuff too:

http://www.abacom-tech.com/transmitters.htm
http://www.abacom-tech.com/receivers.htm

Not sure if these are appropriate for your application.
I'm really not much of an analog guy, the only RF stuff
I've played with is for logic-based data streams and/or
packet based transmissions. If I was doing it I would
digitize on body (via microcontroller) and send data as
a serial stream. If you're willing to do that, then
these VirtualWire modules look interesting. They can
go up to 19.2k baud (not comparable to the OpenEEG
goal of 115.2k but you're only using 9600 now).

http://www.rfm.com/products/vwire.htm

There are many others like this out there. Tons of
different choices.

> What I would like is an analog (probably FM) transmitter
> receiver that will have 12 or more bits of resolution
> and linearity. Also low power at least for the transmitter.

Your the analog guru, and I can't be of much help in
what's required for sending analog data.

Check out these 916 Mhz modules from Laipac
http://www.laipac.com/datasheets/Easy%20Link%20Wireless/TLPRLP916.pdf
http://www.laipac.com/datasheets/Easy%20Link%20Wireless/TLP916F%20Ap-Circuit.pdf

Please don't tell me not to send URLs. The only way to
find what you are looking for is to look at the various
data sheets. I'm definitely not good with analog. But
sending a serial data stream is almost trivial. There
are many RF modules that are designed for sending TTL
or CMOS data streams.

-- Doug



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