Help with vibrations fft without using the sound and vibrations package

[Fulmetalal]

I am looking for help with vibration analysis. I'm using a modified example VI, from NI 9233, to get an accelerometer signal to display the power spectrum using an FFT. I'm not entirely sure whether this is working, as this is the first time I have ever done vibration analysis on LabView. So if you could explain a thing or two about vibrations or FFT, I would be more than willing to hear from you. I have included my code along with a picture of a vibration analysis of the computer I'm working with. (again I don't know if its working I just thought it might be good to show an output)

Brandon

Specs:

I have LabView 2011

I have FPGA and Real-Time

I have a Wilcoxon Research Model 797-33 accelerometer

With a NI 9233

On a cRio-9012

[Fulmetalal]

Here are the VIs that I am using.

Brandon

[Carisa_L]

Hi Fulmetalal,

From your attached picture it looks like you are acquiring data and performing the FFT correctly. What kind of analysis are you looking to perform on your data exactly?

Here is a document that elaborates on FFT: http://zone.ni.com/devzone/cda/tut/p/id/4278

Hope this helps,

Carisa

[Fulmetalal]

Carisa,

I'm using the FFT to calculate the magnitude of accelerations from the accelorometer at different frequencies. I'm also trying to figure out what is the magnitude scale that is outputted by the fft.

Brandon

[Carisa_L · Accepted solution]

Hi Brandon,

You can use the Complex FFT (picture attached) to calculate the magnitude of the accelerations at different frequencies. You'll have to take it a step further to build a new waveform with this output, which includes d0,df, and the output from the FFT. In order to calculate the df, please refer to the user manual on page 10-3. As far as the magnitude scale that is output by the FFT, it should be the same as the input. Hope this helps answer your questions. Thanks!

Cheers,

Carisa Leal