[Eeglablist] question about frequency resolution with demodulation technique

[Paul Kieffaber]

He EEGlab list,
I'm hoping that someone will help me to figure out how to compute the
frequency resolution using complex demodulation.  As near as I can figure
it has to do with the full-width half maximum of the low-pass filter, but
I'm not exactly sure.  Here is the code I'm using...

[b,a]=butter(4/2,5/(1000/2)); %4th order Butterworth filter, low-pass of 5
hz, 1000hz sample rate.
H=exp(2*pi*i*freq*(0:length(signal)-1)/srate); %freq=6, srate=1000
demodsig=H.*double(signal);
demodsig=filtfilt(b,a,demodsig);

I really appreciate the feedback.
thanks,
Paul

-- 
-----------------------------------------------------
Paul Kieffaber, Ph.D.
Associate Professor
Department of Psychology &
Program in Neuroscience
The College of William & Mary
(757) 221-1965
pdkieffaber at wm.edu
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