Choosing the right spectrum (periodogram)

I’ve explained here how to choose spectrum. A good spectrum is the one that shows cycles with obvious high and narrow peaks. There are two extreme cases in evaluation of spectrum quality that you should avoid: 1) “White-noisy“ spectrum - when too many cycles are revealed. It makes practically impossible to specify what cycles are the most important ones; 2) “High-entropy“ spectrum - when peaks on the periodogram are too wide, i.e. spectrum reveals a presence of some cyclical activity around certain period value. However, the wide peak does not allow to specify the exact period of this cycle. This fact brings a lot of uncertainty to the projection line. PS. This is not related to max entropy spectrum. We just use entropy as a measure to evaluate a degree of uncertainty.