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What does ais mean?
AIS stands for Automatic Ship Identification System. Automatic ship identification system refers to a new navigation aid system applied to maritime safety and ship-to-shore and ship-to-ship communication. It is usually composed of VHF communication machine, GPS locator and communication controller connected with ship-borne display and sensor, which can automatically exchange important information such as ship position, speed, heading, ship name and call sign. AIS installed on the ship sends these messages and also receives messages from other ships within VHF coverage, thus realizing automatic response. In addition, as an open data transmission system, it can be connected with terminal equipment such as radar, ARPA, ECDIS, VTS and the Internet to form a maritime traffic control and monitoring network, which is an effective means to obtain traffic information without radar detection and can reduce ship collision accidents.

concept

The automatic identification system (AIS system for short), which consists of shore-based (base station) facilities and ship-borne equipment, is a new digital navigation aid system and equipment integrating network technology, modern communication technology, computer technology and electronic information display technology. Automatic Ship Identification System (AIS) was born in 1990s, and it was developed from the friend-or-foe identifier of ships and aircraft. The AIS system cooperates with the Global Positioning System (GPS) to broadcast the dynamic information such as the ship's position, speed, course change rate and course, and the static information such as the ship's name, call sign, draft and dangerous goods from VHF to the ships and shore stations in the nearby sea area, so that the nearby ships and shore stations can grasp the dynamic and static information of all the ships in the nearby sea area in time, communicate with each other immediately, and take necessary avoidance actions to effectively ensure the navigation safety of the ships.

According to the requirement of the International Maritime Organization that international ships must install AIS system within a time limit, the Maritime Safety Administration of the Ministry of Communications put forward the goal of building a national AIS backbone network to achieve AIS signal coverage in key sea areas and energy ports in 2003. Among them, the shore-based facilities in the northern sea area were built by Tianjin Maritime Safety Administration. The construction of a is shore-based network system in the northern sea area is divided into three stages: AIS phase I shore-based network system project in Bohai Bay, AIS phase I shore-based network system project in the northern sea area and AIS phase II shore-based network system project in the northern sea area.

On June 5438+ 10, 2004, the first phase of AIS shore-based network system in Bohai Bay started construction. The AIS Center in Yantai area and two base stations, Chengshantou and Kongtong Island, were completed and put into use on June 5438+065438+ 10, 2004, basically covering the route from Yantai to Dalian and the sea area near Chengshantou. The three base stations of Haiyang, Tuandao and Rizhao and the AIS center under the jurisdiction of Qingdao in the AIS phase I shore-based network system project in the northern sea area were successfully debugged and operated at the end of 2005. In the same period, two base stations under Yantai's jurisdiction, Beichangshan and Weifang, were also successfully debugged and operated.

By the end of 2005, the AIS Center and four AIS base stations had been built at Yantai Navigation Mark. There are AIS center and three AIS base stations in the jurisdiction of Qingdao Navigation Mark Office.

The automatic ship identification system (AIS) is developed from the friend-or-foe identifier of ships and aircraft, and cooperates with the global positioning system (GPS) to broadcast the dynamic information of ships, such as ship position, ship speed, change rate and course, and static information of ships, such as ship name, call sign, draft and dangerous goods, from VHF channel to ships and shore stations in the nearby waters, so that the nearby ships and shore stations can grasp the dynamic and static information of all ships in the nearby waters in time.

At present, AIS has developed into a universal automatic identification system (UAIS).

function

The correct use of AIS is helpful to strengthen the safety of life at sea, improve the safety and efficiency of navigation and protect the marine environment. The functions of authorized institutions include:

1, identify the ship;

2. Assist in tracking the target;

3. Simplify information exchange;

4. Provide other auxiliary information to avoid collision.

AIS can strengthen collision avoidance measures between ships, enhance the functions of ARPA radar, ship traffic management system and ship report, display visual information such as the course, route and name of all ships on electronic charts, improve the maritime communication function, provide voice and text communication methods with ships identified by AIS, enhance the overall awareness of ships, and make the maritime community enter the digital age.

cause

The ship port traffic management system that collects target signals by shore-based radar is called VTS, and the radar that collects target signals by ship-based radar and displays its own course and speed and can simulate collision avoidance is called ARPA collision avoidance radar. The 1970s and 1980s were the golden age of rapid development of VTS and ARPA radars. Almost all ports in the world have installed VTS, and all long-distance ships have installed ARPA radar. From 1978 to199 in February1year, 20 VTS stations of different sizes and types have been built in China (excluding Taiwan Province Province). The performance of VTS and ARPA radar is indeed a big step higher than that of similar products before, and it is described as "perfect" for a time.

The ship echo (target) received by shore-based radar can be seen on the display screen of VTS center. The staff need to obtain the name of the ship and identify the target through VHF direct inquiry, inquiry, VHF call plus VHF direction finding, VHF short message, etc. The marked target will follow the ship (target) until the ship (target) leaves the VTS area. In order to get the name of the ship and confirm its position on the display screen, VHF dialogue with the ship is quite common. Walking into the VTS center computer room, "What's the name of the ship with lights drifting?" ""Please name this ship. " "Please report the name of the ship after sailing to the report line. "When VHF communication kept shouting, this shouting became a major feature of the VTS center. The work of confirming the ship's name and position by VHF consumes considerable energy of VTS center staff and weakens the function of VTS. With the development of navigation and the improvement of people's requirements for navigation communication and navigation instruments, the problem that VTS and ARPA radars cannot directly identify targets is prominent.

question

The problems that need to be solved in direct target identification (AIS) on VTS and ARPA radars are: high-precision positioning means, MMSI code, automatic time division multiple access technology, electronic chart and so on. These technical problems have been solved. High-precision positioning means and global positioning system (civil GPS) positioning have been able to ensure the accuracy better than 10m (the measured accuracy can reach 3m). Meet the positioning requirements of AIS.

MMSI code is the only code of a ship in the world, also known as the ship identification number. Every ship is given a unique MMSI code in the world from the beginning of construction to the end of use. IMO adopted the resolution of popularizing MMSI code in 1987.

SOTDMA (Automatic Time Division Multiple Access) technology is a link technology through data encapsulation. AIS technical standard stipulates that every minute is divided into 4500 time periods. Messages with no more than 256 bits can be published in each time period, and messages with more than 256 bits need additional time periods. Each ship will release its own information by asking (automatically) to choose a time period that does not conflict with other ships and the corresponding time period. On the unified VHF channel, any ship in AIS can send and receive reports from all ships (shore stations) without interference, which is the technical core of SOTDMA. AIS system (same area) can accommodate 200-300 ships at the same time. When the system is overloaded, only the long-range target will be abandoned to ensure the priority of the short-range target, which is the main object of AIS ship-to-ship combat. In practice, the capacity of the system is unlimited, and it can provide services for multiple ships at the same time. In the implementation of SOTDMA, two dedicated VHF channels for AIS are needed, and relevant organizations have applied to ITU and obtained approval.

Electronic Chart Display and Information System (ECDIS) is a new technology in modern navigation, which plays an important role in ensuring navigation safety and improving navigation efficiency. ECDIS not only displays electronic charts on computers, but also integrates a real-time navigation monitoring and display system for drivers. ECDIS can automatically calculate the relative position of a ship with land, objects on charts, destinations or potentially dangerous objects in real time, which can be said to raise the navigation safety technology to a new height.

kind

There are many kinds of reports, mainly including: ship position report, base station report, channel management and so on. The reported digits (binary numbers) range from 168 to 1 192. The position report includes: information identification code (6 digits); User identification code (30 digits, MMSI code); Navigation status (2 digits, 0= in navigation; 1= anchoring; 2= Not indicated; 3= limited flexibility); Longitude (28 digits,110000 degrees, 180 degrees,+in the east,-in the west, minimum unit ≈0. 1852 meters); Latitude (27 digits, l/ 10000 degrees, 90,+for north,-for south) and other fields. The total * * * is represented by 168 bits.

frequency

The frequency of location reporting is:

Ship type: reporting frequency

Anchored ship: 3 minutes/time

0- 14 section: 12 seconds/time.

The speed of the ship is 0- 14 knots, and the ship changing course: 4 seconds/time.

14-23: 6 seconds/time.

Ship speed 14-23 knots, change course: 2 seconds/time.

Ships with a speed exceeding 23 knots: 3 seconds/time.

Ships whose speed exceeds 23 knots and change course: 2 seconds/time.

The static information of the ship and navigation-related information should be updated every 6 minutes or as needed (automatic response, no user operation).

Cross medal for outstanding service

Digital Selective Calling (DSC) precedes AIS system, and its basic method is to automatically send out DSC inquiry information on VHF 70 channel, and the ship receiving the inquiry sends its basic information back to the inquirer on the same channel. DSC inquiry is broadcast, and the inquired object is judged by the address code in the information, and the inquired ship will respond, but other ships will not respond. The system adopts digital automatic transmission technology, combines ship position information with electronic chart, and can display ship position.

Although DSC system has outstanding advantages compared with the original products, IMO still thinks that premature calibration is not conducive to the development of science and technology, and DSC technology still has the possibility of development. 1September, 1996, at the 42nd meeting of IMO NAV, the member countries had an in-depth discussion on the selection of DSC and AIS systems. Considering the future communication, we decided to adopt a more advanced AIS system.

ask

Specific requirements for the installation of automatic identification system (AIS) stipulated by the International Maritime Organization All international navigation ships of 300 gross tonnage and above, non-international navigation ships of 500 gross tonnage and above and all passenger ships shall be equipped with automatic identification system (AIS) according to the following requirements:

International sailing ships built before July 2002 1: passenger ships built not later than July 2003 1; No later than the first inspection day after July 1 2003; Not later than July 2004 1, ships with a gross tonnage of 50,000 tons and above, except passenger ships and oil tankers; For ships with 10000 gross tonnage and above but less than 50000 gross tonnage, except passenger ships and oil tankers, no later than July 1 day, 2005; For ships of 3000 gross tonnage and above but less than 10000 gross tonnage, except passenger ships and oil tankers, no later than July 1 day, 2006; Except passenger ships and oil tankers, ships with a gross tonnage of more than 300 tons but less than 3,000 tons shall not later than July 2007 1.

affect

Since the issue of ship identification in VTS was paid attention to and the viewpoint of AIS was put forward, IMO's discussion, research, demonstration, limit test, calibration and popularization of ship identification and AIS have never stopped. Many AIS meetings are held every year to make corresponding decisions. The Safety Committee of the International Maritime Organization has also set up a special AIS team to coordinate AIS work and procedures.

The research of AIS is a huge project, and its discussion, research, demonstration, limit test, calibration and promotion need the cooperation of member States participating in the International Maritime Organization. Part of the cost of testing and calibration is paid by the International Maritime Organization, and there is no report of China's participation in this work. Looking up the relevant conference documents, China has sent personnel to attend relevant conferences, but few people have participated in the discussion and published papers on the automatic ship identification system. The research on artificial intelligence system in China is in a rather backward position.

Relationship between 1, AIS, VDR and ECDIS

Automatic Ship Identification System (AIS), Ship Voyage Data Recorder (VDR), Electronic Chart and Information System (ECDIS) are independent systems, but they are closely related. The data obtained by automatic ship identification system and ship navigation data recorder need to be displayed on electronic chart and information system; Automatic ship identification system and ship-borne navigation data recorder can refer to each other's data accuracy, and their standards need to be consistent, so the International Maritime Organization puts ECDIS, AIS and VDR together for research, design and calibration. AIS and VDR have irreplaceable complementary functions. AIS ships can obtain static data such as ship name, call sign, captain, cargo type and other dynamic data such as ship's sailing course, speed, position and relative distance in real time. VDR can save the recorded data and recover and reproduce these data after the accident. The accuracy of restoring events and the degree of providing original data for accident cause analysis are incomparable with traditional methods.

2. The influence of 2.AIS on ship collision avoidance.

The AIS system will also be an independent system, without a shore station, showing the navigation dynamics of the surrounding ships. There are relatively few ships in open water, because AIS system has the function of taking the nearest ship as the main target ship and displaying its main data on the display screen. AIS system will naturally display the main data of the other ship on the display screen, and the display purpose is to facilitate the avoidance and communication between ships. That is, when two ships collide due to improper avoidance, because the data of the other ship is automatically stored in AIS system, the site can seize the time to confirm the collision facts and understand the loss situation, without asking the other ship's name, shipping company name and other basic data first as before. In the stage of understanding the accident situation and investigation, due to the function of AIS system to automatically save the navigation data of the other ship, the dynamics of both parties are clear, and the responsibility for the accident is naturally easy to distinguish. It is futile for one party to deliberately tamper with it.

3. The influence of 3.AIS on VTS and ARPA.

After the implementation of AIS, it has great influence on VTS and ARPA. For VTS, it can expand the work scope of VTS, improve the accuracy of VTS, identify ships from scratch, and improve the work efficiency of VTS personnel. The situation that VTS staff use VHF communication to shout is gone forever, and VHF communication shouting is no longer a feature of VTS center. After AIS is implemented, VTS will play a better role in maritime safety. For ARPA, AIS will make great progress in identifying targets and assisting ships to avoid, which will play a good role in reducing collision accidents.

AIS is not everything. Without AIS, AIS can't find some small ships. The problem of "AIS can't find small ships" can be solved by popularizing the installation of cheap and simple AIS equipment for small ships after AIS has been implemented for a period of time.

4. The impact of 4.AIS implementation on navigation AIDS.

Waterway excavation is a huge investment project. Generally, the design of navigation trough is to meet the safety requirements and make the excavation more economical. In order to let the ship see the position of the channel clearly, it is necessary to set up navigation marks on both sides of the channel. Because the navigation mark is located in flowing water, the drift radius is about 10-30 meters due to the influence of current. In order to achieve the same safety factor, the navigation slot must be widened accordingly. As far as AIS system is concerned, the situation is different. The position of the electronic navigation mark is not affected by the current, and the requirement for the channel excavation width can be reduced under the same safety factor. Thereby reducing the waterway construction cost.

Light drift is a navigation mark that is easy to drift. Once drifting, it is easy to cause the ship to run aground. This situation can be completely changed under AIS system. Because the electronic navigation mark in AIS state will not shift, the factors that lead to ship grounding due to light drift will not be established, and some grounding accidents can be avoided. If the current physical navigation mark is needed in the case of AIS system, it can be solved by installing AIS device on the current light mark. When the navigation mark is offset, AIS equipment on the offset navigation mark can report the offset position and give an alarm, which is very beneficial to navigation safety.

At present, the setting of shipwreck markers needs approval, and the cycle is long. The information displayed by shipwreck markers, such as left-handed markers and independent navigation AIDS, is also less. Take AIS system as an example, every ship can publish shipwreck information by SMS. During the period from the sinking of the ship to the setting of the shipwreck sign, the ship management department can set up the electronic shipwreck sign, which can not only contain the specific coordinate position, but also contain simple information such as the left sign and the independent navigation mark, as well as the relevant information of the specific warning area (region) and the comprehensive information of the crisis level. When the sunken ship needs to be moved due to tidal current and other factors, the current sunken ship needs manpower and material resources, but in the case of AIS system, the sunken ship can be moved with a click of the mouse.

5. The impact of 5.AIS implementation on navigational warnings and navigational notices.

Some existing navigation warnings, such as long-distance towing and sinking of super-large ships, will be replaced by the new ship notification method of AIS system. At present, in addition to approving the navigation permit, long-distance towing of super-large ships also needs to issue navigation warnings on the particularity of long-distance towing of super-large ships, when to set out, when to arrive at (pass by) a place and other matters that may need the assistance of other ships to avoid, so that ships receiving navigation warnings can estimate the meeting time and actively assist in avoiding. After the implementation of AIS, the navigation warning of long-distance towing of super-large ships will be replaced by the display interface marked with special signals of super-large ships by AIS. If necessary, the special signal of this super-large ship can be set as an alarm to remind the operator that its effect is much better than the current navigation warning. Navigation warnings, such as gale warning and emergency rescue, will definitely be very different from the current practice, and the result will greatly improve work efficiency and facilitate users.

App application

The automatic ship identification system is less disturbed by external natural factors, and plays a unique and important role in ship navigation, collision avoidance, ship communication, ship-shore communication, maritime search and rescue, maritime investigation and so on. Ships sailing in open waters can automatically obtain all kinds of information of ships without VHF wireless telephone call; Ships sailing in restricted waters can not only automatically obtain information of other ships, but also obtain various navigation information and port information through VTS broadcasting. This can prevent ship collision and various maritime accidents to the greatest extent, and bring unprecedented security to the shipping industry. In order to reduce operating costs, modern international shipping is developing towards large-scale, high-speed and full automation. In order to ensure the safety of ship navigation and protect the marine ecological environment, an automatic ship identification system is needed. The automatic ship identification system can also change the operation and management mode of shipping enterprises. In the application of automatic ship identification system, BLM-Shipping integrates fleet management, ship positioning and tracking and voyage management on one platform, which promotes shipping enterprises to enter the era of e-commerce and greatly improves the management efficiency and service level of shipping enterprises.