Annex 1 - Description of AIS

  Components

  1. In general, an onboard AIS (see Figure 1) consists of:

• antennas;
• one VHF transmitter;
• two multi-channel VHF receivers;
• one channel 70 VHF receiver for channel management;
• a central processing unit (CPU);
• an electronic position-fixing system, Global Navigation Satellite System (GNSS) receiver for timing purposes and position redundancy;
• interfaces to heading and speed devices and to other shipborne sensors;
• interfaces to radar/Automatic Radar Plotting Aids (ARPA), Electronic Chart System/Electronic Chart Display and Information System (ECS/ECDIS) and Integrated Navigation Systems (INS);
• BIIT (built-in integrity test); and
• minimum display and keyboard to input and retrieve data.

With the integral minimum display and keyboard unit, the AIS would be able to operate as a stand-alone system. A stand-alone graphical display or the integration of the AIS data display into other devices such as INS, ECS/ECDIS or a radar/ARPA display would significantly increase the effectiveness of AIS, when achievable.

  2. All onboard sensors must comply with the relevant IMO standards concerning availability, accuracy, discrimination, integrity, update rates, failure alarms, interfacing and type-testing.

Figure 1 AIS Components

  3. AIS provides:

• a built in integrity test (BIIT) running continuously or at appropriate intervals;
• monitoring of the availability of data;
• an error detection mechanism of the transmitted data; and
• an error check on the received data.

  Connections

  The connection of AIS to external navigational display systems

  4. The AIS can be connected either to an additional dedicated AIS display unit, possibly one with a large graphic display, or to an existing navigational system such as radar or an electronic chart, but in the later case only as part of an integrated navigation system.

  The connection of AIS to external portable navigational equipment

  5. It is becoming common practice for pilots to possess their own portable navigational equipment, which they carry on board. Such devices can be connected to shipborne AIS equipment and display the targets they receive.

  The connection of AIS to external long-range radiocommunication devices

  6. AIS is provided with a two-way interface for connecting to long-range radiocommunication equipment. Initially, it is not envisaged that AIS would be able to be directly connected to such equipment.

  7. A shore station would first need to request that the ship makes a long-range AIS information transmission. Any ship-to-shore communication would always be made point-to-point, and not broadcast, and once communication had been established, the ship would have the option of setting its AIS to respond automatically to any subsequent request for a ship report from that shore station.

  8. Users are reminded that SOLAS regulation V/11.10 provides that the participation of ships in IMO-adopted ship reporting systems shall be free of charge to the ships concerned.