Fourier Transform and the DAQ Assistant

[Coq_Rouge]

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Really I'm disappointed with Labview, this is such a simple task.  If I plot the output from the Labview stock FFT functions, it tries to give me a graph of data in the time domain...

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All computer program do have the bad habit of doing that they are told to do. They really do not care about what you hope it will do. Take a look at the case structure and see then the code inside is run ;). You've got to ask yourself one question, but not do I feel lucky? . But rather is everything in the while loop needed. It is your piece of code now

Good luck  

[nyair24]

Thanks for the help coq rouge.  I took your code, which seemed to have better signal stability than mine, and mixed it with the write to spreadsheet functionality from this thread and then analyzed everything in matlab.  Your FFT actually was a lot better than the labview one, but I don't have the time right now to go through and master the software so I would know how you did it.  Thanks again though 🙂

[Dennis_Knutson]

Your original and new code both use FFT functions from LabVIEW so saying that one works better than the other does not make any sense. The difference is the last version removes the large dc component and if you had done that in your original program, you would have had much fewer problems.

Also, never post a VI that is set to auto run when opened.

[Coq_Rouge]

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Dennis Knutson wrote:

The difference is the last version removes the large dc component and if you had done that in your original program, you would have had much fewer problems.

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In his last version, he is using some old Labview 6 code I created in a EMP project. I find it useful then people struggle with spectrum analysis. Anyway the DC offset is not removed, but then using a dB scale. Large DC offsets is not so dominant in the spectrum view

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Dennis Knutson wrote:

Also, never post a VI that is set to auto run when opened.

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Well this is my fault, I did some quick and dirty modifications and posted it. But I see your point