an introduction to ssds concepts and development · an introduction to ssds concepts and...

516 JOHNSHOPKINSAPLTECHNICALDIGEST,VOLUME22,NUMBER4(2001)

J. E. WHITELY JR.

T

AnIntroductiontoSSDSConceptsandDevelopment

John E. Whitely Jr.

hegoalofShipSelf-DefenseSystems(SSDSs)istoprovideleak-proof,affordabledefenseofownship fromcruisemissileattack.Likeotherairdefense systems,anSSDScomprisesthedetect,control,andengagefunctionsthatoperatelogicallytodefeatattack-ingaircraftormissiles.Thesystemisabasicbuildingblockofairdominanceandhastheprerequisiteeffectivenesstoprotectshipsoperating“inharm’sway.”

TheNavy’soperationalconceptforthelittoralspositionsshipswithintherangeofAnti-ShipCruiseMissiles(ASCMs)thatmaybe launched fromaircraft, submarines, ships,orground-basedlaunchers.Inahostileregion,theship’ssensorsmustbeabletodetectraidsofsmall,fast,maneuveringtargetsflyingatlowaltitudejustastheycrossthesensors’hori-zon.Targetdetectioninlittorals ismademoredifficultbyanomalouspropagationcondi-tionsandlandbackgroundclutter.Simultaneously,thesystemmustreacttothethreat,rely-ingonautomatedcommandanddecisionprocessestoselectandfireitsweapons.Veryfast,highlymaneuverable,extremelyaccurate,andlethalshort-rangehomingmissilescompletetheengagement.Forsomeshipclasses,thelast-ditchdefenseisaveryhigh-rate-of-firegunsystem.ThetechnicalperformanceofsuchamodernSSDSisbasedonaprovenAPLcon-ceptforadistributedsystemsarchitecturethatintegratesexistingsensorsandweaponsusingcommercialoff-the-shelf(COTS)components.ThearticlesinthissectionoftheTechnical Digestprovideinsightsintothetechnicaldevelopmentofthesenewsystems.

Thelittoralshaveproventoberegionsofuncertaintywhereirrationalactscanoccur.Thefollowingvignette—paraphrasedfromaconcept-of-operationsdocumentforanti-airwarfare(AAW)–integratedshipdefense—isaboutanAmphibiousReadyGroup(ARG)operatinginalittoralregion.WorkingwiththeNavy’soperatingpersonnel,APLengi-neersdevelopedanddocumentedtheconceptofoperationsastheprimarybuildingblockofrequirementsanalysis.Itillustratesthepowerandflexibilityofmodernself-defensesys-temstoprotecttheships.

The night action in the Gulf was over in less than 5 minutes, and nowthe watch officers in the ARG were collecting after-action reports via theclassifiedInternet.ThreeASCMshadbeendestroyed,alongwiththelone“rogue”

JOHNSHOPKINSAPLTECHNICALDIGEST,VOLUME22,NUMBER4(2001) 517

SSDS CONCEPTS AND DEVELOPMENT

aircraftthathadlaunchedtwoofthemattheARGanditsescorts.SixmissileroundshadbeenexpendedtokilltheASCMsandthelaunchaircraft.Afourthtargethadbeentrackedandlost,apparentlyhavingbeenseducedbyadecoy.Theescortingdestroyershadalsoexpendedfivelandattackmissilerounds,counterat-tackingthecoastalbatteriesthathadlaunchedtwooftheASCMs.Thesecond-aryexplosionsashorecontinuedtolightupthepredawnsky.

Dayinanddayout,thethree-shipARG—anLSD,LPD,andLHD—hadplied the waters of the Gulf, remaining just offshore and under the layers ofairdefenseprovidedbyAegisshipsandthecarrier’sairwing.Anti-governmentmobviolenceinandaroundthemajorportsandairportshaddecreasedsincetheARGanditsembarkedMarineshadbeenseenoninternationalTVnews.Monthsearlier,afewmilitaryunitshadreportedlyalignedthemselveswithanti-governmentorganizations,but itappearedthatdisciplinehadreturnedtotheranksaftertherecentexecutionsofafewrebelofficers.

Onthismoonlitnight,thecarrierhadsecuredfromflightoperations,run-ning downwind with the escorts to join an underway replenishment group.TheCarrierBattleGroupCommanderhadassignedanAegisdestroyerandcruisertoremainwiththeARGCommandertoprovideareadefensecover-agewhilethecarrierwasoff-station.Soasnottosparkhostilitiesinthetensesurroundings,therulesofengagementwerehighlyrestrictive,effectivelycol-lapsingthebattlespace.Routinelyduringthecampaign,theARGCommanderhadensuredlocalforce-protectionreadinessbyexercisingthequick-reactionairdefensedoctrineineachoftheships.Thisflexiblecapabilitywasdesignedinto theSSDSs that form the innermost layerof air defense for thesenon-Aegisshipclasses.

When the rogue aircraftwas detected leaving thedense commercial air-crafttrafficpattern,thecompositeidentificationonthis“unknown,assumedfriendly” track changed to “unknown, assumed hostile,” and immediatelychangedto“positivehostile”whentheASCMsweredetectedas separatingfrom it.Earlier in theevening, theTacticalActionOfficers (TAOs),usingtheirknowledgeofthreatandmutualinterferencealongwiththeARGCom-mander’s instructions, had entered the local self-defense doctrine for theseSSDS Mk 1 and 2 equipped ships. As the aircraft’s track changed fromunknowntopositivehostile,eachSSDSalertedtheTAOs,allowingthemtoevaluatethetargets,engagetheminsemi-automaticmode,andfinallyengageinfullautomaticmodetomakethelastkills.

Sensor integration in these ships is performedat themeasurement level,usingbothownship’ssensorsandthoseofothershipsinthesensornetworktocomputecompositetracks.ThiscapabilityissharedbytheSSDSandtheCooperative Engagement Capability (CEC), and that night it dramaticallyimprovedthetotalsensorcoverageoftheARGandcarrierbattlegroup.Thecombinationofnettedsensorsprovidedthetargetdetectionsintheavailablesensorspectrum,overcomingtheadversepropagationconditionsandthelargeclutter “foldover” from the land background. Likewise, the correctness andaccuracy of air tracks observed in the different ships enabled the real-timeevaluationoftheaircraftaspositivehostileandprovidedthelaunchlocationsofthecoastalmissilebatteries.

TheshipshadbeenarmedwithimprovedmissilessuchastheEvolvedSeas-parrowMissile(ESSM)andtheRollingAirframeMissile(RAM)—whichalsogreatlyenhancedtheirabilitytoannihilatetheraidsofattackingaircraftandASCMs.Inthisaction,twoESSMandthreeRAMroundswerecreditedwiththeASCMkills,whileasingleStandardMissilehadkilledthelaunchaircraft.AlthoughtheLSDintheARGwasnotinthetacticaldatalinknetwork,itsurvivedtheattackbecauseitsSSDSMk1hadautomaticallyreacted,launch-ingaRAMandkillingthe“leaker”ASCM.


J. E. WHITELY JR.

TheLaboratorycontinuestomakecriticalcontribu-tionsintheevolutionofself-defensesensors,weapons,and combat systems. An understanding of the opera-tionalchallengesoflittoraloperations,aknowledgeofthe technologiesavailable toperform in thisenviron-ment,andacharacterizationofthreattrendsareessen-tialinhelpingwarfighterstodefinetheirrequirements.Havinggonetosea,measuredthelittoralenvironments,and characterized the various effects on sensors andweapons,ourengineershaveanalyzedanddefinedthetechnicalperformancerequiredtoprotectvariousshipsagainstprojectedthreats.

TwocriticalcapabilitiesexistatAPLthatarenec-essarytounderstandtheeffectivenessofanysystemtomeettheoperationalconcept:(1)theexpertisetoeval-uate technologies that can be applied to the problemand (2) experience in the conduct of critical experi-ments and demonstrated proofs of concept alongsidethe warfighters. Insights from the technologies or thecritical experiments are not inherently obvious with-outhavingthisin-depthbackgroundandunderstandingoftheoperationalneedandsurroundingenvironments.Authorsofthearticlesthatfollowthisintroductionwillbearoutthisassertion.

HISTORICAL BACKGROUND TheperformanceofmodernSSDSshasevolvedsig-

nificantlyoverthelast30years,havingbeenstimulated

by three major milestone engagements. These eventswereofgreatconsequenceinthattheyallendedtrag-ically, with great loss of life and either the loss of orseveredamage to the ships. Importantly, these eventsalso provide insights into the causes and effects ofrequired performance as well as the rate at whichnew capabilities were deployed. Figure 1 ties togetherthe pacing systems and threats as they have evolvedovertime.

Thedefininghistoricalengagementswerethesink-ingoftheIsraelidestroyerElathduringthe1968MiddleEastWar, the lossof theBritish frigateHMSSheffield attheFalklandsin1982,andthenearlossofthefrig-ateUSSStark in thePersianGulf in1987.TheElathandSheffieldengagementsstimulatedthedevelopmentand deployment of the Basic Point Defense MissileSystem(BPDMS),PhalanxClose-InWeaponsSystem(CIWS),andRollingAirframeMissile(RAM)GuidedMissile Weapon System. The BPDMS integrated theair-to-airSparrowMissileandshipboardlauncherwitha manually steered X-band tracker/illuminator. TheCIWSintegratedanewtrack-while-scan(TWS)radarwiththeVulcangunsystem,anotherairborneweapontechnology, aimed at detonating the ASCM warheadaway from the ship. The 5-in.-dia. RAM integratedthe shoulder-launched Stinger Missile’s medium-waveIRseekerwithanewradio-frequencyguidancesystemdesigned to home on the ASCM seeker. This com-bination gave RAM the needed maneuver advantage

1950 1960 1970 1980 1990 2000

Styxdevelopment

begins

1960,Styx

SS-N-2Aoperational inOSA-1 and

Komar boats

1967,Israeli

destroyerElath sunk

by Styx

1970,Israeli

merchant shipsunk by Styx

1971,Pakistanidestroyerand minesweeper

sunk

1974,Start RAM

development

1978,SLQ-32

operational

1982,PhalanxCIWS

operational

1985,Mk 214chaff

operational

Several Styxemployed in

Iraq–IranWar

1992,RAM

operational

1999,RAM BLK I

DT/OT

1958–1962,French Exocetdevelopment

1969,Basic Point

defense

1975,NATO

SeasparrowIOC

1982,HMS Sheffield andAtlantic Conveyorsunk by Exocet

(AM 39)1987,

USS Starkhit by Exocet

1980–1988135 ships

hit byExocet in

“Tanker War”

1992,SSDSdemo

1995,ESSM

development

1996,Capstone

requirements

1997,SSDSIOC

1998,Nulka

operational

2000,ESSMDT/OT

Figure 1. The influence of history on ship self-defense.



overtheASCMandmatchedaccu-racywith the lethalityof its smallwarhead.

These systems were based onthe need to ensure single-shotkills against the expected ASCMthreats. The battle over the Falk-lands also demonstrated the effec-tiveness of chaff to decoy theattackers, enabling a measure of“softkill” forprotection.TheFalk-landsprovedthedifficultyofoper-ating in a severe littoral environ-ment,and,importantly,itsignaledto all navies the existence of agrowing and uncontrolled ASCMmarket.TheStarkengagementsig-naledtheneedforveryquick-react-

The intelligence community has reported on over100 existing and projected varieties of these missilesthatcanhavespeedsfromsubsonictosupersonic,rangesfromhigh-altitudediverstoseaskimmers,andfuelrangesofover100nmi.Ofparticularinterestarethetrendsinmaneuver,multimissileattacks,andcountermeasuresaspenetrationaids(Fig.3).

Two significant studies conducted in the late1980sprovidedsupportingtechnicalrationaleforinvest-ment decisions for developing current SSDSs. Theso-called “Kuesters’ Study” provided a roadmap forsystem improvements and development investments.The NATO AAW System (NAAWS) Study, com-pleted in 1991, was conducted by engineers from theUnited States and a NATO consortium; it providedmanyofthetechnicalconceptsfoundinmodernSSDSs.APLengineersconductedtechnicalanalysesandcon-tributedsignificantlytobothofthesestudiesandledtheoveralltechnicaldirectionfortheNAAWSStudy.

CONCEPT AND DEVELOPMENTThe requirements for today’sSSDSweredrivenby

the operational necessities described above. Figure 4illustratestheraidannihilationproblemsolvedbytheSSDS.Theship’soperatorsenterappropriatesemi-auto-matic and automatic engagement doctrine parametersfor the system. The ship’s sensors search the volumeanddetectsupersonic,low-flying,maneuveringASCMsastheycrossthehorizon.Targettracksareestablishedwithinthesystem,andcompositetracksarecomputedby associating the measurements from all the sensors.Customfiltersoptimizethetrackandmeasurementdataforthreatevaluation,weaponassignment,andfirecon-trol computations. Operators monitor the sensor andweaponcontroldoctrineandtheirdynamicallychang-ing statuswhile the systemcontinues to compute theweapon laying and engagement solution. The system

Figure 2. More than 70 nations have an ASCM capability.

ingend-to-endsystemsolutionsforkeepingpacewiththeevolutionandproliferationofASCMthreatsaroundthe world. The attack on Stark showed the need forinstantresponse,eventhoughnotatwar.

Theseeventsalsostimulatedimprovementsforship-board sensors that increased the volume of the bat-tlespace.Evolutionarychangestothethree-dimensionalS-bandAN/SPS-48radarandtheL-bandAN/SPS-49radarhaveimprovedhigh-altitude,long-rangevolumesurveillancecoverage.Electronicwarfaresystemshaveevolvedtobettersupportbothdetectionandjammingofthreatmissiles,aswellasdeploymentofcountermea-suressuchaschaffanddecoys.TheCIWSTWSradar,withitshighrotationspeed,providedtheneededdetec-tion, tracking, and data rates for closed-loop spottingand pointing of its very high-rate-of-fire gun. Its Ku-bandradarprovedtobehighlyeffectiveinpropagationconditionsthatdegradedtheperformanceofradars inotherfrequencybands.Andcommercialcomputertech-nologies, displays, and modern program designs haveenabledsensorsandweaponstobeintegrated,combin-ingalltheirattributestomeetthedemandsoflittoraloperationsandcountertheprojectedthreats.

CHALLENGES IN SHIP SELF-DEFENSE Today’schallengesinshipself-defensearestillabout

tomorrow’s threats and the projected operating envi-ronmentsoftheFleet.Theproblemiscomplexbecausemanyofthemissionsarepeacekeepinginnature,beingcarriedoutunderhighlyrestrictiverulesofengagementand often in concert with other friendly or coalitionforces. The advantage goes to an attacker, who canconceal himself in the indigenous air activity muchin thewaya terroristoperates.More than70nations(Fig. 2) have obtained an air-, sea- or land-launchedASCMcapability,havinggainedpotentialfordenyingaccessortransitinthelittoral.


J. E. WHITELY JR.

continuestomanagetheengagementsandensuresweaponssupportthroughmissileintercept.

The engineering concept for the SSDS was demonstrated aboard USSWhidbey Island(LSD41) in1993.Thisproof-of-conceptdemonstrationoftheQuickReactionCombatCapability(QRCC)wasengineeredandmadereadyforat-seademonstrationinjust20monthsbyAPLengineersincol-laborationwithateamofengineersfromtheNavalSurfaceWarfareCenter,DahlgrenDivision,andHughesAircraftCorporation.Thesysteminfrastruc-turecompriseddistributedsystemcomponents,physicallyintegratedwithalocalareanetwork(LAN)sharingacommonmiddlewarecomputerprogram.TheuseofCOTSequipment and computer programs, similar to those inthe CEC development system, facilitated development of the demonstra-tion system and at the same time provided an opportunity to evaluatethe development of LAN technologies. Employing the same principle ofCECforsensorintegrationatthemeasurementlevel,thesystemcomputedcomposite tracks from the AN/SPS-49, the IR Search and Track SystemAN/SLR-8,andtheCIWSTWSradarmeasurements,presentingtheminamuchenhancedsurveillancedisplaytotheoperators.Alocalcommandand

decision capability provided theTAOwithameansofselectingandcontrollingtheengagementdoctrineneeded for the reaction time andsupportingtheweaponassignmentsforRAMandCIWS. The successof this demonstration resulted intheformalprograminitiationforanoperational system, now known astheSSDSanditsvariants.

THE ARTICLES Raid annihilation is the funda-

mental performance attribute forSSDS. Each ship class is assigneda probability of raid annihilationPRA against a range of potentialthreats.TheChiefofNavalOper-ations (CNO) established opera-tional requirements for ship self-defenseforthedifferentshipclasses.These requirements are derivedbased on the ship’s mission, theship’s expected operational envi-ronment, and the ability of areadefenders to reduce the raid size.The article by Prengaman et al.describestheprocessbywhichPRAisusedtoquantifytheperformanceoftheSSDS.Thisperformanceallo-cation, in turn, drives the techni-cal performance requirements forcompositetracking,systemreactiontime and automatic doctrine, andthecustomweapon–threatresponseto defeat the most sophisticatedthreats.Theauthors thendescribethe methodology for testing theSSDStomeetitsPRArequirement.

ThedemonstrationQRCCsys-tem and SSDS Mk 1 are inno-vations in combat system archi-tecture. Norcutt describes the useof COTS computer programs andcomponents comprising real-time,high-volume,low-latencycomputerprocessesdistributedviaLANs.Thearticlealsodetailstheinformation-oriented concepts and features oftheSSDSMk1systemarchitecture,along with the advantages of theapproach,anddiscussesthephysicalarchitectureofthesystemnetwork,includingitssuitabilityforreal-timeweaponssystemsupport.

Speed Altitude Raid density IR signature

Radar cross section Maneuverability Smart jamming

Figure 3. Threat trends of ASCMs.

Figure 4. SSDS engagement doctrine is controlled by ships’ operators.



TheSSDSMk2designistheproductofanin-depthanalysis of technical performance requirements con-ductedbyAPLengineers.TheCECisbeinginstalledin battle groups to provide a shared display of thenetworked long-range surveillanceandvolume searchradars, and SSDS uses its track database to meet itsAAW mission requirements. The details of how thisanalysiswasconductedandhowthecustomfiltertech-nologyledtoafundamentalallocationofperformancerequirements is detailed by Thomas et al. For themostadvancedthreats, thecriticaldriver inshipself-defense is reaction time.Thekeyelementofmeetingtheengagementtimelineistheaccuracyandtimelinessofestablishingthetargettrack.AninnovationofAPL’scustomfiltertechnologyisthesystemtrackpromotionconceptformultisensortrackpromotion.Customfiltertechnology has also been applied to certain weaponintegrationfunctionsforRAMandESSM.Thomasetal. also discuss other important elements of combatsystemintegrationsuchasautomaticengagementcon-troldoctrineanddisplayandtheengagementsystems.

ESSMhasbeendevelopedtokeeppacewithevolv-ingASCMthreats.ItscapabilitiesareessentialtothelayeredairdefensesinourNavy.ThearticlebyFrazeretal. traces thevariousaspectsofdevelopmentunderthe NATO consortium and discusses how the missilemeetstheneedsofthemembernations.Underpinningthissuccessfulprogramarethemissilesystemsengineer-ingcontributionsmadebyAPLengineers.

RAM is a critical weapon for ship self-defensebecause itcanhitmaneuveringtargetsatcloserange.Laboratoryengineershavea longhistory in the tech-nicaldevelopmentofRAMguidance technologies, aswellas IR sensor technologiesemployed in theRAMprogram.TheRAMisa“fire-and-forget”weapon,rely-ing on the accuracy of the ship’s designation systemanditsownrobustguidance.RAMBlockIincorporatesanautonomousIR(AIR)homingmode,andthelatestmissile upgrade to keep pace with the ASCM threat.TheBlockIvariantsuccessfullycompletedoperationaltestandevaluationinlate1999,andadditionalmodi-fications to theguidancecomputerprogramarebeingdesignedtoenablethemissiletodefendtheshipagainstattacking low-speed aircraft, helicopters, and surfacecraft. The article “Rolling Airframe Missile Develop-ment, Test, Evaluation, and Integration” by Elko etal.providestechnicalbackgroundforthedevelopmentdecisionsinRAMBlockI,alongwiththemethodologyfor thepredictive analysisprior to testing.TheRAM

programisacooperativemissiledevelopmentprogramwith Germany; Denmark also contributed funding totheBlockIdevelopment.

Integration of the existing electronic support mea-sures(ESM)systemAN/SLQ-32A(V)withSSDSMk1is essential to support RAM engagements. It alsoprovides kill assessment for emitting threats, and itaugments local situational awareness. The article byKochanski and Bredland covers the development andtechnicalbasisforthisintegration.

Theverynatureofdevelopmentandoperationaltestingof self-defense systems andweapon components againstmodernthreat-representativetargetsdictatesremotecon-troltestoperations.Althoughagreatdealofsimulationandpredictiveanalysisisconductedtosupportconfidenceinsystemperformance,live-firetestsarerequiredtosup-porttheacquisitionmilestonedecisionsfortheweapons.In1987,theNavydesignatedthedecommissionedUSSDecatur(DDG31)astheSelf-DefenseTestShip(SDTS)tosupportlive-firetesting.Variousshipself-defensecon-figurationshavebeeninstalledintheSDTS,andAPLengineersintegratedtheremotecontroloperations.Thearticle by York and Bateman describes the integratedremotecontrol systemused to supportweapon systemtests.Mostrecently,CIWSBlockIBandRAMBlockIoperationaltestsandESSMdevelopmentaltestshavebeenconductedfromtheSDTS.

CONCLUSIONHistorically, advances in ship self-defense systems

have been stimulated by ASCM attacks that resultedinthetragiclossesofshipsandpersonnel.Theselosseshave common themes that underscore the need forquick-reactingsystemsthatarehighlycapableofengag-ing difficult targets in the harsh operating environ-ments of the littorals. Notwithstanding the potentialforadversariestoobtainimprovedASCMs,theadvan-tages of networked sensors, distributed systems archi-tectures,embeddeddoctrine,andquick-reactionweap-ons in combat systems can outperform these threats.Thisnewgenerationofcombat systems is essential tothe Navy’s operational concepts for access in the lit-toral.Theyarealsofundamentaltoemergingconceptsfor hard kill and soft kill integration, reduced crewmanning,andnetwork-centricwarfare.APL’stechnicalcontributions to thesecombat systemswill add to theconfidence of warfighters to defend themselves in thecloseoperatingquartersoftheworld’slittorals.


J. E. WHITELY JR.

THE AUTHOR

JOHNE.WHITELYJr.istheProgramAreaManagerforAPL’sSelf-DefensePro-gramsintheAirDefenseSystemsDepartment.HereceivedaB.S.fromtheU.S.NavalAcademyandanM.S.inelectricalengineeringfromtheNavalPostgraduateSchool,Monterey,California.Afterhavingserved28yearsintheNavy,hejoinedAPLin1988andmanagedADSD’sadvancedandspecialprojectsuntilassuminghiscurrentpositionin1998.Mr.Whitely’snavalexperienceshaveincludeddutiesasamajorprogrammanagerintheCruiseMissileProject,DepartmentOfficerattheNavalSurfaceWeaponsSystemsEngineeringStation,participationintheTerrierCG/SM-2Project,andsignificantcombatassignments.Since1998hehasalsobeeninvolvedintheestablishmentofbattleforce–levelprojectsforarchitectures,systemsengineering,[email protected].

an introduction to ssds concepts and development · an introduction to ssds concepts and...

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