Automatic Identification System (AIS)
Automatic Identification System (AIS) is the name given to an international maritime communications protocol developed back in the late 90s. AIS is now one of the most widely used and significant navigation safety technologies since the introduction of radar. The system was originally developed as a collision avoidance tool to enable commercial vessels to ‘see’ each other more clearly in all conditions and improve the helmsman’s information about his surrounding environment.
AIS uses GPS and VHF radio technologies to automatically communicate between vessels allowing vessel identity, position, course and speed (and other data) to be shared to other AIS users within range. These could be vessels, aircraft, coast stations or satellites. A single AIS transmission (message) can contain up to 27 pieces of information and can be used to carry numerous different types of data.
AIS is a MESH network using real-time data communications technology. The IMO developed the standard to minimise the risk of collisions in the ocean when vessels may be out of range of any land based system so it can’t rely on a central network. An AIS transponder is a mandatory fit on all vessels greater than 300 tonnes or carrying 12 or more passengers.
AIS forms an important part of a toolbox of aids to navigation. Information received via AIS can supplement and improve radar information and therefore is a valuable aid to assist in collision avoidance. It’s affordable, easy to install and also easier to interpret for leisure users compared to small radar systems.
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Benefits of AIS
CPA and TCPAMost navigation system can calculate the Closest Point of Approach (CPA) of every AIS target and also the Time to CPA (TCPA). The navigation system can trigger an audible and visual alarm when dangerous targets are detected.
IdentificationReceive MMSI number, vessel name and boat type of all AIS equipped vessels. Useful to find any of your friends’ boats.
Collision AvoidanceReceive clear and regular position reports of all AIS equipped vessels in your area. You can identify and make a DSC radio call to a dangerous vessel using their MMSI number.
MonitoringEmergency services and port authorities are using AIS for surveillance, safety with quick and easy vessel identification. Also, your friends and family can use online AIS services to track your trip/race from home.
See around cornersUseful to see around corners vessels, AtoNs, rescue Craft, etc. AIS is a low power and low cost alternative to radar for small boats.
Types of AIS
Digital Yacht’s extensive range of AIS products provides solutions for every type of boat, from an open cockpit RIB to a SOLAS Super Tanker. An AIS which sends and receives data is known as a transceiver (or often called a transponder). There are also simple devices called AIS receivers which pick up transmissions and decode for displaying on a compatible chart plotter or PC based navigation system – or even an iPad or tablet.
THERE ARE 3 TYPES OF AIS TRANSPONDERS: CLASS B, CLASS B+ AND CLASS A. THEY ALL INTEROPERATE:
Class B AIS Transponder is for recreational craft installation and is a simplified, lower powered 2W transceiver which is normally a black box and uses a connected chart plotter to display local AIS targets. It transmits every 30 seconds regardless of vessel speed and can’t transmit additional data like destination port.
Class B+ AIS Transponder (also called Class B SOTDMA) is a new standard that utilises SOTDMA format transmissions which offer a 5W power output (2.5 x more powerful than a regular Class B), a guaranteed time slot for transmission in busy traffic areas and faster update rates depending upon the speed of the vessel. It’s ideal for ocean sailors requiring the best possible performance and future proof satellite tracking applications, fast power boats and smaller non-mandated commercial vessels.
Class A AIS Transponder must have a dedicated (and type approved) display to show the location of nearby AIS targets and transmits at 12.5W. Data is sent at up to every 2 seconds depending upon the vessel speed and the display also allows for data to be inputted to the transmission such as vessel destination. A Class A device is normally used on commercial vessels as its Type Approved to IMO specifications.
THERE ARE ALSO OTHER TYPES OF AIS:
ATON (Aids To Navigation) is an AIS transceiver specifically for use on marine infrastructure and buoys to provide real time hazard alerts as well as live monitoring data such as weather, sea and lantern status. ATON transmissions can be displayed on compatible chart plotter and ECDIS systems and allow a buoy or structure to be positively identified as well as the ability to display local wind, tide or metrological data.
AIS SART (Search And Rescue Transmitter) is a homing beacon designed for use in an emergency. When activated an AIS SART transmits its GPS position using AIS in a special SART message. This message is recognised by the AIS display systems on other vessels (and potentially on shore) as an emergency message and generates an alarm.
An AIS SART can be used to locate a life raft or lifeboat in an emergency situation. Available in vessel versions (SART) or personal versions (PLB) with the difference being size and range. An AIS SART with its position close to the waterline and limited 2W output would typically have a maximum range of 5-6NM. A PLB device would typically have a range of 2-3NM.
AIS base stations are fixed (non-mobile) stations that port authorities use to monitor and control vessel traffic. Major ports and harbours install these systems to give additional control over local AIS users. These base stations can also control other AIS devices with the ability to turn other AIS devices on or off, reserve time slots for special transmissions, control which time slots mobile AIS devices use and even control the power level of AIS transponders.
Besides all types of AIS, Digital Yacht also manufacture many accessories such as AIS alarms, interfaces for AIS and Zero-Loss VHF antenna-splitter allowing the VHF antenna to be shared with an AIS receiver/transponder and with a VHF radio.
Discover our products
The most extensive AIS Receiver range of any Marine Electronics manufacturer, with a model to suit every application.
Our range of AIS transponders include Class A, Class B and Class B+ units for Commercial and Pleasure vessels.
Splitters & Antennas
All our VHF antennas and Zero Loss VHF splitters for any AIS receivers and transponders.
Our AIS Beacons products such as an AIS Sart, an MOB beacon and an AIS alarm box.