From: sleeper75se (sleeper75se_at_yahoo.se)
Date: 2002-05-10 16:15:14
Hi Jake,
> 1. How well does the hardware work right now?
Well, there are three projects. Two that I work on, and one that
Joerg Hansmann and Mortiz v Buttlar work on.
All three projects have these parts in common: They will all have an
analog section and a digital section, and a power-system.
The analog section consists of a sensitive input amplifier and an
anti-aliasing filter.
The digital section consists of an AD-converter, a microcontroller
and an optical link to a serial port.
I can't speak Joerg's and Moritz's 'ModularEEG', but my hardware is
not finished. The digital section works great, but the amplifiers and
power system need to be reworked.
> 2. Is a serial port going to have enough bandwidth?
a-b: Yes
c-d: It depends. The bandwidth is 10kbyte/s. What you do with it is
up to you - the microcontroller is easy to program.
> 3. Have you considered using a USB port?
Yes, but since it is more complex and expensive to use, it might be
better to begin with serial port and add USB later. This is a sub-
project someone with knowledge in digital electronics could work on.
Volunteers?
> 1. What are the current problems?
I have problems with noise, but I'm working on it. I could use some
help with designing a good DC/DC converter filter.
Trying to find parts that are available on several continents is a
*major* headache. Compatible resistors and other passive components
and most IC's are fairly easy to find. Enclosures and connectors are
not.
> 2. What needs to be done now?
A FAQ! (I have been nagging about this before... Please, anyone,
HELP!)
> The hardware is going to have to procede before
> the software, unless you are willing to release a
> spec. and stick to it, which could slow us down.
A previously set goal was to be able to interface with any hardware
on the market. A minimal specification is a 2-channel EEG device that
communicates over the serial port.
> Sorry to ramble, but does anyone have any
> experience with any soundcard based EEGs?
It has been discussed. A lot of boards have a 20Hz highpass filter
that removes the very signals we are interested in. On modern sound-
cards, this is done with digital filtering, so you can't turn it off
either. A possible way around this is to input the signals digitally,
via an SPDIF interface. AM or FM modulating the signals have been
discussed too, but I think we came to the conclusion that the
resolution would be too low (less than 8 bits).
Regards,
Andreas
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:43 BST