《航海学》课程参考文献（地文资料）CHAPTER 28 GLOBAL MARITIME DISTRESS AND SAFETY SYSTEM

CHAPTER 28GLOBALMARITIMEDISTRESSANDSAEETYSYSTEMDEVELOPMENT2800.Introduction(IHO),WorldMeteorological Organization(WMO),International Maritime Satellite Organization (INMARSAT),The Global Maritime Distress and Safety Systemand others.(GMDSS) represents a significant improvement in marineThe GMDSS offers the greatest advancement in mari-safety overtheprevious system of shortrange and high seastime safety sincetheenactment ofregulations following theradiotransmissions.Its manyparts includesatelliteas wellTitanic disaster in 1912. It is an automated ship-to-ship,as advanced terrestrial communications systems.Opera-shore-to-ship and ship-to-shore system covering distresstional serviceof theGMDSSbegan on1February1992alerting and relay,theprovision of maritime safety infor-withfullimplementationscheduledby1February1999mation (MSI)andbasic communication links.Satelliteandadvancedterrestrial systems areincorporated intoamodern2801.Backgroundcommunicationsnetworktopromoteand improvesafetyoflife and property at sea throughout the world. The equip-The GMDSS was adopted by amendments in 1988 byment required on board ships will depend not on theirtheConferenceofContractingGovernmentstothe Interna-tonnage, but rather on the sea area in which the vessel oper-tional Convention for the Safety of Life at Sea (SOLAS)ates. This is fundamentally different from the previous1974.This was the culmination of more thana decade ofsystem, which based requirements on vessel size alone. Thegreatest benefit of the GMDSS is that it vastly reduces theworkbytheInternationalMaritimeOrganization(IMO)inconjunction with the International TelecommunicationschancesofshipssinkingwithoutatraceandenablessearchUnion (ITU),International Hydrographic Organizationand rescue(SAR)operationsto be launched withoutdelaySHIPREOUIREMENTS2802. Ship Carriage RequirementsSea Area A2An area, excluding sea area Al,within the radiotelephone coverageof at least one MF coast station inBythetermsoftheSOLASConvention.theGMDSSwhich continuous DSC alerting isprovisions apply to cargo ships of 300 gross tons and overavailable, as may be defined by aandshipscarryingmorethan12passengersoninternationalContracting Government. The gen-voyages.Unlike previous shipboard carriage regulationseral area is from the Al limit out tothat specified equipment according to size of vessel, theabout 100miles offshore.GMDSScarriagerequirementsstipulateequipmentaccord-ingtotheareathevesseloperates inTheseseaareasareSea Area A3An area, excluding sea areas Al anddesignated as follows:A2, within the coverage of an IN-MARSATgeostationary satellite inSea Area AlAn area within the radiotelephonewhich continuous alerting is avail-coverageofat leastoneVHFcoastable.Thisarea is from about70°Ntostation in which continuous Digital70°S.Selective Calling (DSC - a radio re-ceiver that performs distress alertingSea Area A4All areas outside of sea areas Al, A2and safety calling on HF,MF andand A3. This area includes the polarVHF frequencies)is available, asregions, where geostationary satel-may be defined by a Contractinglite coverage is not available.Governmentto the1974SOLASShips at sea must be capable ofthe following function-Convention.This area extends fromalGMDSSrequirements:the coastto about 20miles offshore397

397 CHAPTER 28 GLOBAL MARITIME DISTRESS AND SAFETY SYSTEM DEVELOPMENT 2800. Introduction The Global Maritime Distress and Safety System (GMDSS) represents a significant improvement in marine safety over the previous system of short range and high seas radio transmissions. Its many parts include satellite as well as advanced terrestrial communications systems. Opera￾tional service of the GMDSS began on 1 February 1992, with full implementation scheduled by 1 February 1999. 2801. Background The GMDSS was adopted by amendments in 1988 by the Conference of Contracting Governments to the Interna￾tional Convention for the Safety of Life at Sea (SOLAS), 1974. This was the culmination of more than a decade of work by the International Maritime Organization (IMO) in conjunction with the International Telecommunications Union (ITU), International Hydrographic Organization (IHO), World Meteorological Organization (WMO), Inter￾national Maritime Satellite Organization (INMARSAT), and others. The GMDSS offers the greatest advancement in mari￾time safety since the enactment of regulations following the Titanic disaster in 1912. It is an automated ship-to-ship, shore-to-ship and ship-to-shore system covering distress alerting and relay, the provision of maritime safety infor￾mation (MSI) and basic communication links. Satellite and advanced terrestrial systems are incorporated into a modern communications network to promote and improve safety of life and property at sea throughout the world. The equip￾ment required on board ships will depend not on their tonnage, but rather on the sea area in which the vessel oper￾ates. This is fundamentally different from the previous system, which based requirements on vessel size alone. The greatest benefit of the GMDSS is that it vastly reduces the chances of ships sinking without a trace and enables search and rescue (SAR) operations to be launched without delay. SHIP REQUIREMENTS 2802. Ship Carriage Requirements By the terms of the SOLAS Convention, the GMDSS provisions apply to cargo ships of 300 gross tons and over and ships carrying more than 12 passengers on international voyages. Unlike previous shipboard carriage regulations that specified equipment according to size of vessel, the GMDSS carriage requirements stipulate equipment accord￾ing to the area the vessel operates in. These sea areas are designated as follows: Sea Area A1 An area within the radiotelephone coverage of at least one VHF coast station in which continuous Digital Selective Calling (DSC - a radio re￾ceiver that performs distress alerting and safety calling on HF, MF and VHF frequencies) is available, as may be defined by a Contracting Government to the 1974 SOLAS Convention. This area extends from the coast to about 20 miles offshore. Sea Area A2 An area, excluding sea area A1, within the radiotelephone coverage of at least one MF coast station in which continuous DSC alerting is available, as may be defined by a Contracting Government. The gen￾eral area is from the A1 limit out to about 100 miles offshore. Sea Area A3 An area, excluding sea areas A1 and A2, within the coverage of an IN￾MARSAT geostationary satellite in which continuous alerting is avail￾able. This area is from about 70°N to 70°S. Sea Area A4 All areas outside of sea areas A1, A2 and A3. This area includes the polar regions, where geostationary satel￾lite coverage is not available. Ships at sea must be capable of the following function￾al GMDSS requirements:

398GLOBALMARITIMEDISTRESSANDSAFETYSYSTEM1.Ship-to-shore distress alerting3.Capability of initiating a distress alert from a navi-2Shore-to-ship distress alertinggational positionusingDSConeitherVHF,HF orMF;manuallyactivatedEPIRB;or ShipEarth Sta-3Ship-to-ship distress alertingtion (SES)4.SAR coordination5.On-scenecommunicationsSea Areas Al and A26.Transmission and receipt of emergency locatingsignals7.TransmissionandreceiptofMSI1.Radio telephone MF 2182kHz and DSC on 2187.58.General radiocommunicationskHz.9Bridge-to-bridgecommunications2.Equipment capable of maintaining a continuousDSCwatchon2187.5kHz.To meet the requirements ofthe functional areas above3.General workingradio communications intheMFthefollowing is a list of theminimum communicationsband1605-4000kHz,orINMARSATSES4.equipment needed for all ships:Capability ofinitiating adistress alert by HF (usingDSC),manual activationofanEPIRB,orINMAR-VHF radio capable of transmitting and receivingSAT SES.1.DSC on channel 70and radio telephony onchan-nels 6, 13 and 16.Sea Areas A1, A2 and A32.Radioreceiver capableofmaintaining a continuousDSCwatchonchannel70VHFRadio telephone MF 2182 kHz and DSC 2187.5kHz.1.Search and rescue transponders (SART), a mini-3.2.Equipment capable of maintaining a continuousmum of two, operating in the9GHzband.DSCwatchon2187.5kHz4Receiver capable of receiving NAVTEX broad-INMARSAT A, B or C (class 2) SES Enhanced3.casts anywhere NAVTEX service is available.Group Call (EGC), or HF as required for sea area A45Receiver capable of receiving SafetyNET any-4.Capabilityof initiatingadistress alertbytwoof thewhere NAVTEX is not availablefollowing:6.Satellite emergency position indicating radiobea-INMARSATA,BorC(class2)SESa.con (EPIRB),manually activated or float-free self-b.Manuallyactivated satelliteEPIRBactivated.c.HF/DSCradiocommunication.7. Two-way handheld VHF radios (two sets minimumon 300-500gross tons cargo vessels and three setsSea Area A4minimumoncargovesselsof5o0grosstonsandupwardandonallpassengerships)1.HF/MFreceivingand transmitting equipmentfor8.Until1Feb.1999,a2182kHzwatchreceiver.band 1605-27500 kHz using DSC, radiotelephoneand direct printingAdditionally,each sea area has its own requirements2.Equipment capableof selecting anysafety and dis-underGMDSS which are asfollows:tressDSCfrequencyforband4000-27500kHzmaintainingDSCwatchon2187.5.8414.5kHzandSea Area Alat leastoneadditional safetyand distressDSC fre-quency in the band.General VHF radiotelephonecapability.13.0Abilityto initiateadistress alertfroma navigationalFree-floatingEPIRBtransmittingDSConchannel2.positionvia thePolarOrbitingSystemon406MHz70VHE,or satelliteEPIRB(manualactivationof406MHz satelliteEPIRB)COMMUNICATIONS2803.TheINMARSATSystemcommunications,efficiencyandmanagementof ships,aswell asmaritime correspondenceservicesThe International Maritime Satellite OrganizationThebasic components of theINMARSAT system(INMARSAT), a key player within GMDSS, is an interna-include theINMARSAT space segment,Land Earthtional consortiumcomprisingover75intermationalpartnersStations (LES), also referred to as Coast Earth Sta-tions (CES),andmobileShipEarth Stations (SES)whoprovidemaritimesafetycommunicationsforshipsatsea.In accordance with its convention, INMARSAT pro-TheINMARSATspacesegment consists ofllgeosta-videsthespacesegmentnecessaryforimprovingdistresstionary satellites.Four operationalINMARSAT satellites

398 GLOBAL MARITIME DISTRESS AND SAFETY SYSTEM 1. Ship-to-shore distress alerting. 2. Shore-to-ship distress alerting. 3. Ship-to-ship distress alerting. 4. SAR coordination. 5. On-scene communications. 6. Transmission and receipt of emergency locating signals. 7. Transmission and receipt of MSI. 8. General radio communications. 9. Bridge-to-bridge communications. To meet the requirements of the functional areas above the following is a list of the minimum communications equipment needed for all ships: 1. VHF radio capable of transmitting and receiving DSC on channel 70 and radio telephony on chan￾nels 6, 13 and 16. 2. Radio receiver capable of maintaining a continuous DSC watch on channel 70 VHF. 3. Search and rescue transponders (SART), a mini￾mum of two, operating in the 9 GHz band. 4. Receiver capable of receiving NAVTEX broad￾casts anywhere NAVTEX service is available. 5. Receiver capable of receiving SafetyNET any￾where NAVTEX is not available. 6. Satellite emergency position indicating radiobea￾con (EPIRB), manually activated or float-free self￾activated. 7. Two-way handheld VHF radios (two sets minimum on 300-500 gross tons cargo vessels and three sets minimum on cargo vessels of 500 gross tons and upward and on all passenger ships). 8. Until 1 Feb. 1999, a 2182 kHz watch receiver. Additionally, each sea area has its own requirements under GMDSS which are as follows: Sea Area A1 1. General VHF radio telephone capability. 2. Free-floating EPIRB transmitting DSC on channel 70 VHF, or satellite EPIRB. 3. Capability of initiating a distress alert from a navi￾gational position using DSC on either VHF, HF or MF; manually activated EPIRB; or Ship Earth Sta￾tion (SES). Sea Areas A1 and A2 1. Radio telephone MF 2182 kHz and DSC on 2187.5 kHz. 2. Equipment capable of maintaining a continuous DSC watch on 2187.5 kHz. 3. General working radio communications in the MF band 1605-4000 kHz, or INMARSAT SES. 4. Capability of initiating a distress alert by HF (using DSC), manual activation of an EPIRB, or INMAR￾SAT SES. Sea Areas A1, A2 and A3 1. Radio telephone MF 2182 kHz and DSC 2187.5 kHz. 2. Equipment capable of maintaining a continuous DSC watch on 2187.5 kHz. 3. INMARSAT A, B or C (class 2) SES Enhanced Group Call (EGC), or HF as required for sea area A4. 4. Capability of initiating a distress alert by two of the following: a. INMARSAT A, B or C (class 2) SES. b. Manually activated satellite EPIRB. c. HF/DSC radio communication. Sea Area A4 1. HF/MF receiving and transmitting equipment for band 1605-27500 kHz using DSC, radiotelephone and direct printing. 2. Equipment capable of selecting any safety and dis￾tress DSC frequency for band 4000-27500 kHz, maintaining DSC watch on 2187.5, 8414.5 kHz and at least one additional safety and distress DSC fre￾quency in the band. 3. Ability to initiate a distress alert from a navigational position via the Polar Orbiting System on 406 MHz (manual activation of 406 MHz satellite EPIRB). COMMUNICATIONS 2803. The INMARSAT System The International Maritime Satellite Organization (INMARSAT), a key player within GMDSS, is an interna￾tional consortium comprising over 75 international partners who provide maritime safety communications for ships at sea. In accordance with its convention, INMARSAT pro￾vides the space segment necessary for improving distress communications, efficiency and management of ships, as well as maritime correspondence services. The basic components of the INMARSAT system include the INMARSAT space segment, Land Earth Stations (LES), also referred to as Coast Earth Sta￾tions (CES), and mobile Ship Earth Stations (SES). The INMARSAT space segment consists of 11 geosta￾tionary satellites. Four operational INMARSAT satellites

399GLOBALMARITIMEDISTRESSANDSAFETYSYSTEMprovideprimarycoverage,fouradditional satellites(includ-INMARSATB system that uses digital technologytogiveing satellites leased from the European Space Agencybetterqualityfax andhigherdata transmission rates.(ESA)andtheInternationalTelecommunicationsSatelliteINMARSAT Cprovides a store and forward dataOrganization(INTELSAT)serve as spares and three re-messagingcapability(but novoice)at600bits per secondmaining satellites (leased fromCOMSATCorporation,theand was designed specifically tomeet the GMDSS require-U.S.signatory to INMARSAT)serve as back-upsmentsfor receiving MSIdata on board ship.These units areThepolar regions are not visibleto the operational sat-smalllightweightand useanomni-directional antennaellites and coverage is available from 70°N to 70°sSatellite coverage (Figure 2803) is divided into four re-2804.SafetyNETgions, which are:SafetyNETisa service ofINMARSATC'sEnhanced1.AtlanticOcean-East (AOR-E)Group Call (EGC) system. The EGC system (Figure2.AtlanticOcean-West(AOR-W)2804)is amethod usedtospecificallyaddressparticularre-3.PacificOcean(POR)gions or ships. Its unique addressing capabilities allow4.IndianOcean (IOR)messages tobe sent toall vessels in bothfixed geographicalareas orto predetermined groups of ships.SafetyNET is theservicedesignated bythe IMO through which ships receiveTheLES'sprovidethelinkbetweentheSpaceSegmaritime safety information.The other service under thement andtheland-based National/International fixedEGC system, called FleetNET,is used by commercialcommunicationsnetworks.Thesecommunicationsnet-companiestodirectly(andprivately)communicatetotheirworks arefunded and operated by the authorizedindividual fleets.communications authorities of a participating nation.Thisnetwork links registered informationproviderstotheLESSafetyNET is an international direct-printing satellite-The data then travelsfrom theLES to theINMARSATNet-based serviceforthepromulgationofnavigationalandmete-work Coordination Station (NCS)andthen down totheorological warnings, and distress alerts,forecasts, and otherSES's on shipsat sea.TheSES'sprovide two-way commu-safetymessages.It fulfills an integral role in GMDSS as de-veloped by the IMO.The abilityto receive SafetyNETnicationsbetweenshipand shore.INMARSAT AtheoriginalINMARSATsystem,operatesatatransferrateofservice information is necessary for all ships that sail beyondup to 9600 bits per second and is telephone, telex and fac-coverageofNAVTEX(approximately200milesfromshore)simile (fax)capable.It isbeing replaced bya similarly sizedand isrecommendedtoall administrationshaving thePacificindianAtlanticOceanOceanOceanRegionRegionRegionAOREASTIORPORCFigure2803.Thefourregionsof INMARSATcoverage

GLOBAL MARITIME DISTRESS AND SAFETY SYSTEM 399 provide primary coverage, four additional satellites (includ￾ing satellites leased from the European Space Agency (ESA) and the International Telecommunications Satellite Organization (INTELSAT)) serve as spares and three re￾maining satellites (leased from COMSAT Corporation, the U.S. signatory to INMARSAT) serve as back-ups. The polar regions are not visible to the operational sat￾ellites and coverage is available from 70°N to 70°S. Satellite coverage (Figure 2803) is divided into four re￾gions, which are: 1. Atlantic Ocean - East (AOR-E) 2. Atlantic Ocean - West (AOR-W) 3. Pacific Ocean (POR) 4. Indian Ocean (IOR) The LES’s provide the link between the Space Seg￾ment and the land-based National/International fixed communications networks. These communications net￾works are funded and operated by the authorized communications authorities of a participating nation. This network links registered information providers to the LES. The data then travels from the LES to the INMARSAT Net￾work Coordination Station (NCS) and then down to the SES’s on ships at sea. The SES’s provide two-way commu￾nications between ship and shore. INMARSAT A, the original INMARSAT system, operates at a transfer rate of up to 9600 bits per second and is telephone, telex and fac￾simile (fax) capable. It is being replaced by a similarly sized INMARSAT B system that uses digital technology to give better quality fax and higher data transmission rates. INMARSAT C provides a store and forward data messaging capability (but no voice) at 600 bits per second and was designed specifically to meet the GMDSS require￾ments for receiving MSI data on board ship. These units are small, lightweight and use an omni-directional antenna. 2804. SafetyNET SafetyNET is a service of INMARSAT C’s Enhanced Group Call (EGC) system. The EGC system (Figure 2804) is a method used to specifically address particular re￾gions or ships. Its unique addressing capabilities allow messages to be sent to all vessels in both fixed geographical areas or to predetermined groups of ships. SafetyNET is the service designated by the IMO through which ships receive maritime safety information. The other service under the EGC system, called FleetNET, is used by commercial companies to directly (and privately) communicate to their individual fleets. SafetyNET is an international direct-printing satellite￾based service for the promulgation of navigational and mete￾orological warnings, and distress alerts, forecasts, and other safety messages. It fulfills an integral role in GMDSS as de￾veloped by the IMO. The ability to receive SafetyNET service information is necessary for all ships that sail beyond coverage of NAVTEX (approximately 200 miles from shore) and is recommended to all administrations having the Figure 2803. The four regions of INMARSAT coverage

400GLOBALMARITIMEDISTRESSANDSAFETYSYSTEMresponsibility for marine affairs and mariners whorequire ef-1.Area calls can be to a fixed geographic area such asfectiveMSI service in waters not served byNAVTEX.one of the 16 NAVAREA's or to a temporary geo-graphic area selected by the originator. Area callsSafetyNET can direct a message to a given geographicwill bereceived automaticallybyanyshipwhose re-area based onEGCaddressing.Thearea maybefixed,as inceiverhas been setto oneor more fixed areas orthe case of aNAVAREA or weather forecast area, or it mayrecognizes anarea bygeographicposition.beuniquelydefinedbytheoriginatorThisisparticularlyuseful formessages such as local stormwarnings ora ship-to-shoredistressalertforwhichit wouldbeinappropriateto2Group calls will be received automatically by anyalert ships in anentire oceanregionship whose receiver acknowledges the unique groupidentity associated witha particularmessage.SafetyNET messages can be originated by a Regis-tered InformationProvider anywhere inthe world andbroadcast to the appropriate ocean area through an IN-Reliable delivery of messages is ensured by forwardMARSAT-C LES. Messages are broadcast according toerror correction techniques.Experiencehas demonstratedtheir priority (i.e.,Distress, Urgent, Safety,and Routine)that the transmission link is generally error-free and low er-ror receptionisachieved undernormalcircumstances.Virtually all navigable waters oftheworld are coveredbythe operational satellites in the INMARSAT system.Given the vast ocean coverage by satellite, someEachsatellitebroadcastsEGCtrafficonadesignated chan-form ofdiscrimination and selectivityinprintingthevar-nel.Any ship sailing within the coverage area of anious messages is required.Area calls will be received byINMARSAT satellite will be able to receiveall the Safety-all ships within the ocean region coverage of the satel-NET messages broadcast over this channel. The EGClite, however,they will be printed only by thosechannel isoptimized toenablethesignal tobemonitoredbyreceivers that recognize the fixed area or the geographicSES'sdedicatedto thereceptionof EGCmessages.This ca-position in the message. The message format includes apabilitycanbebuilt intootherstandard SES's.It isafeaturepreamble that enables the microprocessor in a ship's re-of satellite communications thatreception isnotgenerallyceiver to decide to print those MSI messages that relateaffected by the position of the ship within the ocean region,to thepresentposition,intended route or a fixed areapro-atmospheric conditions, or time of daygrammed by the operator.This preamble also allowsMessages can betransmitted eitherto geographic areassuppression ofcertain types of MSI that are not relevant(areacalls)ortogroupsof ships (group calls):to a particular ship.As each message will also haveaSELECTED SHIPSFLEET·HYDROGRAPHICOFFICEAREA·METEOROLOGICALOFFICE+RESCUECO-ORDINATIONCENTREFLAG·SHIPPING COMPANIESNEWS SERVICESALLSHIPSFigure2804.SafetyNETEGCconcept

400 GLOBAL MARITIME DISTRESS AND SAFETY SYSTEM responsibility for marine affairs and mariners who require ef￾fective MSI service in waters not served by NAVTEX. SafetyNET can direct a message to a given geographic area based on EGC addressing. The area may be fixed, as in the case of a NAVAREA or weather forecast area, or it may be uniquely defined by the originator. This is particularly useful for messages such as local storm warnings or a ship￾to-shore distress alert for which it would be inappropriate to alert ships in an entire ocean region. SafetyNET messages can be originated by a Regis￾tered Information Provider anywhere in the world and broadcast to the appropriate ocean area through an IN￾MARSAT-C LES. Messages are broadcast according to their priority (i.e., Distress, Urgent, Safety, and Routine). Virtually all navigable waters of the world are covered by the operational satellites in the INMARSAT system. Each satellite broadcasts EGC traffic on a designated chan￾nel. Any ship sailing within the coverage area of an INMARSAT satellite will be able to receive all the Safety￾NET messages broadcast over this channel. The EGC channel is optimized to enable the signal to be monitored by SES’s dedicated to the reception of EGC messages. This ca￾pability can be built into other standard SES’s. It is a feature of satellite communications that reception is not generally affected by the position of the ship within the ocean region, atmospheric conditions, or time of day. Messages can be transmitted either to geographic areas (area calls) or to groups of ships (group calls): 1. Area calls can be to a fixed geographic area such as one of the 16 NAVAREA’s or to a temporary geo￾graphic area selected by the originator. Area calls will be received automatically by any ship whose re￾ceiver has been set to one or more fixed areas or recognizes an area by geographic position. 2. Group calls will be received automatically by any ship whose receiver acknowledges the unique group identity associated with a particular message. Reliable delivery of messages is ensured by forward error correction techniques. Experience has demonstrated that the transmission link is generally error-free and low er￾ror reception is achieved under normal circumstances. Given the vast ocean coverage by satellite, some form of discrimination and selectivity in printing the var￾ious messages is required. Area calls will be received by all ships within the ocean region coverage of the satel￾lite; however, they will be printed only by those receivers that recognize the fixed area or the geographic position in the message. The message format includes a preamble that enables the microprocessor in a ship’s re￾ceiver to decide to print those MSI messages that relate to the present position, intended route or a fixed area pro￾grammed by the operator. This preamble also allows suppression of certain types of MSI that are not relevant to a particular ship. As each message will also have a Figure 2804. SafetyNET EGC concept

401GLOBALMARITIMEDISTRESSANDSAFETYSYSTEM(standard narrow-band direct printing,also sometimesunique identity,thereprintingofmessagesalreadyreceivedcorrectly is automatically suppressed.called Sitor)safetymessages on the internationally standardmedium frequency of 518 kHz. It is a GMDSS requirementMSI ispromulgated byvarious informationprovidersfor the reception of MSI in coastal and local waters. Coastaroundtheworld.MessagesfortransmissionthroughtheSafetyNET servicewill,inmany cases, be theresult ofco-stations transmit during previouslyarranged time slots toordination between authorities.Information providers willminimize mutual interference.Routine messages are nor-mallybroadcast four times daily.Urgent messages arebe authorized to broadcastvia SafetyNETbyIMO.Autho-broadcast upon receipt, provided that an adjacent station isrized information providers are:nottransmitting.Sincethebroadcastusesthemediumfrequency band,a typical station serviceradius ranges from1.National hydrographic offices for navigational100to500NMdayand night (althougha 200mileruleofwarningsthumbisappliedintheU.S.).Interferencefromorreceiptof2.National weatherservicesformeteorological warn-stations farther awayoccasionallyoccurs at night.ingsandforecastsEach NAVTEXmessage broadcastcontains a four-3.Rescue Coordination Centers for ship-to-shoredischaracter header describing:identification of station (firsttress alerts and other urgent information.character);messagecontentortype(second character);and4.In the U.S., the International Ice Patrol for Northmessage serial number (third and fourth characters).ThisAtlanticicehazards.header allows themicroprocessor in the shipboard receiverto screen messagesfrom onlythose stationsrelevanttotheEach information provider prepares their SafetyNETuser,messages ofsubject categories needed by the user andmessages with certain characteristics recognized by themessages notpreviously received by the user,Messages soEGC service.Thesecharacteristics,knownas“C"codesarescreened are printed as they are received, to be read by thecombined into ageneralized messageheaderformatas fol-mariner when convenient. All other messages are sup-lows:C1:C2:C3:C4:C5.EachC"codecontrolsadifferentpressed. Suppression of unwanted messages is becomingbroadcast criterion and is assigned a numerical value ac-more and more a necessity to the mariner as the number ofcording to available options.A sixth"C"code,"Co"maymessages,including rebroadcast messages,increasesyear-beused to indicate the ocean region (i.e.,AOR-E,AOR-W,ly.With NAVTEX, a mariner will not find it necessary toPOR,IOR)whensendingamessagetoanLESwhichoper-listen to, or sift through, a large number of non-relevantates inmorethan oneocean region.Becauseerrors inthedatatoobtain the informationnecessaryforsafenavigation.header format ofa message mayprevent its being released,TheNAVTEXreceiver is a small unitwith an internalMSIproviders must installanINMARSATSafetyNETre-printer, which takes a minimum of room on the bridge. Itsceiver to monitor the broadcasts it originates.This alsoantenna is also of modest size, needing only a receiveensuresquality control.capability.The"c"codes are transparent to the mariner but areusedbyinformationproviders to identify various transmit-2806.MaritimeSafetyInformation (MSI)tingparameters.C1designates themessagepriorityfromdistress to urgent, safety,and routine.MsI messages willMajor categories of MSI for both NAVTEX and Safety-always be at least at the safetylevel.C2 is the service codeNETare:ortypeofmessage(forexample,longrangeNAVAREAwarning or coastal NAVTEX warning).It also tells the re-1.Navigational warningsceiver the length ofthe address (the C3 code) it will need to2Meteorological warningsdecode.C3 is the address code.It canbe thetwo digit code3.IcereportsfortheNAVAREAnumberfor instance,or a1Odigitnum-Searchandrescue information4bertoindicateacircularareaforameteorologicalwarning5.Meteorological forecastsC4 is therepetition code which instructs theLES in howlong andwhentosendthemessagetotheNCSforactual6.Pilot service messages (not in the U.S.)broadcast.A six minute echo (repeat)may also be used toElectronic navigation system messages (ie..7.ensure that an urgent (unscheduled)message has been reOMEGA,LORAN,DECCA,GPS,DGPS,SAT-ceivedbyallshipsaffected.C5isaconstantandrepresentsNAV, etc.)apresentationcode,InternationalAlphabetnumber5"o0"Broadcasts of MSI in the international SafetyNET ser-Broadcasts ofMSI inNAVTEX international service are invice are in English.English, but may be in languages other than English, to meet re-quirements of the host government.2805.NAVTEX2807.Digital Selective Calling (DSC)NAVTEXisamaritimeradiowarningsystem consist-Digital Selective Calling (DSC)is a method of auto-ingof a series of coast stationstransmittingradioteletype

GLOBAL MARITIME DISTRESS AND SAFETY SYSTEM 401 unique identity, the reprinting of messages already received correctly is automatically suppressed. MSI is promulgated by various information providers around the world. Messages for transmission through the SafetyNET service will, in many cases, be the result of co￾ordination between authorities. Information providers will be authorized to broadcast via SafetyNET by IMO. Autho￾rized information providers are: 1. National hydrographic offices for navigational warnings. 2. National weather services for meteorological warn￾ings and forecasts. 3. Rescue Coordination Centers for ship-to-shore dis￾tress alerts and other urgent information. 4. In the U.S., the International Ice Patrol for North Atlantic ice hazards. Each information provider prepares their SafetyNET messages with certain characteristics recognized by the EGC service. These characteristics, known as “C” codes are combined into a generalized message header format as fol￾lows: C1:C2:C3:C4:C5. Each “C” code controls a different broadcast criterion and is assigned a numerical value ac￾cording to available options. A sixth “C” code, “C0” may be used to indicate the ocean region (i.e., AOR-E, AOR-W, POR, IOR) when sending a message to an LES which oper￾ates in more than one ocean region. Because errors in the header format of a message may prevent its being released, MSI providers must install an INMARSAT SafetyNET re￾ceiver to monitor the broadcasts it originates. This also ensures quality control. The “C” codes are transparent to the mariner but are used by information providers to identify various transmit￾ting parameters. C1 designates the message priority from distress to urgent, safety, and routine. MSI messages will always be at least at the safety level. C2 is the service code or type of message (for example, long range NAVAREA warning or coastal NAVTEX warning). It also tells the re￾ceiver the length of the address (the C3 code) it will need to decode. C3 is the address code. It can be the two digit code for the NAVAREA number for instance, or a 10 digit num￾ber to indicate a circular area for a meteorological warning. C4 is the repetition code which instructs the LES in how long and when to send the message to the NCS for actual broadcast. A six minute echo (repeat) may also be used to ensure that an urgent (unscheduled) message has been re￾ceived by all ships affected. C5 is a constant and represents a presentation code, International Alphabet number 5, “00”. Broadcasts of MSI in the international SafetyNET ser￾vice are in English. 2805. NAVTEX NAVTEX is a maritime radio warning system consist￾ing of a series of coast stations transmitting radio teletype (standard narrow-band direct printing, also sometimes called Sitor) safety messages on the internationally standard medium frequency of 518 kHz. It is a GMDSS requirement for the reception of MSI in coastal and local waters. Coast stations transmit during previously arranged time slots to minimize mutual interference. Routine messages are nor￾mally broadcast four times daily. Urgent messages are broadcast upon receipt, provided that an adjacent station is not transmitting. Since the broadcast uses the medium fre￾quency band, a typical station service radius ranges from 100 to 500 NM day and night (although a 200 mile rule of thumb is applied in the U.S.). Interference from or receipt of stations farther away occasionally occurs at night. Each NAVTEX message broadcast contains a four￾character header describing: identification of station (first character); message content or type (second character); and message serial number (third and fourth characters). This header allows the microprocessor in the shipboard receiver to screen messages from only those stations relevant to the user, messages of subject categories needed by the user and messages not previously received by the user. Messages so screened are printed as they are received, to be read by the mariner when convenient. All other messages are sup￾pressed. Suppression of unwanted messages is becoming more and more a necessity to the mariner as the number of messages, including rebroadcast messages, increases year￾ly. With NAVTEX, a mariner will not find it necessary to listen to, or sift through, a large number of non-relevant data to obtain the information necessary for safe navigation. The NAVTEX receiver is a small unit with an internal printer, which takes a minimum of room on the bridge. Its antenna is also of modest size, needing only a receive capability. 2806. Maritime Safety Information (MSI) Major categories of MSI for both NAVTEX and Safety￾NET are: 1. Navigational warnings 2. Meteorological warnings 3. Ice reports 4. Search and rescue information 5. Meteorological forecasts 6. Pilot service messages (not in the U.S.) 7. Electronic navigation system messages (i.e., OMEGA, LORAN, DECCA, GPS, DGPS, SAT￾NAV, etc.) Broadcasts of MSI in NAVTEX international service are in English, but may be in languages other than English, to meet re￾quirements of the host government. 2807. Digital Selective Calling (DSC) Digital Selective Calling (DSC) is a method of auto-

402GLOBALMARITIMEDISTRESSANDSAFETYSYSTEMmaticallyplacing a call directly from one radio to another.sea-water.The manual ones are controlled by a switch.Un-This is accomplished by addressing the call so it will bere-derGMDSS, satelliteEPIRBswill operateeither on 1.6GHz (the INMARSATE, L Band) or the 406 MHz frequen-ceivedautomaticallyby the other radio.It permits aradiotobeused likeatelephone,SincetheDSCsystem will soundcyusedbytheCOSPAS-SARSATsysteman alarm (much like a ringing telephone) when it senses anGMDSS requires1 satelliteEPIRB alongwith2searchincoming call, there is no need for dedicated, aural watch-and rescue transponders(SART's).These SART'sgeneratestanding.DSC techniques can be usedwith VHF,HF anda series of response signals when interrogated byany ordi-MF radio communications. DSC's principal uses are in dis-nary9 GHz radar set.The signals produce a line of 20 blipstress alerting and safety calling. Numerous frequenciesontheradar screenof therescue shiporaircrafthave been assigned.They are 2187.5kHz in the MF band;Under GMDSS, the COSPAS-SARSAT and INMAR-4207.5kHz,6312kHz,8414.5kHz,12577kHzandSAT communication systems are the two basic media16804.5kHz in the HF band; and 156.525 MHz (channelthrough which the EPIRB signal is relayed to ground and70) in the VHF band.sea stations.COSPAS-SARSAT is a joint international sat-ellite-aided SAR system operated by multi-national2808.EmergencyPosition-IndicatingRadio Beaconsorganizations in Canada, France, the U.S. and the RussianFederation.It uses lowpolar orbiting satellites which re-EmergencyPosition-IndicatingRadioBeaconsceive and relay distress signals from EPIRBs and determine(EPIRBs)are designed to transmit a satellite alert in thetheir position.INMARSAT,with over75membernations,eventof sudden accidenteitherautomaticallyormanually.operates a global satellite EPIRB system (excluding theThe automatic models are designed and mounted so thatpoles). Further details of the COSPAS-SARSAT systemthey will float free of a sinking vessel and be activated byarefound inChapter29,PositionReportingSystems

402 GLOBAL MARITIME DISTRESS AND SAFETY SYSTEM matically placing a call directly from one radio to another. This is accomplished by addressing the call so it will be re￾ceived automatically by the other radio. It permits a radio to be used like a telephone. Since the DSC system will sound an alarm (much like a ringing telephone) when it senses an incoming call, there is no need for dedicated, aural watch￾standing. DSC techniques can be used with VHF, HF and MF radio communications. DSC’s principal uses are in dis￾tress alerting and safety calling. Numerous frequencies have been assigned. They are 2187.5 kHz in the MF band; 4207.5 kHz, 6312 kHz, 8414.5 kHz, 12577 kHz and 16804.5 kHz in the HF band; and 156.525 MHz (channel 70) in the VHF band. 2808. Emergency Position-Indicating Radio Beacons Emergency Position-Indicating Radio Beacons (EPIRBs) are designed to transmit a satellite alert in the event of sudden accident either automatically or manually. The automatic models are designed and mounted so that they will float free of a sinking vessel and be activated by sea- water. The manual ones are controlled by a switch. Un￾der GMDSS, satellite EPIRBs will operate either on 1.6 GHz (the INMARSAT E, L Band) or the 406 MHz frequen￾cy used by the COSPAS-SARSAT system. GMDSS requires 1 satellite EPIRB along with 2 search and rescue transponders (SART’s). These SART’s generate a series of response signals when interrogated by any ordi￾nary 9 GHz radar set. The signals produce a line of 20 blips on the radar screen of the rescue ship or aircraft. Under GMDSS, the COSPAS-SARSAT and INMAR￾SAT communication systems are the two basic media through which the EPIRB signal is relayed to ground and sea stations. COSPAS-SARSAT is a joint international sat￾ellite-aided SAR system operated by multi-national organizations in Canada, France, the U.S. and the Russian Federation. It uses low polar orbiting satellites which re￾ceive and relay distress signals from EPIRBs and determine their position. INMARSAT, with over 75 member nations, operates a global satellite EPIRB system (excluding the poles). Further details of the COSPAS-SARSAT system are found in Chapter 29, Position Reporting Systems