Issue 2: Advanced 2D Charts Features
m+p Analyzer offers four different types of charts for specific data analysis needs: 2D Single chart, 2D Multi-chart, 3D Waterfall chart and Colormap chart. The second article of our series „m+p Analyzer basics“ will focus on the advanced functionality of 2D charts.
Chart Overview Zoom
The overview feature is useful when post-processing and reviewing large data sets. It allows to select a zoom region and pan this region in the overview field to get a close-up view of a subset of data.
Chart Cursors on a Time History
To review the data values at specific time instances, vertical and horizontal cursors may be used. Besides the charts a display with useful metrics at the cursor location is displayed. Multiple cursors may be linked with the "band cursor" feature where slave cursors will move together with the master cursor at a given distance. Together with the "seek to peak" feature, extrema and their relative distances (in time or frequency) may be easily tracked and displayed in the chart legend.
Chart Cursors on a Spectrum
2D charts offer specifically tailored cursors for the analysis of spectra (basically anything with a frequency axis). The harmonic cursor displays slave cursors at frequency locations of the 1st, 2nd, 3rd, ... harmonic based on the master cursor frequency. The sideband cursor displays slave cursors equally spaced to the left and right around the master cursor.
The tacho tool can be used to extract RPM values from a tacho signal or sine wave. It is a simple tool that is real-time capable in that it can be used at acquisition time. More advanced features "tacho spline fit" and "RPM extractor" are part of the m+p Analyzer "Rotate" toolbox and allow for more complex RPM extraction methods such as smoothing of the extracted RPM signal and extraction of RPM from vibration data. In the following example we will show the basic tacho tool which comes with the 2D chart. Suppose a sine sweep from 20 Hz to 100 Hz was recorded. We can now configure the tacho tool displaying the rotational speed, which - in the case of our sine sweep - yields an RPM range of 1200 to 6000 RPM. The result may either be shown as a cursor on the original data or shown as a new signal "RPM over time". In this example we use a sine sweep, yet any rectangular pulse train - which is typically measured by tachometers - is applicable.
Reference traces may be overlaid in the 2D chart to compare previously acquired results to the currently acquired data in real time. Besides showing recorded measurements as a reference, this feature is also useful to show, for example, upper and lower limits when measuring time signals such as forces. In the following example we show how to set up a previously acquired spectrum as a reference trace and perform several impulse response measurements which can then visually compared to the reference response. Tip: Reference traces may be added quickly by holding the "alt" key while dragging and dropping a measurement into the chart.