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