Waterfall and Octave Waterfall Graphs (Sound and Vibration Measurement Suite)
December 2007
NI Part Number:
372416A-01
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Waterfall displays allow you to represent visually the results of various analyses of nonstationary signals, such as machine or engine run-up, coast down, and transients.
The following front panel shows a sample Waterfall graph.
The following front panel shows a sample Octave Waterfall graph.
You can use the Waterfall graph to display frequency or order spectra from frequency analysis, transient analysis, or order analysis. You can use the Octave Waterfall graph to display octave spectra from octave analysis. To use a Waterfall graph or an Octave Waterfall graph, locate the graph on the Sound & Vibration controls palette and place the graph on the front panel window. You then can wire the appropriate output of a VI to the Waterfall or Octave Waterfall graph on the block diagram.
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Tip You can change the perspective of the Waterfall graph or Octave Waterfall graph by <Ctrl>-clicking and dragging the display. |
The Waterfall graph and Octave Waterfall graph are XControls that include properties you can access manually by right-clicking the graph on the front panel or programmatically by using the Property Node on the block diagram. You can use the properties to set characteristics such as color, perspective, and transparency.
You can use the Display VIs to buffer the results of frequency analyses to mimic the behavior of a chart on a Waterfall graph, to convert a Waterfall graph to a Colormap, and to convert a Colormap to a Waterfall graph.
Refer to the following VIs for examples of using the Waterfall graph or the Octave Waterfall graph:
- SVXMPL_Waterfall Display (Simulated) VI: labview\examples\Sound and Vibration\Waterfall Display\SVXMPL_Waterfall Display (Simulated).vi
- SVXMPL_Waterfall Display for Octave (DAQmx) VI: labview\examples\Sound and Vibration\Waterfall Display\SVXMPL_Waterfall Display for Octave (DAQmx).vi
Displaying Analysis Results with the Waterfall Graph and Octave Waterfall Graph
You can display frequency analysis results in a Waterfall graph by bundling the data with z-axis information, as shown in the following block diagram.
This example uses the SVFA Power Spectrum VI to perform a frequency analysis of an analog waveform signal. The Bundle function then adds the z-axis information to the data output of the SVFA Power Spectrum VI so the Waterfall graph can display the individual power spectrum plots along the third dimension.
Some Sound and Vibration VIs, such as the OAT Spectral Map VI, allow you to output data directly to the Waterfall graph. Place the Waterfall graph on the front panel window, then select the Waterfall instance of the VI. You then can wire the appropriate output to the Waterfall graph on the block diagram, as shown in the following block diagram.
You also can display octave analysis results in an Octave Waterfall graph, as shown in the following block diagram.
This example uses the SVT Third-octave Analysis VI to perform an octave analysis on an analog waveform signal. Similar to the previous example, the Bundle function adds the z-axis information to the data output of the SVT Third-octave Analysis VI so the Octave Waterfall graph can display the octave analysis plots along the third dimension.