Question about octave analysis

[AndreiN2014]

Hello !

I have the following question about the octave analysis vi's.

When the single octave analysis is made, shouldn't there be 3 bands below 100 Hz ?

According to the octave analysis subvi, the bands should be located at 16, 31.5 and 64 Hz.

I've tryed to make a comparison between octave, 1/3 octave and 1/24 octave.

It seems there is no difference.

I'm running LabView 8.5.1 with SVT 6.0 on windows 7 professional.

This is not happening. See the attached vi for an example of the problem.

P.S. : The file Engine runup is a sample. please rename extension to WAW.

Thank you.

[JÞB]

8.5.1 and Win 7

That's a problem 

Supported Platforms

LabVIEW supports Windows Vista/XP/2000. LabVIEW does not support Windows NT/Me/98/95, any of the Windows Server editions, or Windows XP x64. LabVIEW does support Windows Vista x64

I'm surprised you have a functiong system at all and you should anticipate "unexpected" results. 

[GarPar]

Hi Andoro-

     Your octave anaylsis express VI's are configured as 1/3 Octave, measuring between 20Hz and 20000Hz.  With this configuration, you are going to see measurements at 20Hz, 25Hz, 31.5, 40, 50 63, 80, and 100Hz (which is what you are seeing).  If you set the bandwidth to 1 Octave, then you will see the three bands at 16, 31.5 and 64Hz.  Your express VI's only allow the default value of 1/3 octave to be chosen in the API.  You can choose the other bandwidth values in the configuration window and run it there, but only the 1/3 octave bandwidth is selectable in LabVIEW.  This is a limitation of the express VI.

     I hope this helps.  Best of luck with your application!

[dkfc]

I also have problems with octave analysis, I'm making the acquisition of a pink noise from my audio card and checking the response curve through an analysis of octaves, to obtain a flat response curve, I need to set a number of samples of at least 88200, but this way I can not get a high-speed acquisition, only about one aquisition/second, putting a value of 2000 samples the speed is adequate, but the response curve in octaves loses response below 1000 Hz gradually until around 20 Hz is practically nil, I need help please.

best regards.

[GarPar]

dkfc-

     This question should be posted to a new forum post so that we can have it better documented for future users.  Be sure to clarify in your post what your sampling rate and sample size is, and the card you are using.  Have a great weekend!