Difference of doing a PSD estimate of data and logarithmic transformed data?

1. Which method is used to find PSD?
2. What is PSD in vibration analysis?
3. How PSD is calculated?
4. What are the difficulties in FFT based power spectral estimation methods?

Which method is used to find PSD?

The PSD is estimated by averaging these individual DFTs of overlapping segments. A wider EEG window may lead toward better frequency resolution. Another technique utilizing auto regressive (AR) modeling may also be implemented to estimate the PSD.

What is PSD in vibration analysis?

What is a Power Spectral Density (PSD)? Vibration in the real world is often "random" with many different frequency components. Power spectral densities (PSD or, as they are often called, acceleration spectral densities or ASD for vibration) are used to quantify and compare different vibration environments.

How PSD is calculated?

The power spectral density (PSD) is simply the (overall level)^2 divided by the bandwidth. Again, the unit [ GRMS^2 / Hz ] is typically abbreviated as [ G^2 / Hz ]. A plot of the power spectral density function is shown in Figure 5, represented as a bar graph. Figure 5.

What are the difficulties in FFT based power spectral estimation methods?

The common problem of the two methods is that the variance of the estimation is not good, and the estimated value along the frequency axis of the fluctuation is more severe; the longer the data, the more serious the phenomenon.