Working of AIS

The AIS system on ships includes a VHF transmitter, two VHF TDMA receivers, a VHF DSC receiver, and a marine electronic communications link to the ship’s display and sensor systems.

To determine position and timing information, it uses an internal or external GPS receiver. Other information is obtained electronically from shipboard equipment via standard marine data connections.

Each station transmits and receives over two radio channels to avoid interference and communication loss from ships.

AIS stations sync themselves continuously to prevent overlap of slot transmissions. One AIS station’s position report fits into one of the 2250 time slots established every 60 seconds.

It is easy to install AIS, as it is usually integrated with ship bridge systems or multifunctional displays, but standalone installation is as simple as connecting a couple of cables and turning on the plug.