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 is most often used.
You should select Linear amplitude axis scaling and narrowband frequency axis scaling 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