How are the values of alpha_absolute computed?



I am trying to figure out how the values of alpha_absolute of each channel are computed from the raw signal following the description in the section “Absolute Band Powers”, where it says that they are “…the logarithm of the sum of the Power Spectral Density of the EEG data over that frequency range”. I computed the PSD using Welch’s method with Hamming window but could not match my results with the values in alpha_absolute. Which kind of time window is used and how many samples it has? Could you describe the exact process to obtain the alpha_absolute values from the raw eeg signal of one channel?
I have a MUSE 2016.

Thank you,