The acronym “AIS" comes from English and gives meaning to the British acronym Automatic Identification System or what is the same, Universal Automatic Authentication System of ships.
The AIS is ultimately a technological aid in navigation that allows, among other functions, to identify the name of a vessel, locate its call, its location or coordinates, the direction it follows, its destination, the speed of knots that it is developing and including, the physical characteristics of the ship.
With this advanced navigation system, the captain of a ship has real time information about his own ship as well as the relevant data of the rest of the vessels that travel the waters during his trajectory.
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The authorities also draw on this information provided by the AIS systems of each ship to prevent possible collisions, warn of the risks of certain sea routes and provide crucial information in the maritime rescue operations.
We must clarify that the AIS system is not a radar so the information it provides depends on the GPS systems. This detail is relevant given that the GPS antennas are placed on the bridge of the ship and, consequently, the total length of the ship must be quantified.
Specifically, the AIS System is mandatory for vessels adhering to the Solas Convention that have a gross tonnage greater than 500 GT, ships on international voyage with gross tonnage greater than 300 GT, as well as all passenger ships, regardless of the size they hold. .
Focusing on the functioning of the AIS , say that it has two sources of information input, on the one hand, the data provided by the GPS itself and, on the other hand, data that the ship's user unilaterally introduces. Both sources of information will be issued by two frequencies of marine band which guarantees an excellent and balanced transmission system.
Regarding its range, this is identical to that provided by the VHG marine band frequency, with an approximate range of about 30 nautical miles, with an automatic data update that greatly facilitates navigation to the user.
Finally, within the operating section, the AIS system through its kinematics provides the reference calculation between the CPA and minimum distance of passage and the TCPA or time to the minimum distance of passage. With this calculation, and contrasting it with the MARPA (Polyvalent Aquatic Rescue Material) we will have reliable information about the collision risk between two vessels, which will allow us to make safe navigation decisions.
At the time of interpreting the information provided by the AIS System, it should be noted an IMO recommendation that warns us that a complementary screen should be used to reflect this data and not to superimpose it on the radar of the ship itself. With this way of proceeding we can perform real-time comparisons of data and detect erroneous or misrepresented information popularly known as "false echoes".