ISO Human exposure vibration analysis

[drk-NE]

Good Morning,

I am trying to use LabView 7.1 with the Sound and Vibration toolkit in processing some data in accordance with ISO 5349-1:2001. In this standard, data needs to be collected in 1/3 octave bands from 6.3Hz to 1250Hz then weighted and the RMS taken. Data collection and RMS are not a problem, the challenge I am having is with the octave analysis and creating the custom weighting. Am I just missing the obvious VI's in SVT 3.1? Is there a custom weighting example? How does one perform octave analysis below the low frequency cut-offs of the existing VI's?

Thanks,
DRK

[bspears]

Hi DRK,
I believe the answer to your question can be found in the LabVIEW Sound and Vibration Toolkit User Manual which should have installed when you installed the toolkit. Just go through your start menu to All programs>>National Instruments>>LabVIEW Sounds and Vibration Toolkit 3.1>>User Manual. Chapter 5 talks all about weighting and pages 5-11 through 5-14 have LabVIEW examples.

Let me know if you need more assistance!
Brian Spears

[drk-NE]

Thanks!

Unfortunately, that does not answer the question. Chapter 5 is great if using the SVT stock weighting filters and octave analysis. Unless I've missed the VI's, the correct weighting filter doesn't not already exist. How do you make a custom weighting filter (without buying the filter design toolkit) and tweak the fractional octave tools to have a lower center frequency?

DRK

[bspears]

Hi DRK,
thanks for posting again. A few things:

1) In the same user manual on pages 9-9 and 9-10 there's this info:

Performing Third-Octave Analysis Outside the Audio Range
You might need to perform third-octave analysis on signals outside of the
20 Hz–20 kHz range. For example, you might need to evaluate human
exposure to whole body vibration with potential signals of interest in
the 0.5 Hz–80 Hz range. To perform third-octave analysis outside the
20 Hz–20 kHz range, use either the SVT Fractional-octave Analysis
[ANSI] VI or the SVT Fractional-octave Analysis [IEC] VI and select a
bandwidth equal to 1/3 octave, as illustrated in Figure 9-7.

2)We don't have a weighting filter according to that standard currently but we would like to discuss the standard a little more with you, if possible. Can you give us a phone number (preferably) or an email address that we can contact you at?

Thanks!
Brian Spears

[drk-NE]

I was playing with adjusting that last night... kept getting errors, partially because I didn't finsh all of the parameters needed in the VI, I'll get to it more later today. If I can split out the octave components, should be able to weight each one individually.

Email address should be visible on my profile, phone is 402-472-5880 x104

[drk-NE]

Update on increasing the frequency range of the 1/3 Octave filters to lower frequency of 6.3Hz:

It is a cascading fix. When you edit the upper level VI, you then need to work your way down through the subVI and increase the range in each of those as you go. Unless there is a simpler way to force all of the range changes?

Jack and Brian, thanks for your help so far. We'll get to the bottom of it yet.

[drk-NE]

To continue the discussion with myself:
I looked into using the 1/n octave filter... works much better than my approach of decontructing all 1/3 octave subVIs. The weighting that is required can then be applied to each individual array element. Still working on it.

[rIKY]

Hello drk-NE,
I'm also using LabView 7.1 with the Sound and Vibration toolkit in processing some data in accordance with ISO 2631-1. In this standard, data needs to be collected in 1/3 octave bands from 0.5 Hz to 100Hz then weighted and the RMS taken. I think it's really similar to your work... and I have the same problem, with SVT I cannot analize frequency below 20 Hz... how did you fixed that problem?
Thank you
best regards
Riccardo Issoglio

+351 963434409
trampolando@gmail.com

[drk-NE]

Use the 1/n octave VI and you can more easily adjust the range for the 1/3 octave. The help for it is pretty good. The challenge then comes in getting the correct weighting filter.

[rIKY]

Hello!
Thanks, now I can divide the signal in the third octave, with the right frequency range...
Do you know how to make a custom weighting filter? the VI is protected by password, and so I cannot define a custom filter, and I cannot see how it works...
Can you mail me your VI, to see how you solved that problem?
Thanks
best regards


Riccardo Issoglio
trampolando@gmail.com
+351 963434409