Shortwave radio

 https://wavefarm.org/ta/archive/artists/vft3nw

https://en.wikipedia.org/wiki/The_Conet_Project Sampled by BOC, PT, and Wilco

https://www.sigidwiki.com/wiki/Number_Stations
https://www.short-wave.info/

http://websdr.ewi.utwente.nl:8901/

https://priyom.org/blog/long-lost-evidence-shows-g01-run-by-french-sdece