Counter UAV Optical Detection, Location, and Negation Feasibility Study

Contract Final Report For the period covering 10 September 2003 to 24 March 2004

Sponsored by

CORL 0002 Doc. No. A001

24 March 2004

Prepared for:

Contract: MDA972-03-C-0071 Advanced Technology Office

r ne> I

Prepared by: Advanced Systems and Technology

Information and Electronic Warfare Systems P.O. Box 868

Nashua, New Hampshire 03061-0868

Defense Advanced Research Projects Agency (DARPA) Advanced Technology Office/ATO Program: Counter-UA V Optical Detection, Location, and Negation Feasibility Study ARPA Order No. QI41/00 Program Code: 3E30 l.ssued by DARPA/CMO under Contract No. MDA972-03-C-0071

The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Defense Advanced Research Projects Agency or the U.S. Government.

BAI:; SYSTEMS Information and Elcmonk Warfan: Systems

REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188 Pibric repor1ing bu~ fcr llU cdlection of iofonna~on Is es11ma1ed IC> a....,ra-;ie 1 tiour per re<:pmso. onducf.ng ll>e ~,... fOf reviewing inslrudi0t1S. seatchlng ulsfng Oata soorces, galhemg and rnaintairlng fw dala needed, Md """'l"•ttng ar>d re..,;e,.;"l) lllis collec6oo cl inl0<matton. Ser>d commef11s regat'Jing lhl$ bU1~n u~mate or any olhe• aspecl of 1tis cotecliO<> el i"""""'4ion. inclu!Jng suggest;on• for t~ 1his burden to Oepa~mtnl of Defen"8, Wa5t>no1on Hoodqu1~en1 SeMCes. 0.1ecioratll lor lnl0<mabon Operations and Regoru (0704-0168). 121~ JeNerson Davia Highway. Wtt 1204. A'1"'9ton. VA 22202· 4302. Respondents stiould be aware thae notW1lh$1andl"9 any o!her provision°' l aw. no pe~on s~a11 t)e !utljec• le any penet1y tor lai~ng lo c.OOlply ¥ilh 1 eo1t1c.-on of infomufiM ii" does t'!Ot di.splay a cu"en~y valid OMB conlrol °""'b<lr. PLEASE DO NOT RETUllN YOUR FOAM TO THE ABOVE AOORESS.

1. REPORT DATE (00-MM-YYYY) , 2. REPORT TYPE 18 March 2004 Final

4 . TITI.E AND SUBTITLE

Counter UAV Optical Detection, Location, and Negation Feasibility Study

6. AUTHOA(S)

7. PERFOAMl~G ORGANIZATION NAME(S) AND ADDRESS(ES)

BAE SYSTEMS Advanced Systems & Technology TEWS PO Box 868 Nashua, NII 03061-0868

9. SPONSORING I MONITORING AGENCY NAME(S) AND AODRESS(ES) Defense Advanced Research Advanced Technology Off i ce 3701 N. Fairfax Dr Arlington, VA 22203-1714

3. OATES COVERED (From· To) 10 Sep 2003 to 24 Mar 2004

5a. CONTRACT NUMBER MOA972 - 03 - C-0071 Sb. GRANT NUMBER

Sc. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

5e. TASK NUMBER

51. WORK UNIT NUMBER

8. PERFORMING ORGANIZATION REPORT NUMBER

03DAJ

10. SPONSOR/MONITOR'S ACRONYM($) DARPA

ATO 11. SPONSOR/MONITOR'S REPORT

NUMBER(S)

12. DISTRIBUTION I AVAILABILITY STATEMENT ~f!mm!Strar~re O~ '1f{ !}If a~~f

Discribution authorized 10 U.S. Government Agcncies<aR3~litlff~ij~~a1:i.ors. Other requests for this document shall be referred 10: Dl!fense Advanced Research Projeccs Agency. 3701 Fairfax Drive, Arlington, YA 22203-1714

13. SUPPLEMENTARY NOTES

14. ABSTRACT

The BAE Systems approach identifies the key DARPA hard technology development required in order to realize the Counter UA V mission vision. This Concept Development study developed several CONOPS and engagement scenarios that serve to define the preliminary system~ requirements analysis. From chis analysis, we developed several simulations lo help analyze system concept approaches and performance issues. We then performed technology trades to determine the applicability an<l maturity of current sensor technologies to the problem. A field test was performed where actual data was collected and analyzed. Finally, directed energy countermeasures were investigated as a means to defeat these threats at stand-0ff ranges.

15. SUBJECT TERMS

16. SECURITY CLASSIFICATION OF: Unclassified

a. REPORT b. ABSTRACT

17. LIMITATION OF ABSTRACT

18. NUMBER 19a. NAME OF RESPONSIBLE PERSON OF PAGES

c. THIS PAGE

BAE SYSTEMS lnfonnation and Ekcfn)nic Wasfarc Systems

19b. TELEPHONE NUMBER (includearoa code)

Standard Form 298(Rev. 8-98) Pr .. crlbod br ANSJ Sid. Z39. 18

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DOCUMENT CHANGE HISTORY

DOCUMENT NO.: AOOI

TITLE: Contract Summan' Rcoort Final

Date Re\1• Description

24 Mar 2004 - Report Subn1ittal

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SOURCE INFORMATION

Applicacion: :tviicrosoft \Vord 7.0

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TABLE OF CONTENTS

Summary .. . ............... I

2 Introduc1ion ....................... """" 3 2.1 Scope ...... """""""' .............. 3 2.2 Motivation .... . ................. 3 2.3 Document Classification ...... 3

3 Concept Development Study Overview ............................................ .. ...... 4 3.1 Introduction ................ ,. ........... .. "" 4

3.1.1 Operational Overvie\\' ................ . .................. .- ... .- ..... 4 3.2 Threats and CONOPS...... ................ . ........................... 6

3.2.1 Threats···············"·· ........................... ................. ............. . .......... 6 3.2.2 Concepl of Operations (CONOPS). ..................... .. .............. IO 3.2.3 Requirements......... ............. .. ........... ....... . ...................... 13

3.3 "DARPA Hard" Problem Summary. . .................... 14 3.4 Key Technology Issues.... . ........ 16

3.4.1 Introduction........................................................... .. .......... 16 3.4.1 I Search. Detection. and Identification ......................... 17

3.5 Evaluation Methodology...................................... .. ........ , ....... ., 19 3.5. 1 Counter UA V Trade Space . .................. . ................... 20 3.5.2 Sensor Architecture ......................... .. ............. 21 3.5.3 Detection Architecture .. ........ . ........... . . .... 23

3.6 System Architecture... ............. . .............. . ...... 25 3.6. 1 Introduction ................. .............. . 25

3.6.1.1 Approach. ..................... ............... . .............. ,...... .. ..... 26 3.7 Evaluation of Technologies and Concepts .,............. .. ..... 27

3.7. l Sensor System Performance...... ................... .. ..... 27 3.7.2 Optical Augmentation.................... ............. .. ............. 32 3.7.3 Technology development....... ............... .............. .. .... 33

3.8 Field Tests..... ............................ . . ........... .. 34 3.8.1.1 Configuration ...................... ..................... . .. 34 3.8.1.2 Absolute radiance measurements.. .. ................ 38

3.9 Countermeasures..... ................... .. 43 3.9.1.l ln1roduction ................. ............... . ............................................... 43 3.9.1.2 DirectedEnergy,. .......... , ........................... .. .......................... 43 3.9.1.3 Beam Wander............................. .. .......................... 46 3.9.1.4 Counterrr1easure Effectiveness .......... 48 3.9.1.5 Optical Scattering and Reflection (OSAR).. .. .... 49 3.9.1.6 Close Proximity Countenneasures ....... ................ .. 50 3.9.1.7 High Po\ver Micro1,.vaves. . ................................................................... 51

3.9.2 Sun1mary.......... .................... ............. ..... ........................ . . 52

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TABLE OF FIGURES

t~i&~!XrJ : __ [g_untcr tJ/\ \/ envisinne9..!2L~QX£t!.l9!J ...

fjgl}.[!;. .. f .~ounter LlAV sy~tem OQ!il~H.i9.Jl·,,-·

f.i£_1lre 3: Typical Fixed wing UAV and VTOL UAV ..

Firrnrc 4: :\erosonQe and Pninter purpuse built rnilitary lJ.i\ Vs

.Figure 5· Ti,vo example~ of n1odel airplanL'S that n1av b.: used as Ui\ Vs ...

Bz.v.rr; .. 1 .. hQ!J.!!.\fr . .V,'.\_V opcratio11al scena1io

f.:i.&lJ.If'. .. ~ ... h:QYD.\S:I UA Y S\ sten1 operation block di a grain

Fi"llfL' 9: Counter lJAV nii~~Jon and tL'L'hnu!ugy ena\1ler" .................... .

Fioure 10: Counter UAV n1is~ion anJ technology enablers ............. .

Fi2ure 11: Couoter UA \! tCL'hnol01!\ trade space ................ ..

Fioure 12: ID i:.;ipge profile sc-11.~or ..................... .

Figure 13: 2L) anidc-angk; ~ensor ...

Figur:.~.l-1: ~D angl_e-nnglc-ran_g_e ~c-nsnr

Fi!!ure 15: Ra\LCr scan LA DAR architCl2,\JIH'.

fio-ure 16: Lincscan LADAR architcctyrg ............ ..

figl1re 17· Fla~h LAll<\R urchltei.:tur~: ........................... -. .... ..

tig.ur.i;:.J~ ... {\.tJ.£.1.0.:illll,!le-rangc Flash LAL1AR architecture ....

[i_gure 19: BAF- Sy-;re--m" S\VISS detector for flash LAD,-\R

Figun: 20: Prohahi[ity of deh.x:tion. 1.:la-.sificatio11, and idcntifjca!ion ..

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Fi o'ure 21 · Proba]JjJi.t.J'. . .Q.f..sJs~l\'<fJjQJl, .. S:J.\.!,~5.i.fi.S:§;\.i.9.D,.J.~g_Qj_r;l\:ntification for a I n1etlT targr.L.<!D.od .. i! .. f. n1eler tar!!Cl ....................................................... ,.... . .................... 29

Fi,,ure 22: Dcll'tlipn. cltJs~ificatiorL and idcl}tification ranl!e .......... . . ................... 30

Fie-ure 23_~---S_~_n_~_Qf __ ~i_gnJ.!::tQ_~_!_lQ)_~~--P.?tforn1ancc for system and targel value~ listed in Tciblc 4 aud Tahlc 5 .......... . ................ .................................. . .......................... 31

Fi~>:11re 24: Si:n~or prohahilitv of dt!tcction prrfnrn1ancc ft!f ~v-~ien1 ilrld tarl:!el valUL\~ li:-t.~.sLLn I;!hl~ .. 4 .. ~I!9 Jable 5 ......... , ..................... ,.............................. .,......................... .. 31

Fi£ure 25: Ootical Augrnentation pc:rfunnance in tern1s of cfoss ~e1.:tion as a function of tanzet .~\J)J~J1J!I\o'5~Ll!.JJlGt£X ... . . ........... ................ .. ...................... ., ..... ., 32

Fioure 26: TechnoJ9g,\: __ [Q!!_dJJJ.:JJ1 __ (~?I __ ~~_n~_QI __ llD.9 __ RJ;;W technologies. :>4

Figure 27: Threat n1ounted on rest stand \\'Ith QJackbodY calibr.g1i.~?.fl .. ;!Ql!J.~f. i.n .. b.\lcf.b.&1:£11!.nQ. .. 35

Fiann:: 18: Threat n1oun~ed on t..:st stand to facilitate l!.!:-'J.J~Hl.t~.Jn.t;h;.~J!.lg ...

fj_g,11.rY..£9: A.ssen1tily of threat prior to flight. ..

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. ........................... 36

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Fi 0 ure 30: Thr§.\Jt.i.ii.~'.!J.<;.~.~~~t.f~.~!:JJroper operatinn ..•••• 36

figure 31: Thr1:,;1Lh~.lQ .. l2~'..9.lli'.I:?J.~I in hucket prior to launch ........... ""' ..... "' 37

Fi 1Yurc 32: Threat tak~.:;.fLi;;bJ..Yfl~X.EY.l.~:~l~~ .. ~) operator .............. .

tis_nre 33: BAE S\'sten1s data C()Jlef.;tion in1'trun1entation

Figure 34· Side vie\'' of BAE Sv$tc1ns instrun1entation ..

Fi!!un:' 3.5: Band I r<1dion1L'tric data ..

Fioure 36: Band JI radion1etric datg.

Fi£ure 37: B,1nd IV radion1etric data ...

Figure 38: 8 tn 12 un1 L\VlRradiornctric data .............................. .

Firrure 39: Threat on test stand in visib.k ...... .

Fi~i:1.11e 40. San1c thteat on test stand in L\VIR

Fi!!ure 41: Block diaonnn of_l)f:':\\t operation and scqufnee

Fic:ure 42: Factors aff..:cting bcatn propagation through the atn1osph~re

Fi1.1:i1rc 4~: Abc1-r1ugd Oeo111 Cleft} and con·t'i:ti;sLb.~H!ILLLlg.hJJ

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38

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Fie:ure 44: La~er tran<;mittcr diamett'r vs, Beam wander at I 0 km ... ,. ... ,. .. ,,, ............. .,. ..... 46

. 47 Fiaure 45: Enerry·on··target \Nithont ab<;,tTati1lll corn1Jen5ation .. .

Fu:nll"e 46: Enl're:y-nn-t;u·e~'! y,:it h aberration i.:0111pcni;41 ion ........... . .. ............ 47

Fie:ure 47: :Enhanccn1ent factor sho\vs sign,.ificant i;rain for £ffectual enyruy on target ............... 48

'" 49

Figure 49: DE\V counter1ncasurc cffcctivenes\ at JO K\\.: level:..... . ... 49

Figure 50: Scene photogrnph (left! ;;tnd ~un1e ~i.:cne photograph ~YH.11.().S.AR .......... 50

Figure 5 I: Dcpiclil1n nf proxirnity cuu1l!~t:!J.1~'..~!~.Uil,'..t:..J;.!J$A§.!.!!.!g . .<.~ .. !}g.~~- 9Jj1nsti!c l.JAVs .. 51

figure 52: Depiction of proxi.DJi!.X .. S:9.~D.t£L[lJ!-;.Q'.:!!!.~.~.!!!:.i.!!g. HPM ene:a0 i n<> a fleet of ho'>!ilc U AV s .... .... ............... .................. ................. . .... 52

TABLE OF TABLES

I;:i._R_l~_J ___ I_hr~_i!1.~_h.a,racteri stic:. ................ ,, ... , .. , ........................ . .. .............................. 8

I!!b.l~ __ J ___ Q1u~_olitati ve radar cro<;.s section dat;tf or selectr:d ,.,\Qccle:. of hi rd~ ............... . lO

Tahle 3: Counter UAV perforn1.ince reguirc111cnts.

Tahlc 4: Systen1 parameter' ............ ..

Table 5: Taq;ct paran1etcrs ..

Tahle 6: ~1axin1um radiance at anzl~ ............................ .

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1 Summary

The BAE Systems approach identifies the key DARPA hard technology development required in order to realize the Counter UAV mission vision. This Concept Development study developed several CONOPS and engage1nent scenarios that serve to define the preliminary syste1ns requirements anaJysis. From this analysis, we developed several simulations to help analyze system concept approaches and performance issues. Vv'e then performed technology trade~ to determine the applicability and maturity of current sensor technologies to the problem. A field test was performed v.1here actual data was collected and analyzed. Finally, directed energy countermeasures were investigated as a means to defeat these threats at standoff ranges.

The Counter UAV system is envisioned to provide support to forward batterie~. observers, or emplacements. The system would be rnouuted on a tracked or wheeled vehicle and would consi~t of a laser radar (LADAR) that would provide both the search, detection, and identification capability. With this information, range, range bearing, angle track. and time to arrival will be determined. A directed energy v.1eapon (DEW) would then provide the countermeasure capability. Here, high energy lasers (HEL), high pov.'er micro1,vaves (HPM), or optical jamming, optical scattering and reflection (OSAR) would be used to defeat the threats. Additionally, the LADAR v.·ould provide kill a~ses~ment.

""' -"""

r.-.~-­' -~. ,•'

¢ --Threat UAV• approaching

::. LADAR detects threats and mepe. position

~ Single or multiple threatl!I Mll'>rot,.rt 11nrl iriAntffifff'I

t?l(1-4 .... OEW c1,1td to lhrnt position ;;_ DEW engage.t and ....,,.111" thn>,.t llAV

Figure I: Counter UAV envisioned operation

The steps in a typical engagement include: 1) scanning the horizon for threats; 2) threat detection and spatial positioning with target-object map forn1ation; 3) identification of threat~ to the extent they can be discriminated from other objects in the vicinity (here, LADAR has a distinct advantage as the anticipated angle-angle-range imagery \Vould provide visual threat verification);

BAE S'r'STE~1S Information and Ele~1ron1~ W;u-fore Sy11¢rll';

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4) positioning of the DEW to lhe region of interest (v,ihile the depiction above shows a ground based countermeasure, proximity countermeasures may be employed that engage the threat at the threat location), and; threat engagement and defeat (the LADAR will view and verify threat defeat).

This study effort included the completion of the Concept of Operations (CON OPS), mission capabilities, require1nents definition, technical trades, sensor concepts and evaluation, and sensor concepts as a function key mission needs. The Final DARPA briefing is ~heduled for 17 March 20Cl4 at DARP:\" The program completion i~ scheduled for 10 March 2004.

Deliverables for the study includes the final briefing/report documenting the concept development \vork, trade studies and analysis that form the ba~is for a strong technical rationale and framework for a follow-on multiple phase DARPA program. As part of the obj~ctive for this effort and a result of this study \.Vas identifying the besc solution and recommendations for DARPA and compelling mission need that can then use to provide the foundation for a new DARPA program start.

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2 Introduction

2.1 Scope

This document and its Appendices provide a summary of the work accomplished on contract MDA972·03·C-0071. Section 2 provides an overview of the system and a surnniary of the development chronology. Section 3 describes the work accomp!L~hed along with a discussion of the studies. ex.perin1ents, demonstrations and tests carried out during the contract life. Section 4 lists the conclusions. Section 5 puts forth the recon1mendations based on the Vi1ork accomplished. The prime contractor was BAE Systems Information and Electronic Warfare Systems.

2.2 Motivation

'fhe proliferation of small and very small Unmanned Aerial Vehicles (LTAVs) that can be outfitted with inexpensive intelligence sensors (e.g. cameras and Infrared {TR) imagers) and potentially be used to deliver payloads (e.g. N/B/C or Explosive) is an immediate threat to homeland security and forces and installations a.broad. Inexpensive nwans 1nust be developed to detect these small aotonomous aircraft and disable or destroy both the sensors and/or the aircraft \.Vith no collateral damage and in open field and dense urban environ1nents.

Several challenges rnust be overcome to develop a robust detection and negation capability. The I'[ challenge is detection. Small and very small (e.g. Micro Air Vehicles) UAVs are difficult to detect due to size which results in a extretnely sn1all cross-section, non~ferrous ma1erials used in their construction, and low altitude flight. ·rhe detection method must include persistent volumetric search and the ability to cue a narrow field of view sensor or negation device to the aircraft. Multiple means of detec1ion (e.g. optical, RF, acoustic) tnust be employed that exploit the unique characteristics of small UAVs and their sensors. This must be d<)ne without affecting other aircraft in flight or personnel on the ground.

The 2"" challenge is pointing accuracy. These small aircraft exhibit significant wobble in flight and are highly maneuverable requiring high precision tracking in order to accurately cue negation me1hods. lligh precision mechanical pointers nlay not provide sufficient accuracy electronic methods of steering beam:<. and controlling optics may be required. The 3rd chal1enge is negation. Methods to dazzle or disable UA V ~borne optical sen:<.ors with very srnall optical apertures in multiple bands (visual and IR) must be developed. This may require one to several optical sources and receivers to cover the range of sensors that may be employed. The nature of the sensors themselves must be understood to determine how to effectively deceive or destroy the electronics elements within the sensor. A unique aspect of these aircraft is their construction materials. Foam, carbon fiber coverings, light \VOod, plastic propellers, are most often used in the construction making des1ructlon of the aircraft itself a promising possibility with affordable solid state laser technology.

2.3 Document Classification

This document is unclassified in its entirety.

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3 Concept Development Study Overview

3.1 Introduction

This Concept Development study developed several Concept of Operations <CONOPS) and engagen1ent scenarios that serve to define the preliminary systems requirements analysis. From this analysis, we developed several simulations to help analyze system concept approaches and perfor111ance issues. We then pe1formed technology trades to determine the applicability and maturity of current sensor technologies to the problem. A field test was performed where actual data was collected and analyzed. Finally, directed energy counlenneasures were investigated as a means to defeat these threats at standoff ranges.

• DARPA A TO conducting feasibility studies to countering hostile ll A Vs

• Detect, engage, and defeat sn1all hostile force UAVs that can present a threat to friendly forces in fop.vatd operating areas.

3.1.1 Operational Overview

Operation envisioned may include detection, identification, and suppression of individual threats as well as detection, identification, and suppression of threats in groups. Threats may include purpose built lfAVs and UAVs constructed fron1 n1odel airplane components. These threats may carry payloads that can include visible or infrared optic~ to gather intelligence data, or disrupting electronics or jammers to interfere with friendly forces operations. CONPOS may include a single hostile UAV with optics Lo locate forward ernplacernents, a single hostile lfAV with electronic jammers to disrupt forward radar, or multiple hostile lJAVs i.vith optics and electronics to observe and disrupt forv.'ard operations.

'rhe Counter UAV system is envisioned to provide support to forward batteries. observers, or e1nplacen1ents. The system would be mounted on a trarked or wheeled vehicle and would consist of a laser radar (LADAR) that would provide both the search, detection, and identification capability. With this information, range, range bearing, angle track, and tln1e to arrival will be determined. A directed energy v.ieapon (DEW) would then provide the countermeasure capability. Here, high energy lasers (HEL), high power micro\Vilves (HPM), or optical jamming, optical scattering and reflection (OSAR) \\'Ould be used to defeat the threats. Additionally, the LADAR "'ould provide kill assessment.

Typical operation is shown in Figure 2 and the steps in a typical engagement include: 1) scanning the horizon for threats; 2) threat detection and spatial positioning Y.lith target-object map formation; 3) identification of threats to the extent they can be discriminated from other objects in the vicinity (here, l~ADAR has a distinct advantage as the anticipated angle-angle-range imagery would provide visual threat verification): 4) positioning of the DEW to the region of interest (while the depiction above shows a ground based countenneasure, proximity countenneasures may be employed that engage the threat at the threat location), and; threat engagement and defeat (the LADAR will view and verify threat defeat).

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1. ThreBI UAVs &llPfOKhinq

' ... Figure 2: C:ounter LTAV system operation

A key elernenl to this concept study phase is to identify: "What are the high value military payoffs that the Counter UAV systen1 provides that is not available to the warfighter today,'' and will not be enabled by other DARPA programs. ll is envisioned that a Counter UAV system will possess the following attributes:

1. Detector··Suopressor for the threat VA \l Combat Mission

• Search, detect, engage, and suppress threat UAVs

2. High Resolution of multiple small sign(lfure fast moving targets

• Angle-angle-range LADAR imagery

3. Advanced LADAR in1agery enabling

• Search, detection, identification and engagement of multiple targets

• Active object discrimination at stand-off ranges

4. Directed Energv Weapon

• Aberration con1pensation for turbulence correction and fine aimpoint control

Based upon the studies conducted here, the proposed solution would consist of an Angle-angle­range Flash LADAR enco1r1passing uride-area scan with high resolution imagery providing detection and ID. This approach enables rapid man-in-the-loop threat confirmation for immediate target engagernent and suppression.

The recommendations presented in this report are the result of methodical systems analysis and performance trades to pennit the idenlification and definition of specific enabling technologies to

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perform the Counter lJAV mission. The discrete sti:ps perforn1ed in this analysis leading to the recommendations and conclusions presented here include:

• !\.fission capabilities and requiren1ents definition

• Operational concept

• Identification of candidate technologie~

• Trade space definition

• Trade analysis and technology feasibility assessment

• System a«hitecture development and technology suite refinement

• Preliminary concept

• Performance p~jections; modeling and simulations

• Final technical presentation/report

~rhe Counter UA V study included an initial progran1 kickoff meeting held at BAE Systems AS&T facility in Merrirriack, Nev.· Harnpshire. An interim program review was conducted 21 January 2004 at BAE Systems AS&T facility in Merrimack, New Hampshire. The intent of this meeting was to brief results of the program to date and receive any guidance frorn the DARPA PM as to program direction. At this reviei.v, the DARPA Program Manager instructed us to participate in a live~fire exercise scheduled for 9 through 12 Fe.bn1ary at Ft. Bliss. A final program briefing is scheduled for 20 March 2004 at DARPA.

3.2 Threats and CONOPS

3.2. 1 Threats

Threat UA V information was obtained from a number of open and classified sources; although no classified information is presented here. There are many UAV programs undef\\.·ay in many foreign countries that are both friendly and hostile to the- US. There are currently 161 operational UAV programs in 50 countries. Al:;.o, the UAVs range in size from very small, the principal threat here, to very large (the large threats have been excluded here). The threats researched here include those that have a spatial extent of about 2 meters at their largest point. Hence. they are very small; and, fron) this per!ipective, very difficult to detect.

The open literature v.'as extensively researched to provide information about threats and threat characteristics. In this capacity, the literature search included only those threats that had an ex.tent of 2 nleters, could carry optical or electronic payloads, and are purpose built or built from simple, and readily available, 1nodel airplane components .. <\\so, National Air and Space Intelligence Center (NASIC) and National Ground Intelligence Center (NGIC) were queried as to any infonnation that had concerning thi1> class of UA V. NASIC provided BAE Systems with a classified CD containing threat and signature information for a variety of UAVs.

A live-fire exercise was scheduled at Ft. Bliss where UAVs were flown and missiles fired to defeat ther.e threats. BAE Syste1ns in~trumented a data collect to obtain both absolute and relative measurements of these- live fire exercises. Here, BAE Systen1s collected data of the threat, threat-missile engagen1ent, and threat radiometric data over the test series.

Sources of threat information used in this study include:

• Open literature threat infonnation

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Jane's, PeriscopcOne

Internet Site:->

• Classified literature threat infonnation

NASIC and NGIC

• Modeled and measured RCS data

• Limited IR signature data

• BAE Systems Ft. Bliss field measurement~

Absolute threat radiance measurements

• Calibrated 3-band radiometer

Relative threat radiance

• Visible carnera

• MWIR (3 to 5 µn1) camera

• LWIR (8 to 12 µm) camera

BA£ SYSTEM$

Classes of lhreats include conventional fixed "'-ing types as well as rotary wing and vertical take­off and landing (VTOL). Intended missions include:

• Intelligence/Surve1llance/Recon

• Target attack (Land and sea)

• Electronic warfare

• Suppression of air defen~e (SEAD)

• Unmanned fighter aircraft

• Co1nn1unica1ions

• Propaganda

Photographs of two typical purpose built UAVs are sho\vn in Figure 3. UA V threats n1ay consist of fixed and rotary wing variety, Their missions may include intelligence gathering, surveillance of forward emplacements, and recce n:tissions. They may be used for target attack with conventional. or unconventional. weapons, perform electronic v.1arfare missions, SEAD, or, in more sophisticated incamations, be used as unmanned fighter aircraft.

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, ••. ,.,...,,_,.,..,,,,, ;Pt'

Figure 3: Typical Fixed wing UAV and VTOL UAV

'J'hreats and their physical and operational characte-ristics are shown in Table I for UAVs from several countries. All threats here address the spatial extent lin1its of 2 meters.

Table l: Threat characteristics

IN a me "ountrv lMeiJ•ht llljn.,snan - -n .. th M 'I" . ~~.~.~!?-.& .. ~.~~&~ '-"'1

K• M M Ft Km KPH

SLURS USA 4.54 1.52 1.22 500 9.3 100

Rackpack "SA 11.34 0.91 0.98 5000 9.3 NIA

Sea Ferret lJSA 68 1.83 l.83 20000 296 464

Sender USA 4.54 1.22 1.22 5000 93 166

r1elilah ltsrael 185 l.75 2.68 25000 250 797 -- ___ ..:...;:-_:__

IJ.larnv Israel 120 2.03 229 9800 574 249

ark S. Africa 120 2.07 2.41 15000 l 15 209

While the threats here represent a typical cross section of foreign military developed and deployed threats. In reality, however, threats may be as unsophisticated as simple model aircraft 'J'he two UAVs shown in Figure 4 are purpose built to be used for various military applications. They are Aerosonde, Australia origin, and Pointer, US origin. Figure 5 shows two model aircraft that can be used for UA V purposes. They have a wingspan of 2 meters.

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~Figure 4: Aerosonde and Pointer purpose built military UAVs

Figute S: T\\'O examples of model airplanes that may be used as UAVs

Data was collected on birrh; as well as their size and signatures can be representative of UAVs. Also, birds can present false alarm issues relative to sensors. While it is not given here, IR data was collected by BAE Systerrrn at the Ft. Bliss trials of a large hawk that has a signature very similar to the UAV being tested. Birds can represent threat UAVs at detection ranges classification or identification required to discriminate. Do not want to hann birds and, also. must be certain of threat to ensure false alarm reduction. Birds do have quantitative radar cross section as shown in Table 2. While there is little quantitative data in IR and at optical frequencies BAE Systems col!ected qualitative IR data at the Fl. Bliss lrials.

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Table 2: Quantitative radar cross sertion data for selected species of birds

Bird species Radar band Cross settion

- ........... ........................................ .......... J~~sm)

Grackle x -28

s - 26

UHF - 42

SD<tITOW x - 38

s • 29 ···-

UHF • 57

Pii:!eon x - 28

s • 21

UHF' • :lO

3.2.2 Concept of Operations (CONOPS)

Military Commanders have a need to provide protection for their forces in any operational area of the world. Based on the complexity of the battles pace environment. this means having a responsive capability to conduC"t area defen~e for\vard art'as over extended periods of time. Current attack assets available include short range air defense 111issiles, artillery, and small arms fire employed as defense against high value targets. But son1e of these defenses have a relatively lligh cost per target, are very inaccurate. or rely upon close proximity encounters.

In contrast, a sensor that can detect threats before they become a problem, provide an identification and discrimination capability, have an effe-etive, low cost, countenneasure, aod provide kill assessment can provide protection at relatively Jong standoff distances.

Therefore, the need exists for a cost--effective, responsive, precision nttack capability against single and multiple UAVs.

Counter UA V fills the operational need by being a fully autonomous, long range acquisition. and effective countermea'lure. It provides a high endurance !>Carc:h capability for distributed small targets, and can detect, identify. and assess multiple target sets thorough on-board high resolution sensors wtth a man-in-the-loop but, have an upgrade to automatic target identification algorithms when they become available.

To address widely dispersed targets or target sets, Counter UAV has a requirement to carry a search and identification sensor and a DEW countermeasure, to engage and suppress multiple threats at standoff distances. Multiple threats can be attacked in real-time \Vith precision and post--attack imaging can provide immediate battle damage assessment and re-attack if necessary. Low altitude operation of any pla1form places it in a high threat environment, but Counter UAV is projected to have a high discrimination feature built in as well as a man-in-the-loop operation.

DEW coupled with multiple kills against moving targets provides effective low cost per target. High resolution LADAR imagery and geographic location of targets provides key information in areas where enemy defenses may not have been adequately suppressed. This CONOPS is shown in Figure 6.

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Fi-gu"e 6: Counte" UAV CONOPS

The CONOPS for Counter UAV is support to forward observers. radar sites, artillery emplacements, Patriot and Ml.RS batteries. In operation. the system v.·ill search large areas for threat UA \'S, derect and identify threats using angle~angle-range flash 1.ADAR, construct target object map of all objects present within the scan region, and revisit specific areas of interest and identify threats. In this capacity, the sensor will provide the ability to discriminate objects, thus, ensuring they are, indeed, threats. A directed energy weapon is envisioned for threat engagement and suppres~ion \Vith the LADAR providing kill confinnation. To provide protection at standoff distances, a 20 km detection range is envisioned with a 10 km suppression range. A typical Counter UA V operational scenario is shown in Figure 7.

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' ' ..

BAE SYSTEMS

liim / Mobile

Air Defen••/ ,,._~lA SCM Sites

' .

Current FOB .,

.'\

~··

MUS .%

Figure 7: Counter UAV operational scenario

'To perform it's mission, Counter UAV needs to autonomously perfonn a number of mission functions typically perfornied by ntultiplc different platfonns. The engagement sequence proceeds from search and detection, to identification and confirmation. Next tracking and targeting are performed, leading to engagenlent and suppression. During suppression, the sensor can assess target dan1age and re··engage if required. During the search and detection process, Counter UA V must search a large volume near and above the horizon while providing a high probability of detection. Once threat~ are detected, Counter UAV also provides geolocation coordinates of the threat. Counter UA V has the capability to detect and track n1ultiple targets. After detection, Counter UAV enters the target identification and confirmation stage. Here, LADAR images are provided to onboard personnel for target idenlificatlon and threat confirn1ation. Identification must be petformed at sufficient range against srnall targets so that the engagen1ent can proceed at the determined engagement point. Man-in-the-loop operation is provided with growth to ATR algorithms when sufficiently developed. Datalink in1ages and fast target identification should allow the man-in-the-loop authorization to proceed with minimal delay.

Once confirmation has been achieved, Counler UAV \.Viii track the target and collect targeting data for the engagement An appropriate vulnerable aimpoint will be selected and sent to the

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onboard targeting designator or to the- DE,W itself. If multiple targets are present, Counter LIAV will prioritize to ensure that the closest threat is engaged and suppressed first.

During the engagement, Counter UAV can assess the target damage using LADAR imagery and assess, in real·time, whether a follow-on engagement is required. Counter UAV 1nust perfonn the following actions to fulfill mission requirement5:

• Search and Detection

Large volume high-speed search

Target abject map formation

• Identify and Confirm Threats

At sufficient range so they do not pre.~ent a problem

Small to very small cross sections

Man-in-the-Loop capability

• Track and Target

• I<:ngage

Moving and target~

Minimize divergence and boresight errors

Multiple threat engagement prioritization

DEW for suppression

Prioritization based upon LADAR data

• Assessment

Assess target defeat

Re~attack if nece~sary

3.2.3 Requirements

A set of notional requirement were constructed based upon discussions v.'ith DARPA and based upon typical missions. This was performed to have a rnetric to which to n1easure systems performance in the modeling. analysis, and simulation phase of the program. Table 3 provides an initial set of operational requirements for the Counter UA V system. The platform is envisioned to be either a tracked or v.·heeled vehicle that can operate in all environments. Deployment is to forward observation, air defense, or artillery emplacernents. The sys1e1n should be self contained and able to re1nain on station for days. Operation can be on internal or external power. Targets are small UAVs no larger than 2 1neters at their largest extent Detection range. is 20 km while engagement range is 10 km. A flash LADAR system providing angle"angle"range operation will provide detection and identification. This architecture is superior to scanning or imagingwonly (angle"angle) functions.

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Table 3: Counter l!AV perfonnanc.·e requirements

PARAMETER PERFORMANCE RQMT(DIR) ·····················-

Operations worldwide Self-transportable, tracked vehicle, all D environment operation

-···-·-Deployment Forward observation, air defense R

batterv, artillerv batterv Endurance Multiple days on statiorl-.--·internal or R

external power Tan.'lets Small hostile UAVs R Taraet size 2 meters at laraest extent R Tan:ret detection range 20 km D Taraet enaaaement ranae 10 km D System payload Flash LADAR - detect D

Flash LADAR - identify HEL for SU

Minimum search area 10 km~ D Minimum search rate 1.25 km~/min D Probabilitv of detection > 0.9 D Probability of classification > 0.9 D False alarm rate .< .. 1 oer 2 ~ 5 km~ D Spatial resolut!2r:i 1 to3cm D

3.3 "DARPA Hard" Problem Summary

Many factors affect detection of threats in real-world environment<>. These include attributes of the target background, and environment, which, for the most part, remain fixed \Vith respect to sensor operation. Attributes pertaining to the system include sensor perfonnance, physical search geometry. and spatial resolution. Ofthe5e, backgrounds and environinent will have the greatest direct impact upon sensor system performance. While background and the environment have u direct in1pact upon sensor performance, and can degrade performance severely, techniques such a~ range~gated~lmaging can irnprovc performance to permit feature extraction from highly cluttered scenes.

Sensor perfonnance will be manifested as a detection probability, false alarm rate. and maximu1n range where the SNR is above threshold conditions. Geometry depends upon the platfonn aspect in relation to lookMahead angle and altitude, if the area belov·; is desert, urban, or forested, and the types of obscurations present. Spatial resolution is dependent upon target characteristics, density of threats, and the size of the threat.

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Backgrounds Environment Sensor Target • Path scattered radiance •weather • Pdet

•Type • Sky scattered radiance '--

• Atmosphere •FAR • Solar illumination • Obscuran Spatial Res' •Range

•Operation et

•Stores •Range • Target densi

• Line-of-sight • FOV I IFOV • Configuration • Obscuration

Counter UA V must detect and identify small airborne targets in a forward battlespace environnlCnt Targets of opportunity include small threat UAVs with a 2 meter spatial extent at their longest dio1en.~ion. Hence, system performance was driven by the detection of 2 meter threats.

The threats must be detected and identified from an ground based platform. J1ere, a LADAR approach is identified as the best solution to providing sufficient resolution at standoff ranges to detect the most difficult threat!'. Man-in-the-loop operation is envisioned with ATR when it becomes available. An operator will ai'h'ays make the final decision and will augment any ATR function.

Threats must be acquired at suffic;ient range to not impact forward base operations. To this end, detection and identification must be lo the limits of detection performance driven by sensor range performance. Counter UA V will prioritize threats so a$ to engage the rnost threatening first, then engage and defeat all threats.

The challenge for the Counter UA V progran1 is the following:

• The autonomous detection and identification of iunall threat UA Vs in varied environments

Purpose built UAVs and modified RC aircraft

Small cross sections

• Detect and identify from ground platform

Use active systems (LADAR) approach

Sufficient re5olution at standoff ranges

Man-in-the~loop with ATR as available

• Acquire at ranges sufficiently long to impact target

Prioritize threats

Engage and defeat

There are several challenges for Counter UAV that fall v.1ith the realm of "DARPA Hard." These include the sensor search volurne where a large area has to be searched with such fidelity to locate 2 m targets. To this end, threats must be located and identified BEFORE they become a

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problem. Also, the sensor sy:;;tem n1ust be abl~ to identify threats to determine exactly what they are. Threat cross sections will be very small; hence, sensor spatial resolution is driven by the 2 111

requirement. Ambient environment will impact sensor performance, and, her1ce, drives performance. To this end, atn1ospheric effects such as transn1ission, particulate scattering, and upv.·elling and downv.:elling radiance must be considered. Also, the environment mu!:.t be considered in tenns of viewing geometry. and natural and 1nanmade obscurants.

Bean1 divergence and boresight errors can affect sensor performance by compromising pointing Of both the LAD AR and the DEW bearn. While this is a n1inor issue with detection it beconies a great issue with HEL. The handoff between target angle sensors is dependent upon update rates and track stability. In both the case of beam dive.rgence and handoff, compensation can be employed, if necessary, to provide the degree of pointing and handoff accuracy desired. The system must operate at eyesafe wavelengths so as to not present a hazard to friendly troops, personnel on the ground, or friendly aircraft operating in the vicinity. The spatial and range resolution required dictates laser pulsewidths on the order of 3 nsec or less.

3.4 Key Technology Issues

3.4.1 Introduction

Baseline systen1 performance is predicated upon the area coverage which is specified by target location error, the speed of the platfonu, operating altitude, and look angle. Here, altitude and look angle \vill have minimal impact as the range to target is defined as I/cos *altitude. The. angular resolution is specified by the nun1ber of pixels that fall on the target Hence, for reliable detection, classification, and identification a certain number of pixels n1u~t be on the target; these are derived from the Johnson criteria. With the approach described here, however, we are using single pixel detection due to the long detection ranges anticipated. The pixel rate i~ the number of pixels that can be covered in a given time and is simply the field~of~regard FOR/scan time. Range to target beco1nes a function of sensor look angle that will vary with altitude and detect and ID functions; for small angles the range only may be considered. Since, according to the Johnson criteria, detection requires less pixels than identification, it can be performed at greater ranges. Hence, the detect range will ah.vays be greater than the identification range. Range resolution determines the range to which the target can be measured and is dictated by the laser pulse\1.-·idth. Hence, shorter pulsewidths have smaller range resolutions. In the Counter lTA V case., range resolution on the order of 1 mis sufficient which dictates a 3 nsec pulsewidth.

• Area cu-rerage

Specified by target location error (TLE), platform speed, altitude, and sensor look angle

• Angular resolution

Specified by number of pixels on target

• Possibly only one pixel on target at 20 Km detection range

Required for reliable acquisition

• Pixel rate

FOR (in pixels)

• Range to target

Function of threat altitude and look angle

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• Negligible at small angles

Varies with detect and ID functions

• Range resolution

Precision to Y..'hich range-to-target can be measured

Desire :5 I m range resolution

• Use digitized multi-·pulse approach

3.4.1.1 Search, Detection, and Identification

BAE SYSTEMS

Counter UA V will search for threats using a wide area search. Threats are detected, is there an object present. is a closer look required, classified, to what class does the object belong and does it present a potential threat, and identified, y,·hat specifically is the object, is the object a threat or an asset, and, if a threat, v.·hat is the threat potential. Threats are then tracked and evaluated to prioritize those which repre~ent the most imminent threat and to prioritize for engagement A decision is then made to either ignore the threat and move on, perhaps it wa!I not a threat, auto­engage, where the platform and ATR functions provide the engage decision, or, most likely, handoff to an operator_ The operator will make to decision to engage by evaluation the imagery and the ATR data. Finally, the threat will be engaged and suppressed and suppression confirnied. An operational block diagran1 of the Counter UAY system operation is sho\vn in Figure 8.

Ignore and

.-----------------~- moveto

Detect • Is an object present • Is a closer look required

Classify • What class is the objeet • Is It a potential threat

Identify • What is the object

: next threat

Detect, '.Track and , . clafilfy, and

identify .. , .... evaluate 1-... >( ....... Or

Conflm> 1--+---~-;aupprenlon

Engage and

suppress

Figure 8: Counter UA V system operation block diagram

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Detection consists of a wide area search with an active imaging sensor providing ang\e-angle­range data of targets. Identification may be from multiple aspects and will coordinate with an operator-in··the-loop. Here, a short pulse laser is required for range resolution. Engagement is for threat lJA Vs. Here, the LAD AR will observe the engagement. Typical Counter UA V mission and technology enablers are sho\lo-·n in Figure 9.

• Detection

Wide area search

Large FOR

MUS

Identification

Angle·angte­range

Engage

Mutti"'3spect

ATR function

Short oulse

Threat UAVs

LADAR queue

DEW

High accuracy

Figure 9: Counter U AV mission and technology enablers

Counter UAV requires confident threat detection and confirrnation. Hence, an active sensor approach is recom1nended as this will provide multi-perspective inforn1ation relative to targets position in space and provide positive identification. The Counter UAV sensor will be operator­in~the-loop, but can be upgraded to ATR capable as target recognition is based upon spatial feature recognition. Detection will be at the one pixel level while classification and identificati()n will be at the Johnson limit. Targeting will be performed for precision engagen1ent. The LADAR sensor will also provide kill assessment.

A LADAR is the best sensor, after evaluating many candidate concept;;, for the Counter llAV mission. In this capacity, Flash LADAR, which is a single shot evolution of classic scanning LADAR, is the superior choice. This sensor will provide- target ID in stressing environments. This sensor will provide angle~angle-range information, thus providing infonnation about the target on a pixel-by-pixel level. Hence, range will be to each pixel. This architecture can provide multi-perspective viev.·ing. The LADAR 1,vill also provide range. range bearing, and angle track infonnation for the DEW used in engagement. Here, the LADAR can be used \1/ith the engagement laser to monitor the event in real time. Hence, providing kill assessment. A man-in­the~loop will be required for the en gan:1e as people will make the final engagement decision. Figure 10 depicts the BAE Systems solution for achieving Counter UAV system performance against the notional program requirements.

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Requirements

• Perform confident threat Solution

detection and suppression • LADAR is best candidate sensor

20 km detection Angle.angle-range flash LADAR

Provides both range and intensity

1 O km suppression • Angle-angle-range information

• Resolve threats at range Detect and ID capability

Small cross section High spatial and range resolution

• LADAR provides DEW pointing Positive identification Angle and range

• DEW Suppression Use LADAR to view engagement

Low cost per shot • Man-in-the-loop for end game

Deep magazine People make final engagement decision

Figure 10: Counter UA V mis.c;ion and technology enablers

3.5 evaluation Methodology

Counter lTAV requires a large volume. high speed, search that is eye safe, Threats must be identified and confirmed at standQff ranges before they become a problem. Very large to very small cross section threats represent those likely encountered. Precision pointing and tracking are required both for detect and identify functions, and for precision munitions delivery.

In this capacity, the la:'>er average power must be reasonable; 20 W was assumed as it represents that required to perform the intended functions at the ranges encountered. A detection threshold of 1 pixel is driven by probability of detection for 2 m targets. The FOR, detection range, and franw rate must be consistent with the threat size and revisit time. l'hreat s.ize drives the number of pixels for a given JFOY. Short pulses are required for meeting range resolution.

Required is a large volume, high-speed, eye :;afe search capability. Next, threats have to be detected, identified, and confirmed to ensure the correct targets are being engaged. 'rhis must also be perrornled at sufficient range so that threats do not become a problem. Precise pointing and tracking of the directed energy \1/eapon is required with respect 10 the threats so as to minimize beam divergence and boresight errors and to correct for the effect of turbulence which can seriously degrade the amount of energy delivered to the target. System design drivers are:

• 20 km detection range

Small targ~t cross section

Laser power drives detection range

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Detection threshold of 1 pixel

• ID drives pixels~on~target

Require 144 pixels for ID

Consider 64 pixels for classification

• Angle-angle-range flash architecture

Provides single pixel detection of multiple object~ in FOR

Re-visit objects of interest

Close-look via ransom access pointing to object of intere~t

3.5.1 Counter UAV Trade Space

BAE SYSlElli'IS

The Counter UA 'I trade space encompassed both passive and active sensors of both r;imple and complex architectures. Paramount is addressing the 2 m target size at typical operational altitudes. Here, various concepts were assessed with respect to meeting sensor system performance in the battlespace environments likely encountered. Concepts and perforniance were traded against target cross sections and operational environments to determine the best candidate sensors. Here, scanning LADAR and flash L.ADAR represented the best candidate~ based upon objectives. Thus, LADAR was the method of choice .. To this end, an analysis \Vas performed to determine the performance of scanning vs. flash LADAR for an airborne platform role. It was found the flash have several distinct pe1forn1ance advantages over a scanning architecture, and, wa~ thos selected. The technology trade space, relevant technologies examined. and technology readiness levels (TRL) ror the respective technology is shown in Figure 11.

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Candidate Trades

Large volume search High speed search Ambient environment Revisit time Image/signal processing Small tarqets

··························-·----4

Tcuget cross section Looallzo/' Sensor resolution I) Ambient environment

Long range detection

Si1u11licm AWllrtme1

ttandoff

'"' """'

On platform processing Algorithms ATR/ATI

Pointing stabllity Boresight T racl<-while-engage

CounltlrUAV Trad•sp.tte

HIGH TRL

Passive IR (FLIR)

Scanninq LADAR

Vis/NIR Multlspectral

Mechanical Beamsteerlng

Eyesafe l11sers

Off board signal processing

LOWTRL

Hyperspectral

IR Multlspectral

Flash LADAR

Electronic Beamsteerl119

Short-pulse eyesafe lasers

Onboard signal processing

Figure 11: Counter UA V technology trade space

3.5.2 Sensor Architecture

7+

6

6

6

7

6

4

4+

,. ' 4

'

The LADAR sensors considered include: I) ID range profile. Here the information i~ range only with no visual information. It is comprised of a single pixel detector. lt is very mature and presents little risk: 2) 2D angle-angle. This sensor provides image type pictures of objects within the range gate of the sensor. While it does provide significant information relative to a "snapshot" like i111age, it is intensity only with no range inforrnation. One pulse provides one return i1nage: 3) 3D angle-angle~range where inten::.ity plus range infonnation is available. This i~ the most immature detection architecture and, hence, requires further development. Both linear avalanche mode. and (}eiger mode detectors may be considered.

The first system architecture evaluated, shown in Figure 12, i~ ID range profile. Here, range only is available. It is the most mature technology having its foundation in moi;t laser rangefinders and essentially gives many returns from one pulse. Typically, the detector captures information from tht" first pulse, last pulse, or some number of pulses in~betwecn. Little infonnation about the target is avallable fron1 this technique.

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·~:: .,.,., "'"'

Figure 12: tD range profile sensor

The second system architecture evaluated, shown in Figure 13, is 2D angle~angle. Here, intensity only is available: there is no associated range component. It is the niost ntature i1naging LADAR technology having its foundation in laser range gated imaging systems and yields target intensity data from one laser pulse. Ho1,1;·ever, the laser power must be increased to accomrnodate all pixels in the array, hence, the amount of laser power required is the amount needed lo produce the desired SNR for a single pixel time~ the total nun1ber of pixels in the array. Since this technique is capable of producing images, much target information is available. One significant drawback is the fact that the range of the target must be known so as to set the gates to capture the object of interest within the desired gate width. Therefore, necessitating some sort of first pulse range.

Transmit PUise <

Rellm

------Figure 13: 2D anglc·angle sensor

The third system architecture evaluated, shown ln Figure 14, is 3D angle-angle-range. Here, both intensity and range- are available, thus providing range-per-pixel. It is the most immature imaging LADAR technology, but, has the greatest payoff in the sense that all target information is available on a single Ja..,er pulse. As with the 20 angle-angle approach, the laser power must be increased to accommodate all pixels in the array. hence, the an1ount of laser po\ver required is the amount needed to produce the desired SNR for a single pixel times the total number of pixels in the array. Since this techniq11e is capable of producing images, much target information is available. As this technique produces tange-per~pixel, pixels may be rotated in space to gain different perspective views of the- object.

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Relum

Figure 14: 3D angle-angle-range sensor

3.5.3 Detection Architecture

Three detection architecrures were exa1nined. The first is a classic scanning approach using a single element detector and scanning over this element. Here, one dimension is scanned using a HOE scanner and the system is scanned azimuthally to construct an image. While rhis approach has been used with great success, it does take significant tirne to build an image and typically requires a very high PRF to build an image quickly. Hence, range ambiguity becomes an issue, Resolution is determined by the beam size.

The second approach is a linear detector array of I x. N ~vhere an elevation scan provides the image in one dimension and an azimuthal scan provides the other. Here, a higher pix.el rate is achieved than with a raster scan and the resolution is determined by the detector size. Although superior to the raster scan, it docs take time to build an image.

The last approach is a flash architecture where irnages are constructed on a single laser pulse. Resolution is determined by the detector (pixel) size and image formation is near instantaneous. Due to the one-flash, one-image advantage, large areas can be scanned very quickly.

Our selection for a base-line Counter LIA V LAD.i\R architecture c-0nsis1s of flash providing angle­angle-range imagery.

The first detection architecture, a raster scan approach, is shown in Figure 15. Here, resolution i~ determined by the beam si?.e. This approach has a moderate search rate where the ultimate rate is determined by the rate of the scanner and the pulse repetition frequency (PRF) ofrhe laser, While laser power is modest, issues are image build time, where sonte lime interval, seconds or minutes depending upon the instantaneous field~of-vie\.v (IFOV) of the sensor, the scan rate, and the laser PRF, and range ambiguity for a very high PRF.

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Counter Rotating Holographic Optical Elements (HOEs)

Each pixel is discrete point

Pulsed laser

Pixels correspond to points in space

Raster scan of search volume

Figure 15: Raster scan LADAR architecture

The second detection architecture, a line scan approach, is shown in Figure 16. Here, resolution is determined by the detector size. This approach has a nloderate search rate where the ulti1nate rate is determined by the rate of the scanner and the pulse repetition frequency (PRF) of the laser. While laser power may range from modest to high, issues are image build time, scan rate, laser PRF, and range ambiguity for a very high PRF.

Pulsed laser

Linear detector array

Pixels correspond to points in space

Figure 16: 1.-ine scan [,ADAR architecture

Line scan of search volume

The third detection architecture, the flash approach, is shown in Figure 17. Here, as with the line scan approach, re~olution is detern1ined by the detector size. This approach has a fast search rate where the ultimate rate is determined by the laser PRF, and the focal plane array read~out time. While laser power can be high, image formation is near instantaneous. Also, range per pixel is given with an image consisting of both range and intensity information. Due to the relatively lov>' PRF, range ambiguity is not an issue with this approach.

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Beam director

Pulsed laser

FPA!

Pixels correspond to points in space

Figure 17: Flash LADAR architecture

3.6 System Architecture

3.6.1 Introduction

BAE SYSTEM$

2D array no scanner

An angle·angle·range flash LADAR is selected based upon superior performance for the Counter lJAV 1nission. Here, the sensor would provide range-per-pixel on a single laser pulse with a single illuminated pixel providing detection. Using this approach. the far field can be scanned by tiling, thus covering more area on a single laser pulse. As an example, a single 64 :x. 64 array would be able lo address 4,096 pixels on a single laser pulse while a scanning system would have to scan individually over this area. By tiling, a larger field-of-regard can be covered in a shorter time than with a corresponding scanning system where each pixel must be scanned, This recommended architecture is based upon the following crileria:

• Range per pixel

Angle~angle (intensity) with range images

Modest laser power

• Area scan for long range detection

Tile scan area

Single hit detection

• FLASH for identification

Angle~angle~range in1age

Provide positive ID before engage

• System simplification

Two functions in one architecture

• Increased area coverage

High frame rates.

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Fast acquisition time

• Simplified pointing

One pulse gives the infonnation

1111 lligh accuracy

Angular resolution oF array

SAE SYSTEMS

The angle-angle-range flash LADAR represents the nexl generation LADAR. A sy~tem concept for the angle-angle-range flash LADAR is shown in Figure 18.

Flash illuminated

Receiver IFOV /\ area Nx.N pixel \ ~

Optics/beam director

"". --~ ~t-·i: ::j;., Array output

Laser

Receiver FPA and RO!C

otal FOV -~-- -~..,;,.A; Display or . _ Processor

N x N pixels -----~,- U Y ATR ·. ·

Figure 18: Angle~Angle-Range Flash LADAR architecture

3.6.1.1 Approach

A larget search must be e111ployed to detect and identify threats. Tiling the area provides the ability to search large areas within a short tirne, therefore, increasing situational awareness. Once a detection is made, objects are cataloged and revisited for identification. The angle-angle-range sensor produces high~resolution images of the objects, thu!>, facilitating discrimination. Target search required to detect AND identify threats. This requires a large volu1ne search to detect objects at the desired 20 km range. Once objects are detected, a target-object map is constructed to facilitate tacking of objects. The preferred scan approach is step-FLASH which is, essentially, stare with tile. While this approach requires some pointing, tile overlap en.\:ures object detection within the total search volume. The approach \vill be a long range, WFOV search with flash LADAR coupled with a medium range, positive ID function, agaln, 1,.vith flash LADAR. Here, a specific area will be able to be investigated, thus ensuring positive threat ID. In this capacity, random access pointing will perrnit exainination of a specific object corresponding to its location on the target object map. With this approach, positive ID with angle-anglewrange is achieved.

The detector is the key to a flash LADAR system. Detectors are currently available for anglew angle information, providing only intensity information. Geiger mode detectors area also available, but operate at non-eyesafe wavelengths. To be successful, detectors must evolve to angle-angle-range wilh greater sensitivity. Since pri1ne laser power scales as the power received per pixel times the number of pixels in the array, laser power can gray,· to unmanageable

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proportions. Hence, more sensitive detectors v.·ilh superior noise characteristics are required. APD's are the most sensitive detectors and can operate in linear or Geiger mode. Geiger mode is attractive because of its photon counting ability, but, with small fill factors, can provide only limited angll.'-angle infornlation. However, with a sufficiently short pulse laser these in1ages can be rotated in space to reveal depth to the object. Room temperature lnGaAs shov>'s much promise as a Geiger mode detector array rnaterial.

Also, sub~arrays should be considered as alternatives to full size arrays. So as sufficient pixels are available to perform the detection and identification functions, arrays can be as sn1all as 64x64. In this capacity, laser po\ver is able to be reduced, a11d with a n1odest PRF, and area can be scanned in sufficient time to perform the target detection and identification tasks, A photograph and SEM photograph of BAE Systems SWISS detectQr is shown in Figure 19.

Detector arr~y

Figure 19: BAE Systems Sl\'ISS detector for nash LADAR

3.7 Evaluation of Technologies and Concepts

3.7 .1 Sensor System Performance

Probability of Target ID for 30 Images does not have the traditional, mathen1atical n1odels or accepted standards that probability of target ID for 2D intensity images do. Hence, the 20 probability-of-detection models were used here. The follov.:ing data is taken from Rozel, 1969. A 2D intensity image will ultimately be used by the operator to determine the target ID of an observed object. 30 infonnation will be important to remove clutter and asse1nhle an image from multiple looks. It will also allo\\' the viewed image to be rotated and viewed from the unique perspectives. The 30 image will also allO\'I proper shading to be applied to a captured image.

As shown in Figure 20, and from Rozel, target detection can occur 1,~rith very few pixels on target. Target detection with probability of 95% will occur with about 4 pixels on the target. Target classification will occur with 8 or more pixels on target. Target identification will be perfom1ed with 12 pixels, to the first level, 18 pixels, to the second level, and 32 pixels to the third level. Given a l meter cross section target, the spatial resolution required will be 4 cm or less; the 2

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Doc. No. AOOI ----------- ------------- l:f,i@ifjij,\fj

meter cross section target resolution will be 8 cm. At lower signal to noise ratio the required number of pixels on target may be more leading to finer spatial resolution requirements.

1

0.9

0.9

O.T ;;; '- o.s ~ 0.5 ii ... 0 0.4 L

0.

• • • : :·

• • • • . : • ~Good: • • • • •

• • •

• • • • • • • • •

Better • ' ' ' ' • • •

' • 0.3 • • . • •

0.2

0.1

0

0

2m target spatlal rese>lution (cm) 40

1m target spatial recC>lutlon (cm) 20

• • • • • t •

10

~ .: .I ~

20

PIK "Is on I 1.rget

20 14119 I

10 8 6 5

Best

30

7

• Pr·:ib ~t .. Pr·!lb ¢1CICC

, P1·1Jb 10 12

• Frob ID 1$ ... Fr·:ib ID 32

Figure 20: Probability of detectioni classification, and identification

40

• 3

Figure 21 shows a family of IFOV curves. The ordinate on the graph is the number of pixels that fall on the target. lf the focal plane has only 64 pixels in one direction then on some portion of the curve less than 100% of the target will be covered (blue). The narrow green portion of the graph indicates where the proper number of pixels covers the target for good Prob. ID and the target is 100% covered. The yello\.v portion of the graph indicates where the target is not covered with enough pixels. ·ro overcome these issues on limited TFOV and Jes.~ than required number of pixels on the target numerous looks at the target will be required. The diffraction limit is about 7 µrad for a 30 cm aperture.

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·~ ~-------------~ '"' ~---------------10 ..... <1

1 meter target

.~--~-

•

~ 1011Md

--2~W"<l

sow~

100 ~~d

i • f "

2 meter target - -251¥11d 5il IK~d

100 ~~d

Figure 21: Probability of detection, classification, and identification for a 1 meter target and a 2 meter target

Figure 22 shows lhe detection, classification, and identification range as a function of altitude. Here, for a threat flying at 2 kft. and with typical system operating paran1eters, identification can be performed to nearly 25 km range, classification out to about 14 km range, and identification out to 10 km range. The system parameters are given in Table 4 while target parameters are given in Table 5.

Table 4: System parameters

Parameters Values

.. ~avelenP-th t .. m) 1.54 --···

.. QP.£~~5-~iameter (cm) 30

Svstem F~number 10 ·····································-

Pixel titch (11n1) 25

Number of oixels 64 x 64

Pulse enercrv (mJ) 2 to 16

Divere:ence (n1rad) 0.1

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Table S: T11rget parameters

Parameters Values

Small UAV

As"""ct chantres with look an"le

Length (1n) 2

Winrrsoan (m) 2

Hei11ht ( m) 0.5

Cross section (m2/sr) 0.3

R~ Detection, Cla~~lfica11on and ldenti~cation ;s Function ofR~nge,Nlitude 10~--~-~~-~~--~--~~~

9 .••••.••.•.• .•..•• ... / ! - ., T ..

, __ , _ . . I :. ···-····:!::. :: './···-·

:: ..... ··~·- ,. . .:.j f .... ··········!-- .......•..........•.................. , ....•..........

: : I , ~ : : I ,

:···1··········::~;r:·::·...-:····:····;~ldent1,~~--. ..... ~·····;•····~···········~········ ~f- Classrficat1on : ' : ; ; ······· Delect1on

10 15 20 25 30 35 Ho11tontal Distance {km)

F'igure 22: Detection, classification, and identification range

Signal lo noise, Figure 23 and detection probability perronnance, Figure 24, is shown for a target cross sections of 0.3 m2 for a 100 µrad divergence and a 30 cm aperture. Here, a 0.3 m2 target can be detected to 20 km with 2 ml pulse energy. An 0.98 probability-of-detection occurs at 17 km. To achieve n1ore 1han 0.98 probability~of~detection requires a pulse energy of 4 m.J, still within acceptable limits.

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1~ .... ::~ -1- ~: .. :: .. ; .. ~::::: :::·:::!::: :: • .. •---~,,.~1 - ,_ -· '-···· ........... -- - rx111r?.OO~J x,". . ····-·· · 11 •Hui ,__ 'V\ \ - •••.•• I··· .. -: .... - rl'rr •500~~

4 -· • -~~\-'.;\1'\·~- ~-- ·- ··- -·-j - - r~::•aoo11

10. •• !· -'.:~,,_, •.•... ' -fa1111 •1Dlll~J ••.•..•. :: 1::: ·.'<:1.: ... "'"····l·-····l--·... h •lilll~J ••••• I·•·(•• .. ,;(};'"' )<'1' • '""'"'"'''""' 101 : ' ~ ...... ,. ~:..-.-;_, .. - ••• ,. •• •• - fa, .. ·a.00~1 ....... - --- ,- --- -, --\:-,; ~\ :\ •.• , ...... - I< -1500~!

' ' ' "'.''··"'' • jll•

.. ...• ··------' . ' ' . ' ' ' ' ' ' ' 10''---'--'--'---'--'---'--'-...!.......Jl-.J

0 1012141618

Figure 23: Sensor signal-to-noise performance for system and target values listed ill Table 4 and Table 5

0 BC·····-'··········'···

o; .

"l

0( - T<,,,·'.1.00~!

- 1'11,•400•1 - T'pirSOOml

T>m•&l'!ll•J

0.2 - ri,,,d~fOrlll ·I··· T•,11 •11ITTtJll

- Tll",·l~ll:l~J T1"1·1'00rlll

'o 10

\ \\! \ .\ 1\\\ : I: 1 I

• I \' •····· . \ \

: \ 'i ' t t

t

' \ \

! \"'

Figure 24: Sensor probability of detection performance for system and target values listed in Table 4 and l'able 5

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3.7.2 Optical Augmentation

Optical Augmentation (OA) is a very attractive method to locate optical objects. It provides a tremendous gain in detection relative to the target cro~s ~ection without OA. A I m2 target has a dodn of about 0.03 012, while a corresponding OA cross section of the same size is 105 n12; a gain of 3,500. Hence, OA can provide tremendous gains in target detection. However, if the target does not have any optics, or if the optics arc out of band to the laser, OA will not V.'ork.

Reflectivity is not given for focal planes (or most optical sy."tems). Therefore. it is assumed that the fill-factor (ff), being the fraction of area with detectors has a low renectivity ( ~O. l) and the remaining area (I-ft) has the reflectivity of the material. In most cases the material index is 3 -4, so the reflectivity is 0.34. Now, ff may vary from 25o/c to 90%, therefore, a value of 75% is selected for the ff, giving a reflectivity value of 0.16. The diameter of the collecting optics has been found to range between 13mm and 150mm. The collector size affects both area and solid a1\gle of return, the latter through diffraction effects. A 13mm aperture is selected as a worst case for both area and solid return angle. This also assumes normal incidence on the optic, area being reduced off axis.

Figure 25 shows how the OA cross section increases as a function of aperture diameter. Note that even for small apertures. the cross section can be very high.

10'

1~'--l.--'---'---'---'---J 15B48!l 19'1i"Ji !S 11F.B 316233 JJB1U7

T..-grt Op!1col ~rrtura (mrn) =>

Figure 25: Optical Augmentation performance in terms of cross section as a function of target aperture diameter

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• Optical augmentation (OA) uses target optics to increase the apparent cross section

Enhancing the visibility of small signature targets

• To work1 OA has three requirements

Target must be located by search beam

Search beam must be in FOV of target optics

Search beam must be in passband of target optics

• OA limited by

Precision of target optics

Environment

Target jitter in atmosphere

Atmospheric distortion

This is most important

3.7.3 Technology development

Counter UA V requires development of key critical component and system technologies. Here, short pulse lasers able to achieve range resolution of less than 1 meter are required. These lasers n1ust operate with pulsewidths of about 3 ns. As the number of pixels will deterrnine pritne laser pov.1er, average powers in the 20 to 40 W class are required, Also, the lasers must be eye.~afe. Phased array lasers show promise to achieving high peak power output, n1odet.t average power, short pulses, with a scalable architecture, and the potential for pha'ied array beamsteering.

Focal plane arrays will require a significant amount of development in bo1h the detector and ROIC. Evolution to angle-angle-range sensors are required to achieve JD imagery. Within the FPA area, both linear and Geiger mode APDs must be examined. A technology roadmap is shown in Figure 26 that shows the progression of technology development for angle-angle-range LADAR sensors as Y.'ell as compact DEW v.rilh deep magazine capability.

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MEMS FPAIROIC FPAIROIC I h""m 123' 128 51Z < 512 steel hl!_1

High-power Short-pul$e Ang!<!· diffractive

(O.~ ns~ angle-range LM:Htlll

"Y~sole lo.~er F~A ~tooririg

:2002 2003 2004 2005 2006 2007

.....

I ·swiss· Sl10rt..pulse Pl"tased·m-r~· dctootur \(),6 11$) la!lOr~

320 :x "'YP.SOfF! lil~Ar

2se O'MP beam Precision Gelgtr mode steen11g

n1irror lnGMsF~A beorn

$teering

,,, .. ,.,,,,d ·fj

2008

FPAIROIC 512 x 612

Figure 26: Technology roadmap for sensor and DEW technologies

3.8 Field Tests

3.8.1.1 Configuration

A live fire opportunity was presented where BAE Systems was afforded the opportunity to collect absolute and relative data on a threat UA V, This effort was conducted at Ft. Bliss the week of 9 February 2004. An assortment of instrumentation was assembled from the BAE Systems Jam Lab facility and transported to Ft. Bliss for the collection. This instrumentation included: 1) a calibrated. banded radiometer; 2) an integrating MWIR camera; 3) a staring MWIR can1era; 4) a visible camera, and; 5) an L WIR Microbolometer camera. A laser range finder was taken as •.veil, but, die to its low operating power, only provided liinited re~ults.

The equipment was calibrated and tested at BAE System~ facility prior to shipping to ensure proper operation. At the test site, data was taken of both static and dynamic UAVs, In all bands, Up(>n conlpletion of the field trials, the data was analyzed and the reliults presented here. Static measurements were performed to measure absolute radiance from the target \'iith a calibrated. banded, radiorneter. In this capacity, absolute radiance was measured in the three primary midM wave missile IR seeker bands.

Prior to beginning data collection a blackbody reference source was placed at the same distance as the threat. This ensured accurate calibration of the radiometric instrumentation during the data collection. Changing solar conditions caused by the sun's transit and clouds obscuring sunlight can compromise the fidelity of data collected. 'I'hus, re-calibration is perfonned incrementally to ensure all instrurnentation is operating properly, The blackbody permits calibration at the beginning and end of a test hence, ensuring the calibration did not change during the entire series.

Both the threat and calibration source are seen in Figure 27 that depicts the threat and calibration s.ource located in close proximity. To facilitate data collection, and to permil precise measurement, the threat was mounted on a tripod and indexed at 10 degree intervals. Figure 28.

34

Doc. No. AOOl BA& 5't$TEMS:

Figure 27:

·, ..A .. ,· .. ~ •;. -,;. _, 1it'~,.,, " ,_ ,:. ·' ::': \.., .. -. - -

Figure 28: Threat mounted on test stand to facilitate accurate indexing

Assembly and check-out of the LTA Vs are shown in Figure 29 and Figure 30. Proper operation is verified prior to launch.

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Figure 29: Assembly of threat prior to flight

•• Figure 30: Threat is checked for proper operation

Threat launch is usually accomplished by having an operator run along the ground and throw the threat into the wind. During one day, due to stagnant air conditions, the UAVs have to be launched from a bucket truck as shown in Figure 31 and Figure 32.

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·;;:'

Figore 31: Threat held by operator in bucket prior to launch

.. !""""'. .. .. ;.> '~ • "",!' ...,. ~·' ·. . \~ ,_ .... ....,.. ,,,J ... ·" •. '. "'·: . ................ ~­...... ., • .-1 ...... ,._ • '• ~ 'I,.;~ c~llt-

Figure 32: Threat takes tlight after release by operat-0r

The BAE Systems instrumentation was mounted on a tripod with a tilt-pan head to facilitate tracking. All instrumentation was contained in the back of a cargo truck to facilitate operation and to provide shelter. 1'wo photos of the BAE Systems instrumentation showing the calibrated 3·band radiometer, 3 to 5 µm MWIR camera, visible video camera, and the 8 to 12 µm Microbolometer camera are shown in Figure 33 and Figure 34 ..

BAE SYSTEMS Information and Electro!\!c Warfart Sy;tems

37

BAE SYSTEMS

8 to 12 µm camera

\''is video camera

3 hand radion•eter

3 to 5 µm carnera

:.· .... '· . •' ~·

Figure 33: BAE Systems data collection instrumentation

, Figure 34: Side view of BAE Systems instrumentation

BAE SYSTE~IS Jnforma1ion !lfl<l E\,,,ctroni~ Warfare Sysrnm,

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3.8. 1.2 Absolute radiance measurements

Absolute radiometric measurements of the UA V ¥.'ere made in the three radiorneter bands to determine the amount of emission within each band. The UAV was mounted on the test stand and operated at full throttle; a short "warm-up" period was observed to ensure the engine and exhaust came to normal operating ten1perature. The threat was indexed every 10 degrees to ensure complete circumferential coverage.

A calibration source was located at 1he san~e distance as the threat and referenced to ensure calibration. Also, since the background conditions constantly change due to cloud, and solar transit, a constant calibration ensures accurate measurements.

• Radiometer was calibrated to blackbody source

Source Jcx:ated al same distance as threat

Done to cancel path differences

• Radiometer calibrated for radiance in

Band I

Band 11

Band IV

Results of the radiometric nleasurements in mW/sr are shown in F'igure 35 for Band I. Figure 36 for Band II, and Figure 37 for Band IV. Also, since the 8 to 12 µ m Microbolometer camera \\1orked so \'<'ell detecting and tracking the threats, the radiance for this device in the 8 to 12 µm LWIR region was extrapolated from the Band IV data and is shov.·n in Figure 38.

Figure 35: Band I radiometric data

BAE SYSTEMS lnformauon a11d E!eC!fOntC Warfare $}%:In'

39

DocNo.AOOI

30

:r==i===i~ 10

11 21

26

29

28

27

Figure 36: Band II radiometric data

8

::1-+--1-_, 9

f"'-1-l-l-l 10

19

Figure 37: Band IV radiometric data

11

12

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BAE SYSTEMS

Doc. No. AOOI

30

29

28

27

26

19

8

d.-l-H"""1 9 ~\--+-+-+--' 1 0

11

12

Figure 38: 8 to 12 µm LWIR radiometric data

BAE SYSTEMS

Maximum radiance and the specific angle where this occurred was now determined and is shown in Table 6. Note that the greatest radiance in Bands 11 and N, and the L WlR occurred at roughly 340 degrees. This wa$ where the engine exhaust was located.

Table 6: Maximum radiance at angle

Band Annie Radiance

Band I 120 10.7 mW/!;r

Band II 320 16.5 mW/sr ,,

Band IV 340 29.5 1nW/sr

LWJR 340 383.6 tnW/sr

Note that the radiance in the LWIR is significantly higher than in any of the other bands. The following conclusions conclude that to had detection at 20 km ranges, and active system approach is required.

• Very low Band l radiance

Expected with a target of this type

• Low radiance Band II and Band IV radiance

Highest radiance at engine exhaust

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• Moderate radiance In L WIR

Expected at the lo\v NEDT

This band did acquire and track the threat to 2.5 km ranges

BAE S,YSTEMS

The target in the visible and LWJR are shov.•n in Figure 39 and Figure 40, respectively.

.... -- .... ~·••Jr.'> \ .. ' '

;:·~:,,.... ~·- -.:olJllllllf'""'....;.... '::.,if!' - ' Figure 39: Threat on test stand in visible

Figure 40: Same threat on test stand in LWIR

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3.9 Countermeasures

3.9.1.1 Introduction

Threats are typically slow moving, typically moving at lens of 1neters/second, but, present a very small cross section. To be effective, a countermeasure rnust defeat the threat by causing physical dan1age which cause'> operation to cease, or damage on-board sensors so they cannot perform their function. Two countermeasures v.·ere evaluated here: I) directed energy weapons (DEW} consisting of lasers and high power n1icrowaves, and; 2) sensor jan1n1ing using optical ~cattering and reflection (OSAR) techniques. Note that if the UA V payload does not consist of optical based sy:;tems, then OSAR ja1nming 'Nill not function. Hence, DEW to sufficiently damage the vehicle to tern1inate is flight is the best option

• Threats typically slo"' mo\ing

Propeller driven

Typically tens of m/sec

• Small cross section requires very pNcise pointing and tracking

Sub mrad accuracy

Small CEP

Jilter from both platfonn and beam motion

• Must ac1,;ount ror bias fron1 both of these

• Countermeasures considered defeat small UA V threat"

Directed energy

• HEL, HPM

Sensor jamming

• OSAR, damage

3.9.1.2 Directed Energy

High energy lasers are very attractive as countermeasures. 'fhey are poY.·erful. highly directable, and can cause catastrophic damage to the target. However, beam divergence and borcsight issues require compensation for turbulence induced aberrations, scintillation, refractive index changes, and bearn wander. Hence, to be practical and over the 10 km engagement range, some type of aberration compensa1ion is required.

• Will require atmospheric aberration compensation

Compensate for turbulence induced distortions

Provide fine ai1npoint correction

• Maximize energy-on-target and minimize atmospheric loss

To diffraction li1nit

Scattering and absorption prime losses

• Maximize laser energy on target

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Decrea~e in beam divergence

Minimize atmospheric loss

Increase pointing accuracy

• Decrease energy variance on target

Maximize effectual energy

• Capability for sequential multiple target engagement

BAE SYSTEMS

In operation, the LADAR detects and identifies the threat. The DEW is pointed in the threat direction and fine aimpoint control is affected through the LADAR; in this capacity, constant rnnge, bearing, and angle information is updated into the fire control solution. lJpon engagement, the I)EW must follow the threat, keeping po'll.1er concentrated. Finally, the LADAR will continue to 1nonitor the progress of the engagement, hence, providing assessment of kill.

The functional capability for the DEW sequence is shown in Figure 41 where there is a large volume high speed Search to Deteet1 identify, and confimt threats. This is performed at standoff range using an angle-angle-range, 30, flash LADAR sensor. Once the threat is confirmed, an operator-in-the-loop will make the decision to engage. Note that when available, this function can be performcd using ATR.

lgn ore and lllllll!l•mmm•m•••-mlillllm..,m ... 1nowto

ne><l 1hre;t

Se.vch for tlne.lfS

Detect ct..1;1;sify. il!HI

kl~rtlJY thre;ts

Tr.lCk a1HI evalo.lte tlue:.m

01>er<itor ;.. ..... decision to

etl!J•"1e

• ______ .,.,....,.,,,al Co11firn1 Sllppression

Eng<'ttje awl

SllptHe!iiS

H.lndoff to ~'lJOllS

control

Figure 41; Block diagram of DEW operation and sequence

Aberration compensation is essential to HEL DEW application. Hence. over the 10 ktn engagement path, some sore of correction is required. Factors affecting laser propagation are sho\vn in Figure 42.

• Optical waves experience distortion as they propagate through the atmosphere

• Distortions caused by

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Temperature variations

Solar heating of the atmosphere

Turbulent motion of the air due to winds and convection

• Classic example

Shimmering images when looking over a desert

• l,aser beam divergence and boresight issues

Beam periodically moved off target doe to turbulence

Image dancing and blurring

1'he Figure 43a shows an aberrated beam after passing through the aln10S'phere and Figure 43b is its con·ected counterpart

• Factors affecting atmospheric laser propagation

- Beam wander - Beam spread

- Beam breakup

- Scintillation

• Turbulence • Refractive Index changes

Figure 42: factors affecting beam propagation through the atmosphere

Figure 43: Aberrated beam (left) and corrected beam (right)

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3.9.1.3 Beam Wander

Figure 44 shows increase in "bucket" over transmitter dianieter to turbulence strength over a propagation path of 10 km. Constant turbulence strength, Cn7

, of 10- 1 ~ is assumed. At smaller aperture sizes conjugation fidelity and energy~on~target decrease. Hence, there is a dependence upon turbulence variation along propagation path. Turbulence closer to platform is easier to correct than a.ri aberrator of silnilar strength near the target. Turbulence jitter is inversely proportional to beam diameter and altitude.

JO 0 ,~,,

0

\ '~\ ::\.\ \'. ,.,

.~

'00 Ol

":::, ---·

~ o.•

'

''''''' I

G.111<:,i,m I-b~.1m: T .ir {j~l ollf.~51J()'

I-- {;,\0$'ll•lH ~ b11,1m:T.u1t1

<111:•1 I(" cJ

- Pl,111ew.wtt: IM{jflt illl. • 1K I-

'·, '""'· ~-

~· f"'ec":::' ~---;.---~·~

Figure 44: Laser tran'Smitter diameter YS. Beam wander at 10 km

Aberration compensation improve.s DEW performance greatly as sho\.vn in Figure 45, without aberration compensation, and Figure 46, with aberration compensation. Without compensati~1n, for turbulence strength of 10" 1 ~, roughly IOo/c of the energy is available on target. With compensation, for the same conditions, roughly 80% of the energy is delivered to the target.

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0.1

-atm.limit

-e-16

-•·15 --•·14

0.01 10

Range (km)

100

Figure 45: Energy-on-target without aberration 1.·ompen.sation

0.01

'

-~,limit

--it-1&

--•-15 -0·14

100

Figure 46: Energy-on-target with aberration compensation

The enhancenlent factor is shown in Figure 47 for turbulence strength of 10·". Here, at a range of 10 km a gain of about 10 is seen.

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1000

~ 100 .. .El E ~ ~ c • -E 10 w

-ij·16

--D-15 -e-14

10

Range (km)

BAE SYSTEMS

100

Figure 47: Enhancement factor shows significant gain for effectual energy on target

3.9.1.4 Countermeasure Effectiveness

Figure 48 and Figure 49 show the effectivene~!i of DEW to accomplish various sensor and material effects. Typically. sen!ior blinding (OSAR) requires the lov•est amount of intensity, typically from microwatts to milliwatts of intensity. Nest is sensor damage, which requires milliwatts to y;atts of intensity. Last is material damage which requires watls to many \Vatls. The drivers in DEW are typically the sensor architecture, sensor material. or threat n1ateriaL Some sensors, due to their architecture, are more vulnerable than others to laser illumination. Also, damage to sensor n1aterial varies widely, again, depending upon the sensor n1aterial. Finally, niaterial damage is the most difficult mechanism and varies widely depending upon the n1aterial.

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1E+3

1E+2

1E+1

1E+O N E 0

:!< 1 E-1

~ 0 1E~2 c • £

1E-3

1E·4

1E~5

1E·6

Sensor damage

Sensor blinding

10

Range (tc:mJ

Bl'E SYSTEMS

100 KW

100

Figure 48: llEW countermeasure effectiveness at 100 KW levels

1E+3

1E+2

1E+1

;:, 1E+O E u

~ 1 E-1

"' " 1E-2 c • :s 1E-3

1E4

1 E.S

1E.S 1

Sensor blinding

--40 km vi~. 0.1 nv11d _,,_23 km vis. 0.1 mrad

-·· 40 km v•~- 1 mrad -23 km vi~. 1 mr:KI

10

Range (km)

100

Figure 49: DEW countermeasure effectiveness at 10 K\V levels

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3.9.1.5 Optical Scattering and Reflection (OSAR)

OSAR is a very powerful technique for defealing optical sensors. Typically, depending upon the inten~ity of the laser pulse, a sensor is either blinded or damaged to the point it can no longer function. Figure 50a and Figure 50b sho\v OSAR and how sensor performance is degraded. In the Figure 50a, the trees and pylon are clearly visible. In Figure 50b, OSAR effects prevent the scene from being viewed.

• Optical Scattering and Reflection

Known as OSAR

Used with great effect in certain jan1mers

• Threat sensor blinded by intense laser light

- Looses ability to see

• "J'e1nporary or permanent depending upon intensity

- Threat sensor damage possible at high intensity

Figure 50: Scene photograph (left) and same st·ene photogra1Jh with OSAR

3.9.1.6 Close Proximity Countermeasures

Proximity countermeasures are effective in the sense that a vehicle can maneuver to the threat area and effect localized counterrneasures. Typically, OSAR or high power microwaves can be delivered in this manner. A vehicle, such as the Class II OAV would intercept the threat lJAVs and affect the countermeasures. In this manner, the countermeasure platform would carry the countermeasure sources required. A LADAR and camera on board the countermeasure vehicle would provide feedback to an operalor~in~the.Joop as to effectiveness and confirm defeat. A depiction of proximity countermeasures enlisting an OAV ~type platfonn is shown in Figure 51.

• Mount C~i on UA V platforn1

Consider eta~/> II OA V

• Outfit with variety of Cl\1

OSARjammers

HPM modules (FCG)

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µ-munitions

• Typical operation

Base station LADAR provides range and bearing

On-board sensors provide guidance and navigation to intercept

• Also provided localized information

Once in region of threat

• Platfonn assesses situation

• Effects CM

• Monitors effects

• Provides assessment

Threats

OSAR beam I

BAE SYSTEMS

• Class II OAV

LADAR range, bearing, and track

Figure 51: Depiction of proximity countermeasures engaging a fleet of hostile UA Vs

3.9.1.7 High Power Microwaves

High power microwaves (HPM) is a viable DEW alternative. They possess n1any of the attributes as lasers, and can affect the same countermeasures. Also, HPM modules consisting of flux compression generations, soda can si1,ed devices, can be delivered to the threat area and detonated. In this capacity, countermeasures would be affected to the threat localized region. HPM has the advantage of damaging or destroying the communication and navigation capability of the platform within a localized region. Also, HPM may be affected by a number of methods. Flux compression generators, explosive devices that generate tremendous, localized effects can be used at standoff distances. Also, BAE Systems lJK has developed directable ~IPM weapons that can be used in close proximity to the threat. These devices are electrically po'.ll'ered, compact. and have a deep magazine capability. Output powers a.re in the GW region. Fig·\lre 52 shows hoYI' lIPM may be used as a proximity countermeasure.

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• Speed~of~light all weather capability against hostile electronic systems

• Precision strike at selected CM lel'els

Damage, destroy. degrade

• Coverage of multiple targets

Within same area

• Highly directable

Minimum collateral damage

• Simplified pointing and tracking

Cued from LAl)AR

• Deep magazine

Reasonable operating cost

Threats ....., .., ..... .............

-t~~-·i:o;-:x ----"-------..... ~.,,../~. .. .. LAD AR range, '":~:2. ,-' bearing, and track ___ ..,_ ·-·-".'·;.,

-= ·: ;.,; :~.

BAE SYSTEM$

figure 52: Depiction of proximity countermeasures using HPM engaging a fleet of hostile UAVs

3.9.2 Summary

The n1ilitary have a need to protect their forces from hostile UAVs. A capability is required to perfonn a wide area search, detection, ID, and engagement and suppression of hostile UA Vs at standoff distance . .,s.

These small, crude lfAVs can be employed with optical and electronic payloads to disrupt the operations of forward-area operations by 1ransmitting intelligence data about operation!., assets, or troop deployments. Also, hostile UAVs equipped with small electronic jammers can disrupt forward-area operations.

Hence, the need exi.~ts for cost-effective. precision detection and CM capability against single and multiple threat UAVs.

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Mission Payoffs include search, detect, engage, and suppress threat lJAVs at standoff distances before they become a problem. The angle-angle-range LADAR imagery collected will permit high resolution imagery of multiple small signature fast moving targets. In this capacity, the advanced LADAR imagery will enable search, detection, identification and engagement of 1nultiple targets using directed energy as the principal mechanism. The Directed Energy Weapon will require aberration compensation for turbulence correction and fine airnpoint control.

Key technologies required include advanced solid state lasers that provide short pulse(< I ns) operation, high peak and average powers, operate in the eyesafe region of the specttum, and can include phased array lasers utilizing coherent conibining of the arrays to achieve 100 KW operation. With respect to laser radar, focal plane array technology \.Vith independently addressable pixels providing both intensity and range information. Angle-angle-range sensors operating in both linear and Geii~er mode, read out integrated circuits (ROIC) that permit fast readout on nsec or sub-nsec levels, and are lov>' noise.

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