# Best format to plot vibration data?

I am about to present my work on vibrations to a NVH specialist at work and he is supposed to help me.

I have calculated PSD's, now my question (subjective, I know) is how should I plot the data? I've been plotting $PSD \big[\frac{g^2}{Hz}\big]$ against frequency $\big[Hz\big]$, both in linear axes. I've been told the frequency axis should be in logarithmic scale, which makes sense, what about the PSD axis?

• Surely the idea of using a log axis or log-log axis was to get a straight line plot - do you get one or what you get is sufficient. If you can explain your results then the chart you have is sufficient for the purpose. – Solar Mike Jun 20 '17 at 14:15
• One can "prefer" Log PSD-Log f or Log PSD-f for PSD-f plotting, it is preference because this selection may change according to plotted data. Main purpose is to visualize the results in linear. I think the use of "Best Plot" is wrong but there might be a common one. My suggestion is to try both and choose the one suits your plot. – F.Bek Jun 20 '17 at 14:38
• @SolarMike Good point! – jonathan.charbonneau Jun 20 '17 at 14:41
• @F.Bek You're right, I should've asked if there was a standard instead of "what is best". – jonathan.charbonneau Jun 20 '17 at 14:42

## 1 Answer

Typically, a PSD for vibration will have a log scale for both axes.

• Thanks! I spoke to a NVH specialist and this is also what he said. For reference if anyone in the future sees this thread, I used dB on y axis and log on x axis which is apparently not common. As @DLS3141 suggested, log-log is the proper format. – jonathan.charbonneau Jul 6 '17 at 12:14
• This is highly dependent on the application. Floor vibration data is typically plotted in 1/3rd octave bands and can have logarithmic y axes or not; sometimes it is also plotted in true-partite format. Other applications use any combination of linear and/or logarithmic axes depending on what is convenient. – user883521 Jul 31 '17 at 16:07