I'd disagree. STDMA does not transmit to S-AIS and Class-B transmissions to satellites even with SOTDMA are not generally supported. Get it in your skull that AIS on pleasure boats is local, 10 miles or so, satellites are not involved.That is just getting confused.
There are two sets of satellites being talked about. The GPS/Glonass/Galileo ats that transmit the positioning information. All AIS systems use at least one of these sat sets. The various commercial sats carrying specialised AIS receivers that provide data feeds to commercial subscription services.
CSTDMA Class-B transceivers are limited to 2 watts. Generally too low power to be received by any of the satellites carrying AIS receivers. SOTDMA class B and of course class A have higher power (5 and 12 watts respectively) and can be received. Generally it seems the fleet is still using CSTDMA class B. Even if someone did subscribe to one of the services offered by the sat owners with AIS receivers, you would not usually see the fleet.
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