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filter - digitally filter ERP data files
filter filtertype
infile outfile cutoff [cutoff]
filter digitally filters ERP
averaged files with either a lowpass, highpass, or bandpass filter. filter
uses a fast fourier transform (fft) algorithm to represent the data in
the frequency domain, applies an implementation of a 3rd order Butterworth
filter to the data, and finally converts the data back to the time domain
using an inverse fft.
filtertype can be one of "lp", "hp", or "bp", for
lowpass, highpass, and bandpass respectively. infile is the name of the
data file to be filtered. outfile is the name of the file to be created
which will contain the filtered data. cutoff is the cutoff frequency for
the filter. Note that for a bandpass filter, both a lowpass and high pass
cutoff frequency must be specified.
Ronald Ohst
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