Reference Manual Part 2

G-Series Reference Manual 158
12.1 Background
AIS broadcasts information between vessels and shore-based sta-
tions on VHF frequencies in the maritime band. This information is
used to provide fast, automatic and accurate collision-avoidance
data. AIS augments the radar application. It can operate in radar
blind spots and can detect smaller (AIS-equipped) vessels than
radar can.
AIS does not replace radar, because it is unable to detect land or
navigation beacons.
Classes of AIS data
AIS data is defined as Class A or Class B. The sending and receiv-
ing of Class A data is compulsory for larger vessels. You will
therefore be able to view all larger vessels on your AIS display.
Not all AIS receivers will decode all information and not all of the
Class A vessels input all of the required AIS data. For example,
some inexpensive AIS Class B receivers do not decode and output
the ship’s name, IMO number and vessel data.
Class B data is applicable to smaller vessels and is not compulsory.
Do not assume that your AIS will display data for all smaller vessels
in your area.
The following information can be transmitted by a Class A AIS
system:
• Static data: ship name, type, MMSI number, call sign, IMO
number, length, beam and GPS antenna location.
• Voyage data: draft, cargo, destination, ETA, other relevant
information.
• Dynamic data: time, position, COG, SOG, gyro heading, rate of
turn, navigational status.
• Dynamic reports: speed and status.
• Messages: alarm and safety.
12.2 System requirements
To use AIS, you need:
• AIS unit: either a receive-only or full transceiver device.
• VHF antenna
12.3 System settings
For the NMEA port that communicates with the AIS transceiver
unit, specify a baud rate of 38,400 (see page 188).
12.4 AIS setup
The AIS Layer Setup Menu allows you to:
• Select target types displayed (ALL or DANGEROUS).
• Switch AIS safety messages on or off.
• View the list of active AIS alarms.
To display the AIS Layer Setup Menu
1. Ensure the AIS LAYER is set to ON (see Using AIS, below).
2. Press the MENU button.
3. Select AIS Layer Setup.
WARNING
Product installation
Smaller vessels do not have to be fitted with AIS, and
although it is mandatory for larger commercial vessels to
use AIS, do not assume that they all do. Always exercise
due prudence and judgement.
AIS complements radar, it is not a radar substitute.