What are mysterious noise radio shortwave stations?

Question

I hear shortwave radio stations whi transmit strange signals.

Answer 1

Jammers?

Coded messages?

Answer 2

Sounds like train and ship and bip bip bip.

Answer 3

Answer 4

I hear similar sounds.

Answer 5

Answer 6

http://websdr.ewi.utwente.nl:8901/?tune=6085am

This is interesting

https://www.radiobanter.com/shortwave/41393-shortwave-strange-sounds.html

Answer 7

I also hear wind sound on shortwave frequencies and bubbling.