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## Octave analysis (Algorithm)

Hello everyone,

Thank you first of all for reading my post,

I would like to make an octave analysis on my signal using LabVIEW i checked some website & documents but still did not understand how to implement it  ?

wich step do i need to do first !

how many filters do we need is it 3 ?

is it possible to sample more than 44 Khz ?

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## Re: Octave analysis (Algorithm)

Hello Virtman,

The octave analysis is available in the Sound And Vibration Toolkit.

If you don't have this toolkit, you can use the "Mathematics" and "Signal Processing" palette to implement your own octave analysis tool.

Here you can find help for he Octave Analysis Express VI.

What do you mean by how many filters ?

Yes sure, you can go further than 44kHz if needed : http://zone.ni.com/reference/en-XX/help/372416A-01/svtconcepts/third_oct_aud_range/

Regards,

Message 2 of 25
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## Re: Octave analysis (Algorithm)

Assuming you are referring to octave band analysis of an acoustic signal, the analysis methods are defined in ANSI S1.11-2004 or IEC 61260:1995 (both standards are fundamentally the same from a technical point of view).  I don't have either to hand but I do have a few notes.  Each octave band filter can be implemented as a 4th order Butterworth band-pass.  This should give you class 0 or class 1 performance across most of the audible frequency range, depending on the sampling frequency and the octave band number.

The mid-band (centre) frequencies in Hertz may be calculated using:

`f_m = G ^ (x - 30) * 1000`

for any integer x.  The preferred value of G is 10 ^ 0.3.  So for x = 25, f_m = 31.62 Hz and for x = 34, f_m = 15849 Hz, covering the entire audible frequency range.  A sampling frequency of 48 kHz will give you class 0 performance for every band in this range with the exception of the upper limit of the x = 34 band, although this falls within class 1 performance.

In case you haven't found it, the Butterworth filter VI is found on the Signal Processig - Filters palette.  When defining the filter, the low and high cutoff frequencies can be derived from the mid-band frequency as:

```f_l = f_m * 10 ^ (-0.15)
f_h = f_m * 10 ^ (0.15)```

I don't see any issue with sampling above 44 kHz.  Depends on what your frequency range of interest is.

Andy

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## Re: Octave analysis (Algorithm)

Hello PsyenceFact,

I would like to implement my own octave analysis withou using the sound & vibration tool kit ( i dont have this kit )

so what i did in this program is calculating the FFT of a time signal then i calcul a 3rd band octave, so i split my array into 29 band and each band represent a 3rd band octave then i will make a sum of each subarray ( 3rd octave) and display in a graph.

But i have an error that display when i run the code i hope that you could help me in implementing this analysis

I have a 225 KHz as a sampling frequency signal (i recognize that the length of the signal is much longer).

Thank you

Message 4 of 25
(3,761 Views)

## Re: Octave analysis (Algorithm)

Hello PsyenceFact,

I would like to implement my own octave analysis withou using the sound & vibration tool kit ( i dont have this kit )

so what i did in this program is calculating the FFT of a time signal then i calcul a 3rd band octave, so i split my array into 29 band and each band represent a 3rd band octave then i will make a sum of each subarray ( 3rd octave) and display in a graph.

But i have an error that display when i run the code i hope that you could help me in implementing this analysis

I have a 225 KHz as a sampling frequency signal (i recognize that the length of the signal is much longer).

Thank you

Message 5 of 25
(3,758 Views)

## Re: Octave analysis (Algorithm)

Hi virtman,

But i have an error that display when i run the code i hope that you could help me in implementing this analysis

Which error do you encounter?

Best regards,
GerdW

using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 6 of 25
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