TYPES OF AUTOMATIC IDENTIFICATION SYSTEMS
ITU-R Recommendation M.1371-1 describes the following types
of AIS:
Class A
Shipborne mobile equipment intended for vessels meeting the
requirements of IMO AIS carriage requirement.
Class B
Shipborne mobile equipment provides facilities not necessarily
in full accord with IMO AIS carriage requirements. The Class
B is nearly identical to the Class A, except the Class B:
- Has a reporting rate less than a Class A (e.g. every
30 sec. when under 14 knots, as opposed to every 10 sec.
for Class A)
- Does not transmit the vessel’s IMO number
- Does not transmit ETA or destination
- Does not transmit navigational status
- Is only required to receive, not transmit, text safety
messages
- Is only required to receive, not transmit, application
identifiers (binary messages)
- Does not transmit rate of turn information
- Does not transmit maximum present static draught
U.S. Submission to the International Telecommunication Union:
Document
8B/234-E, "PERFORMANCE ASSESSMENT AND INTEROPERABILITY
OF PROPOSED CLASS B AIS WITH EXISTING CLASS A AIS SYSTEM USING
SIMULATION SOFTWARE" (2005).
See a comparison of
Class A and Class B/CS AIS.
Search and Rescue Aircraft
Aircraft mobile equipment, normally reporting every ten seconds.
Aids to Navigation
Shore-based station providing location of an aid to navigation.
Normally reports every three minutes. This may eventually
be used in lieu of racons.
Air Base Station
Shore-based station providing text messages, time synchronization,
meteorological or hydrological information, navigation information,
or position of other vessels. Normally reports every
ten seconds.
AIS Messages >>
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