National Instruments Order Analysis Toolset - page 39

Chapter 3 Gabor Transform-Based Order Tracking
© National Instruments Corporation 3-9 LabVIEW Order Analysis Toolset User Manual
Figure 3-7. 2D Spectral Maps
Figure 3-7(a) is the frequency-time spectral map generated directly from
the Gabor coefficients. The magnitudes of coefficients are shown as gray
scale, with full white indicating a maximal magnitude and full black
indicating a minimal magnitude. Order components are shown as curves.
Because the frequency of each order component shifts as the rotational
speed varies over time, the outline of each curve is similar to the rpm-time
function shown in Figure 3-7(b).
In Figure 3-7(a), notice the horizontal white lines. The horizontal white
lines indicate the large power around the resonance frequencies. The
physical characteristics of the system containing the rotating machinery
determine the resonance frequency. The resonance frequency does not
change as the rotational speed changes.
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0 5 10 15 20 25 30 36 0.0 5.0 10.0 15.0 20.0 25.0 30.0 36.0
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991 1250 1500 1750 2000 2250 2500 2774
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991 1250 1500 1750 2000 2250 2500 2774
Order RPM
Frequency Frequency
RPM
(c) Frequency-RPM Spectral Map
RPM
(d) Order-RPM Spectral Map
Time (s)
(a) Frequency-Time Spectral Map
Time (s)
(b) RPM vs. Time