Owner's manual

35
Computation
parameters
Description
This is the number of lines of the average power spectra. Possible
selections are 1024, 2048, 4096 or 8192 lines. The FFT calculation is
done with a block size of 2*Nbr Lines. For a waterfall graph, a large
number of lines mean a poor time resolution. Conversely, greater
time resolution results in lower frequency resolution. Note that the
overlap parameter can be used to limit this problematic.
This is the time window used for the power spectrum computation.
This parameter allows adjusting the overlap between the time blocks
used for the power spectrum calculation. This parameter can be
adjusted from 0% to 90%. This parameter can be used to increase the
time resolution of the waterfall graph.
The dB/Lin. parameter allows choosing the amplitude scale format.
The choices are dB, dB(A), lin. rms, lin. peak or lin. rms
2
.
The Integration parameter allows applying a simple or double
integration in the frequency domain for an acceleration
measurement. For the simple integration option, the power spectra
are divided by jω. For the double integration option, the spectra are
divided by –ω
2
.
At the time of the computation and if the framework has a considerable amount of data, the
interface asks the user for using a spectrum averaging:
If the user clicks Yes, the software will perform a spectrum averaging to reduce the amount of data.
In this case, the time resolution of the waterfall graph will be reduced. However, the user can adjust
the averaging rate with the button Number of spectra. Then, the number of spectra and the
averaging rate can be adjusted with the following sliding control: