Example of performing a Moving Average

This tutorial guides a DATS user through the steps required to perform a moving average on a given signal. The tutorial explains the concept of the ‘Integration Length’ and the ‘Output Interval Step’.

Initially a signal is required to perform the moving average on. In this tutorial a sine wave will be generated. A sine wave is generated using the parameters shown in Figure 1.

Parameters for creating a sine wave
Figure 1 : Parameters for creating a sine wave

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Averaging Frequency Response Functions From A Structure

The following was written by Adrian Lincoln in response to a customer asking about averaging Frequency Response Functions (FRFs)

Further to your reply it should be noted that there is no such mathematical or physical quantity corresponding to an averaged structural FRF except in those special cases where you are testing a symmetric structure comprised of nominally identical components (such as turbine blades). For symmetric structures, where you can impact at a similar position on each component and measure the corresponding acceleration at a similar response position, then the individual FRF’s should have the same characteristics and therefore can be averaged.

For structures that don’t have multiple symmetric components then you should not perform any sort of averaging because the FRF’s will not have the same characteristics. For example, if you have beam-like structure and are measuring the FRF’s between different locations along the beam, then these FRF’s should only be averaged as moduli and not with respect to phase and coherence.

Creating Order Plots Using The DATS Rotating Machinery Software

In this tutorial we will be creating order plots using waterfall and intensity displays using use the DATS.toolbox and Rotating Machinery Analysis option.

To begin, a noise, vibration or other signal of interest should be captured along with a tachometer signal.

In Figure 1 we have loaded a time series (in this case an acceleration signal) and a time series of a tachometer pulse train into the DATS software.

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How to use an Analogue Channel with Tachometer Signals on the P8000

When using an analogue channel input channel of a P8000, with a tachometer sensor, is it possible to utilise the tachometer processing functions as you would if you were using a tachometer input of the P8000?

For example could you display an RPM on an analogue channel?

When using an analogue channel it is possible to select, from the signal setup matrix, ‘Trigger Type’, with this option set to ‘Tacho’ and the ‘Trigger Level’ set to the voltage crossing threshold several features become available in terms of tachometer processing.

By selecting the above options the user will be able to use the ‘Digital Panel’ display type from the signal display and thus by selecting the ‘Speed’ option in the ‘Display Type’ drop down list an RPM will be available.