# Should I use an IEPE or a charge accelerometer?

What are the advantages/disadvantages of a charge mode accelerometer vs. an IEPE type?

An IEPE accelerometer will have a high pass filter at about 5Hz. The charge type will have a high pass filter at about 0.1Hz. The charge type will usually have a lower measurement bandwidth than the IEPE. Charge accelerometers can be used at higher temperatures.

The high pass filter, in both cases, is built in and isn’t adjustable.

Another accelerometer type to consider is a bridge based one. This type will measure right down to DC. A bridge based accelerometer is based on the Wheatstone bridge (as used in strain gauges). Some bridge based accelerometers are based on strain gauges, but not many. Usually they are capacitive in nature.

# How to set up scheduled data captures

A video that explains how to set up the DATS Data Acquisition software to perform captures at specific, scheduled times.

# [Video] Create AVI files from your structural animations

The DATS Modal Analysis software consists of Hammer Impact Testing, Modal Analysis & Structural Animation (often referred to as Operational Deflection Shapes or ODS and Running Modes). Having measured and analysed your data the Structural Animation software allows you to visualisation your structure under certain operating conditions. These visualisations can then be saved as AVI files. This video shows you how…

# Relative signal levels of a sinusoid with and without background noise

In the process of looking at some order data, a question about the accuracy of the measurement of the signal level of discrete frequency signals which were close to the general noise level.  To answer this question, a small DATS worksheet was created which generated 2 signals.  The first signal was a 35 Hz sinusoid which, by itself the spectrum level was measured to be approximately -9 dB (ref 1 V) as seen in Figure 1.

Fig 1: Spectrum level of 35Hz sinusoid

# Creating calculated signals with DATS Acquisition

Case Study: What can I do if the transducer I am using has a non-linear sensitivity over its measuring range?

## Abstract

Recently a PROSIG user wanted to measure a specific temperature parameter on a running engine. The transducer being used was one of the engine sensors built into the engine operating system to minimize engine emissions and maximize fuel economy. Unfortunately, the sensitivity of this transducer was not constant over the desired temperature range. The question then became, how can the output from this non-linear transducer be used to accurately measure the desired temperature parameter? Continue reading

# How Many Samples Per Revolution Are Required To Study A Particular Order

When working in the synchronous/angle domain, how many samples per revolution are required to study a particular order.

To study the nth order we need $2*n$ samples per revolution. Continue reading

# [Video] Creating speed signals for data with no speed information

So you’ve got some noise and/or vibration data from a rotating machine, but no speed information. Surely that means you can’t analyse against speed or do any order analysis, right? Well, not quite!

The DATS Rotating Machinery option now comes with a tool to create speed v time data using your noise or vibration signals.

Watch the video to find out how…

# What sensors are required to perform a Rotor Runout Measurement?

The DATS Rotor Runout Measurement package can be used on any shaft where the following probes are available…

1. A LVDT (Linear Variable Differential Transformer) probe. This is basically a contact probe. This will allow the measurement of the shaft total runout*.
2. If an electrical runout measurement is also required then an additional eddy current probe (also known as a proximity probe) is needed. This is a non contact probe and can be used in conjunction with the LVDT to measure the electrical runout only.
3. A once per revolution tachometer is also required. This could be optical, proximity, magnetic and so on.

With these three sensors it is possible using the DATS Rotor Runout Measurement package to find both electrical and mechanical runout.

* Total runout is a composite tolerance including the effects of cylindricity and concentricity, co-axiality, straightness and parallelism along the axis.

# [Video] Using reference cursors to measure data

A tutorial by James Wren (Prosig UK) on how to use the reference cursors in the DATS software to precisely measure features in your data.

# How do I find the natural frequency of an inlet manifold?

There are a number of ways to find a resonant frequency of a part like an automotive inlet manifold. Here are three different types of popular test technique. But which one should you use and why? Continue reading