ARIS: Automatic Reporting and Identification System (1987 – 2000)
In 1956, Rotterdam was the first port with a radar system for the guidance of shipping, the ‘walradarketen’. This (then modern) but rather simple system was less and less capable of keeping up with the intensification of shipping. Moreover, the system could not support the operators in determining the identity of the vessels better and more clearly for safety reasons and to link them to the radar echoes. When it was decided to replace the system at the beginning of the 1970s, the identity question came up for discussion. Philips Netherlands conducted a trial with a secondary radar system. Transmission pulses from that system were received by a special receiver on the target (vessel). This receiver is triggered and sends back a (secret) code that is captured by the secondary radar antenna. The test itself was successful, but the consequences of introducing such a system would mean that all ships that would call at the port of Rotterdam would have to have a (then quite large) box on-board to respond to the secondary radar signals. At that time, the system could be implemented. Another major disadvantage was that it would work to identify vessels from shore, but not from ships because radar systems on board did not lend themselves to the installation of an extra antenna for the secondary radar. The shore radar system in Rotterdam was therefore equipped with automatic radar extractors. A radar extractor makes it possible to determine the position, dimensions, etc of a ship can be digitally determined from the radar signal and linked to identity information that is automatically entered from a computer or manually by an operator. This did quite well for isolated targets. In practice, however, it turned out to have a number of limitations when targets are close to each other or cross at a short distance. Identity change or even loss of identity (label) is then the result. This problem not only occurred in Rotterdam but in all comparable vessel traffic control systems that had been built in the meantime.
On board of ships, radar was meanwhile good to get a traffic picture on the bridge, even in bad weather conditions and on the open sea. Here too, the question arose as to the identity of the vessels in the vicinity to come to traffic safety arrangements. In addition, the position of one’s own ship became increasingly available through systems such as Decca, Loran-C and the emerging GPS.
Automatic Reporting and Identification System (ARIS)
In 1985, the International Maritime Organization (IMO) resolution A.578, ‘Guidelines for Vessel Traffic Services‘ stated that ship identification may be supported by technical means; in other words, the legal basis for a form of transponder technology was laid. At the end of 1987, this was a reason for the then Directorate-General for Shipping and Maritime Affairs (DGSM) of the Ministry of Transport, Public Works and Water Management (V&W) to ask TNO-FEL for researching the feasibility of an identification system for shipping based on VHF or UHF radio communication. The system should be a support for operators in a traffic control system. The system should also be suitable for the mutual identification of vessels.
TNO-FEL then designed the Automatic Reporting and Identification System (ARIS) in accordance with the WG3 requirements of the IALA-VTS commission. The ARIS concept consists of a relatively simple transponder on board each ship and a shore station that has radar coverage.
The operation of ARIS can be explained easily. When entering the Vessel Traffic Services (VTS) area, the position of the ship can automatically be detected by radar and used as input for the ARIS shore equipment to initiate an identification request via the VHF radio connection. Periodically, the coastal system of ARIS will interrogate the ‘approach area’ of the VTS to identify ships that have not yet been detected by the radar system. In this way, new ships will automatically be taken over in the traffic image without any manual actions from the operator. But, if an operator wants to identify a target in a VTS centre (ship traffic coordination centre), he/she will point the target to a radar screen (using a mouse or light pen). Because radar knows the position of the ship, the position of the target is transmitted in an ARIS message. All ships with an ARIS transponder receive this message. Only the ship that is at that position with a certain tolerance will send a message back with the identity (name, call sign) as the most important information. However, this mechanism can also be used to transfer other additional information such as course, speed, draft, destination, etc.
The onshore equipment translates the response to computer data that can be presented as readable text and/or in graphical form on the ARIS monitor. Displaying ships equipped with ARIS on an electronic chart or ECDIS is also possible. When ARIS is integrated with the VTS system, the position data can be used to construct the ship traffic chart; the additional data can be used in an information processing system. The system is particularly valuable in busy harbour lanes and can even be used in areas with a radar breakdown or in coastal waters where no advanced VTS system is available.
The ARIS demonstration system developed by TNO consisted of a VHF transmitter at the VTC and several ship transponders. A number of operational tests were carried out in IJmuiden, Hoek van Holland and later Vlissingen. This made ARIS the first maritime radio transponder system in the world. The aim of the tests was to demonstrate the added value of the transponder technology in a maritime traffic environment.
During the trials, a number of presentations were given to the international maritime community. With this, DGSM has opened international discussions within IMO and other organisations about the introduction of maritime transponders for shipping. However, discussions within IMO about the (mandatory) introduction of a new system always take a long time because an agreement has to be reached with all member states.
System configurations: The ARIS shore-based equipment can be implemented in a variety of configurations:
- ARIS in combination with, and completely integrated in a VTS system (for operational actions and the presentation of ARIS data).
- ARIS combined with a standard radar system (in a simple VTS environment). A target position marker is shown on the radar screen.
- ARIS as a stand-alone system (for logistics and planning). The ARIS monitor shows the data of the replies of the identified vessels received.
ARIS was developed with an idea, a vision, but without a preconceived position. There was nothing, no free frequency for the broadcast of ARIS messages, no communication protocol, no standard and a limited technical package of requirements. Everything was developed by TNO-FEL using the then state-of-the-art technologies.
ARIS could, with some limitations, also be used in a ship-ship mode. This means that ships can also question each other’s identity. However, at the moment most ships still have insufficient possibilities on their radar to designate another ship and to offer the position in digital form to the ARIS transponder.
But there was more going on in IMO. For the “Global Maritime Distress and Safety System” (GMDSS) a new digital communication protocol was introduced that works with analogue modem technology: “Digital Selective Calling” (DSC), based on the CCIR (currently UN/ITU) recommendation 825. DSC is designed to exchange information from ship to country and from ship to ship. For the exchange between ship and shore, three different types of information are distinguished:
- Static information: call sign, type of ship, etc. and will normally be programmed into the shipborne ARIS equipment.
- Variable information: this includes load, actual draught, and destination. It will be determined per voyage and will often be available via the ship’s computer system.
- Dynamic information: for example position and course. Dynamic information has to be constantly adjusted and can be accessed through the navigation equipment such as Global Positioning System (GPS).
All three information types can be used simultaneously in order to obtain clear identification.
The maritime community thought it desirable to introduce the future transponder system using the DSC protocol as a basis. That was not a problem, it did not affect the functional functioning of the transponder. That is why an international standard was drawn up for the new transponder technology based on DSC. Then negotiations between the member states about the global introduction started; a process that easily could take ten years. In Scandinavia, very busy with the introduction of GSM, one got the idea that the underlying technology was very attractive for transponder technology, but without a network, without a service provider. And so the idea is born for the “Self Organized Time Domain Multiple Access” (SOTDMA) technique as a communication standard.
In parallel to these developments, TNO-FEL created the technical specifications for the harbour approach system (HAvenNAderingsSysteem or HANAS) for the pilots of the Rotterdam harbour in 1994/95. HANAS which became operational in 1997 and was based on differential GPS (DGPS). HANAS was the successor of the Decca-based Brown Box system.
Automatic Identification System (AIS)
Thus the idea of the “Automatic Identification System” (AIS) is suggested, which. after years of discussion, was also accepted by IMO in 2000. The objective was to make AIS mandatory from 2002 onwards, in phases, until 2008. But that meant that the idea had to be further developed from a global description to a specification. An international standard had to be set up, agreements had to be made to free up frequencies within the International Telecommunication Union (ITU), guidelines had to be put on the use and installation on board and much more.
The Ministry again relied on TNO-FEL because TNO had developed ARIS and had the technical knowledge. They asked TNO to be present in international working groups of the International Association of Maritime Aids to Navigation and Lighthouse Authorities (IALA), the International Electrotechnical Commission (IEC), and ITU. On behalf of V&W, TNO had to actively cooperate with the further development and operationalisation of AIS. Naturally, Dutch interests had to be taken care of. IALA would ultimately play the leading role in this development, also because it links the shipping industry and the world of traffic management.
Then 9/11/2001 happened, after which the identification of ships was given a dominant place in society. Everything has to be speeded up. As of January 1, 2005, every seagoing merchant ship must have AIS on board. AIS is no longer just a contribution to safety but has also become a ‘security’ obligation.
AIS is a success: see www.marinetraffic.com or the AIS web page of Scannernet. Those pages show the current positions and movements of sea vessels around the world. Moreover, after the transponders for seagoing vessels and shore stations, special AIS versions have been developed for recreational shipping and inland navigation. We also see transponders for use on lighthouses, buoys and other maritime objects (such as marking wrecks, oil platforms and wind farms at sea). Special transponders for Search And Rescue (SAR) planes, transponders for satellite observation, for lifesaving and man-over-board transponders, in short AIS plays a role in the maritime community that can not be disregarded.
TNO’s role with AIS has ended, but TNO has been at the basis of this development, laid the foundation stone, and made an important contribution to this successful safety and security development internationally.