Many thanks to SWLing Post contributor, Carlos Latuff, who shares the following video and notes:
Receiving navtex, Radiofax and voice broadcasts in Rio de Janeiro, Brazil…
Click here to view on YouTube.
Wow, Carlos! What an amazing spot to play radio! Thank you for sharing!
Wow Carlos, great!
I now know for sure that…
When my baby smiles at me…
I go to Rio… De Janeiro…
With my ra-dio…
And decode faxes……
And some Navtex…
And hunt some DX…
With coastline effects…
Where the waves reflect…
The beauty of the city known as…
Rio De Janeiro!
73s!
I went to find out more about Navtex. I could not find a retailer or manufacturer with a live website. Around Australia at least it has been replaced by https://www.inmarsat.com/en/solutions-services/maritime/solutions/safety/safetynet.html which is an automated satellite warning system for shipping.
https://www.inmarsat.com/en/insights/maritime/2019/two-million-lives-in-our-hands.html and https://www.inmarsat.com/content/dam/inmarsat/corporate/documents/maritime/solutions-services/SafetyNET_Handbook_Edition_Six_April_2020_Final.pdf.downloadasset.pdf are interesting reads. I assume like all satellite communications these days they are all digital because satellite transponders are not linear so they cause lots of distortion problems to analog signals.
Of course Navies of course within their frequency allocations can use what they like!