CF-5200 Frequently Asked Questions

It is used for the analysis of continuous spectrum signals that have a wide range of frequency components, such as random signals and impulse signals.

This is to create an expression that is independent of the frequency range being analyzed.

Reference:
The frequency response function (transfer function) is expressed normalized to unit input energy.

Chapter of the relevant instruction manual

5.8.3 Power Spectral Density / Energy Spectral Density