Averaging Conventions - National Instruments NI Spectral Measurements Toolkit User Manual

Averaging Conventions

© National Instruments Corporation
The averaging VIs require that you enter an FFT spectrum as a complex
array. You can perform spectrum unit conversion before or after averaging.
For Spectral Measurements Toolkit VIs, averaging refers to the average of
several different data sets from the same process. The following list
contains averaging operations that apply independently to each frequency
bin of the Fourier transform.
F + jF The complex representation of the Fourier transform
R I
of a signal f(t) using real and imaginary values.
< F > = F + jF For vector averaging, real and imaginary parts of the
k R I
Fourier transform are averaged separately using either
linear or exponential weighting over k data records.
| F | The magnitude of the Fourier transform.
X , Y kth instance of input spectrum X and its averaged
k k
output Y.
max(X , Y ) Each complex frequency of spectrum X
k k
in magnitude to its counterpart in Y
is retained. The result is a real spectrum.
conj( ) Complex conjugate.
25 NI Spectral Measurements Toolkit User Guide
is compared
k
. The larger value
k