SIMPLORER User Manual V6.0 - FER-a

FFT (Fast Fourier Transformation)
SIMPLORER 6.0 — Manual 443
Data before calculating Data after calculating
The Fast Fourier Transformation algorithm (Cooley-Tukey algorithm) computes the frequency
spectrum of a channel. See also: Cooley J.M., Tukey J.W.: An Algorithm for the Machine Calculation
of Complex Fourier Series. Math. Comp. 19, 297-301, 1965.
The resulting transformation is displayed in a separate window as a table or graph, depending
on your settings.
The FFT computation algorithm requires the time domain data to be equidistant (equally
spaced), so that there is an equal time interval between each data set entry. SIMPLORER
simulation files are not necessarily equidistant due to the variable simulation time step.
Therefore, the FFT algorithm automatically generates equidistant values while simultaneously
adapting the number of entries in the time window to an integer power of 2.
Data Sets
Select the requested data set.
Source
Select the channel to be analyzed.
Over
Select the reference channel.
Time Window
If the «Automatic» box is checked, the whole time or curser range is used, otherwise you can
define an interval.
Filter
Amplitude values smaller than x% of the maximum are not displayed.
% Evaluation
Maximum value of amplitude is 100%, otherwise define a new value as maximum.
Result
Select the format of the result, absolute value and phase, or real and imaginary part.