Island Air Defence: Challenges, Novel Surveillance Concepts and Advanced Radar System Solutions

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Island Air Defence:Challenges, Novel Surveillance Conceptsand Advanced Radar System Solutions

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ABSTRACTThe present-day air defence surveillance system is designed to

detect threats originating from external airspace in a

conventional military conflict, such as one involving multiple

fast-flying fighters, helicopters and missiles. However, the

operational environment has evolved to be far more challenging

and complex over the past decade, with the emergence of

stealthier targets that make better use of terrain to avoid

detection. At the same time, there is always a desire to see

further than the enemy and to obtain more information about

the target. This paper aims to identify the inadequacies of the

present-day air defence radar system and to propose some

novel sensor solutions which include Ultra High Frequency/

Very High Frequency radar, bi-static/multi-static and passive

radar, elevated sensors, High Frequency surface wave radar

and non-cooperative target recognition techniques. The

advantages, challenges and cost effectiveness of these advanced

techniques will be analysed to develop a picture of future

surveillance systems.

Yeo Siew Yam

Yeo Jiunn Wah

Henry Yip


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INTRODUCTION

It is a never-ending race between those whowant to locate their enemies and those whostrive to avoid being detected, as advances inone technology inevitably lead to thedevelopment of its countermeasures. DuringWorld War II, the British Chain Home airdefence radar system, which consisted of aseries of 300-feet tall towers lining the southand east coast of Britain, was the first radarto be used in wartime operations (Neale, 1985).This primitive radar was able to provide earlywarning of approaching German fighters indaylight, but it relied on the pilot’s eyes tocorrect for the several-mile error range inherentin the system (Buderi, 1996). However, theLuftwaffe was quick to switch to bombing atnight and in bad weather to take advantageof the reduced visibility. For more than a month,the Royal Air Force (RAF) pilots could do littleto take down these intruders. The bombingwas finally deterred when the group led byBritish physicist Edward Bowen invented themagnetron, which enabled the developmentof a radar small enough to be carried by RAFfighters. That marked the beginning of theongoing contest between surveillance radarand detection avoidance technologies.

More than half a century has passed since theend of World War II and the surveillance radaroperational environment has grownincreasingly complicated over the decades.Stealth aircraft and ships have become morecommon in modern armed forces, while terrain-hugging and non line of sight (NLOS) targetscontinue to pose problems for the conventional

Figure 1. Examples of radar cross-sections at microwave frequencies1

surveillance system. On top of that, there isalso a great desire to improve the operationalrange of the existing system and to incorporateadvanced features such as target recognition.

LIMITATIONS OF THE CONVENTIONAL RADAR SYSTEM

1. Stealth Targets

The current air defence sensor systems of manynation-states are designed for use againstconventional threats such as multiple fast flyingmilitary aircraft, helicopters, and missiles thathave a relatively significant radar cross-section(RCS). Figure 1 shows the typical RCS ofdifferent targets at microwave frequencies.Advancements in stealth technologies, asdemonstrated by the very low RCS of stealthaircraft such as F-117, B-2 and F-22, make suchtargets extremely difficult to detect.

2. Physical Limitations

The operational range of ground-based radaris physically limited by terrain, as radio wavescannot penetrate obstacles such as mountainranges. This has been exploited by helicoptersoperating in terrain-masking mode, as well ascruise missiles which can be programmed tofly as low as 20m above ground level(Department of the Army, 2000). The presenceof buildings, which scatters radio waves,remains a challenge for detecting low-flyingair targets over built-up areas.


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Another fundamental limitation in thedetection range of conventional ground-basedradar is the inability to see over the horizondue to the curvature of the earth. In order todouble the horizon distance, the radar heightneeds to be increased four times (Sinnott,1988), but there is a limit to how much a radarcan be elevated. For example, stabilityc o n s i d e r a t i o n s w i l l r e s t r i c t t h eheight of ship-borne radar used formaritime surveillance.

3. Low Observable Targets - Unmanned Aerial Vehicle

Unmannned Aerial Vehicles (UAVs) includedrones which have pre-programmed flightpaths, and remotely piloted vehicles which arecontrolled by ground-based operators. Eachcan perform a variety of missions ranging fromreconnaissance and battlefield surveillance toattack and electronic warfare. UAVs arecharacterised by their small RCS, low speedand small thermal signature, making themdifficult to detect and engage. Mission-dictatedflight profiles can take full advantage of terrainto minimise the probability of detection.

Existing air surveillance systems are notdesigned to deal with the operating speed andaltitude of UAVs. For example, the radars ofAirborne Warning and Control System (AWACS)and Joint Surveillance and Target Attack RadarSystem (JSTARS) early warning aircraftintentionally eliminate slow-flying targets inorder to filter out false targets such as birds.A mini-UAV flying at an altitude of 100m witha speed of 100km/h looks “more like a bird onthe radar screen than the cruise missile of apotential adversary” (Miasnikov, 2005).

Due to its relative low cost and ease ofacquisition, UAVs present concerns on itspotential use for terrorism. UAVs may beexploited to attack targets that are difficult toreach by land (e.g. cars loaded with explosives).They may also be used to launch chemical orbiological attacks in highly urbanised areas.The potential damage achievable by UAVs

demands the special attention of future airsurveillance systems.

4. Identification and Classification of Targets

Today’s air defenders rely mainly onIdentification Friend or Foe (IFF) systems todistinguish between enemy and friendly forcesoperating in the vicinity. However, the use ofco-operative systems to identify targets has itslimitations. For example, a hostile aircraft canbe equipped with a transponder meant forcivilian airliners and use it to mask its identity.Moreover, if the IFF interrogation loop isinterrupted for any reason, such as transpondermalfunction, the target may be misinterpretedas hostile, leading to catastrophic eliminationof friendly forces or civilian aircraft.

There is also high strategic value in being ableto identify the types of enemy targets. Theability to distinguish between a transporthelicopter from an attack helicopter, forexample, can provide valuable informationabout the intent of enemy forces and help thecommander decide the best course of action.With the advanced processing power ofmodern computers, it is now possible to carryout complex target classification algorithmswithin a reasonable amount of time.

FUTURE SENSORSYSTEM SOLUTIONS

Considering the above threat analysis,operational shortfalls in effective targetidentification and the desire to enhance therange and coverage of today’s radar systems,the challenges for future surveillance systemscan be broadly categorised into three mainareas of: (1) Detection of stealthy or lowobservable (small RCS) targets, (2) Detectionof low altitude, NLOS targets such ashelicopters, cruise missiles and UAVs due toobscuring terrain or their being beyond thehorizon and (3) Reliable classification andidentification of non-cooperative targets.


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Figure 2. Normalised RCS of conducting sphere2

Figure 3. The “faceted” F-117A deflects incomingradar waves (Dranidis, 2003)

To meet these future challenges, novel sensorsystem solutions, techniques, and key enablingtechnologies are proposed in the followingsections.

COUNTER-STEALTH TECHNIQUES

1. Very High Frequency / UltraHigh Frequency Radars

Radar-absorbent materials (RAM) and Radar-absorbent structures (RAS) are physically limitedin their abil ity to absorb incomingelectromagnetic energy. This is because thethickness of RAM required is driven by thewavelength of the incoming signal (Dranidis,2003). For example, the most basic Jaumannabsorber, which works on the principle of usinginterference to cancel reflected waves, requireda minimum thickness of half the wavelength.To counter the majority of tracking and firecontrol radars in service today, which aregenerally in the high frequency band of 5GHzto 200GHz, RAM or RAS can easily be appliedonto an aircraft since the wavelengths are on

the order of a centimetre or less. However, ifrelatively low frequency (long wavelength)Very High Frequency (VHF) or Ultra HighFrequency (UHF) radars are used to illuminatethe target, the thickness of the absorbermaterial required will be in the order of metres,rendering its application impractical on aircraft.

The effectiveness of low frequency VHF/UHFradar against targets with low RCS also relieson the resonance effect between the directreflection from the target and scattered waveswhich “creep” around it. This resonance effectoccurs most prominently when the wavelengthof the incident electromagnetic (EM) wave iscomparable to the physical dimension of theobject, which results in large amplitudeoscillations in the RCS. Figure 2 shows thewavelength dependence of the RCS of aconducting sphere. Maximum RCS of the sphereoccurs when the wavelength is equal to itscircumference.

The development of a low frequency (longwavelength) VHF/UHF radar for counter-stealthapplication has its limitations and issues thatneed to be addressed. The size of the antennaaperture has to increase in proportion to thewavelength so as to maintain a narrow beamfor adequate resolution. Another constraintof VHF/UHF radar is that these frequency bandsare already heavily used for commercialcommunication and broadcasts. Mutualinterference will be a major challenge tooperating the radar in such a dense EMenvironment.

2. Bi-static / Multi-static Radars

Besides using RAM to reduce the reflectivityof the airframe, stealth designers also makeuse of geometric design to deflect the majorityof the incoming radar energy to lessthreatening directions, leaving very little tobe reflected directly back to the radar receiveras illustrated in Figure 3. This is because intraditional mono-static radars, the transmitterand receiver are co-located and hence designedto receive target echoes that are returnedalong the same direction it transmits. Designers


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take advantage of the fact that the mostthreatening radar wave will illuminate theaircraft from a point that is much more distanthorizontally than vertically. Since the forwardcone is of the greatest interest in this case,most contemporary stealth aircraft aredesigned to direct large returns out of thissector into the broadside directions.

However, the deflected and scattered energymay still be picked up by bi-static or multi-static radars, as the receivers are separatedfrom the transmitters over a considerabledistance (shown in Figure 4). When the receivedsignals are accurately correlated with theemitted signal from the transmitter, the pointof reflection can be located. Additionaltransmitters and receivers can improve theaccuracy of target localisation throughtriangulation and regression techniques, andat the same time increase the chances ofintercepting reflected energies.

Separating the receiver from the transmitterin a bi-static/multi-static system, however,creates a more complex geometry comparedto the mono-static radar. First, it is necessaryto provide some form of synchronisationbetween the transmitter and the receivers interms of transmitter azimuth angle, instantpulse transmission, and transmitted signalphase so that the received signal can beaccurately correlated with the transmitted

signal. Second, for the bi-static / multi-staticradar to detect the target, line of sight (LOS)is required between the transmitter and thetarget and also between the receivers and thetarget. The placement of both the transmitterand receiver must be carefully considered toprovide the desired coverage. To furthercomplicate the issue, a received signal mayarrive from different directions other than thetrue position of the target, as a result of multi-path or anomalous atmospheric propagation.It is necessary to sort out the direct distancesignal from the unwanted ones before anaccurate estimate of the target location canbe computed.

DETECTION OF LOW ALTITUDE AND NONLINE OF SIGHT TARGETS

1. Elevated Sensors

Since incoming threats will likely fly at lowaltitudes to avoid detection by surface-basedair defence systems, one possible solution toovercome this LOS limitation is to elevate thesensors and integrate them with surface-basedweapon systems. Apart from aircraft and UAVs,elevated sensors can be carried using low life-cycle cost and long endurance “lighter-than-air” aerostats or airships which can be remotely

Multi-static Mono-static

Figure 4: The transmitter and receiver are co-located for a mono-static radar, but are positionedseparately in multi-static configuration. (Dranidis, 2003)


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AWACS / JSTARS Conventional aircraft $20,000 11 hours

E-2C Hawkeye Conventional aircraft $18,700 4.7 hours

Global Hawk UAV $26,500 35 hours

Predator UAV $5,000 40 hours

420K TARS Aerostat $300-500 15-30 days

Zeppelin Airship $1,800 Few days(1 yr lease)

Platform TypeEndurance

withoutunrefuel

Cost/flighthour(USD)

piloted, or flown autonomously. Table 1 showsa cost and endurance comparison betweendifferent elevated surveillance platforms (NavalResearch Advisory Committee, 2005).

Elevation of these sensors enables the airdefence weapon system to look down at thebattlefield at extended ranges unhamperedby terrain masking or earth curvature. Toillustrate the advantage of elevated sensors,it can be calculated that the LOS range of alow flying cruise missile at 50m altitude isextended from 42km to 160km when a ground-based sensor is elevated to an altitude of 1kmas shown in radar height-elevation-range chartof Figure 5.

Table 1. Cost/Endurance comparison for persistent surveillance platforms

Figure 5. LOS range of cruise missile from ground-based and elevated sensors

In addition, the information provided byelevated sensors can be distributedsimultaneously to all cooperative air defenceweapons on the battlefield. This would providea single integrated air picture for the airdefence systems, as illustrated in Figure 6.

When using aerostats and airships, thelimitations and issues of elevated sensorplatforms need to be considered. While typicalaerostats, like the Tethered Aerostat RadarSystem (TARS), which can lift about one tonof sensor equipment to a height of 3,500m,provide persistent surveillance out to over350km and stay aloft for months, they arevulnerable to enemy ground fire and severe


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Figure 6. Elevated sensor air defence to detect low altitude targets3

wind conditions. Moreover, aerostats aretethered to the ground by a cable that alsoprovides power and data links, imposing flightrestrictions in the surrounding airspace.Airships, on the other hand, can move tochange sensor coverage and also operate athigher altitudes (up to 21,000m, as in the caseof High Altitude Airship) to avoid enemyground fire. However, its higher maintenancecost and significantly reduced endurance (forexample, limited power supply) compared toaerostats need to be taken into consideration.

2. Passive Surveillance

Another emerging concept in the detection oflow altitude and NLOS targets is thedevelopment of passive radar systems. Byexploiting signals from "illuminators ofopportunity" such as commercial TV and FMradio transmitters and cellular base stations to

Figure 7. Passive radar concept of operation using FM broadcast (Griffiths, 2003)

illuminate targets (Figure 7), passive radar candetect and track targets in real-time withoutan intrinsic active transmitter (Griffiths, 2003).

The basic principle of passive radar is to performcross-correlation of the received signals witha copy of the direct LOS signal (which is usuallyreceived on a separate, dedicated receiverchannel). As the target is moving, it is necessaryto cross-correlate the signals with severalhundred frequency-shifted replicas of thereference signal, in order to take into accountevery potential Doppler shift and subsequentlycancel out unwanted direct signals to preventthe masking of small reflected signals. Havingdetected targets in the Range-Doppler spaceby cross-correlation, sophisticated trackingalgorithms are then used for plot-to-targetassociation and to estimate the target location,heading and speed from the measurements.



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The range performance of passive radar isclosely associated with the type of illuminatorused. Systems exploiting GSM mobile cellulartransmitters may only have a range of 20km,while FM radio stations are able to coveraround 100km to 150km. High power televisionbroadcast stations can achieve a range that isseveral times higher.

Passive radar and its concept of operationoffer many distinct advantages overconventional active radar system. They arehighlighted below4:

a. Passive radar is inherently survivableand ideal for covert operation since it has noRF "signature" that might give away its positionduring operation.

b. Passive radar reuses commercialbroadcast signals from existing transmitterswithout requiring dedicated frequencyallocation. It allows the deployment ofsurveillance systems in areas where aconventional UHF/VHF radar would have tocompete with interference from an alreadydense electromagnetic environment.

c. Most importantly, passive radar hasexcellent low altitude coverage, allowing it todetect and track low altitude and NLOS targetsthat are masked by terrain. This is because TV,FM and mobile cellular broadcast stations aredesigned to focus their RF energy toward the

Earth’s surface, thereby providing the necessaryillumination of low flying targets for detectionand tracking. Besides that, the geometricdiversity of these commercial transmittersresults in simultaneous and multi-directionalillumination of a target, offering additionalinformation about the target from differentviewing aspects.

d. The use of broadcast signals in the UHFand VHF frequencies also enables the detectionof NLOS targets in the shadow region behindtree tops and low ridges through thephenomenon of knife-edge diffraction, whichis more pronounced for longer wavelengths.This knife-edge effect is explained by theHuygens' principle, which states that a well-defined obstruction to an electromagneticwave acts as a secondary source, and createsa new wave front. This new wave front thenpropagates into the geometric shadow areaof the obstacle, enabling NLOS detection.

e. Passive radar is also a relatively low costsolution compared to conventional radar. It is,in general, a phased array system with norotary mechanical parts. Besides, it has notransmission components. These attributesgreatly reduce power requirements, mechanicalupkeep and cost.

While the concept of passive surveillance seemspromising, there are also drawbacks that needto be taken into consideration. In addition to

Figure 8. Coverage comparison between microwave and HFSW radars(Daronmont Technologies)


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King Air Aircraft $500 per hour $2.5M Typical annual subcontract

Challenger Jet $2,500 per hour $1.0M One 8-hr flight per week

P3 Patrol Aircraft $10,000 per hour $2.0M One 8-hr flight every 2 weeks

Coast Guard Cutter $4,000 per hour $8.0M Seven days at sea per month

HF Radar $10,000 per month $120k

Asset NotesTypical

Operating Cost(USD)

AnnualCost

(USD)

the complex geometry and multi-path issuesthat are inherent in bi-static/multi-staticconfigurations, passive radar is reliant on third-party transmitters, giving the operator littlecontrol over the availability of the illuminators.Moreover, there may be significant challengesin simultaneously fulfi l l ing the LOSrequirements between the transmitter and thetarget, the target and the receiver, and thereceiver and the transmitter .

3. High Frequency Surface Wave Radar

Advances in ship launched cruise missiletechnologies have rendered air defence systemsvulnerable to long-range attacks, as thedetection range of most ship-borne air defencesensors (operating in microwave frequencies)are limited by their LOS range. HF surface waveradar (HFSWR), which operates between 3MHzand 30MHz, is designed to detect low-flyingtargets beyond the horizon as shown in Figure8. The typical detection range of HFSWR is 10times that of the microwave radar (Anderson,Bates, Tyler, 1999). It is also a cost-effectivesolution for maritime surveillance comparedto other candidates, as illustrated in Table 2.

In surface wave mode operation, the HF wavetravels along the ocean surface, which servesas the conducting surface for propagation. By

following the curvature of the Earth, HFSWRcan provide coverage in the order of severalhundred kilometres. Rain or fog does not affectHF signals, making it an ideal all-weathersurveillance system. An example is the MarconiS123 coast-based early warning system, whichhas a range of 250km (low altitude) to 500km(high altitude) with 1km track accuracy.

An operational HFSWR must be able to operatein the presence of sea clutter, ionosphericinterference, and other external interferencesources that include co-channel interference,man-made noise and impulsive noise (Dizaji,Ponsford, Mckerracher, 2003). In addition, itoperates within the congested HF band, placingmany challenges on its signal processor.Another consideration is the ability to deploya HF radar system rapidly. Due to its longwavelength, HFSWR tends to be physicallylarge and it has only been installed at fixedlocations along the coast. A system that canbe remotely sited, unmanned, and autonomousin operation will offer a much more flexiblemilitary capability.

Non-Cooperative Target RecognitionTechniques

The target identification technique used intoday’s air defence systems is based on the“question and answer” interrogation loop of



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unidentified aircraft. Although friendly aircraftcan be identified by this technique, positiveidentification and classification of hostile andneutral aircraft poses significant challenges.The goal of Non-Cooperative TargetRecognition (NCTR) radar techniques is toidentify such targets without their activeparticipation. The basic idea is that thegeometry of an aircraft and its moving partsimposes unique features on the reflected radarsignal. These features can be matched againsta reference database that contains signaturesof different target types for classification andidentification.

The radar range profile method is one of themain NCTR techniques. It classifies an aircraftbased on its high-resolution radar (HRR) images.The scatterers, which are the parts on theaircraft that give strong radar reflection, areprojected onto the LOS to form the HRR rangeprofile. Figure 9 shows a range profile of anaircraft viewed from the left, where responses

from the scatterers (denoted by dots) alongthe radar LOS are projected. The radar rangeprofile contains information on the geometryand heuristic features of the target, such as itsnose to wing-tip distance, single or double tailairframe. By matching these characteristicsagainst a reference database, it is possible toclassify targets into broad categories of civilianairliners, fighters, missiles or helicopters, oreven identify the specific platform types.

Another class of NCTR techniques focuses onthe radar radiation reflected off the rotatingparts of an aircraft. It includes Jet EngineModulation (JEM), Propeller Rotor Modulation(PROM) and Helicopter Rotor Modulation(HERM) methods, which characterise a targetbased on the compressor blades in a jet engine,the propellers of a propeller-aircraft, or rotorson a helicopter, respectively. The radar spectraof JEM, PROM and HERM can be analysed toobtain information pertaining to the type ofengine, propeller or rotor, the number of

Figure 9. HRR range profile of a fighter aircraft (Defence Research Development Canada, 2005)

Figure 10. HERM spectrum of a hovering helicopter (Bullard, 1991)


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blades, the frequency of rotation and otherinformation. An example of a HERM spectrumof a hovering helicopter is shown in Figure 10.Since each type of aircraft has a unique engine,propeller or rotor, these characteristicparameters can be matched against a referencedatabase for classification and identification.

CONCLUSION

We have seen how the surveillance systems’operational environment has evolved to be farmore complex over the past decade. Legacysystems, which are designed to thwartconventional attacks originating outsidedomestic airspace, are in many ways inadequatein dealing with adversaries that are stealthy,low altitude, and NLOS. The novel radar systemconcepts highlighted in this paper offer someinsights into how the evolving threats mightbe dealt with in future air surveillance systems,but they are by no means complete. Newsolutions that are more capable and cost-effective are constantly being sought after. Wemust remember that the contest betweensurveillance and detection avoidancetechnologies is never ending as the adversaryis always searching for loopholes in the currentsystem, requiring even more advancedtechnologies to be developed to stay aheadof the game.



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Buderi, R. (1996). Invention that Changed theWorld: How a Small Group of Radar PioneersWon the Second World War and Launched aTechnological Revolution.

Bullard, B. (1991). Pulse Doppler Signature ofa Rotary-Wing Aircraft. Atlanta: Georgia TechResearch Institute, Georgia Institute ofTechnology.

Daronmont Technologies, SECAR HF RadarTheory. Retrieved on May 2007 fromhttp://www.daronmont.com.au/products_secar_radartheory.htm

Defence Research and Development Canada.(2005). Retrieved on May 2007 fromhttp://www.ottawa.drdc-rddc.gc.ca/html/RAST-309-nctr_e.html

Dranidis, Dimitris V. (2003). Airborne Stealthin a Nutshell: Countering Stealth – Technologies& Tactics, WayPoint Magazine Issue No 6.

Griffiths, H. D. (2003). From a DifferentPerspective Principles, Practice and Potentialof Bistatic Radar. Radar Conference,Proceedings of the International, pp 1-7.

Headquarters, Department of the Army. (2000).US Army Air and Missile Defense Operations.

Miasnikov, Eugene. (2005). Threat of TerrorismUsing Unmanned Aerial Vehicles: TechnicalAspects, Center for Arms Control, Energy andEnvironmental Studies, Moscow Institute ofPhysics and Technology.

Naval Research Advisory Committee. (2005).Light-Than-Air Systems for Future NavalMissions.

Neale, B. T. (1985). CH - The first operationalRadar, The GEC Journal of Research, vol. 3,No.2 1985 pp 73-83.

REFERENCES

ENDNOTES

1. Courtesy of American Institute ofAeronautics and Astronautics. Scanned copyobtained from http://www.f22totalairwar.de/F-22_Total_Air_War_Stealth_Radar_Cross_Section_RCS.htm

2. Taken from http://www.tscm.com/rcs.pdf,which credited Dr. Allen E. Fus.

3. Taken from U.S. Army Space and MissileDefense Command, Joint Land Attack CruiseMissile Defense Elevated Netted Sensor System.

4. Defence Systems Institute - MDTS2005(Group 1), DTS5709: Sensor Technology andSystems Report, Novel Sensor Systems Solutionfor Future Air Defence

5. Courtesy of Raytheon Systems Canada Ltd.

R, Dizaji, A. M. Ponsford, and R. Mckerracher.(2003). Signal Processing Challenges in HighFrequency Surface Wave Radar. Proceeding ofSignal and Image Processing 2003.

Sinnott, D.H. (1988). The Development ofOver-the-Horizon Radar in Australia.

Stuar J. Anderson, Bevan D. Bates and MarkA. Tyler. (1999). HF Surface-Wave Radar andits Role in Littoral Warfare, Journal ofBattlefield Technology, Vol 2, No 3.

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BIOGRAPHY

Yeo Jiunn Wah is Principal Engineer and Technology Manager (DRD). AsTechnology Manager, Jiunn Wah manages R&T initiatives and radar portfolioin the Surveillance Office. He also contributes to the plotting of the technologyroadmap for Advanced Surveillance Radar and prospecting of leadingtechnologies. He graduated with a Bachelor of Electrical Engineering fromthe NTU in 1997. He also attained a Master of Science in Defence Technologyand Systems from Temasek Defence System Institute in 2007 and a Master ofScience in Combat Systems Science and Technology from Naval PostgraduateSchool in 2007 under the DSTA Postgraduate Scholarship. Jiunn Wah has wonthe DSTA Team Excellence Award in 2002, DSTA Innovation Excellence Awardin 2003, Defence Technology Prize (Engineering Team) in 2003 and DefenceTechnology Prize (R&D Team) in 2005.

Henry Yip is Engineer (DRD). He is currently assisting in the management ofR&T projects in the area of surveillance. He graduated with a Bachelor ofScience in Electrical and Computer Engineering from Cornell University in 2006and a Master of Engineering in Electrical and Computer Engineering fromCornell University in 2007 under the DSTA Overseas Scholarship.


Yeo Siew Yam is Assistant Director (Surveillance). As Assistant Director,Siew Yam manages the R&T portfolio in surveillance (including radar, Electro-Optics / Infrared and exploitation tools) in Directorate of R&D (DRD). His otherresponsibilities include fostering R&T in Temasek Laboratories at NanyangTechnological University (NTU) as well as in the Supelec, ONERA, NationalUniversity of Singapore, DSTA research alliance (SONDRA). He graduated witha Bachelor of Electrical Engineering from Nanyang Technological University(NTU) in 1989 and a Master of Science in Electrical Engineering from NavalPostgraduate School in 1998 under the DSO Postgraduate Scholarship.Siew Yam won the DTP team Award in 1992 and 2004.

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Island Air Defence: Challenges, Novel Surveillance Concepts and Advanced Radar System Solutions

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