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B2 Product Manual 2_0
1 WHAT IS AIS?
AIS stands for
A utomatic I dentification S ystem. AIS increases the navigational safety and helps
avoid collisions by interchanging vessel identification and route data between nearby ships and land
based stations. This makes identifying ships and their planned course much easier when not in sight
(e.g. at night, in radar blind arcs or shadows or at larger distance).
According to IALA regulations, AIS is defined as follows:
AIS is a broadcast transponder system, operating in the VHF maritime mobile band (using two VHF
channels: 87B - 161.975MHz and 88B - 162.025MHz). It is capable of sending ship information such
as identification, position, course, speed and more, to other ships and to shore. It can handle multiple
reports at rapid update rates and uses Carrier Sense Time Division Multiple Access (CSTDMA)
technology to meet these high broadcast rates and ensure reliable and robust ship to ship operation.
The IMO defines the performance standards as follows:
Ship to ship working, ship to shore working, including long range application, automatic and
continuous operation, provision of information messaging via PC and utilization of maritime VHF
channels .
The Modules:
GPS system, AIS Transponder, VHF Antenna, and the Power Supply (appropriate application
software connects the individual modules).
AIS systems are required to operate in a variety of modes:
The system shall be capable of
 An " autonomous and continuous " mode for operation in all areas. This is the default
mode but can be forced to/from the following alternatives by an entitled authority;
 An " assigned " mode for operation in an area subject to an entitled authority responsible for
traffic monitoring; data transmission interval and/or time slots may be set remotely;
 A " polling or controlled " mode, where data transfer occurs in response to polling from a
ship or entitled authority.
This illustration depicts a typical AIS System where two or more AIS equipped vessels (and shore
based systems) are automatically communicating with each other: