Averaged RMS vs. averaged FFT peak

[AEI_JR]

I have an application whereby I record several vibration signals of a spinning apparatus.  The recording process is automated for a production stand, and two numbers are displayed for each channel - one is the averaged RMS value of the integrated waveform; the other is the discrete peak amplitude at the run speed frequency.  Normally, the RMS value is larger than the discrete peak, as I expect.  Every once in a while, though, the discrete peak is higher.  Should this be possible?

Note that the waveforms are not recorded as part of the production process, and the observed results are not easily reproduced.

[Greg_J]

Hi AEI_JR,

Could you elaborate on any specific LabVIEW functions that you are using to get your RMS and FFT?  Also, how are you measuring this signal, what kind of numerical values are you expecting, and how often are you seeing these suspected outliers?  This will provide a better understanding of what exactly is expected behavior for your setup.

Developer Zone Tutorial: The Fundamentals of FFT-Based Signal Analysis and Measurement in LabVIEW a...

Thanks!