《航海英语二三副》-Unit 8 Aids to Navigation-edit

Lesson1RadarARPAandCompassVocabularyandExpressionsacronym [ˈækrənɪm] n. 首字母缩略词aerial [ˈeəriəl]n.天线.aluminum [əˈljʊmɪnəm]n. 铝array [əˈreɪ] n. 队列，排列；一大批；basicprinciple基本原则binnaclestrand['bɪnəkl]n.罗盘柜；罗盘针箱brass[brɑːs]n. 黄铜;黄铜制品burst [bɜːst] v. (使)爆裂，胀开;猛冲;突然出现;collisionavoidance防止相撞compassbowl罗经盆，罗经液缸compasscard罗经刻度盘；罗盘刻度盘compasscard[ˈkʌmpəskɑːd]罗经刻度盘；罗盘刻度盘;convenient[kənˈviːniənt]adj. 实用的;便利的;省事的;correspondsto[ˌkɒrəˈspɒndtu] 相当于;device [dɪˈvaɪs]n. 装置;仪器;器具;设备;electromagneticenergy电磁能electronicequipment电子设备emerged [iˈmɜːdʒd] v. (从隐蔽处或暗处)出现，浮现ferromagnetic[ˌferəʊmæɡˈnetɪk]adj.铁磁的;flux[flʌks] n. 不断的变动;;通量;geographical [ˌdʒiːəˈɡræfɪkl]adj. 地理(学)的;gyroscope [ˈdʒaɪrəskəʊp]n. 陀螺仪;回转仪;inconjunctionwith连同…;与…一起independent [ˌɪndɪˈpendənt]adj独立的;自主的;自治的;induce[ɪnˈdjuːs] v.感应；引起;导致;引产;催生;Magnetic [mæɡˈnetɪk] adj. 像磁铁的;有磁性的;磁的;modulate [ˈmɒdjuleɪt] adj变调;转调;调整;调节;控制navigationalaids导航设备Over-burdened[,əuvə'bə:dənd]负担过重Plot [plɒt]v.标绘positionfixing定位；定坐标pulsemodulated脉冲调制过的radiowave [ˈreɪdiəʊweɪvz]无线电波;电波;retain [rɪˈteɪn]v. 保持;持有;保留;retentivity [,riːten'tɪvɪtɪ] n. 记忆力；保持力；保磁性speckle [ˈspekl] n. 斑点，色斑；ultimate [ˈʌltɪmət] adj. 最后的;最终的;终极的;极端的utilizes[ˈjuːtəlaɪz] v. 使用;利用;运用;应用wavelength [ˈweɪvleŋθ] n. 波长;频道，波道;weatherconditions天气状况;

天气情况

RadarI.RadarRadarisanacronymderivedfromthephraseRadioDetectionandRangingandappliestoelectronicequipmentdesignedfordetectingandtrackingobjects(targets)atconsiderabledistances.Thebasicprinciplebehindradarissimple—extremelyshortburstsofradioenergy(travelingatthespeedoflight)aretransmitted,reflectedoffatargetandthenreturnedasanecho.Radarisanactivedevice.Itutilizesitsownradioenergytodetectandtrackthetarget.Itdoesnotdependonenergyradiatedbythetargetitself.Theabilitytodetectatargetatgreatdistancesandtolocateitspositionwithhighaccuracyistwoofthechiefattributesofradar.Radaruseselectromagneticenergyintheformofradiowaves.Inmarineradars,thewavesarenottransmittedcontinuouslybutinpulses.Thepulsestraveloutwardsinadirectionalbeamataconstantspeedof300millionmeterspersecond(161,987nauticalmiles).Whentheradarpulsestrikesareflectivesurface,partofthewavebouncesbackfromtheobject,thewaysoundwavesbouncebackfromanobject,andproducesanecho.RadarstransmitdirectionalmicrowaveradiopulseswitharotatingAriel(thescanner)ina360ºcirclearoundthemachine.Itdetectsthebearingandrangeofechoingpulsereturnsfromsignificantsurroundingtargetstoproduceamaplikedisplay.Radarnowenablesrangeandbearingsforpositionfixing,navigationalaids,andcollisionavoidanceandsearchandrescuedevices.Theformofelectromagneticsignalradiatedbytheradardependsuponthetypeofinformationneededaboutthetarget.Radar,asdesignedformarinenavigationapplications,ispulsemodulated.Pulse-modulatedradarcandeterminethedistancetoatargetbymeasuringthetimerequiredforanextremelyshortburstofradio-frequency(r-f)energytotraveltothetargetandreturntoitssourceasareflectedecho.Directionalantennasareusedfortransmittingthepulseandreceivingthereflectedecho,therebyallowingdeterminationofthedirectionorbearingofthetargetecho.Oncetimeandbearingaremeasured,thesetargetsorechoesarecalculatedanddisplayedontheradardisplay.Theradardisplayprovidestheoperatorabirdseyeviewofwhereothertargetsarerelativetoownship.Therearetwogroupsofradiofrequenciesallocatedbyinternationalstandardsforusebycivilmarineradarsystems.ThefirstgroupliesintheX-bandwhichcorrespondstoawavelengthof3cmandhasafrequencyrangebetween9300and9500MHz.ThesecondgroupliesintheS-bandwithawavelengthof10cmandhasafrequencyrangeof2900to3100MHz.Itissometimesmoreconvenienttospeakintermsofwavelengthratherthanfrequencybecauseofthehighvaluesassociatedwiththelatter.Basicradarcontrols1.Power/standby/transmitThepower/standby/transmitswitchusuallyhasthreepositions.Pressingthepowerswitchwillactivatetheradartostandby;howeveritdoesn’tcomeonimmediatelyasthemagnetronneedsafewminutestowarmupbeforeitcantransmit.Theradarwillhavesomeformofvisualsignaltocountdownthiswaitperiod,theapprovedbeststandardbeingwithin120seconds.Theradarcanthenbeswitchedto‘transmit’andonsomesetsashortorlongpulsecanbeselectedatthistime,normallylongpulsewouldbeselected.Alongpulsewillbemorelikelytoshowanechofromaweaktargetoratargetatalongerrange.Ashortpulsewillachievebetterdefinitiononshortranges.2.BrillianceThebrilliancecontrolonanalogueradar(oldstyle)controlsthebrightnessoftherotatingtraceandwillalsoaffectsthebrightnessofthedisplayedechosoitneedstobeadjustedsothatthetraceitselfisjustvisible,togiveagoodcontrastbetweenechoandbackground.Onarasterscandisplay(newstyle)thebrilliancecontrolregulatesthebrightnessofthepicture(scaleillumination),makingitbrightenoughfordaylightviewingordimenoughsoasnottoimpairtheoperatorsnightvision.3.GainThegaincontrolmayappeartofunctionlikethebrilliancecontrolinthatitmakesthepicturebrighterordarker,butitiscompletelydifferentsoitisvitalnottoconfusethetwo.Gainaffectsthereceiverandnotthedisplayasthebrilliancedoes.Turningupthegainincreasestheamplificationoftheincomingsignal,makingweakechoeslookstronger,butconfusingthedisplaywithbackgroundspeckleornoise,similartothebackgroundcracklingofanordinaryradio.Turningdownthegainwillreducethesensitivityofthereceiverandreducethenoise,butcaremustbetakennottooverdoasweakordistantechoescanbelost.4.HeadingmarkerTheheadingmarkerandtherangeringscanobscuresmalltargets.Soit’sagoodideatohavetherangeringsturnedoffwhentheyarenotinuseandtodeletetheheadingmarkereveryfewminutestoseeifitismaskingasmalltarget,deadahead.Theheadingmarkerdeletecontrolisusuallyself-cancelling,thatistheheadingmarkerwillreappearassoonasthebuttonisreleased.5.RangeTherangecontrolregulatestherangeatwhichthesetoperatesbychangingthesizeorscaleoftheareaonthedisplay.Changingrangealsoaffectstheradar’spulselength,PRF(pulserepetitionfrequency),andvideopresentation.Youchangetherangejustasyouchangechartsforpassagemakingorclose-inpiloting.Forcoastalnavigationyoumightselectarangeof12milessothatappropriatecoastalfeaturesaredisplayed,forcollisionavoidancearange24milesmaybeappropriate,forpilotageintoaconfinedanchoragearangeof½amilemaybeneeded.6.TuningThetuningcontrolcanbecomparedtothetuningcontrolofanordinaryradio,inthatittunesthereceivertothefrequencyofthetransmitter.Poortuningadjustmentmaynotbeeasilyrecognizedonthescreen.Tuningslightlyoutwilleliminatesomeveryweakechoes,butstillproduceaclearpictureofthestrongerones,hencetheimportanceoffrequentfinetuningoftheset.Notallsetshaveatuningcontrol.7.SeaClutterControl(STC)Theradarbeamwillbounceechoesofftheseaaroundtheship,particularlyiftheweatherisalittlerough.Thisresultwillbeabrightsunburstpatterninthemiddleofthescreenwhichwillbemorepronouncedintheupwinddirection.Youcouldreducethisbyturningdownthegain,thedownsidetothatsolutionhowever,isthattheechoesofmoredistanttargetswillbelostaswell.Thesolutionistheseacluttercontrol.Itworksbyreducingthereceivergainforafewmicrosecondsaftereachpulseistransmitted,andthengraduallyrestoresittoitsformerlevel.Itworksverywell,butitsuserequirescare.Toomuchseacluttercontrolwillresultinthelossofcloserangetargets.Atseatheseacluttercontrolmustbecontinuallymonitoredandadjusted.8.RainClutterControl(FTC)Theraincluttercontrolwillreducetheinterferenceonthescreenduetotherainandincreasethechanceofseeingtargetswithinrainshowers.Theeffectonreturningechoesfromrainonthescreenisusuallynomorethanatransparentsmear,lookingalittlelikecottonwool,butitcanbedenseenoughtoconcealotherechoeswithintheshower.Inatropicaldownpourhowever,theraincancompletelyblockoutallechoes,attimesrequiringtheoperatortostopthevessel.Theraincluttercontrolworksbymakinguseofthefactthatthereturningechofromrainisdifferentfromthereturningechoofasolidobject.Thereturningechofromrainismuchlongerandverymuchlessdensethantheechofromasolidobject.Theraincluttercircuitryworksbypassingontothereceiveronlytheleadingedgeofareturningecho.Thisdoesnotaffectthereturningechofromasolidobjectlikeaship,butdrawnout,weakreturningechoesfromtherainhowever,willbeweakenedconsiderably.9.InterferenceRejection(IR)MutualRadarInterferenceiscausedbyotherradarsinthelocalityoperatingonasimilarfrequencytoyourship’sradar.Theinterferenceshowsupasbrightspotsscatteredoverthescreen,orasadistinctivepatternofdottedlinescurvingoutwardsfromthecentreofthescreen.Itismorecommononlongerrangescalesasonshorterrangescalesonlyafewoftheinterferingpulseswillbedisplayed.Ifonlyoneotherradarisinvolvedthisisnottooserious,butinbusytrafficareasthecluttercanbedenseenoughtocauseconfusion.Aninterferencerejectioncircuitcanminimizethisproblem.Itworksbyrejectinganyechowhichdoesnotreturnfromanytwosuccessivepulses.WhilelargetargetswillnotbeaffectedbyIR,somesmallechoesmaybelost.ThereisnoIMOsymbolforIR.10.EchoenhancementToassisttheoperatortospotsmalltargets,mostmodernradarshavetheabilitytoexpandthem.Usuallynamedechostretchorexpansion,itssoleobjectistomakesmalltargetslookbigger.Thiscanattimesbeagreatbenefit,butitalsotendstodistortthepictureandreducesrangeandbearingdiscrimination.Expansionmaybeusefulattimesbutshouldbeswitchedoffwhennotrequired.ThereisnoIMOsymbolforechoexpansion.11.HeadingmarkerandrangeringsTheheadingmarkerandtherangeringscanobscuresmalltargets.Soit’sagoodideatohavetherangeringsturnedoffwhentheyarenotinuseandtodeletetheheadingmarkereveryfewminutestoseeifitismaskingasmalltarget,deadahead.Theheadingmarkerdeletecontrolisusuallyselfcancelling;thatistheheadingmarkerwillreappearassoonasthebuttonisreleased.12.PulseLengthControlThepulselengthisnormallyselectedautomaticallywiththerangescale.Onmostsetshowever,inthemidranges(6mileto48mileona72mileradar),itispossibletomanuallyselectthepulselength,whichwillhaveasignificanteffectonradarperformance.Alongpulselengthincreasesthechanceofdetectingtargetsatlongrange.Selectingashortpulselengthwillincreaserangediscrimination,makingitpossibletodistinguishbetweenatuganditstowforinstance.InthePPIsshownitcanbeseenthatwhenlongpulseisselectedthesmalltargetalmostdeadaheadisvisible,butthetugandtowaremergedandshownasasinglecontact.Also,ontheleftthelandmasshasmergedwiththeislands.Whenshortpulseisselectedthesmalltargetaheadislost,butthetugandtowareshownasseparateandtheislandshaveseparatedfromthelandmass.13.Off-CenteringByusingtheoff-centeringcontrolthecentreofthepicturecanbemoveddownwardsorupwardsandonsomenewersetsitcanalsobemovedsideways.Movingthecentreofthepicturedownwardsexpandstheeffectiverangeoftheradarforwardsattheexpenseofrangeasternforinstanceonasixmilerange,off-centeringwouldenableyoutoseeninemilesaheadbutonlythreemilesastern.Thiscouldbeanadvantagewhenpilotingbutmaybeadisadvantagewhenusingradarforcollisionavoidanceasafastervesselcancatchuptoyourshipveryquicklyandyoumaybeunawareofitspresenceuntilyouseeitovertakingthroughthewheelhousewindow.Ⅱ.ARPAAutomaticRadarPlottingAids(ARPA)isacomputer-baseddataprocessorthatautomaticallyandcontinuouslyprovidestheuserwithtargetdata.Itconsistsofacomputerusedinconjunctionwithradar.TheARPAcomputerworksoutdataforatrackedtargetinasimilarmannerasanobserverdoingamanualplotofthesametarget,therebymakingnavigationawholeloteasierfortoday’sover-burdenednavigator.ModerndayARPAshavetheirprocessorsincorporatedintheradarresultinginan“integral”radar/ARPAsystem.TheARPAdataisdisplayedonthesamescreenastheradar.NewgenerationARPAshaveahostofnewfeaturesliketouchscreens.MostARPAscanalsobeusedasaidstonavigationbyusingfacilitieslikeNav-LinesorVideomappingandautomaticgroundstabilizationInordertouseARPAtoitsfulladvantage,theusermustnotonlyunderstanditscapabilitiesbutalsorealizeitslimitations.HemustrealizethatARPAisonlyanaidandnottheultimateanswertocollisionavoidance.ARPAcanhelpinassessingthesituationbycarryingoutradarplottingquicklyandaccurately.However,thedutyofficerhimselfmustmaketheapplicationofRulesoftheRoad(ROR)anddecisionsregardingthesuitableactiontoavoidcollision,ineachcase.Ⅲ.MagneticCompassTheprincipleofthepresentdaymagneticcompassisinnowaydifferentfromthatofthecompassusedbytheancients.Itconsistsofamagnetizedneedle,orarrayofneedles,pivotedsothatrotationisinahorizontalplane.Thesuperiorityofthepresentdaycompassresultsfromabetterknowledgeofthelawsofmagnetism,whichgovernthebehaviorofthecompass,andfromgreaterprecisioninconstruction.Magneticcompassesarecomposedofacompassbowlandabinnaclestrand.Thebowlisabowl-shapedcontainerofnonmagneticmaterial(brass)whichservestocontainthemagneticelements,areferencemark,andthefluid.Itissupportedinthegimbalswithinthebinnacle.Thecompasscardisanaluminumdisc,graduatedindegreesfrom0to360.Italsoshowscardinalandinterscardinalpoints.Itcanworksatisfactorilyagainstaninclinationofwithin10degrees.Themagneticneedle(madeofMKmagneticsteel)stickspositivelytothefloat,whichisaluminum,air-filledchamberinthecenterofthecompasscard,anditsmagnetismneverdiminishesduetoageing.Anypieceofmetalonbecomingmagnetized,thatis,acquiringthepropertyofattractingsmallparticlesofironorsteel,willassumeregionsofconcentratedmagnetism,calledpoles.Anysuchmagnetwillhaveatleasttwopoles,ofunlikepolarity.Magneticlinesofforce(flux)connectonepoleofsuchamagnetwiththeotherpoleasindicatedinfigureThenumberofsuchlinesperunitarearepresentstheintensityofthemagneticfieldinthatarea.Iftwosuchmagneticbarsormagnetsareplacedsidebyside,thelikepoleswillrepeleachotherandtheunlikepoleswillattracteachother.Magnetismisingeneraloftwotypes,permanentandinduced.Abarhavingpermanentmagnetismwillretainitsmagnetismwhenitisremovedfromthemagnetizingfield.Abarhavinginducedmagnetismwillloseitsmagnetismwhenremovedfromthemagnetizingfield.Whetherornotabarwillretainitsmagnetismonremovalfromthemagnetizingfieldwilldependonthestrengthofthatfield,thedegreeofhardnessoftheiron(retentivity),andalsoupontheamountofphysicalstressappliedtothebarwhileinthemagnetizingfield.Thehardertheironthemorepermanentwillbethemagnetismacquired.Ⅳ.Gyro-compassAgyro-compassisatypeofnon-magneticcompasswhichbasesonafast-spinningdiscandrotationofourplanettoautomaticallyfindgeographicaldirection.Althoughoneofimportantcomponentsofagyro-compassisagyroscope,thesearenotthesamedevices.Gyro-compassesarewidelyusedfornavigationonships,becausetheyhavetwoSignificantadvantagesovermagneticcompass：TheyfindtruenorthasdeterminedbyEarth'srotation,whichisdifferentfrom,andnavigationallymoreusefulthan,magneticnorth,andTheyareunaffectedbyferromagneticmaterials,suchasship'ssteelhull,whichchangethemagneticfieldAgyro-compassissubjecttocertainerrors.Theseincludesteamingerror,whererapidchangesincoursespeedandlatitudecausedeviationbeforethegyrocanadjustitself.OnmostmodernshipstheGPSorothernavigationalaidsfeeddatatothegyro-compassallowingasmallcomputertoapplyacorrection

Lesson2ECDISGNSSandIBSVocabularyandExpressionsacknowledge [əkˈnɒlɪdʒ] vt. 承认;鸣谢;告知已收到;altitude[ˈæltɪtjuːd]n. 海拔;海拔高度;高程;approvedby经…批准aswellas既…又…;除…之外;此外besatisfied惬怀；安；惬意；惬意的beusedfor用于calculate [ˈkælkjuleɪt]v.计算;核算;预测;推测;complementary[ˌkɒmplɪˈmentri]adj.互补的;补充的;相互补足的;constellation[ˌkɒnstəˈleɪʃn]n.星座;一系列(相关的想法、事物);experiment[ɪkˈsperɪmənt]n.实验;试验;尝试;实践forcertain确切地;无疑地global [ˈɡləʊbl]adj. 全球的;全世界的;整体的;hazard [ˈhæzəd] n. 危险;危害Hydrographic[ˌhaɪdrəˈgræfɪk]adj水道测量的；水文地理的;inrelationto关于；与……相比较；涉及independent[ˌɪndɪˈpendənt]adj.独立的;自主的;自治的infrastructure[ˈɪnfrəstrʌktʃə(r)]n.基础设施，基础建设;IntegratedBridgeSystem 综合驾驶台系统latitude [ˈlætɪtjuːd]n. 纬度.longitude [ˈlɒŋɡɪtjuːd]n. 经度.mandatory [ˈmændətəri]adj. 强制的;命令的;受委托的nationalsecurity国家保密；国家安全navigationsatellite导航卫星orbital[ˈɔːbɪtl]adj.(行星或空间物体)轨道的;外环路的permit[pəˈmɪt]v. 允许;准许;使有可能prevalent[ˈprevələnt]adj.流行的;普遍存在的;盛行的;principle[ˈprɪnsəpl]n.行为准则;规范;法则;原则;原理Progressively[prəˈɡresɪvli]adv.持续稳定地;逐步地;愈益;qualifyas有资格作……Satellite[ˈsætəlaɪt]n. 人造卫星;卫星;sensor[ˈsensə(r)]n. 传感器，敏感元件，探测设备;Superimposed[ˌsuːpərɪmˈpəʊzd]v.(图像甲)叠映在(图像乙)上;使重叠;使叠加;使附加于;timesignal报时信号;I.ECDISTheInternationalConventionontheSafetyofLifeatSea(SOLAS)includesarequirementforallshipstocarrytoup-to-datenauticalchartsandpublicationsfortheintendedvoyage.Progressivelyfrom2012,thechartcarriagerequirementforcertainclassesofvesselsistobesatisfiedbyelectronicmeansusinganElectronicChartDisplayandInformationSystem(ECDIS).ECDISisanon-boardelectronicchartsystemthatconformstotheSOLASrequirementsforuseasaprimarymethodofnavigationandwhichcomplieswiththestandardsoftheIMOandthespecificationsoftheIHO.ThemainpurposeofanECDISistomakenavigationsaferbyusingitscomputerizedabilitytocontinuouslyshowthepositionofthevesselcarryingitinrelationtoland,chartedobjects,aids-to-navigationandnavigationalhazards,alongwithprovidingotherusefulnavigationalinformation.

IMO'sdefinitionofanECDISisthatitis'anavigationinformationsystemwhichwithadequateback-uparrangementscanbeacceptedascomplyingwiththeup-to-datechartrequirementofregulationV/19.2ofthe1974SOLASConvention,bydisplayingselectedinformationfromasystemelectronicnavigationalchart(SENC)withpositionalinformationfromnavigationsensorstoassistthemarinerinrouteplanningandroutemonitoring,andifrequireddisplayadditionalnavigation-relatedinformation.'Ofthemanycommercialelectronicchartsystemsavailable,onlythosewhichqualifyasanECDISbymeetingthestandardsoftheIMOandthespecificationsoftheIHO,andwhichareapprovedbyanationaladministration,satisfySOLAScarriagerequirementsandarethereforeofficiallypermittedtobeusedforprimarynavigation.Therearetwobasictypesofelectronicchartsystems.ThosethatcomplywiththeIMOrequirementsforSOLASclassvessels,knownastheElectronicChartDisplayandInformationSystem(ECDIS),andallothertypesofelectronicchartsystems,regardedgenericallyasElectronicChartSystems(ECS).IfanECSiscarriedonboard,thecontinuoususeofup-to-datepaperchartsremainsessentialforsafenavigationandtofulfillcarriagerequirements.TosatisfythechartcarriagerequirementsofSOLASChapterV,ECDISmustuseElectronicNavigationalCharts(ENCs).ThesearevectorchartsproducedtoInternationalHydrographicOrganizationstandardsandofficiallyissuedbyorontheauthorityofaGovernmentauthorizedHydrographicOfficeorotherrelevantgovernmentinstitution.Atpresent,ENCdataisnotavailableworld-widewhichlimitstheuseofECDISinsomeareas.Thissituation,however,israpidlychangingandcomprehensiveENCcoverageoftheworld'smajortradingroutesandportsisforecasttobecompletedinthenearfuture.TheENCcontainsallthechartinformationnecessaryforsafenavigation,andmaycontainsupplementaryinformationinadditiontothatcontainedinthepaperchart(e.g.sailingdirections)whichmaybeconsiderednecessaryforsafenavigation.ItshouldbenotedthattheECDISisonlyatoolthathelpsamarinersafelyandeffectivelynavigateaship.OneofthebiggestriskswiththetransitiontoECDISisanoverrelianceintheinformationprovided.Periodicalchecksandlookoutmustbeperformedandbasicprinciplesofwatchkeepingtobeobserved.Ⅱ.GNSSAsatellitenavigationsystemisasystemofsatellitesthatprovideautonomousGeo-spatialpositioningwithglobalcoverage.Itallowssmallelectronicreceiverstodeterminetheirlocation(longitude,latitude,andaltitude)towithinafewmeresusingtimesignalstransmittedalongaline-of-sightbyradiofromsatellites.Receiverscalculatetheprecisetimeaswellasposition,whichcanbeusedasareferenceforscientificexperiments.AsatellitenavigationsystemwithglobalcoveragemaybetermedasglobalnavigationsatellitesystemorGNSS,Globalnavigationsatellitesystem(GNSS)isageneraltermdescribinganysatelliteconstellationthatprovidespositioning,navigation,andtiming(PNT)servicesonaglobalorregionalbasis.WhileGPSisthemostprevalentGNSS,othernationsarefielding,orhavefielded,theirownsystemstoprovidecomplementary,independentPNTcapability.Asof2010,theUnitedStatesNAVSTARGlobalPositioningSystem(GPS)istheonlyfullyoperationalGNSS.TheRussianGLONASSisbeingdevelopedtowardsfullglobalcoverage.ThePeople’sRepublicofChinaisintheprocessofexpandingitsregionalBeiDounavigationsystemintotheglobalCompassnavigationsystemby2020.TheEuropeanUnion'sGalileopositioningsystemisaGNSSininitialdeploymentphase,scheduledtobefullyoperationalby2020attheearliest.1.BDSTheBeiDouNavigationSatelliteSystem(hereinafterreferredtoastheBDS)hasbeenindependentlyconstructedandoperatedbyChinawithaneyetotheneedsofthecountry’snationalsecurityandeconomicandsocialdevelopment.Asaspaceinfrastructureofnationalsignificance,theBDSprovidesall-time,all-weatherandhigh-accuracypositioning,navigationandtimingservicestoglobalusers.2.GPSTheGlobalPositioningSystem(GPS)isaU.S.-ownedutilitythatprovidesuserswithpositioning,navigation,andtiming(PNT)services.Thissystemconsistsofthreesegments:thespacesegment,thecontrolsegment,andtheusersegment.TheU.S.AirForcedevelops,maintains,andoperatesthespaceandcontrolsegments.TheGPSspacesegmentconsistsofaconstellationofsatellitestransmittingradiosignalstousers.TheUnitedStatesiscommittedtomaintainingtheavailabilityofatleast24operationalGPSsatellites,95%ofthetime.Toensurethiscommitment,theAirForcehasbeenflying31operationalGPSsatellitesforthepastfewyears.GPSsatellitesflyinmediumEarthorbit(MEO)atanaltitudeofapproximately20,200

km(12,550

miles).EachsatellitecirclestheEarthtwiceaday.ThesatellitesintheGPSconstellationarearrangedintosixequally-spacedorbitalplanessurroundingtheEarth.Eachplanecontainsfour"slots"occupiedbybaselinesatellites.This24-slotarrangementensuresuserscanviewatleastfoursatellitesfromvirtuallyanypointontheplanet.Ⅲ.IBSAnintegratedbridgesystem(IBS)isdefinedasacombinationofsystemswhichareinterconnectedinordertoallowcentralizedaccesstosensorinformationorcommand/controlfromworkstations,withtheaimofincreasingsafeandefficientship'smanagementbysuitablyqualifiedpersonnel.IBSisakindofnavigationmanagementsystemwhichlinksothersystemstoprovideallthedetailspertainingtoship’snavigationatoneplace.ItistonotethatnotalltypesofshipshavethesametypeofIBS.Thesystemwouldvaryaccordingtothedesignoftheship’sbridge,varioustypesofequipmentusedbytheship,andgenerallayoutoftheequipmentofthebridge.AccordingtoSOLASChapterV,Reg.19“Integratedbridgesystemsshallbesoarrangedthatfailureofonesub-systemisbroughttotheimmediateattentionoftheofficerinchargeofthenavigationalwatchbyaudibleandvisualalarms,anddoesnotcaus