The Automatic Identification System uses global positioning system and VHF transmissions to send and receive information about the position, speed and heading of a maritime vessel. AIS provides information on ships on a local, regional and national level.
A VHF transponder within each ship constantly sends and receives information, which is updated up to every two seconds according to the U.S. Coast Guard. The information received is used on chart plotters and PCs to show the exact position of each vessel on a maritime chart.
AIS uses the time division multiple access system sends and receives information over two channels, awarding one of 2,250 slots on each channel to each vessel. The International Electrotechnical Commission produced internationally recognized standards to ensure the safety and compatibility of different brands of AIS systems.
Using a PC or chart plotter allows the user of the AIS system to obtain information on surrounding ships, each vessel has a line showing heading and speed. AIS can be used to obtain the name and call sign of surrounding ships to make ship to ship communications easier.
