CSBA-水下戰(zhàn)新紀(jì)元（英文）-2021.5-21正式版

THEEMERGINGERAIN

UNDERSEAWARFARE

BRYANCLARK

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TheEmergingErainUnderseaWarfare

Introduction

U.S.defensestrategydependsinlargepartonAmerica’sadvantageinunderseawarfare.QuietsubmarinesareoneoftheU.S.military’smostviablemeansofgatheringintelligenceandpro-jectingpowerinthefaceofmountinganti-access/area-denial(A2/AD)threatsbeingfieldedbyagrowingnumberofcountries.Asaresult,underseawarfareisanimportant,ifnotessential,elementofcurrentandfutureU.S.operationalplans.America’srivalsworryinparticularabouttheaccesssubmarinesprovideforU.S.power-projectionoperations,whichcanhelpoffsetanenemy’snumericalorgeographicadvantages.1

Broadlyspeaking,underseawarfareistheemploymentofsubmarinesandotherunderseasys-temsinmilitaryoperationswithinandfromtheunderwaterdomain.Thesemissionsmaybebothoffensiveanddefensiveandincludesurveillance,insertionofSpecialForces,anddestroy-ingorneutralizingenemymilitaryforcesandunderseainfrastructure.

America’ssuperiorityinunderseawarfareistheproductofdecadesofresearchanddevelop-ment(R&D),asophisticateddefenseindustrialbase,operationalexperience,andhigh-fidelitytraining.Thissuperiority,however,isfarfromassured.U.S.submarinesaretheworld’squi-etest,butnewdetectiontechniquesareemergingthatdonotrelyonthenoiseasubmarinemakes,andthatmayrendertraditionalmannedsubmarineoperationsfarriskierinthefuture.America’scompetitorsarelikelypursuingthesetechnologieswhilealsoexpandingtheirownunderseaforces.Tosustainitsunderseaadvantagewellintothiscentury,theU.S.Navymustaccelerateinnovationinunderseawarfarebyreconsideringtheroleofmannedsubmarinesandexploitingemergingtechnologiestofieldanew“familyofunderseasystems.”

OwenR.Cote,Jr.,AssessingtheUnderseaBalanceBetweentheU.S.andChina,StrategicStudiesProgramWorking

Paper(Boston:MassachusettsInstituteofTechnology,February2011);DavidAxe,“ChinaThinksItCanDefeatAmericaInBattle,”RealClearDefense,September24,2014,availableat/articles/2014/09/24/china_thinks_it_can_defeat_america_in_battle_107461.html.

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Overthenextyear,theCenterforStrategicandBudgetaryAssessments(CSBA)willexploretrendsinunderseawarfaretechnologyandoperationsaspartofanewresearchinitiative.ThegoalofthiseffortistoidentifynewapproachesthatexploittheunderseadomaininordertomaintainU.S.militaryadvantagewhilepreservingtheabilitytodenyuseoftheunderseatoadversaries.Thisinitialreportdescribeshowunderseacompetitionsevolvedoverthelastcen-tury,thedisruptivetrendsthatmayleadtoanewerainunderseawarfare,andtheelementsthatwillcompriseaneffectiveapproachtothenextchapterinunderseacompetition.

EvolutionoftheUnderseaCompetition

Tounderstandhowunderseawarfaremaychangeinthefuture,itisusefultoreviewhowitevolvedoverthepastcentury.Whileminingandmineclearinghaveexistedalmostaslongasships,underseawarfarefirstemergedasasignificantareaofoffensiveanddefensivemilitaryoperationsinWorldWarI(WWI).Severalcountriesinthatconflictbegantousesubmarinesonalargescaletoattackcivilianshippingand,occasionally,enemywarships.Thiscreatedtheneedforantisubmarinewarfare(ASW)andbegana“hider-finder”competitionbetweensubmarinesandASWforces.Inthecenturyfollowingthewar,thiscompetitionevolvedthroughseveraldis-tinctphases,eachcharacterizedbythepredominantASWdetectionmethod.

InWWIandWorldWarII(WWII),thehider-findercompetitionbetweensubmarinesandASWforceslargelyplayedoutabovethewater,throughradioandradartransmissionsintheelectro-magnetic(EM)spectrum.Submarineswererelativelyslowandlimitedtoshort-rangevisualdetectionoftargets.2Theyneededtobe“cued”ordirectedtowardconvoysbyradiocommuni-cationsfromshoreorothersubmarines.ThesecommunicationscouldbeinterceptedbyASWforces,whichdecryptedsubmarineordersandreportsorgeo-locatedtransmittingsubmarinesusinghigh-frequencydirectionfinding(HFDF)equipment.Further,submarinesinbothwarswerevulnerabletovisualand(inWWII)radardetectionbecausetheyweremorelikesubmers-ibleshipsthantruesubmarines.Theycouldonlyoperatesubmergedfor1–2daysandspentmostoftheirtimeonthesurfaceinordertousetheirdieselenginesforfasterpropulsion,torefreshtheiratmosphere,andtorechargetheirbatteries.

TheWWIIhider-findercompetitionledtoacycleofmovesandcountermoves;asASWforcesdevelopednewwaystodetectsubmarines,submarinesattemptedtocounterbyemployingnewmethodstoevadedetection.Forexample,submarineforcesdeployedradar-warningreceiv-ers(RWR)oncetheyrealizedradarwasbeingemployedsuccessfullyagainstthem.ASWforcesrespondedbyfieldinghigher-frequencyradarsthatweremoreeffectiveandnotdetectablewiththeexistingRWRs.Oncesubmarineforcesrealizedtheywerebeingtrackedbynewradarfre-quencies,theydevelopedanewRWRtocompensate.Similarly,whenonesidedeterminedits

AsurfacedWorldWarIIsubmarinehada“heightofeye”ofabout20feetorless.Heightofeyeistheheightofasensor(includingaperson)abovetheocean’ssurface.Thehigherthesensor,thefartherawaythesensorcanseebecauseitshorizonisfartheraway.Mathematically,thedistanceasensorcanseeisdeterminedbytheformula:Range(nm)=1.14x√Heightofeye(ft)

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communicationcodeswerelikelybroken,newcodeswouldbeintroducedtorestoretheabilitytosecurelycoordinateoperations.Inturn,thesenewcodeswouldeventuallybebroken.Thesecyclesrepeatedwithincreasingspeeduntilthewarended,asreflectedinFigure1.

FIGURE1:LIFETIMEOFADVANCEMENTSINTHEWWIIASWCOMPETITION

AlthoughASWforcesinbothWorldWarsperiodicallygainedanadvantageintheEMspectrum-basedhider-findercompetition,theywereunabletosinkasignificantnumberofenemysubma-rinesuntillateineachconflict.Shippinglossestosubmarineattack,however,decreasedshortlyafterdedicatedASWeffortsbegan,asillustratedinFigure2.3Thissuggeststhat,insteadofelim-inatingsubmarines,ASWeffortsreducedsubmarineeffectivenessbyslowingtheirdeploymenttopatrolareas,preventingthemfromgettingintofiringposition,anddisruptingtheircoordina-tionofattacks.ThisASWapproachexploitedtheinherentdisadvantagesofsubmarinesinthattheyarerelativelyslow,lackself-defensesystems,andcannotrapidlyassesstheeffectivenessof

ThiscompetitionisdescribedindetailinJohnStillionandBryanClark,WinningBattleNetworkCompetitionsinthe

21stCentury(Washington,DC:CenterforStrategicandBudgetaryAssessments,2015).

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anincomingweapon.Asaresult,evenunsuccessfulASWattacksoftencompelledasubmarinetoevadeandlosetheinitiativeormadeitmoredetectableforASWre-attacks.

FIGURE2:SHIPPINGANDSUBMARINELOSSESINTHEBATTLEOFTHEATLANTIC

Thefirstmajordisruptioninthehider-findercompetitioncamewiththeintroductionofsnor-kels,improvedRWRs,and“burst”communicationsinthelatterpartofWWII.4Thiscombina-tionofcapabilitiesenabledsubmarinessuchastheGermanTypeXXItoremainsubmergedandminimizetheirvulnerabilitytoradardetectionwhensnorkeling,effectivelyendingtheEM-basedsubmarine-ASWcompetition.Submarineforces,however,wereunabletodeploytheseadvancementsinrelevantnumbersbeforetheendofthewar.

Thesubmarinesnorkel,similartothoseusedbyswimmerslookingatcoralreefs,enablesasubmarinetointakeairfromabovethewaterwhilethesubmarineremainssubmerged(apartfromthetopofthesnorkel).Thisenablesthesubmarinetorunitsdieselengine,whichprovidesgreaterpropulsionpowerandspeedthanthebattery,andexchangetheairinthesubmarinewithfreshair.Whenradarswereusedtodetectsnorkels,RWRsenabledsubmarinestolowerthesnorkelandavoiddetection.“Burst”communicationsenabledthemtoreducethelengthoftransmissionsandtheirsusceptibilitytointerception.NewRWRswerepermanentlymountedonsubmarinemastsandcouldbeoperatedwhilethesubmarinewasatperiscopedepth.Previously,RWRantennaeweretemporarilymountedonthesubmarine’sbridgewhileitwassurfaced.Theyhadtobebrokendownandbroughtinsidebeforethesubmarinecouldsubmerge.RWRswerealsolimitedintheirfrequencyrange.Attheendofthewar,newRWRssuchastheTuniscoveredthehighestfrequencyrangesthatwereusefulforsubmarinesearchanddetection(“X-band”).

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FIGURES3AND4:GERMANTYPEXXISUBMARINEANDTHEUSSNAUTILUS

NaviespursuedseveraleffortsafterWorldWarIItousesonarforASW.5Butsubmarinesprovedtooquiettohearwithpassivesonarwhentravellingonbatterypoweranddisappearedinsurfacenoiseorsoundedlikediesel-poweredsurfaceshipswhensnorkeling.Activesonarwassomewhateffectiveagainstsubmarineswhentheywereoperatingatshallowdepths,suchaswhensnorkeling,butthedetectionrangewasshortduetopropagationlossesincurredasthesoundtravelledbothtoandfromthesubmarine.

ThischangedwiththeintroductionofthenuclearsubmarineearlyintheColdWar.Nuclearsubmarinesdidnotneedtosurfaceorsnorkel,makingthemnearlyimpossibletofindwithradarandactivesonar.However,duringearlyexerciseswithnuclearsubmarinessuchasUSSNautilus,theU.S.Navyrealizedthenewboatshadanunexpectedvulnerability—theygeneratedcontinuousnoisefromtheirnuclearandsteamplantmachinery.ThissoundcouldbedetectedatlongrangewithpassivesonarstheNavydevelopedtofinddieselsubmarines.AstheSovietsshiftedtousingmostlynuclearsubmarinesforoperationsoutsidetheirhomewaters,theU.S.NavyadoptedpassivesonarasitsprimaryASWsensor.Thisbegananewhider-findercompeti-tionbetweensubmarinesandASWforcesbasedonpassivesonar.

TheU.S.Navyexploitedits“firstmover”advantageinpassivesonarbystartingamethodi-calsound-silencingprogramforitsnuclearsubmarinesandestablishingthepassiveSoundSurveillanceSystem(SOSUS)networkofftheU.S.coastaswellasatkeychokepointsbetweentheSovietUnionandtheopenocean.Theseeffortsenabledanoperatingconceptfromtheearly1960stothelate1970sinwhichSOSUS,patrolaircraft,andsubmarineswouldtrail—andbepreparedtoattack—Sovietnuclearsubmarinesthroughouttheirdeployments.

ThisASWconceptdependedonatemporaryU.S.submarinesilencingadvantagethatbegantoerodeinthemid-1970safterSovietleaderslearnedoftheirsubmarines’acousticvulnerability

“Passive”sonarinvolveslisteningfornoiseemanatingfromthesubmarine;“active”sonarbouncessoundoffsubmarinestolocatethem(alsoknownasecho-location).

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fromtheJohnWalker-ledspyringandsubsequentlyobtainedtechnologyforsubmarinequiet-ing.6TheresultingsilencingprogramproducedSovietsubmarinessuchastheAkulaandSierraclassesthatapproachedthesoundlevelsofcontemporaryU.S.boats.7Consequently,U.S.ASWforceswouldnotbeabletocontinuouslytrackSovietsubmarines,andtheoperatingconceptofdestroyingthemattheoutsetofconflictwasnolongerexecutable.

Inresponse,theU.S.Navyadoptedanewapproachinthe1980sthatappliedlessonsfromWWIandWWII.RatherthanplanningtosinkSovietsubmarines,U.S.ASWeffortswouldfocusondegradingtheiroperationaleffectiveness.8U.S.nuclear-poweredattacksubmarines(SSNs)deployedtowatersnearRussia(alsoknownas“bastions”)toseekoutSovietballisticmissilesubmarines(SSBNs).ThisoperatingpatterncompelledtheSovietstokeeptheirbestSSNsinthebastionstoprotecttheirSSBNs,ratherthandeployingthemoutintotheAtlanticandPacificoceanstoattackU.S.navalforces.AsmallportionoftheU.S.Navy’sdozensoffront-lineSSNswereneededtoconductthisoperation,butthecoststheyimposedontheSovietsweredispro-portionatelylargesincetheSovietshadfewerthan10comparablesubmarines.

FIGURE5:ATLANTICSOSUSCOVERAGE

OwenR.Cote,Jr.,“TheThirdBattle:InnovationintheU.S.Navy’sSilentColdWarStrugglewithSovietSubmarines,”

U.S.NavalWarCollegeNewportPapers,16,2003.

JohnR.Benedict,“TheUnravelingandRevitalizationofU.S.NavyAntisubmarineWarfare,”NavalWarCollegeReview,58,no.2,Spring2005,pp.93–120.

Cote,“TheThirdBattle”;JohnB.HattendorfandPeterM.Swartz,“U.S.NavalStrategyinthe1980s,”U.S.NavalWar

CollegeNewportPapers,33,2008,p.33.

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FIGURE6:AKULA-CLASSSUBMARINE

Thisnewapproach,however,wouldalsobetemporary.WhentheSovietseventuallydeployedlargernumbersoftheirownquietSSNs,theywouldbeabletobothprotecttheirSSBNsinthebastionsandoverwhelmASWforcesdefendingtheU.S.fleet.FortheU.S.NavythismeantthatASWforceswouldonceagainhavetoadapt;inthiscase,movingawayfrompassivesonartoanewwayoffindingsubmarines.OnepromisingoptiontheU.S.Navycontemplatedwaslow-fre-quencyactivesonar,whichwasfirsttestedinthelate1980s.9ButjustasinWorldWarII,ASWforceswere“savedbythebell”whentheColdWarendedbeforetheSovietscoulddeploymorequietsubmarines.

DespitethefalloftheBerlinWall,underseaplatformscontinuedtoimproveandproliferate,increasingthechallengeforASWforces.Nuclearsubmarines,suchastheU.S.Navy’sVirginia-class,becamequieterwhilenewnon-nuclearsubmarinesincreasedtheirendurancewithair-independentpropulsion(AIP)enginesandbetterbatteries.Bothtypescannowemploylong-range,supersonicanti-shipcruisemissiles(ASCM)abletodefeatmanycommonshipboardairdefensesystems.Unmannedunderseavehicles(UUV)andremotelyoperatedvehicles(ROV)alsohavecomeintocommonuseforsurveyingandmaintenanceofinfrastructureoffshoreandinthedeepocean.Andtodaysensor,processing,power,andcommunicationtechnologiesareonthevergeofbreakthroughsthatcouldrevolutionizethecapabilitiesofunderseaplatforms.

GordonD.Tyler,Jr.,“TheEmergenceofLow-FrequencyActiveAcousticsasaCriticalAntisubmarineWarfareTechnology,”JohnsHopkinsAPLTechnicalDigest,13,no.1,1992,pp.145–159.

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UnderseaGameChangers

Technologicaladvancements,manyofthemdrivenbyrapidincreasesincomputerpro-cessingpower(or“bigdata”),willlikelyspuranewroundofdramaticchangesinunderseawarfarethrough:

NewASWcapabilitiestofindandattackunderseaplatforms;

Underseaplatformimprovementsthatwillenhancetheirenduranceandstealth;and

Newunderseaweapon,sensor,andcommunicationsystems.

ASWcapabilities.SincetheColdWar,submarines—particularlyquietAmericanones—havebeenassumedtobelargelyimmunetoanti-accessthreats.Yettheabilityofsubmarinestohidethroughquietingalonewilldecreaseaseachsuccessivedecibelofnoisereductionbecomesexponentiallymoreexpensiveandnewdetectiontechniquesmaturethatrelyonphenomenaotherthanthesoundsemanatingfromasubmarine.Whilethephysicsbehindmostofthesealternativetechniqueshasbeenknownfordecades,theyhavenotbeenexploitableuntilveryrecentlybecausecomputerprocessorsweretooslowtorunthedetailedmodelsneededtoseesmallchangesintheenvironmentcausedbyaquietsubmarine.Today,“bigdata”isprovidingthecapabilitytorunsophisticatedoceanographicmodelsinrealtimesothesedetectiontech-niquescanbeused.Andascomputerprocessorscontinuetoshrink,someofthemwillsoonbesmallenoughtofitonships,aircraft,UUVs,anddeployablesystemsplacedontheseafloor.Thesesystemshavethepotentialtomakecoastalareasfarmorehazardousformannedsubma-rines,likelydrivinggreaterrelianceonUUVstoconducttacticaloperationsinenemylittorals.

Emergingacoustictechniqueswillcontinuetoexploitnewformsofactivesonarandmethodsofanalyzingtheambientnoisealreadypresentintheocean.Mostactivesonarsonshipsandsubmarinesare“mediumfrequency”(MF),meaningtheytransmitsoundbetween1000and10,000hertz(Hz).“Lowfrequency”(LF)sonar,atlessthan1000Hz,hasgreaterrangethanMFsonarbecausethesoundsufferslessattenuation,butitalsoprovideslessprecisebearingandrangeinformation.Advancementsinmodelingandcomputerprocessingwillenhancethistargetinformationsimilartohowphotographicimagescanbeenhanced.ThiswilllikelymakeLFsonarusefulasatacticaloroperational-levelASWsensor.“Bigdata”couldalsoenabledetec-tionofasubmarinebycomparingexpectedambientnoisefrommarinelife,waves,andseismiceventstomeasurednoisefields,possiblyidentifyingwheresoundsarebeingreflectedoffasub-marineorobscuredbyitshull.10

AndrewR.Frey,JosephR.Gagnon,andJ.H.Tart,“Detectionofasilentsubmarinefromambientnoisefieldfluctuations,”UMAPJournal,17,no.3,September1996.

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FIGURE7:T-AGOSCOMPACTLOWFREQUENCYACTIVESONARSHIP

FIGURE8:VIRGINIA-CLASSSUBMARINE

Emergingnon-acousticdetectiontechniquesalsoshowgreatpromise.11Thetheoreticalpossi-bilitiesofdetectingminutechangesontheocean’ssurfacecausedbyasubmarineorthewakeitleavesunderwaterhavebeenwidelyrecognizedsincetheColdWar,butonlynowhavepro-cessingpowerandoceanographicmodelingimprovedtothepointwheretheseapproachesmay

DanielG.Daly,ALimitedAnalysisofSomeNonacousticAntisubmarineWarfareSystems,master’sthesis(Monterey,

CA:NavalPostgraduateSchool,March1994);SangmookShin,“SimulationofTwo-DimensionalInternalWavesGeneratedbyaTranslatingandPitchingFoil,”O(jiān)ceanEngineering,72,November2013,pp.77–86.

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beoperationallyfeasible.MethodstodetectradiationorchemicalsemittedbyasubmarinealsodatefromtheColdWarandmaybenefitfromtheimprovedsensitivity“bigdata”couldprovide.

Lasersandlightemittingdiodes(LED)cansupportnon-acousticASWbybouncinglightoffthesubmarinehull,similartoactivesonar.Duetomaterialandcomputercontrollimitations,previousgenerationsofthesesystemscouldonlyoperateinfrequencyrangesinwhichthelightenergywashighlysusceptibletoattenuation(beingturnedintoheat)orabsorptionbywaterorothermolecules.EmerginglasersandLEDs,however,canbepreciselytunedtowavelengthsinwhichthelightenergysufferssmallerlosses,increasingtheirrangeofdetectiontooperation-allyusefuldistances.

Incombination,newsensorsandrelatedimprovementstotorpedoseekerscouldenablecom-pletelynewapproachestofindingandattackingsubmarines.Mostsignificantly,ASWforcescouldshiftawayfromtoday’sskill-andlabor-intensivetacticsthatresultfromtheshortdetec-tionrangeofsensorsthatarepreciseenoughtosupportASWengagements.ThislimitationrequiresASWshipsandaircrafttomethodicallysearchawideareaforasubmarine,thentrackituntiltheycangetwithinweaponsrangeforanattack.Newsensorandseekercapabilitiescouldinsteadenablea“fireandforget”approachinwhichASWforcesdetectasubmarineatlongrangeandapplycomputerprocessingtoobtainenoughprecisionforanattackusinglong-rangemissileswithtorpedowarheads.Thiskindofattackmaynotsinkthesubmarine,butwouldlikelycompelittoatleastevade,breakingitsinitiativeandmakingitmoredetectable.

Platformenhancements.Newtechnologywillalsoaddressthelimitedenduranceofnon-nuclearunderseaplatformsandthegrowingvulnerabilityofmannedsubmarines.Advancesinbatteryandfuelcelltechnologyareexpectedtoenablenon-nuclearsubmarines,UUVs,andotherunderseasystemstoconductlong-durationmilitaryoperationsfarfromfriendlywaters.12Forexample,thenewestJapaneseSoryu-classsubmarineswilluselithium-ionbatteriesinsteadofAIPforpowerwhensubmerged.13AndlargeUUVsareexpectedtoachieveonetotwomonthsofendurancewithinthenexttwoyearsusingacombinationoffuelcells,batteries,andtradi-tionalpropulsionsources.14Thesevehiclescouldcarrysensorsforcoastalsurveillancemissionsand/orlargeweaponssuchastorpedoesandmines,makingthemabletotakeonsomemissionsconductedtodaybymannedsubmarines.

AlanBurke,“Systemmodelingofanair-independentsolidoxidefuelcellsystemforunmannedunderseavehicles,”JournalofPowerSources,158,no.1,July2006,pp.428–435;E.Lennon,A.A.Burke,M.Ocampo,andR.S.Besser,“MicroscalePackedBedReactorforControlledHydrogenPeroxideDecompositionasaFuelCellOxidantAboardUnmannedUnderseaVehicles,”JournalofPowerSources,195,no.1,January2010,pp.299–306.

PaulKallender-Umezu,“JapantoMakeMajorSwitchonSubPropulsion,”DefenseNews,September29,2014.

DavidHambling,“LargeDisplacementUnmannedUnderwaterVehicleSteamingAhead,”AviationWeek,April1,2012,availableat/awin/large-displacement-unmanned-underwater-vehicle-steaming-ahead.

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FIGURE9:ECHORANGERLARGEUUV

PhotocourtesyofBoeingDefense,Space&Security.

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FIGURE10:RECOVERYOFANMK-18UNDERSEASURVEILLANCEANDMINEHUNTINGUUV

Thesameimprovementsthataremakingsubmarinedetectioneasiermayalsoenableanewgen-erationofsophisticatedcounter-detectiontechnologiesandtactics.Againstpassivesonar,asub-marineorUUVcouldemitsoundtodrownoutitsownradiatednoise,similartothemethodusedinnoisecancelingheadphones,ordeploydecoystocreatefalsetargets.Againstactivesonars,underseaplatformscould—bythemselvesorinconcertwithUUVsandotheremitters—conductacousticjammingsimilartothatemployedbyairborneelectronicwarfaresystemsagainstradar.Bothactiveandpassivecounter-detectionsystemswillbenefitfromcontinuedimprovementsincomputerprocessingandoceanographicmodelingthatwillenablethemtocontrolandadapttheiroperationsinrealtimeaspartofanoverallunderseadeceptionoperation.15Oneimplica-tionofnewstealth-enhancingcapabilitiesmaybethatmannedsubmarineswillneedtobelargertohostadditionalon-boardanddeployablesystems.

NingHan,XiaojunQiu,andShengzhenFeng,“ActiveControlofThree-DimensionImpulsiveScatteredRadiationBasedonaPredictionMethod,”MechanicalSystemsandSignalProcessing,30,July2012,pp.267–273.

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Underseasystems.TheabilityoflargeUUVsandsubmarinestoconductandcoordinateoperationswillimprovewiththeintroductionofnewweapon,sensor,andcommunicationsys-tems.Forexample,theU.S.NavyisfieldingtheCommonVeryLightweightTorpedo(CVLWT),whichislessthanathirdthesizeofthesmallesttorpedocurrentlyoperatedbythefleet.16AlthoughtheCVLWThasashortrange,largeUUVscouldcarrysubstantialnumbersofthemasoffensiveweaponsandexploittheUUV’squietnesstopositionthetorpedoesclosetoatarget.CVLWTscouldalsobeemployedasactivedefenseweaponsbysubmarines.Similarly,small,unmannedairvehicles(UAVs)suchastheNavy’sExperimentalFuelCell(XFC)UAVhaverel-ativelyshortendurancebutcanbelaunchedbysubmarinesorUUVsclosetoanadversary’scoast.Theycanexploittheongoingminiaturizationinelectro-optical,infrared,andradarsen-sorstoconductsurveillanceorelectronicwarfaremissions,providingtargetinginformationdirectlyvialine-of-sighttoasubmarineorstrikeaircraftinthevicinity.17Suchsystemscouldevencarrywarheadsandbeusedasloitering,anti-radiationhomingweaponstoattackenemyairdefenseradars.

FIGURE11:COMMONVERYLIGHTWEIGHTTORPEDO

P.V.Bharati,S.K.Rao,andA.R.Krishna,“GenerationandAnalysisofTacticsforAnti-TorpedoDefenseSystem,”presentation,IEEEConferenceonInformationandCommunicationTechnologies,April2013,pp.382–387;AnthonyReese,“FirstCarrierCountermeasureAnti-TorpedoLaunched,”U.S.Navy,N,June6,2013,availableat/submit/display.asp?story_id=74665;U.S.Navy,UnmannedUnderwaterVehicleMasterPlan(Washington,DC:U.S.Navy,November2004).

DanielParry,“NavyLaunchesUAVfromSubmergedSubmarine,”U.S.NavalResearchLaboratory,pressrelease,December5,2013,availableat/media/news-releases/2013/navy-launches-uav-from-submerged-submarine.

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FIGURE12:EXPERIMENTALFUELCELLUAV

Newtechnologywillalsoaddressthelongstandingvulnerabilityofunderseaplatformswithregardtocommunications.Inpreviouscompetitions,submarinestransmittingoveroperation-allyrelevantdistancesoftendidsoattheriskofjeopardizingtheirgreateststrength:theirstealth.WithnewASWtechnologies,underseaplatformswillriskbeingdetectedevenwhenpassivelyreceivingcommunicationsnearthesurface.Theseriskscouldbereducedinthefuturewithneworimprovedunderseacommunicationmethodsthatwillenableunderseaplatformstocom-municatedirectlywithoneanother,withsystemsontheoceanfloor,andwiththeabove-waterjointforcewhileremainingdeeplysubmerged.Ingeneral,underseacommunicationsbene-fitfromthesametechnologicaladvancementsasASWdetectionmethods.Inparallelwithimprovementstoactivesonar,acousticcommunicationsareincreasingtheirrangeandband-widthtothepointwheretheycansupportunderseaoperationsoverrelevantdistancesinrealtime.18Inadditiontotheiruseinunderseasensing,tunablelasersandLEDscouldprovidehigh-bandwidthunderwatercommunications,albeitatshorterrangesthanacoustics.Anddriftingorseabed-mountedcablesandfloatingradiotransceiverswillenablesubmergedplat-formstocommunicatewithforcesabovethesurfacewithoutriskingdetection.19Increasing

DouglasHornerandGeoffreyXie,“Data-DrivenAcousticCommunicationModelingforUnderseaCollaborativeSystems,”AutonomousUnderwaterVehicles,2012IEEE/OES,2012,pp.1–7.

H.HemmatiandA.Biswas,“ImprovingtheEfficiencyofUnderseaLaserCommunications,”SPIEProceedings,8971,March2014,pp.1–7.

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computingpowerwillalsoenableunderseasystemstodomoreonboardprocessingofsensordatatoreducetheamountofcommunicationbandwidthneededtopasstheirinformationtounderseaplatformsorbattlenetworks.

The