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Holger

Quote:

Originally Posted by Larry

"Lyn & Tony" wrote in
oups.com:

Several base
stations are on the way but that is all.

I think there are some misconceptions that to make a bouy show up on
everyone's AIS it needs to have a transmitter on it. This just isn't true.
ONE shore station with a tall tower can provide the AIS users with every
bouy, every obstruction or any other type of warning from its data stream.
It doesn't matter where its antenna is. This ISN'T some kind of radar
system, it just looks that way on the display. To show up, any object
needs data transmitted in range of your receiver from anyplace. The data,
not the transmitter's location, determines where the object is displayed.

Larry, true, this is one method of transmitting AIS data for floating objects. As far as buoys are concerned, AIS provides the possibility to allow them to transmit themselves or remotely from a basestation. Self-transmitting is normally used when environmental data is also transmitted.

I quote from the AIS specifications:
"There are three categories of Aids to Navigation in the AIS system:

Real AtoN: The AtoN is equipped with an AIS Station designed to generate
the appropriate AIS messages using local data from the aid and transmitting it via VHF.

Synthetic AtoN: The AIS message for the AtoN is transmitted from another
location (normally a base station) and the AtoN is physically located at the position given in the
AIS message.

Virtual AtoN:The AIS message is an aids to navigation message but no real aid exists at
the location indicated in the AIS message.

Holger