really basic question.
can anybody tell me how these data calculate out .thanks very much.

Presentation1.ppt (310 Kb, 39 downloads)

Not sure what you're question is...
Are you trying to understand why RMS values are different for each graph??
The time domain (bottom graph) is in acceleration (G's) and the FFT (top graph) is in velocity (mm/s).
If my poor memory serves me right, total power in rms is the sqrt of sum of the squares for each bin. I suspect each manufacturer has their own algorithm (length of sampling window, etc.) but (hopefully) we have standardized on the general process. Others on this forum can elaborate.
If this was no help, please explain question in more detail.

Regards
Jim P

forgive my poor english skill
I try explain more clear at next presentation.

Presentation2.ppt (338 Kb, 25 downloads)

This new file shows the calculation for the rms value. Nothing surprising there and I believe this is standard practice.
Your ?? seems to point between PK value from the frequency domain plot (velocity) to the RMS value in the time domain (acceleration) plot.
Two different animals. So again I'm not sure of your question.
In time domain, peak/or rms measurements depends on the vendors choice (I think - others out there may know). It certainly depends on a sampled window length. Do they take the average value of all the peaks or the maximum value of the largest peak?? I have no idea.

I know that some instruments have circuits that quickly charges to the max value and then applies a discharge time constant and the peak would be different depending on that particular design. What CSI chooses or how they implement is beyond my knowledge. Have you tried to contact them to get an answer??

Jim P