Read UFF58 files & Convert real and imaginary spectra to magnitude and phase (sound and vibration)

[redsand01]

Hello Everyone,

I am new to Labview. I am not sure if this is the right board to post my questions, if not, please let me know.

I did some modal testing using the impact test project file that came with the Sound and Vibration Suite. The frequency response data were stored in a UFF58 file. I worked with other universal files before and was able to open those files using ASCII or binary text readers such as Notepad ++, then read those data into Matlab to process. However, I could not open this UFF58 file by any ASCII or binary text readers, not able to read the complete data set into Matlab either. I could be wrong about this, but seems like there are no easy way to read those UFF58 data back into the "Impact Test"project once exited from that VI. 

So I am writing a VI to read the frequency responses in the UFF58 file. I got the real and imaginary parts of the data, but I have issues converting them to magnitude and phase using the "SVFA Real and Imaginary to Magnitude and Phase" VI. There is no output from the "magnitude spectrum", and "phase spectrum" output is just the imagniary part.

Since the data file contains more than 50 spectra, I also want to add a function so that I can look at the frequency response one by one. For instance, when I select one index value from the array properties of the data set, the graphs would automatically update to that spectrum I selected. But I am not sure how to do this in Labview.

Attached are a screenshot and the labview VI I am trying to build, please let me know your suggestions. Any ideas or feedbacks would be greatly appreciated.

Thank you in advance!  

[caro16av]

Hi redsand01,

Could you upload the uFF58 file so that we can try to reproduce the issue? Have you tried to record the file again just in case it might not have written the correct data?

To update the graphs to a selected spectrum you could have like a pull down menu and with an event structure you can select which graph to show, an idea for this I found in this forum: 

Select Plots on Waveform Chart - Discussion Forums

http://forums.ni.com/t5/LabVIEW/Select-Plots-on-Waveform-Chart/td-p/168199

Regards,

Carolina 

[redsand01]

Thank you for your reply Carolina! 

Attached is the uff file. Soory for the file size, I am not sure how to cut it into smaller size. I am not sure how to record the file again either.

I really appreciate it if you could check the VI using this uff file.

Regards,

Tina 

[caro16av]

Hi redsand01,

Thanks for posting the file.

I belive I see where is the issue coming from, the  SVFA Real and Imaginary to Magnitude and Phase VI has an input called spectrum info in , if you go inside this VI you will see that there is a Case Structure, which uses the compelmentary units of the spectrum to select the case,the default is "none",that case has nothing wired to the magnitud spectrum output, but the phase spectrum is wired to the imaginary spectrum, that is why you do have an output in the phase spectrum, but not in the magnitud spectrum.  This is an image of that VI:

Let me know if this helps you. Also in the "imaginary" case you can check how is the conversion actually done, and you could implement it yourself as well.

Regards,

Carolina 

[redsand01]

That works! Thank you so much Carolina!

I didn't look into the sub-VIs, thank you for pointing it out. It is tricky that the "Complimentary spectrum units" in spectrum info needs to be change to "imaginary" to make it work. I wish the help file had specified that.  

Thanks again!

Tina

[caro16av]

You are welcome Tina!

And you are correct, the "spectrum info in" should be a required input. I will pass that to R&D, hopefully in the future that will be specified. 

Regards,

Carolina