Reference frequency for third octave filters

A DATS user asked…

We are using the third octave band filter at very low frequencies (~1Hz)  and I noticed that the response of the filter could introduce very significant errors for short or transient signals. Looking a bit more in details at the function, the help says:

“For audio work ISO standards use a reference frequency of 1kHz not 1Hz”

Does that implies that for non-audio work, a reference frequency of 1Hz should be applied? If yes, is it possible to change this reference frequency in the dats function?

Dr Mercer replied…

Essentially there is no problem and no need to change the reference frequency provided you use Base 10 mode and not Base 2. Base 10 is the ANSI S1.11-2004 preferred scheme. (more…)

Continue ReadingReference frequency for third octave filters

How do I balance a shaft?

“How do I balance a shaft?” seems like a fairly straightforward question, but there are a number of things that we need to understand first. Here we look at a number of key concepts that need to be understood in order perform balancing.

What does balance mean?

Well broadly speaking to balance a shaft, mass must be added or removed at certain angles. The concept being that the centre of gravity and rotational centre of the shaft will be equal when the shaft is balanced. (more…)

Continue ReadingHow do I balance a shaft?

New Version of DATS Out Now – V7.0.23 Released

The latest version of the DATS software is now available. Log in to the Prosig support site to download your copy. The new version, V7.0.23, contains many new features, improvements and bug fixes. Read on to find out a little of what you can expect. (more…)

Continue ReadingNew Version of DATS Out Now – V7.0.23 Released

New Hammer Impact Software – Preview coming soon

After listening to customer feedback, we have completely re-engineered the DATS Hammer Impact software. The new version will ship with the next DATS update (not the soon-to-be-released V7.0.23). In the meantime you will be able to download and preview the new package. You will of course need a P8000 system and a DATS licence with the Hammer Impact option enabled. (more…)

Continue ReadingNew Hammer Impact Software – Preview coming soon

How Do I Get An XYZ Resultant Waterfall

A user has three signals captured using a triaxial accelerometer and asked “What is the simplest way to get the XYZ resultant from run-up file?” He had tried forming a resultant of the raw time histories, but didn’t fully understand the resultant time history.

Of course, the correct way of processing the data is to calculate the individual waterfalls from the x, y & z data and then calculate a resultant waterfall. (more…)

Continue ReadingHow Do I Get An XYZ Resultant Waterfall

What is Source Contribution Analysis (or SCA)?

How do you measure the causes of a noise or vibration with respect to several sources? Which source is causing what part of the response?

For example, how does the noise inside the cabin of a vehicle relate to the engine noise or wheel hub noise and vibration? (more…)

Continue ReadingWhat is Source Contribution Analysis (or SCA)?

What is the difference between Operating Deflection Shapes (ODS) and Operational Modal Analysis (OMA)?

ODS = Motion of structure vibrating naturally (for example bridge vibration) or when excited by an unknown force (for example generator vibration). Prosig’s Structural Animation software performs ODS analysis.

OMA = Modal Analysis
Prosig’s Modal Analysis software performs OMA. (more…)

Continue ReadingWhat is the difference between Operating Deflection Shapes (ODS) and Operational Modal Analysis (OMA)?

How do I plot two curves with two different axes

A user recently asked…
[su_quote]I was hoping you can give me some way that I can create a plot with two different vertical (Y axis) scaling. I want to plot Principle stress and applied load vs. time on the same plot.

I want to show the principle stress increments on the left side of the graph and the load scale on the right side of the graph. I can do this with some other programs but cannot find a way to do it in DATS for Windows.

Is this POSSIBLE?[/su_quote] (more…)

Continue ReadingHow do I plot two curves with two different axes

What is the difference between Transfer Path Analysis (TPA) and Source Contribution Analysis (SCA)?

Transfer Path Analysis (TPA) provides the route of the noise or vibration through the structure, not just which sources cause the response, but the route taken. This is useful for developing and improving components like engine anti-vibration mountings or suspension anti-vibration mountings. (more…)

Continue ReadingWhat is the difference between Transfer Path Analysis (TPA) and Source Contribution Analysis (SCA)?

Using global variables, variable arithmetic & script fragments

One of Prosig’s engineers was recently creating a complex worksheet application that required some complicated arithmetic to be performed on values calculated in the worksheet. Worksheet (or global) variables are ideal for this. The Variable Mods DPU also has an expression evaluator built in. Consider the following worksheet that takes a Named Element from two signals and sums them. (more…)

Continue ReadingUsing global variables, variable arithmetic & script fragments

Finding The Analysis That You Need

I’m sure many users will have been in this situation. You need an analysis function, you know it’s in DATS, but you can’t remember where. One of the major strengths of the DATS package is the depth of analysis functions it provides. Unfortunately, when you have a deadline and can’t find the function that you want that isn’t much help. But assistance is at hand… (more…)

Continue ReadingFinding The Analysis That You Need

Using Named Elements & Global Variables In Worksheets (Part 1)

This article is the first in a series that will introduce two very important facilities that can be used when creating DATS worksheets – Named Elements and Global Variables. It is perfectly possible to perform simple measurement and analysis with DATS without knowingly using either of them. However, knowing how they work and what they can do, will lead to much more efficient and flexible worksheets. The first subject we’ll look at is Named Elements. (more…)

Continue ReadingUsing Named Elements & Global Variables In Worksheets (Part 1)