Hi all,
I'm new to DSP and Matlab and come from a non-engineering background (so go
easy on me!), and have a few basic questions. As part of my psych studies im
tracking the diameter of the pupil over 60s, at 60 samples a second. This is in
response to stimuli of varying frequencies between 0 and 7 Hz. I plan to
investigate the responses using FFT in Matlab
My problem is that if someone blinks, or the pupil is lost by the tracking
software, this returns a data value of 0 for the duration of the blink/loss of
tracking. In practice this can be anything from 3 to hundreds of samples.
1) I have read about zero padding, but it is only mentioned as being applied at
the beginning or end of data. I assume then that my 0 values that automatically
get applied will mess up the FFT? One option is to cut the missing data values
out (that is, those that have a 0 value). This however would mess with the
sampling rate of the data. As i know the sampling rate, should i cut out these
0 values and then specify the time again starting from 0 using the known sample
rate? Any better suggestions?
2) I am trying to pick a filter that will give me the best resolution for
values between roughly 0.25 and 6.5 Hz. Anything to either side of this is
noise for my purposes. The accuracy of the amplitude in this range is of
importance to me. There seem to be a whole heap with very subtle differences,
any suggestion would be great. Of course, I need to be able to easily implement
it in Matlab.
Cheers for your help,
Daniel
