Resultant Velocity Power Spectral Density Calculation
Full Video of Analysis: https://info.endaq.com/hubfs/psd_velocity.mp4
First here is the time series data, the resultant is calculated with a root sum of squares = (x^2+y^2+z^2)^0.5
Here it is zoomed in, still very messy and hard to understand!
Power Spectral Density
These initial PSDs are "messy" because of the small bin width.
But they can be converted to 1/3 octave spacing (each frequency point is x2^(1/3) compared to the previous). In this cleaner format, the root sum of the squares can also be determined for a resultant PSD.
And now this can be converted to velocity easily in the frequency domain, attached is a PDF from VibrationResearch which goes into more detail