====== FFT Filter ======

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Filter (Lowpass or Highpass) a signal using a Fast Fourier Transform. The algorithm uses the Fourier harmonic closest to the requested cutoff frequency.

The base frequency of the FFT reconstruction is:

FREQ= 1/(total time)
The maximum frequency of the FFT is:

FREQ_MAS= FREQ * NumFrames / 2
The actual cutoff frequency is the closest multiple of the base frequency to the requested cutoff frequency

**FFT_Filter**
/Signal_Types= The type of signal to be processed
/Signal_Names= The names of the signals to be processed
/Signal_Folder= The name of the signal folder
/Result_Suffix= The ouput signal can have a suffix that can be applied to the original signal name
/Result_Folder= The data tree folder that the resulting signal is placed.
/Frequency_Cutoff= Requested Cutoff Frequency
/Lowpass= True= Lowpass - False= Highpass
**;**