Help! EEG spectral analysis...

Duane Mattern Sverdrup mattern at ariel.lerc.nasa.gov
Mon Oct 28 16:33:00 EST 1991


In article <1991Oct28.051227.4611 at frodo.cc.flinders.edu.au>, psjmt at cc.flinders.edu.au (James Tizard) writes...
>We wish to assess the power of 40Hz activity in short period (100-200msec)
>EEG records sampled at 1khz. The only spectral analysis tool available to
>us is FFT based power spectrum calculation. I'm not at all confident
>that this is the best approach, but have no way to assess this. Could
>anyone *please* help us out ? I guess what I'm asking is whether
>there exists a technique for measuring the power in a limited band, given
>-----------------------------------------------------------------------
> _--_|\        James Tizard  >               psjmt at cc.flinders.edu.au 

There may be other techniques, but since you're looking for spectral info.,
the FFT Power spectrum looks reasonable.  Your frequency resolution is
limited to your sample length (or size).  Since you're making that assumption
that the signal is periodic (to use the FFT), why not either 1) use multiple
copies of the signal strung together with some appropriate matching between
the end points to get a longer signal length, or 2) use "zero padding" to get
the signal lenght extended.  This type of technique is discussed in most
Digital Signal Processing books (for example Oppenheim and Schafer).

Duane Mattern (mattern at venus.lerc.nasa.gov)   (216)433-8186



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