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        ELECTRONICS



          AIS Implementation: a news round-up
                                   Fred Pot, Principal of Marine Management Consulting, gives us the latest news
                                        and developments about Automatic Identification Systems on vessels

        THE REMOTE Automatic Identification            to process AIS information in a timely         showed just 30 minutes (12.1 nm) before        DSC from the AIS standard may be possible
        System (AIS) which the International           fashion, a high-speed, 38.4 kb per second      passing, which was well after each ship        in the future, but type approved transpon-
        Maritime Organisation (IMO) has                version of the same protocol has also been     had      selected    its    channel.   See     ders will probably need to have DSC capa-
        embraced in principal and will require         developed (NMEA 0183-HS / IEC 61162-           http://www.bcmarine.org/wmc/uais/              bility even if it will never be used.
        ships to carry in future, is currently         2). This new version was published on July     cruise.htm for Sea Princess' ECDIS screen
        being defined by government entities           1, 2000.                                       prints of this encounter.                      In heavy traffic areas USCG feels that the
        and by commercial interests. AIS con-              This means that producers of ECDIS,           Although formal analysis of the test        throughput capacity that AIS provides
        sists of a shipboard transmitter that digi-    radars and integrated bridge systems can       data has yet to be completed, bridge           with channels 88B and 87B (19.2 KB per
        tally broadcasts its name, position, speed     now start to develop and test a single stan-   teams reported noticeable differences in       Second) will prove to be insufficient and
        and course along with other details            dard interface that allows their equipment     range and bearing between AIS and              that a third AIS channel will be needed
        via VHF to nearby ships and coastal            to be connected to any type-approved           ARPA targets of the same ship, thus rein-      for base stations to interrogate ships, to
        authorities.                                   transponder.                                   forcing the need for consolidation and         broadcast safety messages and to re-
           An AIS 'transponder' also has two                                                          avoidance of screen clutter. (Since AIS        broadcast AIS information it receives. For
        VHF radios that receive this information       Writing software for an interface between      position information was updated every 2       these purposes USCG intends to remote-
        from other ships. Although a transpon-         ECDIS/radar and an AIS transponder is          seconds for this trial, latency cannot         ly switch one of a ship's transponder's
        der has a small, 3-line display to display     one thing; displaying AIS information on       explain the differences).                      two radios temporarily from 87B or 88B
        the information it receives, it is typically   screen is quite another. AIS provides much        AIS really shone, however, when it          to this third channel.
        connected to a ship's electronic chart or      more information than radar, so new sym-       came to filling in the many radar blind           While this solution increases the
        radar to provide a more practical display      bols and rules will be needed in order to      spots in Alaskan and British Columbian         capacity available for AIS traffic in an
        of AIS information.                            display the many and varied things which       fjords. In one instance, the range between     area by 50 per cent, it does not increase
                                                       AIS can provide, such as actual current        Regal and Sea was only 6.3 nm, but there       the capacity of an individual ship's
        IMO will likely require new ships con-         velocity observations.                         was a 762 m high island in between them.       transponder.
        structed after July 1, 2002 to carry a            Singapore is planning to test display       AIS was able to show a complete picture
        transponder. Existing passenger ships and      alternatives on three Marine and Port          of the traffic situation to the officer on     In     addition     to    87B,     MariTEL
        tankers will need to carry a transponder a     Authority (MPA) vessels starting this fall.    watch almost irrespective of coastal           (www.maritelusa.com) also owns many
        year later, with other existing ships over     An international committee will direct the     geography.                                     more marine VHF frequencies in the US.
        30,000 GRT, to follow a year after that. By    test. Unfortunately this committee lacks          To assist in optimally spotting future      In alliance with several partners, it intends
        2008 even small (>300 GRT) ships that are      representation from ship operators, and        AIS base and repeater stations along a         to build 286 330ft high towers, each with a
        not involved in international voyages will     MPA vessel crews are not necessarily rep-      rocky coast, an analyst will use the AIS       minimum range of 50 nm to serve the
        be required to carry one and many coun-        resentative of important future AIS users:     test data to attempt to fashion a model        marine industry, with analog voice as well
        tries are likely to require domestic tonnage   bridge teams sailing on large ships with       that predicts AIS range given the charac-      as 14.4 kb per second data transmission
        to carry transponders well beyond IMO's        sophisticated integrated bridge systems.       teristics of the surrounding terrain. This     services. All base stations will be connect-
        requirements both in starting date and in      Hopefully, ship operators will involve         will not be easy because AIS' range, just      ed to a central control centre that will
        minimum ship size.                             themselves in the process soon to make         like VHF's range, turns out to be affected     route voice calls and data transmissions,
            But first AIS standards have to be         sure the standard will work for their          by characteristics beyond those that are       verify and charge credit cards and provide
        defined.                                       bridge teams.                                  easily measurable, like terrain height         customer service 24x7.
                                                          Because there is much testing to be         between transponder antennas. In the              The network has been dubbed MariNET
        To make sure that transponders from dif-       done, AIS symbols and display rules will       test, so far, AIS range peaked at about 71     (a name that is already used by a British
        ferent manufacturers can understand each       probably not be complete until the fall of     nm but also was as short as 12 nm,             company that is in a similar business). The
        other, the International Electrotechnical      2001.                                          although the latter may have been              base stations have been designed to sup-
        Commission is in the process of defining                                                      caused by a combination of terrain             port multiple protocols and modulation
        performance criteria for type approval of      Bridge teams of the cruise ships Regal         characteristics and temporary 'technical       methods, including the Time Division
        transponders (Future Publication IEC           Princess, Sea Princess and Volendam have       challenges'.                                   Multiple Access (TDMA) protocol which
        61993-2). International agreement on these     just completed testing AIS in British                                                         could be used to communicate with ships
        criteria is expected to be reached by          Columbia/Alaska under the auspices of          In the US, MariTEL acquired VHF                that are equipped with AIS transponders.
        December of this year.                         an association of private and government       Channel 87B, which has been reserved           With such an extensive infrastructure,
           In the meantime, two of the transpon-       maritime interests (PACMAR). Because           for AIS in the rest of the world, from the     MariTEL may be able to entice USCG to use
        der manufacturers that are actively            this test preceded availability of standards   government along with many other               its infrastructure instead of building its
        involved in defining these criteria, are       for interoperability between transponders      marine VHF channels. USCG is currently         own with tax dollars.
        working out the detailed issues that, so       and standards for interfacing transpon-        negotiating with MariTEL to free up 87B           To achieve 14.4 kb per second,
        far, have prevented actual inter-operabil-     ders with other navigational instruments,      for AIS.                                       MariNET may use a combination of
        ity. "Marine Data Systems (of South            the transponders of a single manufacturer         According to both USCG Capt. Robert         TDMA and Frequency Division Multiple
        Africa) and Saab Transpondertech (of           (Tideland Signal/MDS) were used and            Ross and Thom Belesky, vice president of       Access (FDMA). MariTEL hopes to per-
        Sweden) have in the last two weeks con-        special software was written to interface      MariTEL, the negotiations are going well       suade VHF radio manufacturers to pro-
        ducted an e-mail dialogue regarding the        Regal's transponder to its electronic chart    and it now seems likely that 87B will          duce and sell low cost radio modems that
        schedule for interoperability testing and      (Transas Marine's NaviSailor 2500) and         become available for most approaches to        boat owners can use on the network for e-
        are at the point of preparing proposed         Sea's and Volendam's transponders to their     US ports. Similarly, VHF Channel 88B,          mail, internet access and receipt of AIS
        schedules for this to happen", says Ernie      the integrated bridge systems (STN Atlas'      which has been reserved as the second          position updates from SOLAS ships.
        Batty of Marine Data Systems.                  ChartPilot/MultiPilot II). Once these          channel for AIS in the rest of the world and      This venture is worth watching as it has
                                                       interfaces were available, installation of     is currently being used by Federal             the potential to drive the implementation
        To allow connection of any transponder         transponders proved relatively simple          Government agencies, will likely be freed      of AIS well beyond the boundaries of IMO
        to any electronic chart or radar, AIS 'sen-    with short cable runs.                         up for AIS in the US as well.                  or USCG carriage requirements, a devel-
        tences' are added to the current standard         Bridge teams were generally pleased            Hardware and software to support an         opment which would be to the benefit of
        communication protocol for navigation          with AIS performance. Sea's navigator, for     older type of digital radio communication      the maritime industry at large.
        instruments. This protocol allows ship's       instance, reported that he was able to dis-    protocol (Digital Selective Calling on VHF
        instruments, like differential GPS, auto       cuss sailing through separate channels         Channel 70) was added to the standard for
        pilot, radar, ECDIS, gyro compass, depth       between Skagway and Juneau in Alaska           AIS transponders mostly because 87B and          Fred W. Pot is Principal of Marine
        sounder, etc., to communicate with each        with Regal, because Regal identified itself    88B were not available in the US. It is not      Management Consulting, an AIS
        other over serial cables. Because its          as an AIS target about 1 hour 40 minutes       clear what will happen to this part of the       consultancy based in Seattle. He can be
                                                                                                                                                       reached via www.uais.org.
        throughput capacity is limited to 4.8 kb       (39.8 nm) before the two ships passed each     standard now that, at least for the US, DSC
        per second, which is too limited to be able    other. Regal's unidentified radar target       seems not to be required after all. Deleting

                                                                                 Digital Ship November 2000 page 26

				
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