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THE COMPLETE GUIDE TO

A u t o m a t i c I d e n t i f i c a t i o n S y s t e m


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The Complete Guide toAutomatic Identication

Systems

Leica Geosystems Inc.


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Copyright 2001 Leica Geosystems Inc.


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this is the chapter headline

table of contentsintroduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5chapter 1What is AIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Ship -to-ship d ata exchang e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Fig. 1: Typical ship-to-ship operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Fig. 2: Typical AIS display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Co astal surveillance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Fig. 3: AIS with coastal surveillance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Vessel trafc systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Fig. 4: Integrated AIS/VTS network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Potential bene ts o f AIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

chapter 2AIS Communications Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . 12Fig. 5: AIS cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Fig. 6: Timeslot assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

chapter 3AIS Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

chapter 4AIS Shipboard Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Fig. 7: Functional diagram of shipboard AIS system . . . . . . . . . . . . . . . . . 17

To tal shipb o ard G PS/ DG PS/ AIS solutio n . . . . . . . . . . . . . . . . . . . . . . . . 18

chapter 5Carriage Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

What ab o ut no n-so las vessels? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

chapter 6AIS Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

appendixUseful Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24


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5

introductionIts a dark night. The ofcer of the watch is tracking a dozen or more targets on theradar. One of the blips on the radar screen seems to be turning to the right. TheOOW picks up the VHF microphone.

Vessel on my starboard bow, this is MV Eversail. It appears you may be making aturn to starboard. Do you intend to cross my bow, over?

Eversail, this is MV Seafarer. Are you the ship in the inbound lane near buoy 23,over?

Seafarer, this is Eversail. Thats negative, I am at the junction buoy near Deadmans Reef, over.

This is Seafarer, Roger, out.

Eversail, this is MV Oceanbreeze, I think I am the vessel off your starboard bow. I am outbound in the auxiliary channel from the tanker berth. I am slowing todisembark the pilot, over.

Oceanbreeze, this is Eversail. I have you on my radar. You are not the ship I wascalling, over.

Vessel ve miles off my starboard bow, this is MV Eversail in the outbound channel passing Deadmans Reef junction buoy. What are your intentions, over?

Eversail, this is MV John Brown. I think I am the vessel off your starboard bow,over.

John Brown, this is MV Seafarer. I believe I am astern of you. Are you the shipthats just passing Buoy 23, over?

s i l e n c e

s i l e n c e

a n d s o f o r t h . . .


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Radio exchanges like the above are a commonplace occurrence on ships at sea,especially in busy waterways. The weak link in the current generation of collision-avoidance electronics is the inability to identify any given radar target whenmultiple contacts are being tracked, especially at night or in reduced visibility,when it is impossible to verify a ship s identity visually. This inevitably leads toconfusion, and has been cited as a contributing factor to many collisions andnear-collisions at sea.

A new technology, called Automatic Identi cation Systems (AIS), will help toresolve this dif culty by providing a means for ships to exchange ID, position,course, speed and other vital data, with all other nearby ships and shore stationsthrough a standardized transponder system. The data exchange will be totally

automatic and transparent to the users. The result will be a dramaticimprovement in situational awareness for of cers of the watch, who will have aclear and unambiguous identi cation, as well as other vital information, from allother AIS-equipped ships.

AIS will have a far-reaching impact on safety at sea. It will be required on mostocean-going commercial ships, and will also be integrated into shoresidesurveillance and vessel traf c control systems.

In this booklet, Leica Geosystems presents an overview of this important newtechnology, including a simpli ed explanation of system functionality, carriagerequirements, equipment speci cations and references. Leica has been deeplyinvolved in AIS technology from its inception more than 20 years ago, and is aleading supplier of high-precision GPS and DGPS equipment for the maritimeindustry worldwide.

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AISis a shipboard broadcast transponder system in which ships continuallytransmit their ID, position, course, speed and other data to all other nearby ships andshoreside authorities on a common VHF radio channel. The concept is derived fromthe pioneering work of a Swedish inventor named H kan Lans, who developed in themid 1980s an ingenious technique for spontaneous, masterless communication,which permits a large number of transmitters to send data bursts over a singlenarrowband radio channel by synchronizing their data transmissions to a very precisetiming standard. This data communications scheme is described in the next chapter.

AIS is designed to operate in one of the following modes: In a ship-to-ship mode for collision avoidance As a means for coastal states to obtain information about a ship and its cargo

As a traf c management tool when integrated with a Vessel Traf c System(VTS)

ship-to-ship data exchangeThe primary operating mode for AIS will be autonomous ship-to-ship reporting. Inthis mode, each ship transmits its data to all other AIS-equipped ships within VHFrange. The unique communications scheme permits these data transmissions to takeplace independently without the need for a master control station.

c h a p t e r 1

what is AIS?


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Position and other data are fed automatically from the ship s sensors into the AISsystem, where the data is formatted and transmitted in a short data burst on adedicated VHF channel. When received on the other ships, the data is decodedand displayed for the of cer of the watch, who can view AIS reports from all otherAIS-equipped ships within range in graphic and text format. The AIS data mayoptionally be fed to the ship s integrated navigation systems and radar plottingsystems to provide AIS tags for radar targets. The AIS data can also be logged tothe ship s Voyage Data Recorder (VDR) for playback and future analysis.

Updated AIS messages are transmitted every few seconds, to keep the informationup to date. Note that the ship-to-ship data exchange takes place automaticallywithout any action required by the watch of cer on either ship.

In pilotage waters, a pilot can plug a laptop computer, loaded with his ownnavigation program, directly into the ship s AIS system. In this way, the pilot canmonitor the position and movement of all other vessels in the area independent of the ship s installed navigation systems.

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Typi cal AIS Dis pl ay Figure 2


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coastal surveillanceIn coastal waters, shoreside authorities may establish automated AIS stations tomonitor the movement of vessels through the area. These stations may simplymonitor AIS transmissions from passing ships, or may actively poll vessels via the

AIS channels, requesting data such as identi cation, destination, ETA, type of cargo and other information. Coast stations can also use the AIS channels forshore-to-ship transmissions, to send information on tides, notices to mariners andlocal weather forecasts. Multiple AIS coast stations and repeaters may be tiedtogether into Wide Area Networks (WAN) for extended coverage.

Coastal nations may use AIS to monitor the movement of hazardous cargoes andcontrol commercial shing operations in their territorial waters. AIS data can belogged automatically for playback in investigating an accident, oil spill or otherevent. AIS will also be a useful tool in search and rescue (SAR) operations, allowingSAR coordinators to monitor the movements of all surface ships, aircraft andhelicopters involved in the rescue effort.

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vessel traf c systemsWhen integrated with shore-based vessel traf c systems (VTS), AIS provides apowerful tool for monitoring and controlling the movement of vessels throughrestricted harbors and waterways. The AIS can augment traditional radar-based

VTS installations, providing an AIS overlay on the radar picture, or can provide acost-effective alternative in areas where it is not feasible to establish radar-basedsystems. When integrated with radar, the AIS can ensure continuous coverage,even when the radar picture is degraded by heavy precipitation or otherinterference.

The AIS channels can be used to transmit port data, pilotage, berth assignments,shipping agency information, tides and currents, notices to mariners and otherinformation from shore to ship, as well as ship-to-ship and ship-to-shore AISreports. It is also possible for the VTS to broadcast the complete harbor picture toall ships in the area, so the masters and pilots all share the same big picture.

The VTS center can assume control over the assignment of timeslots for AISmessages to ensure optimum data exchange within the coverage area. Specialdedicated channels may be designated for local-area AIS operations. The shipboardAIS equipment will have the ability to shift to different channels automaticallywhen directed by the shoreside VTS controller.

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For the Of cer of the Watch Imp roved situatio nal awareness

Unambiguo us identi cation of radar targets

Overcome p rob lem of target sw app ing w hen two contacts p ass

clo se tog ether on the rad ar screen

Ability to see aro und b ends or b ehind a landmass, to d etect and

identify other ships Pred ict the p lace and time o f CPA w ith other vessels

Detect a change in ano ther ship s head ing almo st in real time w itho ut

waiting fo r ARPA calculations

Detect vessels that might otherw ise b e hidd en in ano ther vessel s

radar shadow

Real time informatio n abo ut other ship s movements (e.g.,

accelerating o r d ecelerating, rate o f turn)

Automatically swap informatio n o n d estination, ETA, loading

cond ition and o ther d ata with nearby ship s

Red uce VHF vo ice traf c, since d ata is exchanged auto matically

For the VTS Center Watchstander Automatic identi cation of radar targe ts

O vercome target swapp ing o f radar co ntacts

Constant cove rage even when radar p icture is d eg rad ed b y weather

and interference

Tracking o f vessels be hind islands and o b stacles

Ab ility to send p o rt data, weather forecasts and safety messages

automatically to all ships in the area Decrease need for manual input o f static data, such as vessel name,

size, d raft and cargo

Auto matic lo g g ing o f all data

potential benets of AIS


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AISmessages must be updated and retransmitted every few seconds at aminimum, since the usefulness of the data decays rapidly as a function of time. Toaccommodate this high update requirement, AIS utilizes a unique self-organizingtime-division multiple access (STDMA) data communications scheme, which uses

the precise timing data in the GPS signals to synchronize multiple datatransmissions from many users on a single narrowband channel.

Each ship broadcasts its AIS messages and receives messages from all ships withinVHF radio range. The area in which AIS messages can be received is called theship s cell. Each ship is in this way in the center of its own communication cell.

The practical size of the cell can be varied according to the traf c density on theAIS channel. If the number of AIS messages begins to overload the network, theship s AIS system can automatically shrink its cell by ignoring weaker stationsfurther away in favor of those nearby.

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AIS communications scheme


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Under the STDMA protocol, each minute of time is divided into 2,250 timeslots. AnAIS report ts into one or several of these 2,250 timeslots, which are selectedautomatically based on data link traf c and projections of future actions by otherstations currently on the network. When a ship rst enters the cell of another ship, ittakes an unoccupied timeslot. The AIS stations continually synchronize their slotselections with each other.

Timeslots and timeout periods are selected on a randomized basis. When a stationchanges its slot assignment, it announces to all other stations on the channel its newlocation and timeout for that location. Each station continually updates its internalslot map to re ect changes in occupied slots and timeouts. Special provisions aremade for automatic con ict resolution in the event two stations end up in the same

timeslot, to ensure that stations always choose unoccupied slots. In situations of hightraf c density it may be necessary to reduce the number of ships in a communicationcell, as described above. This enables time slots used by weak stations far away, to beused also by a station nearby. The AIS system applies very speci c rules on how thisreoccupation of timeslots is done.

The key to the STDMA scheme is the availability of a highly accurate standard timereference, to which all of the stations can synchronize their timeslot assignments, inorder to avoid overlap. This time reference is supplied by the precise timing signal inthe GPS satellite message. Thus, GPS plays a critical role in AIS, providing theuniversal time reference as well as positioning data for each ship.

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AIS data transmissions utilize a robust 9.6 kbps FM /GMSK (Gaussian MinimumShift Keying) modulation technique, which is speci ed in ITU RecommendationM.1371.1. The International Telecommunications Union (ITU) has designated twodedicated frequencies for AIS. They are 161.975 MHz (marine band channel 87B)and 162.025 MHz (channel 88B). In some parts of the world, such as the UnitedStates, where these frequencies may not be available for AIS, other channels maybe designated.

The ship s AIS station has two independent VHF receivers, which are normallytuned to the two AIS frequencies, as well as one transmitter, which alternates itstransmissions back and forth between the two. The shipborne system can also beretuned to other frequencies, for instance when operating under the control of a

shore-based VTS. This can be done either manually or remotely by the AIS shorestation.

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AISis designed to work autonomously and continuously in a ship-to-ship mode,but the speci cations provide for switchover to an assigned mode for operation inan area subject to a competent authority responsible for traf c monitoring, with thedata transmission intervals and timeslots set remotely by the shoreside authority.Alternatively, the AIS can work in a polling mode in which the data transferoccurs in response to interrogation from another ship or shore station.

Information provided by the AIS falls into several categories:

Static dataIMO number (where available)Call sign and name

Length and beamType of shipLocation of position- xing antenna on the ship

(aft of bow and port or starboard of centerline)

Dynamic dataShip s position with accuracy indication and integrity statusTime in UTC

Course over groundSpeed over groundHeadingNavigational status (e.g., at anchor, not under command,

manually entered)Rate of turn (where available)

Voyage related dataShip s draftHazardous cargo (type)Destination and ETA (at master s discretion)

Safety-related messagesAs needed

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c h a p t e r 3

AIS messages


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Dynamic information is derived from interfaces with the ship s GPS and othersensors. Static information is programmed into the unit at commissioning. Voyage-related data is entered manually by the master through a password-protectedroutine. Safety messages can be inserted at any time by the ship or shore station.

The static and voyage-related data are transmitted every six minutes, whenamended or on request (for instance, when interrogated by a Vessel Traf c Systemoperator). Safety messages are sent as needed. The update rates for dynamicinformation will depend on the ship s status and speed, according to the followingschedule:

At anchor 3 minutes

0-14 knots 10 seconds0-14 knots and changing course 3 1 / 3 seconds14-23 knots 6 seconds14-23 knots and changing course 2 seconds23+ knots 2 seconds23+ knots and changing course 2 seconds

The AIS speci cations also allow for insertion of brief binary messages from shipsor shore stations. Such messages might include notices to mariners, navigationalwarnings, tides and currents, weather forecasts, SAR communications and ship-speci c instructions from a VTS operator. The AIS standard also includes formatsfor transmission of differential GPS error correction data. This can provide valuableredundancy to existing beacon DGPS systems in critical navigation areas.

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IMO Resolution MSC.74(69), Annex 3 (see Chapter 6) states that an approvedshipboard AIS system shall be able to perform the following functions:

Automatically provide information on the ship s identity, type, position,course, speed, navigational status and other safety-related matters toappropriately equipped shore stations, other ships and aircraft.

Receive automatically such information from similarly tted ships. Monitor and track ships. Exchange data with shore-based facilities.

A shipboard AIS system consists of the following elements: An STDMA radio transponder with two VHF receivers and one transmitter

(it is also possible that the transponder have a Digital Selective Calling{DSC} receiver tuned to Channel 70).

A control and display unit, which includes the communications processorand interfaces for taking inputs from the ship s navigation sensors andsending outputs to external systems, such as ECDIS, ARPA, VDR orInmarsat terminal.

One or more GPS/DGPS receivers that provide position information as wellas the precise time base needed to synchronize the STDMA datatransmissions.

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AIS shipboard equipment

AIS Tr anspond er

AIS Reports

AIS Reportsfrom otherstations

Data from GPS/DSPS Time in UTC Position Course Speed

Data programmed into unit IMO number Call sign Length & beam Ship type Location of GPS antenna

Data from other ship sources Gyrocompass Speed log

Data entered by Master Ship's draft Hazardous cargo Destination ETA Route plan

Interface

with ECDIS,

ARPA or

other ship

systems

Special

Port for

Pilot

Hook-up

Control &

Display Unit

Shi pboar d AIS Syst em Figur e 7


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Ship s position and precise timing data are derived from the GPS receiver,augmented by differential corrections when available. Other data is fed into theAIS from shipboard sensors, such as gyrocompass and speed log, via a standardNMEA-0183/2000 interface. Static and voyage-related data are operator-enteredthrough a keyboard. The AIS communications processor organizes the data fortransmission and handles all STDMA communications functions. The shipboardtransponder system receives AIS reports from other ships and shore stations anddisplays the AIS data for each target in text or graphic format. Serial data ports areused to output AIS data for display on an external device, such as ECDIS, ARPAor remote PC.

total shipboardGPS/DGPS/AIS solution

Leica s MX420 Navigatio n System was introd uced to p rovide an

integ rated so lutio n fo r marine G PS, DGPS and AIS. The MX 420

incorporates:

a co mb ined Contro l and Disp lay Unit fo r G PS, DGPS and AIS,

incorp o rating the mo st wide ly accep ted standard man machine

interface (MM I) for marine G PS

the w o rld s most accurate G PS receiver (MX 421), b ased o n new -

generation Silico n G ermanium (SiGe) chip technolo gy, sealed in

a smart antenna radome

a d ifferential GPS b eacon receiver that meets all p rojected IMO

carriage requirements

an IMO -comp liant AIS transp o nde r develo p ed b y industry

p ioneer SAAB Transp o nderTech

The M X420 Navig ation System is b uilt to meet all ex isting

app licab le international marine stand ard s, and it is d esigned to b e

comp liant also to future stand ard s thro ugh so ftware upg rades.


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The M X 420 Control and Disp lay Unit (CDU) collects and

d ecod es AIS repo rts from o ther statio ns and p rovid es a

reado ut o f information from all AIS-eq uipp ed ships and shore

stations. Data can b e v iewed in text o r g raphic form. The M X

420 CDU gathers inputs from ship s sensors and o rganizes the

d ata for transmissio n via AIS. The CDU is also used fo r ente ring

AIS static and voyage-related information for AIS broadcasts,

as well as system setup functio ns. Hig h-sp eed serial data po rts

are p rovided for outputs to the ECDIS, ARPA o r o ther

ship b o ard systems. An extra p o rt has b een p rovid ed for a

ship s p ilot to p lug into the AIS system.

The M X420 CDU come s either as an AIS-o nly CDU, called

M X420/ AIS Basic, o r as a comb ined DGPS and AIS Control

and Disp lay unit, called M X420/ AIS. The M X420/ AIS Basic

connects to an existing G PS o r DGPS receiver o n bo ard , w hile

the M X420/ AIS interfaces to the new M X421 o r M X421B smart

antenna and includ es all GPS navig ation functions.

The M X 421 smart antenna inco rpo rates the new SiGe-based

G PS receiver d eve lop ed jo intly b y Leica and IBM. The resultsare asto unding. The M X 421 d elive rs RM S (roo t mean sq uare)

accuracy o f b etter than 3 meters using auto nomo us G PS

signals in a non-d ifferential mo d e. The d ual-channel DGPS

b eaco n receiver, w ith H- eld antenna, p rovides p o sition

so lutio ns o f better than 1 meter RM S, as well as the inherent

reliability and integ rity mo nitoring p rovid ed b y the DG PSb eacon b roadcasts. The M X421 is a typ e app roved

co mmercial marine G PS o r DGPS sensor that is d esigned to

mee t all existing and p rojected IMO carriage requirements.


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The IMOhas established mandatory carriage requirements for approved AISequipment under the Safety of Life at Sea (SOLAS) Convention. The AIS carriagerequirements will apply to:

all ships of 300 gross tonnage and upwards engaged on international voyages cargo ships of 500 gross tonnage and upwards not engaged on international

voyages all passenger ships irrespective of size

All newbuilds must be tted with an approved AIS after July 1, 2002. Existingships engaged in international voyages constructed before July 1, 2002, must betted according to the following timetable:

In the case of passenger ships, not later than July 1, 2003 In the case of tankers, not later than the rst safety equipment survey after

July 1, 2003 In the case of ships other than passenger ships and tankers of 50,000 gross

tonnage and upwards, not later than July 1, 2004. In the case of ships other than passenger ships and tankers of 10,000 to

50,000 gross tonnage, not later than July 1, 2005. In the case of ships other than passenger ships and tankers of 3,000 to

10,000 gross tonnage, not later than July 1, 2006. In the case of ships other than passenger ships and tankers of 300 to 3,000

gross tonnage, not later than July 1, 2007.

Existing ships not engaged on international voyages constructed before July 1,2002, must be tted not later than July 1, 2008.

A ag state may exempt ships from complying with the carriage requirements if theships will be removed permanently from service within two years of theimplementation date.

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c h a p t e r 5

carriage requirements


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The AIS carriage req uirem ents ap p ly o nly to co mm ercial

ve sse ls sub je ct to the Safety o f Life at Se a (SO LAS)

co nventio n. What ab o ut smaller ve ssels, such as tugs,

w o rkbo ats, f ishing v essels and p leasure yachts, w hich wil l

not b e e q uip p ed w ith AIS? Wil l they b e invisible to

shipb o ard and A IS sho re statio ns?

In so me areas, such as inland rive rs, w hich carry heavy

co mm ercial traffic, i t is l ikely that p o rt states w ill ex p and the

AIS carriage req uirem ents to includ e o ther craft , such as tug-

b arg e co mb inat io ns. Likew ise, so me nat io ns may d ecid e to

use AIS techno lo g y to mo nito r f ishing in their l it toral w aters

b y req uir ing co mme rcial fishing v essels to b e eq uip p ed

w ith A IS.

There is co nsid erab le d iscussio n in marit ime circles abo ut

d eve lop ing a so r t o f mini-AIS simp lif ied t ransp o nd ers

that co uld b e installed o n no n-SO LAS ve ssels. These

d evices mig ht b e sho rter-range co mb ined t ransmit / receive

d ev ices transmitt ing l imited info rmation at a red uced

upd ate ra te , o r in so me cases receive-only terminals

receiving and d isp laying AIS d ata from o ther ve ssels, b ut

no t transmitting STDM A d ata. Sp ecificatio ns are ye t to b e

d e te rmined for these typ es o f eq uip ment.

what about non-solas vessels?


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Thereare three primary international standards for AIS equipment. They weredeveloped jointly by the International Maritime Organization (IMO), InternationalTelecommunications Union (ITU) and International Electrotechnical Commission(IEC). The shipboard AIS equipment must meet the provisions of all threedocuments.

IMO Resolution MSC.74(69), Annex 3, Recommendations on PerformanceStandards for a Universal Shipborne Automatic Identi cation System (AIS)

This document establishes carriage requirements for AIS and performancerequirements for the shipboard equipment. The IMO standard was used bythe ITU and IEC in developing technical and test standards. It was approvedby the IMO Subcommittee on Safety of Navigation at its 45th session in late

2000.

ITU-R Recommendation M.1371-1, Technical Characteristics for a UniversalShipborne Automatic Identi cation System Using Time Division Multiple Access inthe Maritime Mobile Band

This document de nes in detail how AIS and STDMA technology works. Theoriginal standard, adopted by the International Telecommunications Union(ITU) in 1998, was revised in 2001 to clarify design requirements.

IEC Standard 61993-2, Universal Shipborne Automatic Identi cation System (AIS) This standard speci es the minimum operational and performancerequirements, methods of testing and required test results conforming to theperformance standards contained in IMO Resolution MSC.74(69), Annex 3.It incorporates the technical characteristics contained in ITU-R M.1371-1 andtakes into account the ITU Radio Regulations where appropriate. This draftstandard is expected to be approved for publication by December 2001.

Other organizations involved in AIS standards development include the following.

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c h a p t e r 6

AIS standards


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International Association of Lighthouse Authorities (IALA/AISM).IALA has been the primary organization spearheading the development andadoption of universal AIS transponder technology in the marine industry. IALAprepared the rst recommended performance standards in 1996, whichbecame the basis for the ITU standard. The IALA AIS Committee meets fourtimes each year to support continued development of the technology.

Radio-Technical Commission for Maritime Services (RTCM)RTCM Special Committee 101 is concerned with Digital Selective Calling(DSC) and AIS issues. It meets to prepare proposals to international standard-making bodies.

National Marine Electronics Association (NMEA)The latest version of the NMEA 0183 standard for marine electronicsinterfacing includes provisions for data exchange with an AIS transponder.NMEA 0183 will be superseded and supplemented by a new standard,NMEA 2000, which also provides AIS data formats.

Other standards that relate to the AIS application are:

IEC 61108-1 for marine GPS receivers.This standard is currently being reworked in order to enhance the reliabilityand integrity of marine GPS navigation.

IEC 61108-4 for beacon DGPS receivers.There is a new draft of this standard that is intended to provide higherrobustness and integrity in DGPS navigation.

IMO MSC 64(67), Annex 2, Recommendations for DGPS Performance StandardsThis standard was amended by the Marine Safety Committee in November2000. It will establish carriage requirements and performance characteristicsfor DGPS beacon receivers.

These standards will enhance the performance of shipboard GPS and DGPSequipment to fully support the AIS functions.

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useful links

U.S. Coast Guard Navigation Center www.navcen.uscg.gov

G.P.&C. Systems International www.gpc.se

Universal AIS Website www.uais.org

SAAB Transponder Tech www.transpondertech.se

Swedish Maritime Authority www.sjofartsverket.se

International Maritime Organization www.imo.org

International Telecommunications Union www.itu.ch

International Electrotechnical Commission www.iec.ch

International Association of Lighthouse Authorities www.iala-aism.com

Leica Geosystems www.leica-geosystems.com

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appendix


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Con tact Leica Geosystem s: +1 310 791 5300 (USA - Canada),

ais booklet

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