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The 45th meeting of the International Maritime Organization (IMO) Navigation Safety Subcommittee conducted the final review of Chapter V of the revised SOLAS Convention, which was scheduled to enter into force on July 1, 2002. In the equipment requirements for shipboard navigation systems and equipment in Article 20 of the new five chapters, the equipment requirements have been expanded. The most notable is the AIS (Automatic Identification System) onboard automatic identification system.
1. Background generated by AIS
The IMO and the competent national authorities have established and implemented anti-collision rules, stipulated mandatory deployment of necessary navigation aids, established VTS and ship reporting systems to manage the safe navigation of ships, but collisions of ships have occurred frequently. In order to further improve the performance of safe navigation of ships, relevant institutions and manufacturers have continuously researched and developed navigation aids. The rapid development of communication technology and computer technology today provides technical guarantee for research and development in this area. AIS It is based on the development of these technologies.
In the past collision accidents of marine vessels, there have been many cases in which the problems of VHF equipment operation and language communication have not been able to communicate and understand the information of the other ship in time and the intention of the ship, and eventually lead to collision accidents. In the restricted water area or the VTS action area, the control center obtains the information of the ship through wireless telephone inquiry or by the ship using the wireless telephone to report to the control center, and then manually inputs the ship information into the VTS monitoring system to realize the tracking management of the ship. Since the information is input into the system manually, the control center of the VTS area where the ship has a relatively high density is not only work-intensive, but also prone to operational errors, and sometimes the target is lost due to the blind spot. In response to the above situation, some countries in Europe and the United States began to explore and research on the automatic acquisition of ship information and navigational state technology around the 1990s.
2. The development process and current status of AIS
One of the earlier methods was developed based on VHF DSC technology and is called "TRANSPNDER SYSTEM". The basic method is to automatically send the inquiry information on the 70 channel by DSC, and the receiver (the AIS equipment installed on the ship or the shore) that receives the inquiry information will identify the ship's identification code and the ship name according to the channel requested by the inquiring party. Information such as ship position, heading, speed, draught, etc. are automatically transmitted to the inquiring party, thus realizing the automatic answering function, (where the ship identification code and the ship position information are required to be transmitted, it has been deposited when the equipment is installed; the position information is from GPS , connected to the transmitting device through the data interface). In the VTS action area, the onshore equipment continuously sends an inquiry signal to the surrounding area. After receiving the inquiry signal, the ship in the area automatically sends back various types of information to the onshore equipment, and the information is automatically input into the VTS equipment. The VTS Control Center broadcasts this information via VHF, which can be received by ships equipped with such equipment and displayed on electronic charts. Drivers can see the position of the surrounding ships on the electronic chart. , ship name, heading, speed and other information. In addition, the system can also perform digital communication and voice communication. Due to the use of new technologies in VTS, the system's functionality has been added to make it an "enhanced VTS." At the same time, a study on the VHF channel using the European digital trunking standard technology to implement automatic answering and communication functions has been quite successful. Before IMO officially announced the performance standards of AIS, the above systems have been applied in some countries in Europe and America.
IMO attaches great importance to the role of this new technology in safe navigation. At the meeting of the 74SOLAS Convention Secretariat on November 29, 1995, a series of resolutions were adopted, of which Resolution 9 is on the Automatic Ship Identification Transponder/Transceiver System. . In the resolution, it was affirmed that such a device "will greatly improve navigation safety" and proposes that the operational requirements and performance standards of the device should be formulated as soon as possible, and the SOLAS amendments to be adopted through the system configuration of the device should be considered; The Alliance develops the technical standards and appropriate frequencies for the device. In 1996, at the 42th meeting of the IMO Navigation Safety Subcommittee, the draft performance standard of the “Automatic Marine Identification System Device Using VHF DSC Technology†submitted by the technical team was reviewed and referred to as “AISâ€; in the same year, At the 67th meeting of the MSC, it was agreed to consider AIS as a plan to be implemented in the future. In 1997, the IMO's Navigation Safety Subcommittee held 43 meetings and adopted the “Proposal on Global Shipborne Automatic Identification System (AIS) Performance Standardsâ€. The conference briefing described the function of the AIS, saying that the system "satisfies the following needs: 1 collision avoidance with ship-to-ship mode; 2 port state obtains information on the ship and its cargo; 3 as a tool for VTS." The proposal was approved by the IMO’s MSC in 1998. The 45th meeting of the Navigation Safety Subcommittee in 1999 finalized the revision of Chapter V of the SOLAS Convention (according to the procedure, the “New Five Chapters†need to be finalized at the 73 meetings of the MSC in December 2000) and Ships of more than 300 gross tonnage sailing on international routes and ships of more than 500 gross tonnage sailing on domestic routes of the Convention, will be subject to the phased implementation of AIS equipment from July 1, 2002 to July 1, 2008. .
In order to standardize and unify the system technical standards and the rational use of frequency resources, the International Telecommunication Union (ITU) issued the proposal ITU-RM.825 in 1992. WRC-97 (World Radio Administrative Conference 1997) approved the splitting of VHF87 and 88 channels into simplex channels, of which 161.975MHz is AIS1 channel and 162.025MHz is AIS2 channel. After intense discussions, the International Telecommunications Union Radiocommunication Study Group 8 proposed a proposal in 1998 on the Technical Characteristics of the Marine Automatic Identification System (AIS) using TDMA in the VHF band at sea. The proposal uses the SOTDMA system. Used for ship route monitoring and safety, ship reporting, VTS applications, etc., and has been adopted by IMO.
3. Introduction to basic functions and technical features of AIS
(1) System work characteristics:
â— Autonomous and continuous work in all areas;
â— The working mode is assigned by the traffic monitoring center to facilitate the competent department to control the interval and time slot of data transmission;
â— The transmission response of the data comes from the inquiry of the ship or the competent authority, and there are two modes of polling and control.
(2) Static information transmitted by the system: IMO code (if any), call sign and ship name, length and width of the ship, type of ship, position of the positioning antenna on the ship.
(3) Dynamic information transmitted by the system: ship position, international coordination time, ground heading, ground speed, track direction, navigation status, steering rate, heel angle (option), trim and yaw (option).
(4) Navigation related information transmitted by the system: ship draught, dangerous goods type, destination port and estimated arrival time, navigation plan (options), concise safety information.
(5) Technical characteristics: AIS adopts OSI (Open Systems Interconnection) working model, the bandwidth of wireless transmission is 25 kHz or 12.5 kHz (see ITU-RM.1084), the modulation adopts GMSK scheme, the data is encoded into NRZI mode, and the bits of data transmission The rate is 9600 b/s.
4. Development prospects of AIS
From the basic functions and technical characteristics of AIS, the system provides a new and effective means for ship navigation safety and navigation management. According to statistics and predictions made by relevant foreign departments in 1999, although the development of AIS is about ten years later than ECDIS (Electronic Chart Display and Information System), its development speed has greatly exceeded ECDIS, and will remain in the next few years. Development trends. From the perspective of IMO, the mandatory requirements for AIS will be prior to ECDIS. If there is no accident, the new SOLAS amendment will be officially adopted at the end of 2000, which means that it will enter AIS on July 1st, 2002. The implementation period of the equipment.
The 88th Amendment to the 74SOLAS Convention made a major amendment to Chapter 4 of the Convention (Radiocommunication) and proposed the GMDSS program known to the shipping industry. The impact of the implementation of the GMDSS program on the shipping industry and various management departments is enormous. In the AIS plan to be implemented, although the scale and cost of the equipment are not comparable to the GMDSS, its role in ship navigation safety and navigation safety management is very important.