Countermeasure Development and Validationof
On-Board Countermeasure System
including the Directed Infrared Countermeasure System.
Miro DubovinskyJeff Vesely
Electro-Optic Countermeasures Group AOC – Adelaide, 26-27 May 2008
JEWOSU
Scope of the talk
Customer focusEvolution of Onboard Countermeasure systemsCountermeasure development and validation process
1. Modelling and simulations (M&S)2. Validation and verification3. Field trials
Underpinning research1. Laser through the plume propagation studies2. Retro-reflection measurements
Conclusions
Customer Focus:PRIORITY
Large Aircraft Acquisition Projects
DMOTransport (Lockheed-Martin) Air-to-Air Refueler (AIRBUS),Airborne Early Warning and Control (Wedgetail) (BOEING)(and ASPSPO-Echidna)
Customer Focus:PRIORITY
Large Aircraft Acquisition Projects
ADF: JEWOSU: Amberley/Williamtown/Richmond Air Force Bases,The AACT activities,
1. Development of a jam code, complex mathematical approach.
2. Investigation into the synergy between flares and DIRCM systems
3. Sustainment plan is imperative to maintain capability effectiveness
4. Building relationships with stakeholders (inc. industry)
Customer Focus:Large Aircraft Acquisition Projects
Develop and Evolve On-board Evaluation Suite1. Radiometer2. Laboratory laser (DEOS)3. Stimulator (IR source(s)/MALLINA)4. Simulation environment for Countermeasures Development5. Sustainment plan for evolving and emerging requirements
Future R&D1. OSAR – Optical Scattering and Retro-reflection2. Countermeasures to Imaging systems – modeling, and
experimentation with commercially available Focal Plane Arrays3. Propagation of laser beams through the plumes
Evolution of Onboard Countermeasure systems
MODIR
ALQ-144
• DSTO/Fairey (Holden Hill) Aus.• Non-coherent 12xQH radiators• Covert• Modulated• Rear aspect• Band I• Low J/S
• Non-coherent radiator• Modulated• Covert• All aspects• Multiband coverage• Low J/S
Evolution of Onboard Countermeasure systems
ATIRCM
NEMESIS
• Lamp/Laser• Modulated• All aspects• Band I/II/IV• High J/S
• Lamp/Laser• Modulated• All aspects• Band I/II/IV• High J/S
• MOTS
Evolution of Onboard Countermeasure systems
DEOS –Coherent(R&D workhouse)
MURLIN AT
• RF pumped C02• COTS• High PRF
• Multiple bands (Band I/II/IV)• MOTS• Solid state
Countermeasure Development and Validation Process
ImplementHWIL Jammer
Codes
Validate Against Available
Experimental Results
Modify HWIL Simulation for
Validation
HWILSimulation
J/S v Jam Code
Validate Against Further Lab Experiments
Field TrialsField Trial
HWILSimulation
Miss Distance Evaluation
Collimator Blackbody (Target,S)
Data logging systems
Laser Power Supplyand
Waveform Generator
BeamCombiner
Electro Optics simulator
LASER (Jammer, J) - DEOS, Murlin etc
Lenses(Beam
Expandingand Focusing)
Modelling and SimulationOptical laboratory
Attenuator
Optical laboratory
IR tracker is losing the lock from the targetThe IR track is perturbed
Miss distance due to perturbation and gravity
• Miss distance has two components
• Miss due to path perturbationassumes missile continues with perturbed velocity at LOL
• Perturbation miss distance = VN.τVN velocity normal to ref trajectoryτ time to go
• Miss due to gravity dropgravity miss distance = ½.g.τ2
• Total miss distance is sum of gravityand perturbation miss distance
Perturbed trajectory
Loss of Lock
Velocity vectorat LOL
Ideal trajectory
Perturbed trajectory
Loss of Lock
Velocity vectorat LOL
Ideal trajectory
Time to go
Miss distance circles due to perturbation
Fall due to gravity
Time to go
Miss distance circles due to perturbation
Fall due to gravity
Hardware in the LoopModeled Aircraft signature
Detector Input Tracking loop Guidance loop
DAC
Computer Simulationof Detector, Optics, and
Gyro
ADCADC
Computer Simulation of Missile Aerodynamics and Target Flight
Steering Command
Control Fin Position
Signal Injection Facility
Reticle/Detector
Other SignalsJammer
Hardware Simulator
Baseline(No-CM applied)
Modelling and SimulationComputer Simulation Laboratory
(Coverage Diagram)
Engagement Range
Aircraft azimuth
• For flares, once the IR seeker is seduced, it tends to follow the flare – outcome is generally hit or miss− “usual” hit-miss (flare view) is not adequate for analysing DIRCM
performance
• For DIRCM jamming:- Interaction between perturbation of the IR seeker & missile performance- Thus, Computer simulation is only reliable way to analyse DIRCM jamming
• Miss distance embodies time to breaklock and continued jammer efficiency in deviating threat from target.− Graded “miss” outputs for computer simulation
Modelling and SimulationComputer Simulation Laboratory
Interpreting Results
Computer modelsAdvantages: Cheap, repeatable, fine grain, flexible, secureDisadvantages: Validation, believability
Optical test bed (beam combiner)Advantages: Cheap, repeatable, secureDisadvantages: Limited scenarios
Hardware in the loop (HWIL)Advantages: Cheap, repeatable, fine grain, minimises simulation, secureDisadvantages: Validation
Field trialsAdvantages: Believable, validationDisadvantages: Expensive, security, limits to scenarios, repeatability
Modelling and SimulationAdvantages and Disadvantages
On-board Countermeasure Field trials
Here
or there
• Good climate• Littoral• Humidity
Hint: LCDR Mayes
On-board Countermeasure Field trials
• To be ready for the protection of the Large Transport Aircraft
• Each mount 2 or 4 sensors,• Scaleable & larger mount options.
Dual band Hi-Speed DIRCM Test Set
UUT x 4
IR source
Mallina
DIRCM illumination area
rjv39
Slide 18
rjv39 better pixs aroundveselyj, 17/04/2008
Single band DIRCM Test Set
RadiometricHigh data collection frame rate Bandpass matchedEnergy limitingHigh sensitivity
PA10 Outcome
On-board Countermeasure Field trials
On-board CountermeasureFlight Trials
Test objectives(1)
DIRCM performance test1. Testing of the obscuration
path 2. Radiometric Output
Measurements3. Beam quality and pointing
accuracy4. Effectiveness evaluation
On-board Counter measureFlight Trials
Test objectives (2)
System performance end to end testing
Under-pinning Research
DIRCM Laser propagation
1. Plume propagation studies2. Optical scattering and reflection (OSAR)3. Retro-reflection4. Atmospheric propagation studies
i. Scintillationii. Absorption
Parametric study to determine the significance of certain parameters on laser beam propagation through a jet engine plume
1. Temperature2. Cell size 3. CO2 levels4. Turbulent intensity5. Laser beam wavelength6. Laser beam diameter7. Refractive indices
To predict the degradation on a laser beam for given jet engine conditions and beam propagation incident angle
Under Pinning ResearchPlume Propagation (1)
MWIR LaserTurbojet
Backstop & Recording screen
IR cameras
Beam Steering Mirror
Issues and Outcomes• Laser propagation (beam wander
and beam spreading)Tracking capability of DIRCM through a jet plumeCorrective algorithms for the laser and tracker.Operating procedures to minimise effect.
Risk mitigation strategies
Jet engine plume may affect DIRCM tracking performance.
Under Pinning ResearchPlume Propagation (2)
Target OpticalDevice underTest on Pan and Tilt Stage
Laser
Attenuator
Lens Spatial Filter
Pin Hole
Detector
Off-Axis Parabolic Mirror
Mirror A
NB: Beam Splitter removed for OSAR Measurement
Computer to control Mirror A, pan and tilt stage, and record data
Optical Scattering and Reflection
• OSAR is the result of scattering of IR by the imperfections in optical elements in an optical system
• OSAR effects govern the ability of the jamming laser to enable jamming pulses to reach the detector to create false targets or other aberrations with off-axis energy
• OSAR measurements/maps are important in verifying OSAR models, which are critical in obtaining the correct seeker response to infrared jammers
Under Pinning ResearchOSAR Mapping (3)
Retro-reflection is predominantly due to specular reflection from the focal planerelies on a semi-reflective surface in or close to the focal plane ( IR seekers from a reticle, detector or detector array).
Can be characterised by the Optical Cross Section (OCS)OCS (σO )is analogous to Radar Cross Section (RCS)σO = Geometric cross section x reflectivity x losses x directivity. Cross
section (AO)
Ref
lect
ivity
r O
TransmissivitytO
ωB
Simplest expression is for a "top hat" profile
24. . . .O O OO
B
A r tπσω
=
AO is optical arearO is reflectivitytO is optical transmissionωB is reflected beam solid angle
Real beam profiles depend on optical configuration,Top Hat and Gaussian profiles are idealisations
Under Pinning ResearchRetro-reflection(4)
Optic Axis
Target OpticalDevice underTest on Pan and Tilt Stage
Laser
Attenuator
LensDetector
Pin HoleSpatial Filter
Mirror ABeam Splitter
Off-Axis Parabolic Mirror
Retro-Reflection
Spiricon Camera
Optic Axis
Computer to control Mirror A, pan and tilt stage, and record data
Retro-reflection
• Retro-reflection is due to reflections in the focal plane. For infrared seekers this is generally a reticle, for a "simple detector" system
• It generates a strong reflection back along the incident beam and hence has the potential to identify the seeker type and modulation characteristics, range and range rate.
• This provides a basis for selecting a more optimal and hence more potential to monitor jammer effects and provide timing for laser dazzle or damage pulses
Under Pinning ResearchRetro-reflection (5)
Under Pinning ResearchRetro-reflection (6)
DAYTIME (17:03), Laser PRF = 127 kHz modulated with 300 Hz square wave, detector = PbSe radiometer AC coupled, range = 2.626 km
-0.5
0
0.5
1
1.5
2
0 0.1 0.2
Seconds
Vol
ts
SUNSET (19:36), Laser PRF = 127 kHz modulated with 300 Hz square wave, detector = PbSe radiometer AC coupled, range = 2.626 km
-0.5
0
0.5
1
1.5
2
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Seconds
volts
NIGHT TIME (21:34), Laser PRF = 127 kHz modulated with 300 Hz square wave, detector = PbSe radiometer AC coupled, range = 2.626 km
-0.5
0
0.5
1
1.5
2
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Seconds
Volts
Cn2
SUNRISE
DAY
Diurnal Variations
Sunset-Radiometer Detector
Daytime-radiometer Detector Night Time-Radiometer Detector
Atmospheric Structure Constant
Under Pinning ResearchPropagation (7)
Conclusions
On-board CM test capability built and testedModelling and simulation environment under-development with industryResearch underway in collaboration with Allies into,
Optical Scattering and Retro-reflectionLaser propagation under atmospheric effects inc. jet plumes and environmental factorsEffectiveness evaluation criteria