VLF transmissions at 22.5kHz 22.9kHz and 23kHz

In the morning around 08:00 UTC the following transmissions can be received:

• A strong carrier at 23kHz, often modulated
• Then a carrier at 22.9kHz
• Then a carrier at 22.5kHz
• Then a carrier at 23kHz

20170916 08:00:

20170916 11:00 UTC (you can see the signal strength in comparison with the very strong DHO38):

20170916 09:00 UTC:

the next day for comparison 20170917 09:00 UTC:

 

According to Claudio Re these are the russian Beta time stations, which are more active recently:

http://air-radiorama.blogspot.it/2017/07/checking-russian-beta-vlf-frequency-and.html

https://air-radiorama.blogspot.it/2017/06/following-posts-at-links-httpair.html

http://www.vlf.it/russianvlf/russianvlf.htm

The signals were received at SQ5BPF QTH Warsaw/Poland KO02md with an e-field antenna.