Matlab Pwelch: Changing Units of Plot - Urgent Help

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SUMMARY

In the forum discussion, the user Dan seeks assistance with plotting Power Spectral Density (PSD) for acceleration results in MATLAB using the Pwelch method. Dan uses the command Pwelch(x,[],[],2024,fs) with a sampling frequency of Fs=166 derived from a sampling rate of 0.006. He requires guidance on converting the Y-axis units from dB/Hz to ms-2 and desires to apply a line of best fit to the PSD plot for smoother visualization.

PREREQUISITES
  • Familiarity with MATLAB and its plotting functions.
  • Understanding of Power Spectral Density (PSD) and its significance in signal processing.
  • Knowledge of the Pwelch method for estimating PSD.
  • Basic skills in data manipulation and visualization techniques in MATLAB.
NEXT STEPS
  • Research how to convert units in MATLAB plots, specifically from dB/Hz to ms-2.
  • Learn about applying a line of best fit in MATLAB using functions like polyfit and plot.
  • Explore advanced features of the pwelch function for customizing PSD plots.
  • Investigate MATLAB's documentation on signal processing for further insights into PSD analysis.
USEFUL FOR

This discussion is beneficial for MATLAB users, signal processing engineers, and researchers involved in vibration analysis and data visualization in engineering simulations.

19dan87
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Hi,
I am simulating vibrations in simulink and processing my results in matlab. I am trying plot the PSD for my acceleration results using pwlech method.
When I plot the PSD plots from the methods below
(NOTE:I have a sampling rate of 0.006 so that means I am using a sample frequency of Fs=1/0.006=166)
Pwelch(x,[],[],2024,fs)
Or [Pxx,f]=pwelch(x,[],[],2024,fs) plot(f,Pxx)
The results on the Y axis are in the form of dB/Hz. How do I changed the plot/results so that I can plot PSD acceleration, ie. ms^-2 back . I want to show the plots in the form of the units used in the simulations.

Thanks
Dan
 
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also I it would be best if I could show the results of the PSD plots as a smooth line by putting some kind of line of best git through the pwelch values obtained.

Any advice on the above 2 questions will be much appreciated since I have to find a way of doing this into show my results by the end of today.

Thanks

Dan
 

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