National Instruments Order Analysis Toolset - Manual (Page 32)

Chapter 3 Gabor Transform-Based Order Tracking
LabVIEW Order Analysis Toolset User Manual 3-2 ni.com
In Figure 3-1, the magnitudes of coefficients are shown as gray scale, with
full white indicating a maximal magnitude and full black indicating a
minimal magnitude.
Because the rotational speed changes little in each time portion of the
frequency-time spectral map, the spectrum of each order is clearly
distinguishable. As the rotational speed varies over time, the frequency of
one certain order component changes. Thus, the order component forms a
curve with a large magnitude in the frequency-time spectral map, as shown
in Figure 3-1. The white curves have magnitudes larger than the
magnitudes in local neighborhoods off the curves. The white curves
indicate the order components and are referred to as order curves.
From the frequency-time spectral map, you can separate the order curves,
or any other part of the signal in which you are interested, from the intact
original signal. You then can use Gabor expansion to reconstruct time
waveforms of the orders.
Figure 3-2 illustrates the Gabor order analysis process provided by the
LabVIEW Order Analysis Toolset.
Figure 3-2. Gabor Order Analysis Diagram
Order
Waveform
Modified
Coefficients Step 5:
Mask
Operation
Step 4:
Display
2D Spectral
Map
Step 7:
Compute
Magnitude
and Phase
Gabor
Coefficients Step 6:
Gabor
Expansion
Vibration
Signal
Tachometer
Signal
Step 2:
Gabor
Transform
Step 3:
Tachometer
Processing
Step 1:
Data
Acquisition