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Power Spectral Density

The Power Spectral Density option causes the analyzer to normalize the spectrum to a 1 Hz bandwidth.  This is used for making noise power measurements.  For instance, when measuring a noise signal without the PSD option selected, the amplitude will change with FFT size and sampling rate. Using the PSD option, the resulting amplitude will be independent of FFT size and sampling rate.  

You can select between Units / Sqrt(Hz) or Units^2/Hz.  

Units^2/Hz - this produces the power (squared magnitude) spectral density. 

Units / Sqrt(Hz) - this produces the linearized power spectral density

Octave scaling is not allowed when using the PSD option.  

Note: The PSD option is used for noise type signals; it is not accurate for sinusoid (tonal) type sigals.

See Also: Scaling