Russia uses radiocommunications in the ELF band to send messages to it’s nuclear submarine fleet. This transmitter it called ZEVS, the frequency is 82Hz (yes: hertz, not kilohertz, not megahertz). For more info see here: http://www.vlf.it/zevs/zevs.htm
This grabber calculates the spectrum in 80-84Hz every 60 seconds, and makes spectrograms out of it. The files with the spectrum information are not deleted, so out out of coincidence i have a history of data from 25 August 2021 until now (around 10 June 2022).
And since i have this data, it would be nice to do an analysis how the messages to the submarine fleet look like, and how often are they transmitted.
The russian 82Hz ZEVS transmitter stopped working on April 4 2018 around 12:00 UTC, and so far hasn’t resumed operation (this is written on 15 April, 11 days later).
Spectrogram of the end of transmission:
ZEVS can be monitored on the klubnl.pl ZEVS grabber: