Using the signal from the pulse tachometer, after running the Tachometer Analysis, we see the following plot for the run-up and idle down. The plot includes both the Raw (green) and Smooth (magenta) RPM data. Both are plotted. The Raw data is laid down first and the Smooth data is over it.
Using Rotate's Zoom capability in this mode, we can see a close-up of the difference between the two RPM plots. Below is a plot after we have zoomed in on the peak of the curve.
Notice the Raw RPM represented by the jagged, green line. The magenta line represents the Smooth RPM data that Rotate calculated during the analysis. Now that we have generated this smooth spline fit, we can go ahead with more advanced calculations and plots--such as the Rotate2 Waterfall calculations. but first a mention of the Torsional vibration analysis feature. Torsional Vibration Analysis A spectacular new feature of Rotate2.5 is the ability to analyze torsional vibrations. Select Torsional Vibration Analysis from the menu and using a surprisingly simple algorithm, relatively coarse measurements can be refined to produce a computed torsional signature, which is then used to make waterfall and order calculations, and graphics. The approach is based on pulse recordings from encoders and flywheels and will give an accurate kinematical description of torsional vibrations from single station measurements. The fixed sampling rate must be high enough to give a good definition of pulses, but since the algorithm is time domain oriented, aggressive anti-aliasing filters should not be used for the data acquisition. Because of this algorithm, and because Rotate is a post processing package, low cost yet complex torsional vibration solutions are available. You may be able to kiss slip-rings, telemetry and torsional transducers goodbye forever!!!! |
