bonsoir
On a en a parler il y a quelques temps donc je fais un copier -coller de ma réponse
Bonjour
C'est PBB , occupation de fréquence en continu , marine néerlandaise
Voilà ce que j'ai trouvé sur le net , c'est de l'anglais mais compréhensible
This frequency is mainly used for "CARB" messages.
CARB is the acronym for: "Channel Availability and Receipt Broadcast"
Meaning, they inform which frequencies are available for ship-shore communications.
For example:
4 MHz band = channel B
6 MHz band = channel A
8 MHz band = channel B
An X indicates that the station is not active on that frequency band.
Christian