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…)

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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…)

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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…)

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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…)

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Why does Auto-Zero have no effect for IEPE sensors?

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The Prosig P8000 Auto-Zero function is used to remove the DC content of a signal.

For example, if you have a sine wave that is ±5 volts about 0 volts it has no DC offset. But if you have a sine wave with ±5 volt amplitude about 3 volts, then it has a 3 volt DC offset. Below is an example of these two sinewaves.

Two sine waves with and without DC offset

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2nd Annual Prosig Prize for Engineering at Portsmouth University

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Following on from the recent post regarding of the 2012 Survey Prize Draw we have more prize giving news.

Ashley receives his certificate and cheque from James Wren (Prosig UK)
Ashley receives his certificate and cheque from James Wren (Prosig UK)

The 2nd Annual Prosig Prize for Engineering at Portsmouth University has been awarded to Ashley Stehr for his project “Developing an engineering mechanism to reduce the effects of rapid rotational motion caused by the shocks inherent with high speed craft”. (more…)

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Read more about the article 2nd Annual Prosig / Portsmouth University Prize Awarded

2nd Annual Prosig / Portsmouth University Prize Awarded

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The 2nd Annual Prosig Prize for Engineering at Portsmouth University has been awarded to Ashley Stehr for his project “Developing an engineering mechanism to reduce the effects of rapid rotational motion caused by the shocks inherent with high speed craft”. Ashley is in his third year studying for an MSc in Mechanical Engineering. His project was supervised by Dr Ya Huang. Ashley’s project poster is shown below (click for a larger view).

(more…)

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Should I use 50 Ohm or 75 Ohm cables with a Prosig P8000 system?

BNC CableUsing 50? or 75? cable will not have any negative effects on the P8000 at all. (Generally speaking, only large voltages will damage the P8000). The impedance of the cable can only ever effect the signal the cable is carrying. (more…)

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There are tachometer signals available on the vehicle CAN-bus. Can I use these signals instead of connecting my own tachometer signal?

A simple question should have a simple answer and that answer is “No”.

As usual, however, life is never that simple. (more…)

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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…)

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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…)

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