About Your Ais Receiver; About Ais; Static And Dynamic Vessel Data - ACR Electronics Nauticast 2625 Manual

2 About your AIS receiver

2.1 About AIS

The marine Automatic Identification System (AIS) is a location and
vessel information reporting system. It allows vessels equipped with
AIS to automatically and dynamically share and regularly update
their position, speed, course and other information such as vessel
identity with similarly equipped vessels. Position is derived from the
Global Positioning System (GPS) and communication between
vessels is by Very High Frequency (VHF) digital transmissions.
There are a number of types of AIS device as follows:
• Class A transceivers. These are similar to class B transceivers,
but are designed to be fitted to large vessels such as cargo ships
and large passenger vessels. Class A transceivers transmit at a
higher VHF signal power than class B transceivers and therefore
can be received by more distant vessels, and also transmit more
frequently. Class A transceivers are mandatory on all vessels
over 300 gross tonnes on international voyages and certain types
of passenger vessels under the SOLAS mandate.
• Class B transceivers. Similar to class A transceivers in many
ways, but are normally lower cost due to the less stringent
performance requirements. Class B transceivers transmit at a
lower power and at a lower reporting rate than class A
transceivers.
• AIS base stations. AIS base stations are used by Vessel Traffic
Systems to monitor and control the transmissions of AIS
transceivers.
• Aids to Navigation (AtoN) transceivers.
transceivers mounted on buoys or other hazards to shipping
which transmit details of their location to the surrounding vessels.
• AIS receivers. AIS
transmissions from class A transceivers, class B transceivers,
AtoNs and AIS base stations but do not transmit any information
about the vessel on which they are installed.

2.2 Static and dynamic vessel data

There are two categories of information transmitted by an AIS
transceiver: static and dynamic data.
The vessel's dynamic data, which includes location, speed over
ground (SOG) and course over ground (COG), is calculated
automatically using the internal GPS receiver.
Static data is information about the vessel which must be
programmed into an AIS transceiver. This includes:
• Maritime Mobile Service Identity (MMSI)
• Vessel name
• Vessel call sign (if available)
• Vessel type
• Vessel dimensions
In most countries the operation of an AIS transceiver is included
under the vessel's marine VHF licence provisions.
About your AIS receiver
AtoNs are
receivers will generally receive
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