Power Spectral Density for HRV, need help with pwelch function.

I'm looking to analyze heart rate variability data using PSD. I've looked into the MATLAB page and help for the pwelch function, but I am still confused about the scaling and units of the output. Does anyone have a recommendation for further reading into pwelch? I don't necessarily need to know the specifics of how it works, just how to properly plot the power and spectral density data with correct units.

Answer 1

[Daniel kiracofe]

if your input is in volts, then your output is V^2 / Hz. If your inputs are in some other unit, let's call it X, then your output is X^2/Hz. does that answer the question?

here's an example:

http://www.mathworks.com/help/signal/ref/pwelch.html#btulru8-5

[Jonathon]

Thanks for your help, that makes it more clear. If I were to plot using 10log10(pxx), would that be in dB then?