CEMB USA N500 - Manual (Page 36)

6 - 4 FFT analyzer mode
Spectrum analysis (FFT)
The so-called FFT algorithm is applied to the signals acquired with due respect for the
settings made; in accordance with the recommendations deriving from the mathematical
treatment from which it has been taken, such numeric processing is preceded by
application of a Hanning window to the acquired signal. This allows attenuating the edge
effects due to digitizing as well as reducing phenomena of leakage in the spectrum.
The Measurement page appears like the one shown in the figure. It is organized so as to
maximize as much as possible the area dedicated for representation of the FFT graph.
A box Ovrll is located on the left side giving the overall value of the signal for the channel
displayed; it has the same units of measurement as those of the FFT. Such information
allows monitoring the total vibration, also during the analysis of its single components.
Beside the usual graphic control functions (see 2-5 Functions operating on graphs),
namely:
- Set scale
- Show cursor
- Change of displayed channel
- List of peaks in order to display the list of highest peaks in the spectrum (see 2-8
List of peaks).
the following are available:
–
Waveform (see 6-6 Waveform function).
–
Trigger Setup to set a trigger to be used for starting the acquisition
(see 6-6 Trigger Setup).