How can I achieve denormalised Power Spectral Density?

Hi everyone,

I'm attempting to find the Power Spectral Density of some output data for my system (SISO). I've used both periodogram() and pwelch(), but both give me a normalised frequency (in rad/sample). I really could do with the results being denormalised and in Hz, is there any way to do this? I was advised to use PSD() but it's been replaced!

Thanks in advance, Michael