Friday, April 25, 2008

final project for pattern rec



EEGLAB workflow
  • 1) read in data
  • 2) change sampling rate to 256 (this makes 154 points between a [-0.3 0.3] epoch)
  • 3) parse out the right hand and left hand epochs
  • 4) take the average over all 64 electrodes (next try only working with nodes in the 'mu area')
  • 5) take the fft of the average
  • 6)parse the epochs

Saturday, April 5, 2008

Things I don't know about Digital Signal Processing

This is going to be a long list:

How to learn DSP:
http://www.redcedar.com/learndsp.htm

  1. hertz and their relationship to sampling rates
    1. http://en.wikipedia.org/wiki/Nyquist_frequency
  2. Finite Impluse Response (FIR) filter vs Infinite Impluse Response (IRR) filter
    1. FIRFAQ: http://www.dspguru.com/info/faqs/firfaq.htm
    2. IRRFAQ: http://www.dspguru.com/info/faqs/iirfaq.htm
  3. Linear trends?
    1. To attempt to factor out the influence of time on a trend using regressions or other statistical techniques
  4. Regressions?
    1. Regressions are used to quantify the relationship between one variable and the other variables that are thought to explain it; regressions can also identify how close and well determined the relationship is.
  5. ds


Good info:

Referencing data from Earlobe:
Converting data from fixed reference (earlobe or etc.) to average reference is advocated by some researchers, particularly when the electrode montage covers nearly the whole head (as in some high−density montages).

Why filter:
Another common use for data filtering is to remove 50 Hz or 60 Hz line noise. Note: we recommend to filter continuous EEG data although epoched data can also be filtered, each epoch being filtered separately.

Removing Baseline:
Removing a mean baseline value from each epoch is useful when baseline differences between
data epochs (e.g., arising from low frequency drifts or artifacts) are not meaningful and might
otherwise dominate the data. The following window pops up automatically after the data has been epoched.


Dr. Keith's experiment

Rerun experiment, let people respond in real time, subtract stimulus time from response time, figure out overall cohearance, epoch out stim - response AND cohearance, compare

After every three response see the response after. 201 vs 203