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FFT
Item
TRACE LABEL
The FFT command performs a forward fast fourier transform on a trace array. The results of the transform contain
logged magnitude components only.
The FFT algorithm assumes the source trace array is one period of an infinitely long string of concatenated,
duplicate arrays. Thus, in order to avoid discontinuities when the source trace is concatenated, the beginning and
end elements of the source trace array must gradually diminish to the same amplitude value. If the endpoints of the
original trace array were of different amplitudes, the discontinuities in the resulting array series would introduce
false frequency components into the fourier transform. This is illustrated in the following figure.
Description/Default
Alpha character. User-defined label declared in
TRDEF statement.
For window, TRACE LABEL is also defined
by TWNDOW
Fast Fourier Transform
Range Restriction
Trace length must be 1008.
Programming 109
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