About AIS
AIS is primarily used for collision-risk management and navigation safety. It can automatically transmit and receive vessel information, such as the vessel name, MMSI (Maritime Mobile Service Identity) number, vessel code, vessel type position data, speed, course, destination and more information depending on the transceiver class. Information exchanged among vessels and base stations on the VHF maritime mobile band. This information helps to identify other nearby vessel stations.
There are a number of AIS devices as follows:
Class A transceivers - These 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. They 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 SOLAS regulations.
Class B transceivers - These are 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 - AtoN’s 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, AtoN’s and AIS base stations but do not transmit any information about the vessel on which they are installed.
AIS Identifier - The Identifier is a unique, self-contained AIS vessel tracking device. The key features of the AIS Identifier are as follows:
Self-contained VHF and GPS antennas
- Internal rechargeable battery pack for up to 5 days of operation
- Electronic security link to vessel mounting bracket
- Simple installation
Figure 11 : AIS network