YournameChapter4MaritimeMobileServicesAdjustthespacingtoadapttoChinesetypesetting

Theradiospectrumisdividedintospecificradiofrequencybandsforradiocommunications.ThemainfrequencybandsthatconcerntheGMDSSoperatorareasfollows:Mediumfrequency:300-3000kHZHighfrequency:3-30MHzVeryhighfrequency:30-300MHz4.1GeneralIntroduction

Long-RangeServiceUseHFinboththeship-to-shoreandshore-to-shipdirection,InareascoverbyInmarsatitcanusedasanalternativetosatellitecommunicationsandoutsidetheseareasitprovidelong-rangecommunicationcapability,Frequenciesdesignatefor4,6,8,12,16Mhzbandsforthisservice

Medium-RangeServiceUseMFintheship-to-shore,ship-to-shipandshoretoshipdirection2187.5kHzisusedfordistressalertsandsafetycallsusingDSC,and2182kHzbyradiotelephony,includingSARandonscenecommunication,2174.5kHzbydirect-printingtelegraphy.

Short-RangeServiceUseVHFprovideshort-rangeservice,156.525Mhz(CH70)fordistressandsafetycallsusingDSC;156.8Mhz(CH16)fordistressandsafetybyradiotelephony,includingSARandOn-scenecommunication.AM:Theinformationsignalchangestheamplitudebutdoesnotchangethecarrierfrequency.FM:thefrequencyischangedbytheinformationsignalandtheamplituderemainsunchanged.SSB:theynormallyuseJ3Eemissions,whichconsistsofonesidebandandsuppressedcarrier.MF/HFTEL:J3ENBDP:F1B/J2BVHFTEL:G3E/F3EVHFDSC:F2B/G2B(1)ThemodeofemissiontobeusedforRT:

MF/HF:J3E(butintheband2182KHzalsocanbeH3E)(2)Thepeakenvelopepower(峰包功率)ofMFshouldbenotexceed400W,HFnottoexceed1500W,VHFnottoexceed25W.(3)Simplexchannel:CH06,CH08-CH17,CH67-74,77.

DSC(DigitalSelectiveCalling)isanautomaticcallingsystemwhichallowsaspecificstationtobecontactedandmadeawarethatastationwishestocommunicatewithit.

ItisadigitalcallingsystememployinganerrordetectingcodeusedbyshipsandcoaststationsintheMF,HFandVHFmaritimecommunicationbands.

4.2DigitalSelectiveCalling

ItisimportanttonotethattheDSCisonlyanalertingsignalandthatthecommunicationwhichfollowsthecallwillbemadeonanappropriatefrequencybandusingeitherRTortelex.DSCisusedtoestablishinitialcontactbetweenstations.UseofFrequenciesBandsbetween415kHzand526.5kHzTheclassofemissiontobeusedfordigitalselectivecallingandacknowledgementintheautho-rizedbandsbetween415kHzand526.5kHzshallbeF1B.Transmissionsofdigitalselectivecallsandacknowledgementsbyshipstationsshallbelimitedtoameanpowerof400watts.callandacknowledgementTheinternationalfrequencyforanycoaststation:455.5kHzforanyshipstation:458.5kHzOranynationalfrequenciesonwhichcoaststationkeepswatch.Thefrequencytobeusedfortransmissionofacknowledgementshallnormallybethefrequencypairedwiththecallingfrequencyused.watchAcoaststationprovidinginternationalpubliccorrespondenceserviceusingDSCtechniqueswithintheMFbandshould,duringitshoursofservice,maintainautomaticDSCwatchonappropriatenationalorinternationalcallingfrequencies.DetailsofthehoursandfrequencieswillbeindicatedintheITUListofCoastStations.watch

ShipstationsequippedwithDSCapparatusforworkingintheauthorizedmaritimeMFbandsshould,whenwithinthecoverageareaofcoaststationsprovidingDSCservicesinthesebands,maintainanautomaticDSCwatchononeormoreappropriateDSCfrequencieswithinthesebands.ShipsshouldtakeintoaccounttheDSCfrequenciesoperatedbythecoaststations.Bandsbetween1605kHzand4000kHzTheclassofemissiontobeusedfordigitalselectivecallingandacknowledgementinthebandsbe-tween1605kHzand4000kHzwillbeF1BorJ2B.Transmissionsofdigitalselectivecallsandacknowledgmentsbyshipstationsshallbelimitedtoameanpowerof400watts.callandacknowledgementWhenmakingtheircalltoacoaststationbyDSCtechniques,shipstationsshoulduseinorderofpreference:(a)anationaldigitalselective-callingchannelonwhichthecoaststationismaintainingwatch;(b)theinternationaldigitalselective-callingfrequency2189.5kHz.(Theinternationaldigitalselective-callingfrequencyforcoaststationis2177kHz.)AshipstationcallinganothershipstationbyDSCtechniquesshouldusethefrequency2177kHzforthecall.Acknowledgementsofsuchcallsshouldalsobemadeonthisfrequency.Thefrequencytobeusedfortransmissionofanacknowledgementshouldnormallybethefrequencypairedwiththefrequencyusedforthereceivedcall,asindicatedintheITUListofCoastStations.watchWhereacoaststationprovidesaninternationalpubliccorrespondenceserviceusingDSCtech-niquesitshould,duringitshoursofservice,maintainautomaticDSCwatchonappropriatena-tionalorinternationalcallingfrequenciesonthebandsbetween1605kHzand4000kHz.ThesehoursandfrequenciesareindicatedintheITUListofCoastStations.ShipstationsequippedwithDSCapparatustoworkintheauthorizedmaritimebandsshould,whenwithinthecoverageareaofcoaststationsprovidingDSCservices,maintainanautomaticDSCwatchononeormoreappropriateDSCfrequencieswithinthesebands.ShipsshouldtakeintoaccounttheDSCfrequenciesoperatedbythecoaststations.Bandsbetween4000kHzand27500kHzTheclassofemissionusedfordigitalselectivecallingandacknowledgementintheauthorizedbandsinthisfrequencyrangeisF1BorJ2B.Transmissionsofdigitalselectivecallingandacknowledgementsbyshipsinthesebandsislimitedtoameanpowerof1.5Kw.callandacknowledgementAstationcallinganotherstationbyDSCtechniqueswithintheauthorizedmaritimeHFbandsshouldchooseanappropriateDSCfrequency,takingintoaccountpropagationcharacteristics.WhenmakingtheircalltoacoaststationbyDSCtechniquesintheauthorizedHFbands,shipstationsshoulduseinorderofpreference:(a)anationalDSCchannelonwhichthecoaststationismaintainingwatch;(b)ifcallingcannotbemadeonanationalDSCchannel,oneoftheassignedinternationalDSCfrequenciesmaybeused.watchAcoaststationprovidinganinternationalpubliccorrespondenceserviceusingDSCtechniqueswithinthemaritimeHFbandsshouldkeepautomaticDSCwatchontheappropriatefrequenciesfortheservice,duringitshoursofservice.DetailsareindicatedintheITUListofCoastSta-tions.ShipstationsequippedwithDSCapparatusforworkinginthemaritimeHFbandsshouldmaintainautomaticDSCwatchonappropriateDSCfrequencieswithinthesebands.ShipsshouldtakeintoaccountpropagationcharacteristicsandthecallingfrequenciesofcoaststationsprovidingaDSCservice.Bandsbetween156MHzand174MHzTheclassofemissiontobeusedfordigitalselectivecallingandacknowledgementintheautho-rizedbandsbetween156MHzand174MHz(theVHFband)shallbeG2B.callandacknowledgementThefrequency156.525MHz(VHFChannel70)isaninternationalchannelinthemaritimemobileserviceusedfordistress,urgency,safetyandcallingusingDSCtechniques.CallingbyDSCtechniqueswithintheauthorizedmaritimeVHFhand,forpubliccorrespondence,fromshiptocoaststation,fromcoaststationtoshipandfromshiptoshipshould,asageneralrule,bemadeontheDSCChannel70.watchCoaststationswhichmaintainwatch-keepingbyautomaticdigitalselectivecallingonVHFChannel70arelistedintheITUListofCoastStations.ShipstationsequippedwithDSCapparatustoworkintheauthorizedmaritimeVHFbandshould,whileatsea,maintainanautomaticDSCwatchonChannel70.InternationalDSCcallingfrequencies：shipcoastMFⅠ458.5455.5MFⅡ2189.52177.0HF4MHz4208.04219.54208.54220.04209.54220.5HF6MHz6312.56331.06313.06331.56313.55332.0HF8MHz8415.08436.58415.58437.08416.08437.5HF12MHz12577.512657.012578.012657.512578.512658.0HF16MHz16805.018903.016805.516903.516806.016904.0HF18MHz18898.519703.518899.019704.018899.519704.5HF22MHz22374.522444.022375.022444.522375.522445.0HF25MHz25208.526121.025209.026121.525209.526122.0VHF70頻道70頻道Shiptoship2177.0kHzMethodofCalling

(otherthandistress,urgencyorsafetycall)Thecallshallcontaininformationindicatingthestationorstationstowhichthecallisdirected,andtheidentificationofthecallingstation.Thecallshouldalsocontaininformationindicatingthetypeofcommunicationtobesetupandmayincludesupplementaryinformationsuchasaproposedworkingfrequencyorchannel;

Thisinformationshallalwaysbeincludedincallsfromcoaststations,whichshallhavepriorityforthatpurpose.ThemethodusedtotransmitaDSCcallforpubliccorrespondencetocoaststationoranothershipisasfollows:

(a)tunetransmittertotherelevantDSCchannel;

(b)selecttheformatforcallingaspecificstationontheDSCcontroller(individualcall,groupcall,areacallordistresscall);

(c)onthekeyboardselect(orkeyin):

?theninedigitMMSIofthestationtobecalled;

?thecategoryofthecall(routine);

?thetypeofsubsequentcommunication(usuallyRT/ARQ/FEC))

?aproposedworkingchannelifcallinganothership.(d)transmittheDSCcall,andwaitfortheacknowledgement.Notethatallproposedworkingchannelshouldnotbeincludedinacalltoacoaststation.ThecoaststationwillindicateafreeworkingchannelinitsDSCacknowledgement.CallingstationCalledstationCallingIdentificationofcalledstationIdentificationofcallingstationSubsequenttypeofcommunicationProposedworkingfrequencyAcknowledgeSubsequentcommunicationAcknowledgementofCalls

ThereplytoadigitalselectivecallrequestinganacknowledgementshallbemadebytransmittinganappropriateacknowledgmentusingDSCtechniques,acknowledgementsmaybemanualorautomatic.Transmissionofthecallingsignalmustceaseassoonasanacknowledgementhasbeenreceived.

Acknowledgementsshallnormallybetransmittedonthefrequencypairedwiththefrequencyofthereceivedcall.Ifthesamecallisreceivedonseveralcallingchannels,themostappropriateshallbechosentotransmittheacknowledgement.

AcknowledgementofCalls

ThereplytoadigitalselectivecallrequestinganacknowledgementshallbemadebytransmittinganappropriateacknowledgmentusingDSCtechniques,acknowledgementsmaybemanualorautomatic.Acknowledgementsshallnormallybetransmittedonthefrequencypairedwiththefrequencyofthereceivedcall.Ifthesamecallisreceivedonseveralcallingchannels,themostappropriateshallbechosentotransmittheacknowledgement.

Transmissionofthecallingsignalmustceaseassoonasanacknowledgementhasbeenreceived.

AcknowledgementofareceivedCallandPreparationforReceptionoftheTraffic

OnreceiptofaDSCcallfromacoaststationoranothership,aDSCacknowledgementistransmittedasfollows:

*TunethetransmittertothetransmitfrequencyoftheDSCchannelonwhichthecallwasreceived;

*SelecttheacknowledgementformatontheDSCequipment;

*Transmitanacknowledgementindicatingwhethertheshipisabletocommunicateasproposedinthecall.

*Ifabletocommunicateasindicated,nowtunethetransmitterandtheradiotelephonyreceivertotheindicatedworkingchannelandprepareforreceivingthetraffic.typeofcommunicationandworkingfrequencywhenanacknowledgementhasbeenreceivedwhichindicatesthatthecalledstationisreadytoreceivetraffic,theship'stransmittershouldbepreparedfortrafficasfollows:

(a)tunetransmitterandreceivertotheagreedworkingchannelindicated;

(b)initiatecommunicationonthisworkingchannelasfollows:

?theninedigitMMSIorcallsignorotheridentificationofthecalledstation;

?thisis;

?theninedigitMMSIorcallsignorotheridentificationofthecallingstation(ownship).

Ifthestationcalleddoesnotacknowledgethecall,thecallmaybetransmittedagainonthesamecallingfrequency(oranotherfrequency)afteraperiodofatleastfiveminutes(fivesecondsinautomatedVHFsystems).Acoaststationwillacknowledgeacallwithin5s～4.5min(VHF3S).

Normallyitshouldnotthenberepeateduntilafterafurtherintervalof15minutes.

HowtochooseafrequencyforNBDP?Forgeneralcommunicationspurposes,pairedfrequenciesarenormallyusedbetweencoastandshipstations.PairedNBDPfrequenciesarenormallyusedforARQcommunicationswithcoastradiostations.Whenplacingatelexcalltoacoaststation,youshouldalwaysmakesurethefrequencyisnotoccupiedwithnormaltraffic.Listentoshorestation“freesignals”;choosethebandwiththestrongest.4.3NarrowBandDirectPrintingEquipmentandSystems(1)TherearetwomainmodesofoperationnamelyARQandFEC.Forcommunicationbetweentwostations,theARQ(AutomaticRepetitionRequest自動重復請求)modeshouldbeusedwhenavailable.(pointtopoint點對點)

Fortransmissionsfromonecoastorshipstationtotwoormoreotherstations,theFEC(ForwardErrorCorrecting前向糾錯)modeshouldbeusedwhenavailable.(pointtosurface點對面)

BARQmode01.ABmessageShipA’transmitter

ShipB’transmitter

ShipA’receiver

ShipB’receiver

ErrordetectioncodeIfnoerror,shipAwillsendnextmessage,otherwisetheexistingmessagewillre-sent.ARQ(AutomatedRepetitionrequest)FEC(ForwardErrorCorrecting)modeABmessageShipA’transmitter

ShipB’receiver

ShipAsendseachmessagetwiceonly.IftwomessagereceivedbyShipBisidentical,shipBwillprintit.samemessagesentatsecondtimeFEC(ForwardErrorCorrection)CFEC:collectiveFEC（集群性FEC）SELFEC(selectiveFEC,SFEC)選擇性FEC

Againtherecipient’stransmitter(接收者的發(fā)射機)doesnothavetobeactiveanditissimilartoFECinallrespectsexceptthatthetransmissionisaddressedtoaparticularreceivingstation(i.e.byaddressingthecalltotheappropriateMMSI).

(2)AllshipsequippedwithtelextoworkinMF/HFbandsshallbeabletosendandreceiveclassF1BorJ2Bemissions;(3)Chinaallocationofselcallnumbersisasfollows:(分配給中國無線電傳選呼碼)

Shipstations: 19700to20399

Coaststations: 2010to2039(4)Telexanswerbacks

Toensurethatanoperatorhasbeenconnectedtothecorrectcoastradiostation,shipstation,ortelexsubscriberashore,itisnormaltoexchangeanswerbacksatthecommencement(開始)ofatelexlink.

ABCallShipBwithit’sMMSIAnswerown’sanswerbackWhen,forexample,theautomaticradiotelexfacilitycontrolledbycoastalradiostationisaccessed,thefollowinganswerbackwillbereceived:

“004122100XSGCN".

Where:004122100isShanghairadio'sMMSI;

XSGindicatestheidentificationofShanghairadio;and

CN indicatesthecountry—inthiscaseChina.

Aship'sanswerbackmightbe“41217910BRYCX".

Where:41217910indicatestheship'sselcallnumber(MV.LIUHE);

BRYCistheship'sinternationalcallsign;X indicatesthatitisamaritimemobilestation.Acompanyororganizationandfinallythecountryidentifier.e.g.33057COSCOCNMaritimeradiotelephonyreferstoradiotelephonecommunication,whenusingMF,HF,VHFfrequencybands,betweenshipandship,shipandassignedstationorshipstationthroughcoastorlandmobilestationandsubscriber.4.4Radiotelephony(RT)CoastalradiostationInternationaltelephonynetworkSubscriberUseofFrequencies

Single-sideband(SSB)apparatusinradiotelephonestationsofthemaritimemobileserviceoperatinginthebandsallocatedtothisservicebetween1605kHzand4000kHz(MF)andinthebandsallocatedexclusivelytothisservicebetween4000kHzand27500kHz(HF)shallsatisfythetechnicalandoperationalconditionsspecifiedintherelevantITURadioRegulations.ModeofemissionUnlessotherwisespecifiedinthepresentITURadioRegulationsnotablytheuseofdifferentmodesofemissionsonspecifieddistressfrequencies,themodeofemissiontobeusedinthebandsbetween1605kHzand4000kHzshallbeJ3E.Themodeofemissiontobeusedforradiotelephonyonthefrequency2182kHzshallbeJ3EorH3E.ThenormalmodeofoperationforeachcoaststationshallbeindicatedintheITUListofCoastStations.Useoffrequency

Bandsbetween1605kHzand4000kHz(MF)

Frequency2182kHz

Thefrequency2182kHzisaninternationaldistressfrequencyforradiotelephony.

Whereadministrationsprovideattheircoaststationsawatchon2182kHzforreceivingclassJ3EemissionsaswellasclassA3EandH3Eemissions,shipstationsmaycallthosecoaststationsforsafetypurposesusingclassH3EorJ3Eemissions.

Thefrequency2182kHzmayalsobeused:

(a)distress,urgencyandsafetycallandcommunication;

(b)forcallandreply;

(c)

bycoaststationstoannouncethetransmission,onanotherfrequency,oftrafficlists.

Tofacilitateuseofthefrequency2182kHzfordistresspurposes,alltransmissionson2182kHzshallbekepttoaminimum.

Beforetransmittingonthecarrierfrequency2182kHz,astationshalllistenonthisfrequencyforareasonableperiodtomakesurethatnodistresstrafficisbeingsent;thisprovisiondoesnothoweverapplytostationsindistress.

callandreplyShiptocoast:Call:2182KHzoraworkingfrequencyofcoaststationReply:2182KHzoraworkingfrequencycorrespondingtothecallingfrequencyTheworkingfrequenciesforeachcoaststationshallbeindicatedintheITUListofCoastStationsorAdmiraltyListofRadioSignal.TrafficfrequencyAftercontacthasbeenestablishedthroughcallingandreplying,bothshipandcoaststationshouldtransfertoafrequencywhichisdesignatedbythecoaststationorconsultedbytwosides.Bandsbetween4000kHzand27500kHz(HF)ThemodeofemissiontobeusedforRTtransmissionsinthebandsbetween4000kHzand27500kHzshallbeJ3E.ShipRTstationsemployingJ3Eemissioninthebandsbetween4000kHzand27500kHzshallatnotimeusepeakenvelopepowerinexcessof1.5kWperchannel.CallandReplyShipstationsandcoaststationsmayusethefollowingcarrierfrequenciesforcallingonRT.ITUchannelnumbershipfrequenciescoastfrequencies4214125kHz4417kHz6066215kHz6516kHz8218255kHz8779kHz122112290kHz13137kHz162116420kHz17302kHz180618795kHz19770kHz222122060kHz22756kHz251025097kHz26172kHzTheyaredistressandsafetyfrequenciesforHFradiotelephony.Beforetransmittingonthecarrierfrequency4125kHz,6215kHz,8255kHz,12290kHzand16420kHz,stationsshouldlistenonthefrequencyforashortperiodtoensurenodistresstrafficisbeingsent.However,thisprovisiondoesnotapplytostationsindistress.Traffic

Whenusingduplextelephony,thetransmittingfrequenciesofthecoaststationandthecorrespondingshipstationwillbeinpairsasindicatedbyappendix16oftheITURadioRegulations.Thesefrequenciesmaybeusedbyshipstationsofanycategoryaccordingtotrafficrequirements.

duplextelephony

(transmitterandreceivercanworksimultaneously)ABmessageShipA’transmitter

ShipB’