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Spectral Measurement using NI SCOPE

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Hey GerdW,
I have attached VI for V2019. I think it has something to do with axes. For 1kHz it gives 0Hz but for 1MHz peak is close to 0.1.

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Screenshot 2025-08-22 195233.png

Screenshot 2025-08-22 195138.png

Hey Doug Thanks for the info,
Take a look at these, FFTs of 1KHz and 1MHz signals. X-Axis is looks messed up.

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Solution
Accepted by topic author Sahith24426

You can fix the x-axis of the FFT graph by setting the dt of the waveform from the x-increment of the cluster here:

dsbNI_0-1755873453230.png

From your screenshots (and this won't change even after fixing waveform dt ==> FFT df):
The peak for the 1 MHz signal is in the 1M * 4m + 1 = 4001 bin
The peak for the 1 kHz signal is in the 1k * 4m + 1 = 5 bin
You can zoom in on the 1 kHz FFT graph to verify that the peak is not at zero.


Doug
Enthusiast for LabVIEW, DAQmx, and Sound and Vibration
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