Operation Manual

Section 10 - AIS functionality
WARNING
A valid USER MMSI must be entered into this radio before these AIS functions can be
used. See section 5-1.
10-1 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 they are designed to be
fitted on 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 regulations.
• 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. AtoNs are transceivers mounted on buoys or other
hazards to shipping which transmit details of their location to the surrounding vessels.
• AIS receivers. AIS receivers will generally receive 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.
This radio contains an AIS receiver only function.
10-2 AIS - Static and dynamic information
Defined transmit rates for Class A vessels shown below are provided for reference purposes
only. The frequency of messages received will vary due to a number of factors including but
not limited to such factors as antenna height, gain and signal interference.
• Static information is either broadcast every 6 minutes, when data has been amended, or
upon request.
• Dynamic information is broadcast depending on speed and course alteration based on
the following tables:
Ships dynamic conditions Normal reporting interval
At anchor or moored 3 Minutes
0-14 knots 10 Seconds
0-14 knots and changing course 3 1/3 Seconds
14-23 knots 6 Seconds
14-23 knots and changing course 2 Seconds
Ship faster than 23 knots 2 Seconds
Ship faster than 23 knots and changing course 2 Seconds
Platforms condition Normal reporting interval
Class B Shipborne mobile equipment not moving
faster than 2 Knots
3 Minutes
Class B Shipbome mobile equipment moving 2-14
Knots
30 Seconds
Class B Shipbome mobile equipment moving 14-23
Knots
15 Seconds
Class B Shipbome mobile equipment moving faster
than 23 Knots
5 Seconds
Search and Rescue aircraft (airborne mobile
equipment)
10 Seconds
Aids to Navigation 3 Minutes
AIS base station 10 Seconds
Source of information for above tables 1-1, 1-2: (ITU recommendations technical document:
ITU-R M.1371-1)
10-3 Using the AIS receiver
Providing that other vessels with AIS transceivers installed are within radio range of your
vessel, you should see their details appear on the AIS plotter screen. These details are also
repeated on the NMEA ports for display on a compatible chartplotter / MFD.
Specific details of how to configure your chartplotter to make use of the AIS receiver features
will be given in your chartplotter manual. If you are using charting software running on a PC,
please refer to the instructions provided with your chartplotting software for details of how to
configure it to display AIS information.
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