From: Doug Sutherland (wearable_at_earthlink.net)
Date: 2001-12-02 19:31:24
JBilderback wrote:
> restating the question: if there's say 5uv of high frequency noise
> riding on a 100uv EEG signal then what is gained with 12-16
> bit data sampling ??
I'm not much of an analog guy, but according to most of the
published acceptable standards for EEG, at least 12-bit
resolution is required. According to EPTA the noise should
be 2 mV per below.
Noise: 2 m V peak to peak, 0.16--100 Hz
Common Mode Rejection Ratio: greater than 80--100 dB
Sampling Rate: minimum of 200 Hz, preferably 250--400 Hz
Amplifier Dynamic Range: greater than ± 2 mV
High Filter: 15, 30, 50, 70, 100 Hz (- 3 dB or preferably - 12 dB)
Low Filter: 0.16, 0.5, 1.6, 5, 10 Hz (- 3dB)
Notch Filter: attenuation ratio 1:20 at 50 and 60 Hz
Sensitivity: 1, 1.5, 2, 3, 5, 7, 10, 15, 20, 30, 50, 70, 100 mV /mm
A/D Conversion: greater than or equal to 12 bit ADC. The recording
should be able to resolve activity down to 0.5 mV and as high as
several millivolts without clipping.
http://epta.50megs.com/digital.html
It seems that a lot of the newer commercial EEGs are using
16, 22, and even 24-bit ADC. Biosemi defends why they don't go
above 16-bits here ...
http://www.biosemi.com/faq/more_than_16bit.htm
http://www.biosemi.com/faq/adjust_gain.htm
This is a decent presentation on sampling/conversion
http://www.bae.ncsu.edu/bae/courses/bae465/1999/slides/instrumentation/index.htm
-- Doug
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The human-computer interface seems to be stuck on the
WIMP (windows, icons, menus, pointer) model. What I'd
like is to have you call me and my clothing answers.
http://home.earthlink.net/~wearable/jacket-wearable.html
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:32 BST