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Weird Spectrum graph cutoff


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Using the spectrogram function in Labview, I'm getting a weird cutoff in my graph. I'm plotting frequency v time, and on the frequency side, the graph goes up to a certain threshold, and then nothing above that threshold, even though I'm certain that I'm recording frequencies higher than that.

Is there any known problem or limitations with the NI_gmath.lvlib:STFT Spectrogram.vi function? Any suggestions? Thanks!

Jennings

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Using the spectrogram function in Labview, I'm getting a weird cutoff in my graph. I'm plotting frequency v time, and on the frequency side, the graph goes up to a certain threshold, and then nothing above that threshold, even though I'm certain that I'm recording frequencies higher than that.

Is there any known problem or limitations with the NI_gmath.lvlib:STFT Spectrogram.vi function? Any suggestions? Thanks!

Jennings

Are you using a daq card and DAQmx to sample the data?

The only time I have seen this is when I set the sample freq. too low by accident. I've seen NI's Express VIs automatically cutoff anything above the Nyquist freq (which makes sense)

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Are you using a daq card and DAQmx to sample the data?

The only time I have seen this is when I set the sample freq. too low by accident. I've seen NI's Express VIs automatically cutoff anything above the Nyquist freq (which makes sense)

No, I don't have any daq hardware hooked up. I am taking a binary file and converting it to a wave file, which I want to analyze via the spectrogram function. Is there any caveats with this process?

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