Lesson1RadarARPAandCompassVocabularyandExpressionsacronym [??kr?n?m] n. 首字母縮略詞aerial [?e?ri?l]n.天線.aluminum [??lj?m?n?m]n. 鋁array [??re?] n. 隊(duì)列，排列；一大批；basicprinciple基本原則binnaclestrand['b?n?kl]n.羅盤柜；羅盤針箱brass[brɑ?s]n. 黃銅;黃銅制品burst [b??st] v. (使)爆裂，脹開;猛沖;突然出現(xiàn);collisionavoidance防止相撞compassbowl羅經(jīng)盆，羅經(jīng)液缸compasscard羅經(jīng)刻度盤；羅盤刻度盤compasscard[?k?mp?skɑ?d]羅經(jīng)刻度盤；羅盤刻度盤;convenient[k?n?vi?ni?nt]adj. 實(shí)用的;便利的;省事的;correspondsto[?k?r??sp?ndtu] 相當(dāng)于;device [d??va?s]n. 裝置;儀器;器具;設(shè)備;electromagneticenergy電磁能electronicequipment電子設(shè)備emerged [i?m??d?d] v. (從隱蔽處或暗處)出現(xiàn)，浮現(xiàn)ferromagnetic[?fer??m?ɡ?net?k]adj.鐵磁的;flux[fl?ks] n. 不斷的變動(dòng);;通量;geographical [?d?i???ɡr?f?kl]adj. 地理(學(xué))的;gyroscope [?d?a?r?sk??p]n. 陀螺儀;回轉(zhuǎn)儀;inconjunctionwith連同…;與…一起independent [??nd??pend?nt]adj獨(dú)立的;自主的;自治的;induce[?n?dju?s] v.感應(yīng)；引起;導(dǎo)致;引產(chǎn);催生;Magnetic [m?ɡ?net?k] adj. 像磁鐵的;有磁性的;磁的;modulate [?m?djule?t] adj變調(diào);轉(zhuǎn)調(diào);調(diào)整;調(diào)節(jié);控制navigationalaids導(dǎo)航設(shè)備Over-burdened[,?uv?'b?:d?nd]負(fù)擔(dān)過重Plot [pl?t]v.標(biāo)繪positionfixing定位；定坐標(biāo)pulsemodulated脈沖調(diào)制過的radiowave [?re?di??we?vz]無線電波;電波;retain [r??te?n]v. 保持;持有;保留;retentivity [,ri?ten't?v?t?] n. 記憶力；保持力；保磁性speckle [?spekl] n. 斑點(diǎn)，色斑；ultimate [??lt?m?t] adj. 最后的;最終的;終極的;極端的utilizes[?ju?t?la?z] v. 使用;利用;運(yùn)用;應(yīng)用wavelength [?we?vle?θ] n. 波長;頻道，波道;weatherconditions天氣狀況;

天氣情況

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,forpilotageintoaconfinedanchoragearangeof?amilemaybeneeded.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 [?k?n?l?d?] vt. 承認(rèn);鳴謝;告知已收到;altitude[??lt?tju?d]n. 海拔;海拔高度;高程;approvedby經(jīng)…批準(zhǔn)aswellas既…又…;除…之外;此外besatisfied愜懷；安；愜意；愜意的beusedfor用于calculate [?k?lkjule?t]v.計(jì)算;核算;預(yù)測;推測;complementary[?k?mpl??mentri]adj.互補(bǔ)的;補(bǔ)充的;相互補(bǔ)足的;constellation[?k?nst??le??n]n.星座;一系列(相關(guān)的想法、事物);experiment[?k?sper?m?nt]n.實(shí)驗(yàn);試驗(yàn);嘗試;實(shí)踐forcertain確切地;無疑地global [?ɡl??bl]adj. 全球的;全世界的;整體的;hazard [?h?z?d] n. 危險(xiǎn);危害Hydrographic[?ha?dr??gr?f?k]adj水道測量的；水文地理的;inrelationto關(guān)于；與……相比較；涉及independent[??nd??pend?nt]adj.獨(dú)立的;自主的;自治的infrastructure[??nfr?str?kt??(r)]n.基礎(chǔ)設(shè)施，基礎(chǔ)建設(shè);IntegratedBridgeSystem 綜合駕駛臺(tái)系統(tǒng)latitude [?l?t?tju?d]n. 緯度.longitude [?l??ɡ?tju?d]n. 經(jīng)度.mandatory [?m?nd?t?ri]adj. 強(qiáng)制的;命令的;受委托的nationalsecurity國家保密；國家安全navigationsatellite導(dǎo)航衛(wèi)星orbital[???b?tl]adj.(行星或空間物體)軌道的;外環(huán)路的permit[p??m?t]v. 允許;準(zhǔn)許;使有可能prevalent[?prev?l?nt]adj.流行的;普遍存在的;盛行的;principle[?pr?ns?pl]n.行為準(zhǔn)則;規(guī)范;法則;原則;原理Progressively[pr??ɡres?vli]adv.持續(xù)穩(wěn)定地;逐步地;愈益;qualifyas有資格作……Satellite[?s?t?la?t]n. 人造衛(wèi)星;衛(wèi)星;sensor[?sens?(r)]n. 傳感器，敏感元件，探測設(shè)備;Superimposed[?su?p?r?m?p??zd]v.(圖像甲)疊映在(圖像乙)上;使重疊;使疊加;使附加于;timesignal報(bào)時(shí)信號(hào);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