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324 JOHNSHOPKINSAPLTECHNICALDIGEST,VOLUME22,NUMBER3(2001)

F. J. MARCOTTE, G. M. CAREY, and W. J. TROPF

T

TheAPLGuidanceSystemEvaluationLaboratory

Frank J. Marcotte, Glenn M. Carey, and William J. Tropf

heGuidanceSystemEvaluationLaboratory(GSEL)isaprimarytoolusedinAPL’sroleastheTechnicalDirectionAgentfortheNavy’sStandardMissile(SM)Program.ThisfacilityteststheSMguidancesection,itsinterfacestotheweaponsystemandothermissilesections,andmissileperformanceinalltacticalconditions.GSELprovidessup-portforallphasesofmissiledevelopmentandtacticaloperation,fromconceptthroughproduction,aswellasin-serviceFleetbackup.Thefacilityiscontinuouslyevolving,pro-vidingforadvancedmissileversionsdevelopedtoimproveperformanceandcounternewthreats.

INTRODUCTIONTheevolutionoftheAPLGuidanceSystemEvalua-

tionLaboratory(GSEL)generallyparallelsthegrowthofStandardMissile(SM)andtheever-increasingthreatsince SM’s inception in the 1950s. Initially SM wasanX-bandbeam-ridingmissiledesignedprimarilyasahigh-altitude anti-air weapon to counter large Sovietaircraft.Inthe1970scruisemissilesstartedtoappear.Bythe1980sand1990scruisemissileshadrapidlyevolvedinto formidablehigh-speed, sea-skimming threats thatmaintainedavery lowradarreflectivity,makingthemdifficult to detect and engage with the then-currentmissile systems. During the Persian Gulf War (1991),the general public quickly learned of the ability ofrogue states touse tacticalballisticmissileswithcon-ventional, biological, and nuclear warheads. Into thisnewcenturythethreathasexpandedtoincludemuchlonger-range, higher-altitude ballistic missile systemsthat may employ decoys and other countermeasures.Today the Navy is investigating the use of SM in anationalmissiledefenserole.

Figure1 shows the evolutionof themanySMvari-ants and the expanding capabilities of GSEL. Histori-cally,eachfacilityhasservedapurposefor10to15yearsbeforetechnologiesincorporatedintoSMandtheemer-genceofnewthreatshavenecessitatedthesechanges.

BACKGROUNDThe first APL RF GSEL was built in 1963 on the

secondfloorofBuilding1.Thisrelativelysimple,man-uallyoperatedfacilityusedmechanicallymovedtargets,anditsprimarypurposewastoevaluateself-screeningcountermeasures.ThesecondGSEL,onthefirstfloorof Building 1, was built in 1979–1980,1 coincidingwiththedevelopmentofSM-2andtheAegisWeaponSystem.2Newfeaturesincludedmultipleelectronicallymoved targets using a wide-angle array (for standoffjamming), a larger chamber, multipath and clutterenvironments, missile initialization, midcourse flightwithAegiscommanduplink,andclosedloophoming

JOHNSHOPKINSAPLTECHNICALDIGEST,VOLUME22,NUMBER3(2001) 325

GSEL

capability.ThesenewattributesmadeGSELanengage-menttestfacility.

In1992–1994,GSELwasupgradedtoaccommodateinfrared (IR) and dual-mode (IR/radar) guidance. IRtargets,backgrounds (clutter), andheateddomeenvi-ronments were added.3 Separate IR seeker and radarguidancesectionteststations,whichinitiallywerecon-nectedelectrically, provided thedual-mode test capa-bility.Lateradual-modeanechoicchamberwasbuilttotesttacticalradar/IRguidancesections.

Inthelater1990s,newmissionsaroseleadingtosev-eralnewversionsofSM.Thesemissionsincludedendo-andexo-atmospherictacticalballisticmissiles,overlandcruisemissiles,andlandtargets.Inearly1997,theLabo-ratoryannouncedplansforconstructionofBuilding26primarilytomeettheneedsoftheAirDefenseSystemsDepartment(ADSD).Plansforanew,enhancedGSELtomeetfutureneedswerequicklydeveloped,acceptedbytheLaboratory’sExecutiveCommittee,andendorsedbytheNavy.ThenewGSELwouldsupport

• Conceptdevelopment Newthreatandnewalgorithmassessment Technologyassessment Criticalexperiments• Engineeringdevelopment Performancemeasurements Simulationdevelopmentandvalidation Interfaceevaluations Flighttestplanningandpredictions Certificationofflightreadiness Supplementarydesignagenttesting Failureanalysis• ProductionandFleetsupport Productionsurveillance Operationaltestplanningandtestingintegration ofSMwithforeigncombatsystems

Because of the impact that anabrupttransfertoBuilding26mighthave on SM programs currentlybeing supported in the Building1 chambers, a gradual transfer isplanned. New programs that canmost benefit from the features ofthe enhanced GSEL will be inte-gratedwhentheybegin.Initialusesof the facility will focus on thosesystems and subsystems (IR elec-tronics, for example) that rely lesson the ingrained infrastructure oftheBuilding1equipmentsuite.

WHY A NEW GSEL?The need for each new GSEL

arises from current and anticipatedrequirements. One important issue

Figure 1. The evolution of SM over the past four decades from a single-frequency mis-sile to several multimode, multimission variants roughly parallels the associated growth of GSEL (P3I = preplanned product improvement).

is the size of the facility. For example, the dual-modefacility in Building 1 is 2900 ft2. Increasing its size, aswasdonewhentheIRcapabilitywasadded,isacomplextaskthatmustbecoordinatedwithongoingprojects.Theenhancedground-floorGSELinBuilding26,atapproxi-mately8880ft2,isbuilttoovercomethestructurallimi-tationsofthedual-modefacilityandallowsfor

• Amuchlargeranechoicchambersizedtoaccommo-date much higher frequencies than that of currentmissilevariants(specificationsforthechambergoupto100GHz)

• Reliefofovercrowding• Rapidreconfigurationtoaccommodatecurrenttest-

ingofseveralmissilevariants• Muchgreaterweightandflexibilityforfuturegrowth

(e.g.,ratetables,flightmotionsimulators,andotherunanticipatedneeds)

• Special facilities,e.g., itsown loadingdock,adedi-catedhydraulicsroom,liquidnitrogenfromanearbyoutdoor2000-gallonstoragetank,andabridgecrane

AnimportantattributeoftheenhancedGSELisitsreadinessforuseasaSpecialProgramsFacility(SPF)forworkthatrequiresahighdegreeofsecurityandclassi-fication.Asecondsmallerroomwithinthelargerareacanalsobemaintainedatahighsecuritylevelforstor-ageanddataanalysiswhenGSELisbeingusedformoretraditionalprograms.

THE ENHANCED GSEL

Facility LayoutIn1997planning foranewbuildingwas startedto

addresstheneedformoreofficespace.Abaselineplanforatwo-story,50,000ft2structurewasdevelopedwith

SM-1

SM-2 Blk I

SM-2 Blk II

SM-2 Blk III

SM-2 Blk IIIA

SM-2 Blk IIIB

SM-2 Blk IV

SM-2 Blk IVA

SM-2 LEAP

SM-4 LASM

SM-3 ALI

SM-3 Blk I

AdvancedSM

FutureSM-? Blk ?

P3I

RF GSEL Ship System GSEL Dual-mode GSEL Enhanced GSEL

1964 1980 1993 2002 2010



columnsat20ftoncenter.Duringthe project-programming phase ofBuilding 26, the future occupantswereidentifiedbuttheirneedswerefound to exceed the baseline. Athirdfloorwasaddedandalobbyfordirect public access was thereforeintegratedintothebuildingdesign.The need for unique laboratoryspace required several changes tothestructuralplanssuchasincreas-ingthefloor-to-ceilingheightsandexpandingthespacingbetweencol-umns. As this phase continued, anew Warfare Analysis Laboratorywasdesignatedforthethirdfloor,4and laboratories for several Coop-erativeEngagementCapabilitypro-gramswereselectedforthesecondandaportionofthefirstfloors.Theremainderofthefirstfloorwasiden-tified for ADSD SM test facilities. The design of theareaswheretheselaboratorieswereplannedwas“frozen”whileconstructionoftheofficeareascontinued.

ThecurrentSMevaluationspacesareseparatedintothree primary areas: simulation, full guidance sectiontest,andsupport.Theproject-programmingforBuilding26allowedthedesignerstointegrateallthreeintoonelargespace(Fig.2).

The dependence on simulation to evaluate missiledesignduringdevelopmenthasincreasedsignificantlyinthe last 15 years as a means to offset the high cost ofactualflighttests.Existingmissilesimulationlaboratoriesplacerestrictionsontheabilitytoperformfuturetesting.For example, the SM simulation facility has expandedseveral times over the years to occupy three separatesmallfacilitiesinBuilding1,acumbersomearrangementforstaff.Therefore,1900ft2havebeendedicatedtothenewAMSEL(AdvancedMissileSimulationandEvalua-tionLaboratory)inBuilding26,wherehigh-fidelity,six-degree-of-freedom(6-DOF)simulationsofthecompleteSMengagementsequenceareperformed.

ThelargestportionoftheADSDMissileEngineer-ing Branch laboratory space in Building 26 is for theGSEL. The focal point of the facility is a shieldedanechoic chamber located in a 2200 ft2 open area(Fig. 3). Anechoic properties of the chamber enabletestingwithoutconcernforstrayelectromagneticreflec-tionsoffnearbyobjectsorwallsthatwouldnotbeexpe-riencedinflight.AshieldedanechoicchambernotonlyabsorbsRFenergy incidenton its surfaces,butalso iso-latesthetestregionfromanyoutsideRFinterference.

Equipment to support testing in the chamber islocated in areas surrounding it. A second, smallershielded room for RF target generation lies to thesouthoftheanechoicchamber.Here,signalgenerators

Simulation area

Support areas

Full guidance systemevaluation areas

AMSEL

North

Optics Test andAssembly Facility

Special ProgramFacility

Flightmotionsystem

Loadingdock

Utilityroom

GSEL

Anechoicchamber

RF TargetGeneration Room

Radar DevelopmentLaboratory

Test stand

Figure 2. The ADSD Missile Engineering Branch laboratory facilities located on the first floor in Building 26. Areas are dedicated to simulation, full guidance section evaluation, and support. The proximity of these areas to one another helps realize the goal of provid-ing SM with a high-fidelity, hardware-in-the-loop facility.

Figure 3. GSEL anechoic chamber in Building 26: the outside north end of the chamber (top) and an inside view looking north toward the test stand where a guidance section would be mounted (bottom).


GSEL

are used to create an RF target signal that is trans-mitted toward a guidance section mounted at the farendofthechamber.Thesetwochambersmustbeisolatedsothatsignalspassingbetweenthemcanbecarefullycon-trolled.Thisisrequiredsincemanyintermediatesignalsareused tocreate the target signalwhich, ifnotcon-trolled,couldinterferewithoperationoftheequipmentundertest.

Adjacent to the primary facility are smaller roomsdedicatedtotheassemblyandtestofguidancesystemcomponents. The Optics Test and Assembly Facilitycontains optical benches and related test equipmentfor independent evaluation of optical components. Italsocontainsalaminarflow“cleanbench”wherehighlyfiltered air is directed across a workbench, creating asmall,dust-freeregionthatenablesassemblyofopticalcomponents without the need for a dedicated clean-room. Similarly, the Radar Development LaboratoryprovidesadedicatedareafortheassemblyandtestofRFcomponents. Equipment will be transferred as neededbetweenthesesmallerfacilitiesandtheprimaryfacilityfor full guidance system and component-level testing.ThesefacilitieswillalsohelpsupportfieldtestsofSMasneeded.

GSEL Impact on Building 26 ConstructionAsnotedpreviously,thebasicrequirementsforthe

enhanced GSEL were identified while the design forthebasebuildingcontinued.Theseincludedtheperfor-mancespecificationsandservicesneededtosupporttheproposedfacility.

A primary driver for the new anechoic chamber iswideangularcoverageinbothazimuthandelevationtomatchtheangularcoverageoftheantennasystem.Withalongchamberbaselinetosupporthigh-frequencyoper-ation,itfollowsthatawideandtallchamberisneeded.TheoriginalplansforBuilding26calledforconcretecol-umnstobelocatedon20-ftcentersandafloor-to-ceil-ingheightof11.5ft.Acompromisebetweentechnicalandstructuralconstraintssettledonachamberdesignofapproximately60 ft long20 ftwide20 ft tall.Toeffectuate the requireddimensionsof thechamber, theplan and vertical dimensions had to be changed. First,toachievetheverticalheightandallowspaceabovefortheutilities,thefirst-floorceilingheightwasincreasedto15ftbyloweringthefloor2.5ft,raisingthesecondfloor2ft,andincorporatingan8-ft-deeppitintothebuildingplanstoattainanoverallheightof23ft.Second,thedis-tancebetweencolumnswas increasedby2.5 ft to22.5ftoncenters.Thesechangesrippledthroughtherestofthe building but had a relatively minor impact on theremainingplansandconstructioncosts.

The chamber design called for the inclusion ofa future flight motion simulator, an electronicallycontrolled mechanical device that simulates angular

movementofthemissileinflight.Athree-axissystemcanmoveaunitundertestintheroll,pitch,andyawrotationalaxes.Inclosedlooptesting,controlsignalsfrom the guidance section to the rocket motors andtailfinsareinputtotheflightmotionsystemonwhichtheguidancesectionismounted.Inthismanner,fullguidancesystemresponsetosimulatedtargetscanbemeasured.

Thesizeandmovementofaflightmotionsystemputheavy constraints on building construction. The highdynamicloadingoftheunitrequiresthatitbemountedonafoundationseparatefromthebuildingfoundationsothatmodulationscannotbetransferredfromsystemmovementtothebuildingorviceversa.Therotationpoint for the flight motion system must be on theanechoic chamber centerline, requiring mounting onanelevatedpadapproximately5fthigh.

Integrationofthisdeviceisnotplannedforseveralyears,soamanuallypositionedteststandwithasimilarform factor was included into the anechoic chamberdesign.UnliketheBuilding1chamber,wheretheteststandiscompletelycontainedwithinthechamberanda guidance section is brought into the chamber via asmalldoor,thedesignoftheteststandinBuilding26is suchthat it liesonrails.Therefore itcanbepulledbackfromthechamberandtheguidancesectioncanbeinstalledexternally(Fig.4).Thebaseoftheteststandmustthenbecomeaportionof,andmustmaintain,thechambershield.

Thethree-axissystemjustdescribedcanbedesignedas the innerportionofa largerfive-axisflightmotionsystem (Fig. 5). The inner three-axis (roll, yaw, andpitch) portion of the system under test is combined

Figure 4. The three-axis test stand, shown pulled back from the anechoic chamber, is used to hold the guidance section under test. The test stand allows movement in the roll, yaw, and pitch rotational axes. The stand is treated with a radar absorber, as is the rest of the chamber, to reduce undesirable reflections.



withanoutertwo-axis(azimuthandelevation)gimbalthatprovidesindependentcontrolofasimulatedtarget.Five-axis operation is typically used for IR/opticaltesting and takes place in an area adjacent to theanechoicchamber.Aseparateisolatedequipmentpadforthefive-axisunitisincludedinthebuildingdesign.Figure 6 illustrates the sequence to extract the innerthree-axis unit from the larger simulator (see http://techdigest.jhuapl.edu/td/td2203/GSEL26.htmlfordigi-talanimationofthesequence).Theinnersystemweighsapproximately8000lb;therefore,a5-tonbridgecranesystemhasbeen integrated into the facility to lift thethree-axis system from the five-axis pedestal to theanechoicchamberequipmentpad.

Thehallwaysofthebasebuildingdesignthatwouldhaveservedthetypicalofficelayoutwereintegratedintothe facility to increase laboratory space. This allowed

basicperformancecharacteristicsofthe Building 1 GSEL, (2) incorpo-rate theability to supporthigh-fre-quency operation, and (3) supportfuture inclusion of a flight motionsystem.

As noted earlier, the Building1 chamber supports X-band semi-activeandIR(dual-mode)guidancesection testing. An X-band hornarray provides wide-angle (>45°)single-axis coverage. To supportdual-mode testing, IR targets aregeneratedonopticaltablesthatare

Figure 5. The five-axis flight motion system. This unit combines the roll, yaw, and pitch movements of a missile seeker mounted on the inner blue and yellow gimbals; the azimuth and elevation movements of a simulated target are mounted on the outer rust-colored and black gimbals. (Photograph courtesy of Carco Electronics.)

Figure 6. Sequence (from right to left) showing the reconfiguration of the flight motion system from a nested five-axis orientation to a three-axis configuration for use in the anechoic chamber. The three-axis unit would replace the current test stand shown in Fig. 4 (see http://techdigest.jhuapl.edu/td/td2203/GSEL26.html for digital animation).

theGSELto stretch to thenorthendof thebuildingandincorporatetheloadingdockintothedesign,allow-ingguidancesectionsandotherlargeequipmenttobebroughtineasily.

The GSEL facility was constructed to Director ofCentralIntelligenceDirectives(DCID)1/21standardsto meet the security requirements of the SPF. Forex-ample,topreventeavesdroppingonclassifiedcon-versations within the facility, three layers of drywallorother approvedwallboardmaterial are required toeffectively attenuate sound waves; ductwork greaterthan 96 in2 must include a welded grid to preventcovertaccess;andpower,network,andphonepenetra-tionsmustbeminimal.

AstheenhancedGSELplanandtheauxiliaryequip-mentwere identified,the locations for liquidnitrogenoutletsandcommunicationsjackswereselectedtoservetheassignedequipment.Becauseoftheincreasedceil-ing height requirement within the laboratory, a pro-vision was made to run the majority of piping andcablingunderthefloor.Tomeetthisneedandtoallowforfuturegrowthandflexibility,theconcreteslabwasdepressed12in.andaraisedfloorwasinstalledtoallowaseamlesstransitionfromthehallwayintothelabora-tory.

Allofthesechangeswereintegratedintothefit-updesignphaseoftheprojectwhilethefoundationforthebasebuildingwascompletedandwellunderconstruc-tion. However, when the test stand design was com-pleteditwasdiscoveredthattherewasinadequatespacetomaneuveraguidance sectionaroundthe test standwith the bridge crane during the mounting process.Therefore,aportionofthebasebuildingfloorslabnorthoftheexistingteststandpadwasremovedtoincreasethedistancetheteststandcouldberolledbackfromthechamber.

Anechoic ChamberGiven the physical limitations imposed on the

anechoicchamberbytheparentbuilding,chamberdesignstarted with three primary objectives: (1) retain the


GSEL

locatedoutsidethechambershieldbelowtheguidancesection.ThesceneispresentedtotheIRsensorontheguidancesectionusinga“periscope”arrangementthatdirects the sceneupward through the shieldandbacktowardthesensor.Figure7illustratesthelayoutoftheBuilding26anechoicchamber.

Aguidancesectionwillbemountedontheteststandlocatedatthenorthendofthechamber.Thesouthendisreservedforaprimaryantennasystemthattransmitsa simulated RF target signature toward the guidancesection.Thelongchamberbaselinerequiredforwide-bandfrequencycoverage,coupledwithparentbuildingrestrictions, limits angular coverage to approximately±10°, far lower than that of the Building 1 chamber.Toretainsomemeasureofawide-anglecapability,analcove that will contain a secondary vertical antennaarray was incorporated into the west sidewall. As intheBuilding1chamber,optical tables canbe locatedoutsidethechamberbelowtheguidancesectionwhereIRtargetscenescanbegeneratedandpresentedtotheguidancesectionviatheperiscope.

Evaluation of Anechoic PerformanceAgain, a shielded anechoic chamber allows testing

of missile electronics without concern for stray elec-tromagneticreflectionsoffnearbyobjectsorwallsthatwouldnotbeexperiencedinflight.Chamberreflectivityis a quantity defined to characterize the imperfectionof an anechoic chamber and is often taken to meantheratioofunwantedreflectedsignalstotheincident,direct-pathsignalenergyatthesamespatialpositionofan anechoic chamber.Thechamberquiet zone,wherethemissileguidancesectionisplaced,isaspatialregionwherethereflectivitypropertieshavebeenproventobelessthanadefinedvalue.Thequietzonemaynotnec-essarilybethe“quietest”regioninthechamber,andthequietestregionmaynotalwaysbethebestlocationtostagethemissileguidancesectionfortest.

Inchamberdesign,RFabsorbertreatmentisappliedinatrade-offtominimizereflectionsoffsidewalls intothequietzoneandcontainabsorbercost.Thehighest-performanceabsorber(24-in.“black-tipped”) isplaced

Primaryarray area

Specular region

Secondaryarray area

Test stand

Quietzone

Guidancesection

Bridge crane

Flight motion tableisolation pad

Optical equipmentarea

Figure 7. Building 26 anechoic chamber layout. The plan view (top) shows the relation-ship of the antenna array areas to a guidance section mounted on the test stand. The par-tial side view (bottom) similarly shows functionally where optical equipment will be located relative to a guidance section under test. The guidance section is placed in the chamber quiet zone, a region in which stray reflections have been carefully characterized and minimized.

in the specularchamber regions—centerchamberareasofwalls,floor,andceiling—thattypicallyarethegreatest sourceof reflected signals.A lower-performance absorber ofdifferingthicknessisplacedinotherareastomaintaintheperformanceestablishedby thecritical specularregions. Personnel walkways andventilation grills have specializedabsorberstoaddressdualneeds.

Chamberquiet zoneand reflec-tivity performance are evaluatedvia two methods.5 Regardless ofthe method, measurement accu-racyrequiresisolationofthedirectsignal energy from the reflectedsignal energy during the measure-ment.Thefirstmethodisameasure-mentofreflectedsignalinterferenceon the direct path signal. Duringcalibration,adirectfreespacemea-surement is made by transmittinga static frequency signal from anantennalocatedatthefarendofthechamber directly toward a receiveantennalocatedinthequietzone.After calibration, additional mea-surementsarecollectedwhileprob-ingthequietzone,withthereceiveantenna directed away from bore-sight to help isolate the reflectedsignal from the direct path signal.Thecyclicconstructiveanddestruc-tiveinterferenceonthedirectsignalby the reflected signal creates a



Signalgenerator Computer Analyzer

Reference

Transmithorn

Receivehorn

Figure 8. Test setup for performing a swept-frequency vector mea-surement. A calibration sequence to provide a reference is performed by collecting swept-frequency measurements when the antennas are boresighted as shown in the figure. Once calibration is complete, additional measurements are taken with the receive antenna horn pointing at a series of angles off the direct line of sight.

standingwaveratiothatiscomparedwiththefreespacemeasurementtodeterminechamberreflectivity,hencethistechnique’sname,freespaceVSWR(voltagestand-ingwaveratio)measurement.

Thesecondmethod,calledtheswept-frequencytime-gating vector measurement and the type employed intheBuilding26chamberperformanceevaluation,usestime to isolate the direct and reflected signal energy.Since the reflected signal energy will arrive at thereceive antennahornnearly instantaneouslywith thedirectsignalpath,aseriesoffrequency/timetransforma-tions is employed to isolate the two signals. Figure 8showsthetestsetupwhereswept-frequency(amplitudeand phase) data are collected over a somewhat widerfrequencybandthantheprimaryregionofinterest.

Through the use of inverse fast Fourier transforms(IFFT),themeasuredsignalistransformedintothetimedomain, and this timedomain signal (Fig.9) simulatesthearrivaltimesequenceofdirectandreflectedsignals.Once in the time domain, the later-arriving reflectedsignalisclearlydistinctusingthehighresolutionaffordedbythecaptureofwide-bandwidthdatapriortotheIFFT.Asshowninthefigure,thedirectsignalcanbegatedoutandanFFToperationperformedon thegatedportion,resultinginameasurementofreflectivityoveracontinu-ousfrequencyspan.Inthismannertheswept-frequencymethodformeasuringreflectivityperformanceissuperiortothetraditionalVSWRtechnique.

Integration with Other FacilitiesThelocationoftheGSELinBuilding26allowsfor

easyintegrationwithotherlaboratoryfacilities.Apri-marygoalofADSDisatightcouplingbetweenAMSELand GSEL activities. “Plug-and-play” between high-fidelity, real-time6-DOFsimulationelements running

Reference trace in time domain

Reflected signal from sidewall

Gate stopGate start

Direct incident signal

–6 –4 –2 0 2 4 6 8 10Time (ns)

Sig

nal m

agni

tude

(dB

)

–6 –4 –2 0 2 4 6 8 10Time (ns)

Sig

nal m

agni

tude

(dB

)

Figure 9. Time-domain representation of the calibration reference trace and off-boresight reflectivity data. These traces are generated by performing an IFFT on the original frequency domain data. On the bottom trace, the direct incident signal can be gated away before performing an FFT to yield the final reflectivity measurement as a function of frequency.

in AMSEL and GSEL hardware tests are possible asthe speedandcapabilityof computers increase.OnceGSEL/AMSELintegrationoccurs,AMSELsimulationscanbedrivenbyoutputofamissilesystemundertestinGSEL,which in turn reacts to testequipmentandtarget generators controlled by the simulation, thusformingaclosedloopsystem.Asinthepast,GSELwillbeextensivelyusedforsimulationmodeldevelopmentandvalidation.

Otherlaboratoryfacilitiesthatwillbeusedincon-junctionwiththeGSELareADSD’sRooftopFacility(Fig.10)andtheSMCaptiveSeekerSystem(Fig.11).6TheRooftopFacility,locatedatopBuilding13,iscon-figuredsothatthemissileseekerundertestcanviewtheskyandacquireandtrackrealtargets.ForIRorotheroptical-basedsystems,theeffectsofbackgroundradia-tionorstraylightcanbeevaluated.TheCaptiveSeekerSystem has been used numerous times over the past12 years to collect land and sea clutter data and hasbeenusedmostrecentlytoprovethecompatibilityofSMandforeignmilitaryradarsystems.Datacollectedduring Captive Seeker experiments can be replayedback into missile electronics in the GSEL for furtheranalysis to see how the guidance section responds toreal-environment signals such as sea or land clutter,which,becauseoftheirspatiallydistributednature,canbeverydifficulttosimulateinalaboratory.

Finally, telemetrydataareextremely important forthe analysis of actual missile firings. High-bandwidthsatellitelinksmakeitpossibleformissiletelemetrytobetransmitteddirectlytoGSELforimmediatereviewandanalysis.


GSEL

Data recorder GPS antennasCabin-mountedequipment racks

SM-2 antenna

Camera

Figure 11. The Captive Seeker System. The equipment includes a production SM seeker antenna and gimbal assembly mounted in a reconfigured chaff pod. The antenna can be controlled by the Global Positioning System (GPS), TV, or angle tracker. The pod is mounted underneath a Learjet and used in conjunction with an APL-developed equipment suite. Real-time processing of data is performed on five cabin-mounted racks.

CONTINUED FACILITY DEVELOPMENT

The facility infrastructure is now being developed.Thistaskincludesinstallationofwaveguideandcablingforsignaltransportandtestcontrol,anewdigitalcom-puterandhardwareinterfaces,powersupplies,andradartarget generators. These basic facility subsystems pro-videacommontestcapabilityforallmissiles.Guidancesection testing is scheduled for the summer of 2001,with a gradual transition of test activities to the newfacilityoverthenextyear.

Inaddition,amechanicaltargetpositioningsystemisunderdevelopmentfortheradarchamber.Thispro-vides precisely controlled two-dimensional motion oftwoindependenttargetsatthefarendoftheanechoicchamber.Preliminary systemdesignwascompleted inFebruary2001.Constructionof the targetpositioningsystem is under way, with final installation slated forearly2002.

Akey featureof theenhancedGSEL is itsabilityto accommodate our future needs such as the flightmotion table discussed previously. Other new testcapabilities under consideration include a cryogenic

vacuumchamberforspacesensors,alaserradarsensortestsuite,andaone-dimensionalradartargetarray.

SUMMARYTheenhancedGSELfacilityinBuilding26provides

agreatincreaseincapabilitytoaugmentthedual-modefacilitiesinBuilding1.Thelargerchamberallowstest-ingandevaluationofmissilesystemsastheytakeadvan-tageofhigh-frequencytechnologicaladvancestocoun-ter the increasing capability of threat variants. Theincreasedworkareaaround thechamber relieves seri-ous overcrowding in the current dual-mode facilitiesandallowsforconsiderablefuturegrowth.InfrastructuredesignedintotheGSELinBuilding26willaccommo-datesimulatedflightmotionandeasyintegrationwithotherfacilitiesaroundthelaboratory.

REFERENCES 1Gary,W.M.,andWitte,R.W.,“GuidanceSystemEvaluationLabo-

ratory,”Johns Hopkins APL Tech. Dig.1,144–147(1980). 2Witte, R. W., and McDonald, R. L., “Standard Missile: Guidance

System Development,” Johns Hopkins APL Tech. Dig. 2, 289–298(1981).

3Gearhart,S.A.,andVogel,K.K.,“InfraredSystemTestandEvalua-tionatAPL,”Johns Hopkins APL Tech. Dig.18,448–459(1997).

4Dean,R.J.,“WarfareAnalysisLaboratory2000,”Johns Hopkins APL Tech. Dig.21,231–237(2000).

5Anechoic Chamber Reflectivity Final Report for The Johns Hopkins Uni-versity Applied Physics Laboratory Building 26 Chamber,EMCTestSys-tems,Austin,TX(10Feb2001).

6Marcotte,F.J.,andHanson,J.M.,“AnAirborneCaptiveSeekerwithReal-Time Analysis Capability,” Johns Hopkins APL Tech. Dig. 18,422–341(1997).

Figure 10. ADSD’s Rooftop Facility is located on the roof of Build-ing 13 and affords an unobstructed view of a large portion of the sky. It provides a cost-effective means to test seekers in an open-air environment.



THE AUTHORS

FRANKJ.MARCOTTEisaseniorengineerinADSD’sCombatSystemsDevel-opmentGroup.HereceivedaB.S. fromKansasStateUniversity in1983andanM.S.fromTheJohnsHopkinsUniversityin1988,bothinelectricalengineering.HejoinedAPLin1983andworkedasatestandanalysisengineerforseveralTer-rierFireControlSystemupgrades.HehassinceworkedonvariousStandardMis-sile and Aegis programs and has helped design coherent instrumentation radars,includingthoseforantisubmarinewarfareandwing-tipvortexdetection.In1999hewasappointedDevelopmentManageroftheBuilding26GSELFacility.Hise-mailaddressisfrank.marcotte@jhuapl.edu.

GLENNM.CAREYreceivedaB.S.fromtheUniversityofMarylandin1980andiscurrentlyworkingonanM.S.intechnicalmanagementfromTheJohnsHopkinsUniversity.HewasaconsultingengineeratMuellerAssociates,Inc.,for7years,responsibleforthedesignofheating,ventilating,andairconditioningsystems.HealsoworkedasafacilitiesengineerattheJeromeH.HollandBiomedicalResearchLaboratoryoftheAmericanRedCross.HejoinedAPLin1991andwastheGroupSupervisorofConstruction.Heleftin1995tooperateafamily-ownedconstructionbusinessandreturnedtoAPLin1998asaFacilitiesProjectsManagerintheTech-nicalServicesDepartment.Mr.Careyhasbroadexperienceinthedesign,construc-tion,andoperationoftechnicalfacilitiesandisresponsibleforseveralcapitalproj-ects,includingtheLaboratoryfit-upforBuilding26.Heisalicensedprofessionalengineer.Hise-mailaddressisglenn.carey@jhuapl.edu.

WILLIAMJ.TROPFreceivedB.S.andPh.D.degreesfromWilliamandMaryandtheUniversityofVirginiain1968and1973,respectively.HejoinedAPLin1977andwassupervisoroftheElectroopticalSystemsGroupfrom1984to1996.Cur-rently,heheadstheMissileEngineeringBranchoftheAirDefenseSystemsDepart-ment.Hiswork includesconceptdevelopment,performanceanalysis, simulation,andlaboratoryandflighttestingofinfraredseekersforStandardMissile,aswellasmeasuringandmodelingtheopticalpropertiesofmaterials.HeconceivedthenewGSELinearly1997andviewsthisnewfacilityasacornerstoneofsuccessfulmis-siledevelopment.Dr.TropfisamemberoftheAmericanPhysicalSocietyandtheOpticalSocietyofAmerica.Hise-mailaddressisbill.tropf@jhuapl.edu.

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The APL Guidance System Evaluation Laboratory - … · 324 24 JOHNSPPKI4 A24 J24 NOHKLI4TIN 4 T24 24 PHSE34 T The APL Guidance System Evaluation Laboratory ... , a cumbersome arrangement