Shipboard Automatic Identification System Displays Meeting the Needs of Mariners -- Special Report 273 (2003) / Chapter Skim
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1 Introduction
1 Introduction
Pages 15-42
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From page 15... ...
Second, governmental agencies of coastal states that are responsible for the prevention of and response to marine pollution incidents, conservation of natural resources, vessel traffic management, maritime security, and law enforcement are interested in vessel identification as well as in monitoring certain vessel activities and movements. Until AIS and similar technologies came into use, such monitoring required physical sighting and identification of the vessels of concern, voluntary reporting by such vessels, or, in the prox imity of a coast, use of radar or other active surveillance.
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Over the past few years, the Inter national Maritime Organization (IMO) , working through the International Telecommunication Union (ITU)
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From page 17... ...
, a broadcast system operating in the VHF maritime mobile band. The shipboard component is capable of sending information such as a vessel's identification, position, course, and speed to other ships and shore stations.
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The integrity of the static data is not assured. Static data, including data showing the identity of the carrying vessel, are manually entered by an operator.
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Since the focus of this report is AIS shipboard displays, a full description of the underlying AIS technology is beyond its scope. Many sources provide such a description, and they may be consulted to obtain a detailed under standing.
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If the number of AIS messages begins to overload the network, the system can automatically shrink its cell size by ignoring weaker stations further away in favor of those nearby. The size of AIS cells can be varied to reflect the volume of vessel traffic and the types and extent of "safety-related" messages transmitted by shore stations.
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From page 21... ...
The lim itations of the MKD are discussed in Chapter 4. IMO and other bodies have also established a series of AIS international standards governing system performance, technical characteristics of the system, frequency allocation for the VHF communications medium, and Display Assemble Communicate ARPA Laptop HDG GPS/ COG ECDIS ECS DGPS Speed Displays incoming Gathers vessel movement Initiates and controls the vessel information on information and assembles flow of data sentences a suitable device it into an AIS-compliant between participating units data sentence FIGURE 1-1 Elements of shipboard AIS.
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From page 22... ...
8 in developing technical and test standards. ITU-R Recommendation M.1371-1, Technical Characteristics for a Universal Shipborne Automatic Identification System Using Time Division Multiple Access in the Maritime Mobile Band (ITU 2001)
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From page 23... ...
Ship-Originated AIS Messages AIS messages need to be updated and retransmitted every few seconds because the usefulness of some data, particularly data applying to the posi tion and movement of vessels, decays rapidly as a function of time. For vessel position and movement data to be useful, the update rate must be sufficient to develop a cohesive representation of the transmitting vessel's position and track.
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From page 24... ...
In addition to these required data, discretionary data may be transmitted as desired by the vessel master, and optional data may be transmitted if appropriate sensor equip ment is installed and properly connected to the AIS unit for compilation into the AIS message format and timely transmission. From the perspective of the mariner, the data conveyed by ship-to-ship AIS can provide a heightened level of awareness of other vessels and their movements in a waterway.
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Length and beam Set on installation Type of ship Set on installation from preinstalled list IMO number Set on installation GPS antenna location Set on installation Height over keel Set on installation Dynamic information: Dependent on speed (see IALA 2001, Table 1-1) Ship position with accuracy Automatic update from position course sensor indication and integrity Accuracy indication better or worse than 10 meters Position time stamp Automatically updated from main position sensor Course over ground Automatically updated from main position sensor Speed over ground Automatically updated from main position sensor Heading Automatically updated from main position sensor Navigational status Manually entered by the officer of the watch Under way by engine At anchor Not under command Restricted in ability to maneuver Moored Constrained by draft Aground Engaged in fishing Under way by sail Rate of turn (ROT)
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From page 26... ...
When AIS is called on to serve a function such as collision avoidance, shipboard display becomes critical. The display of ship-to-ship data, specif ically the dynamic data that deal with vessel movement, has developed faster than the display of other types of data.
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IMO (2001b) has published recommended standards for the display of ship-to-ship data, including the symbology that should be used to display vessel targets.10 The display of shipboard AIS information is the subject of this report.
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Such an approach, however, could significantly complicate display require ments. CURRENT DISPLAY DESIGNS AND THEIR CAPABILITIES Shipboard AIS displays can take many forms.
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This is a relatively simple AIS display concept incorpo rating a display screen on which simple icons representing AIS targets are plotted. Along with the graphical representation of the vessel traf fic environment, AIS information such as bearing, target angle, speed, and so forth are displayed for each icon.
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From page 30... ...
/electronic charting and display in formation systems/radar/automatic radar plotting aid integration. Arguably the most sophisticated AIS display technology today involves the integration of AIS information with other bridge navigation and information systems, such as ECS and radar.
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From page 31... ...
and the Canadian Coast Guard, issued a mandatory AIS carriage requirement for all oceangoing and lake vessels transiting the seaway beginning March 25, 2003. The seaway authorities are arranging for vendors to rent or lease AIS units to vessels without permanent AIS equipment that transit the seaway after March 25, 2003.
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From page 32... ...
Except as it may affect the overall AIS imple mentation schedule, the long-range application of AIS for security purposes should not affect shipboard display issues. Long-range AIS communications are based on an interrogationresponse system that effectively limits the ship-related data transmitted to one or more of three "long-range data formats" shown in Table 1-5.
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From page 33... ...
as follows: Class A Shipborne Mobile Equipment will comply with relevant IMO AIS car riage requirements. Class B Shipborne Mobile Equipment will provide facilities not necessarily in full accordance with IMO AIS carriage requirements.
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15The personal pilot unit is also known as a personal pilot pack, portable pilot pack, portable pilot unit, and so forth.
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The standard shipboard AIS will be fitted with a pilot/auxiliary input/out put port, which will allow the pilot to plug in his or her own workstation and receive more frequent "own ship" navigational information. In this way the pilot will also receive all other AIS information at the standard AIS rate and be able to forward information to other vessels in the vicinity or to a VTS.
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From page 36... ...
The second component, reporting of voyage/ cargo/passenger/crewrelated data, may fit technically within the capabil ity of ships to transmit short safety-related messages via AIS, depending on the data requirements imposed. Until those requirements have been estab lished with respect to both data content and frequency, the effect on mariner workload and shipboard display requirements remains a matter of 16The relevant portion states, "The Coast Guard will achieve the ability to acquire, track, and identify in real time vessels and aircraft entering America's maritime domain."
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waive the application of paragraph (1) with respect to operation of vessels on navigable waters of the United States specified by the Secretary if the Secretary finds that automatic identification systems are not needed for safe navigation on those waters.
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Such use might require incorporating the capacity for alerting mariners to the receipt or transmission of urgent messages into ship board AIS displays. Such an alerting capability may have wider application than just security.
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AIS functions and shipboard tasks should be matched to the requirements that may be established for displays, and preliminary task analyses on board vessels that might carry AIS displays were conducted to illustrate a systematic approach for setting display requirements. The requirements analysis process
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The recommendations also address the application of human factors design prin ciples to the development of shipboard AIS displays and consider the impact of such displays on future systems and programs. This report addresses the challenges associated with shipboard display of AIS information but does not cover the full spectrum of AIS challenges.
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From page 41... ...
2001. Recommendation M.1371-1: Technical Characteristics for a Universal Shipborne Automatic Identification System Using Time Division Multiple Access in the VHF Maritime Mobile Band.
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From page 42... ...
1990. Vessel Traffic Services (VTS)
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