@niconiconi For what it is worth: At the German Hamradio fair, I have been in a presentation yesterday of the ENAMS project. It has distributed some 50 or 60 stations, most of them in Germany, that continuously measure radio background noise data. It wants to establish what the present state is, compared to the data published as recommendation ITU-R P.372-12 (07/2015) "Radio noise". I understand the latter is mostly based on measurements some 50 years old.