Many thanks to SWLing Post contributor, Carlos Latuff, who writes from Brazil: [Please check out this] audio sample of a signal I heard today (July 20, 2021) around 07h17 UTC on (at least) 4 different frequencies, simultaneously: - 16166 kHz - 16716 kHz - 16747 kHz - 16839 kHz Always the same. Five beeps repeating [...]