Analyzing ZEVS part 2 – 82.0Hz

In previous articles i’ve shown some typical ZEVS messages , and an analysis of the amount of messages per day .

This repository has all of the scripts used during the analysis:

So what more could we get out of the opublished ZEVS dataset ?

Analyzing the 82.0Hz carrier

Before and after the message an 82.0Hz carrier is transmitted. Sometimes it’s transmitted only for a while:

And sometimes it is transmitted for much longer:

So i did an analysis how many minutes the carrier is on each day. The analysis is done by the script.

A large pdf file with the analysis is here:

It seems that the amount of minutes that i receive the 82Hz carrier each day is more or less the same (where there are 0 minutes, it usually means a problem with the receiver). But i can observe periods when ZEVS transmits much less of the 82.0Hz carrier:

2021-11-30 - 2021-12-09
2022-03-07 - 2022-03-13
2022-05-17 - 2022-06-10

These dates don’t seem to match any historical events that i know of (maybe someone else has an idea what they might be?).

During these periods the normal 1-3 messages per day is transmitted. The amount of messages per day can be seen here:: zevs_messages_perday

Interrupted carrier on 82.0Hz

On 2021-10-26 at 9:00 ZEVS transmitted an interrusped carrier 82.0Hz:

The same repeated on 2021-10-27 at 9:00:

I found this while manually looking over parts of the spectrum.

Amateur radio operators will often send dots (short carrier, break, short carrier, break etc) as a test signal. Maybe someone is also testing the ZEVS transmitter.

If you use this work, or have any comments, please send me an email

Author: Jacek Lipkowski SQ5BPF  < sq5bpf (at) >

This article is published under the Attribution 4.0 International (CC BY 4.0)