pesa technology gives blighter radar the edge

TECHNOLOGY FEATURE

30 PESA Technology gives Blighter Radar the Edge

Passive electronically scanned array(PESA) radar technology continues toprovide a low power, lower cost andhighly reliable surveillance solution forboth military and commercial markets

Whether for detecting smugglers, pirates,terrorists, insurgents or illegals in roughseas, hilly or mountainous terrain, atborder crossings, airports and seaports,electronic-scanning Doppler radarsprovide an all-weather, wide-area, lowfalse alarm rate (FAR) and high reliabilitypersistent surveillance capability.

Recent developments in electronic-scanning (e-scan) radars has seen a moveaway from the expensive and power-hungry AESA (active electronicallyscanned array) military radar technology

to the newer and much lower-cost PESA(passive electronically scanned array)radar technology.

Low power PESA technology offerssignificant advantages over alternativearchitectures such as AESA technologybeing used in other e-scan radars. PESAtechnology is simple, though tricky todesign in the first instance, but once thee-scan module is manufactured it can beused symmetrically on both the transmitand receive channels and it requires verylow power consumption leading to lowinternal heating and hence highreliability.

Another benefit of these solid state PESAradars is that during scanning, the radar’smicrowave beam is entirely stationary,

allowing such systems to detect verysmall and slow moving targets inextremely cluttered environments.This improves their detection capabilitiesand reduces the false alarm rate. Contrastthis with mechanically rotating radars,where the reflected signals received bythe radar are always blurred by thecontinuous rotational movement of theantenna.

The Blighter® radar was the firstcommercial electronic-scanning groundsurveillance radar (GSR) on the marketand its modular solid state design –uniquely low power due to the PESAtechnology – continues to give Blighterthe edge over other e-scan radars. It isnow used in scores of countries includingby the British Army for force protection,

PESA Technology givesBlighter Radar the EdgeBy Mark Radford, CEO at Blighter Surveillance Systems

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Heathrow Airport for key zonesurveillance, and by the South Koreans toprotect its demilitarised zone (DMZ).

How PESA works?

The Blighter radar series is based on acommon, state-of-the-art set oftechnologies. Blighter uses a PESAantenna system allowing it to scan up to360°, in steps of 90°, in azimuth with zeromovement inside or outside of the radarsystem. With no moving parts andentirely solid-state technology, Blighteroffers ultra high reliability, a long zeromaintenance period of up to five yearsand an in-service life of up to 15 years.

Blighter’s PESA e-scan modules use aunique waveguide structure to achievethe azimuth beam steering. Unliketraditional AESA antennas, which usemultiple power-hungry power and phasecontrol elements, Blighter’s unique PESAunits require just one efficient transmitterand one receiver unit per radar unit. Dueto this compact and simple architecture,Blighter uses e-scan modules on both thetransmit and receive paths resulting inexceptionally low side lobe levels, whichallows it to operate in complex andcluttered environments without detectingphantom targets from large targetsoutside of the radar beam.

In the case of the B400 series radar, thee-scan modules inside the radar units can

be configured with user interchangeableexternal antennas. For coastal securityapplications the M10S long-range antennais recommended as its 10° elevation beamcan achieve long detection ranges overthe water surface, whereas the W20Santenna is more suited to the groundvariant Blighter radar for use in hillyterrain. Both antenna types allow theDigital Beam Forming of the e-scan

modules to optimally scan the radar beamin only the direction of interest and withno wasteful overspill.

Coactive Doppler fast-scancapability

Blighter’s combination of technologiesincluding PESA e-scan and Doppler, whichare all controlled through sophisticatedDigital Signal Processing (DSP) andWaveform Generation (WG) units, allowsa wide diversity of radar waveforms andazimuth scan speeds. The Blighter radarallows both fast scanning simultaneouswith Doppler velocity filtering using its‘Coactive Doppler fast-scan’ capability.Traditional non-Doppler radar can scanfast, whereas traditional Doppler radarsrotate slowly. Blighter achieves the bestof both capabilities.

Blighter’s advanced frequency modulatedcontinuous wave (FMCW) transmissiontechnology is an alternative to thetraditional Magnetron pulse transmittersor solid-state pulse-compressiontransmitters used by older radars. Keyattributes of FMCW include an enormousinstantaneous dynamic range in thereceiver channel, allowing small targetsto still be detectable alongside largetargets or clutter. FMCW is also veryefficient allowing considerably lesstransmitter power to be required.

The FMCW transmission is like a whispercompared to the shout from traditionalrotating radar’s high power pulsedtransmitters. Blighter’s low power FMCWtransmission therefore cannot bedetected on conventional ‘radar speedtrap warning detectors’ meaning thatintruders are not aware that they arebeing monitored.

Korean DMZ – where Blighter radars provide a persistent surveillance capability.(copyright istock.com-gkgraphics).

Blighter Revolution 360 ground surveillance radar on vehicle mast with long rangecamera system.


32 PESA Technology gives Blighter Radar the Edge

The Blighter radar unit contains anintegrated Digital Signal Processing (DSP)unit that provides all the functionsperformed by a stand-alone radarprocessing unit in traditional systems.The integrated DSP provides the FMCW,Doppler, Thresholding, CFAR, PlotExtraction and target filtering functions.The output from the Blighter radar is alow bandwidth digital data stream overa 10/100BASE-T/TX Ethernet interface.

Blighter’s Doppler Signal Processingfeature is a key benefit. On each andevery radar scan all targets and clutterare measured and characterised by theirDoppler velocity. As colour is to CCTVimages, Doppler is to radar detection.Doppler adds a third dimension to targetdetection, so not only are targetsidentified in Azimuth (PESA) and Range(FMCW), but they are also discriminatedby Doppler velocity. This allows validtargets to be discriminated and separatedfrom the surrounding clutter.

Blighter uses Ku radar band

The Blighter radar operates in theinternationally recognised and approvedKu radar band, at around 15GHz. Ku Bandoffers some unique advantages forsecurity applications. Firstly, the highfrequency used means that radar,including its antennas, has twice theperformance of an equivalent sized Xband radar. Secondly, the Ku Band isconsiderably less congested than X band.

The Blighter radar includes a special ‘RainFilter’ built into the integrated signalprocessor that enables it to continuedetecting valid targets while suppressingunwanted target-like signals produced bythe rain clutter itself.

Inherently low power

The Blighter radars’ FMCW transmissiontechnology, combined with sensitive

Doppler target detection means that theradars requires only a fraction of thetransmitter power used by traditionalsecurity type radars systems.

Blighter transmits only 4 Watts of power,just a little more than a cell phone andequivalent to a modern LED light bulb, yetit is able to detect a man sized target atranges up to 10km away. This low powertransmission requirement also means thatthe total power consumption is a fractionof other radars.

The Blighter B400 series radar consumesjust 100 Watts of power enabling it to beoperated continuously from battery-backed solar or wind powered generators.One square metre of solar panel in fulldaylight can provide enough energy tooperate Blighter, though of courseadditional panels are required to chargebatteries for operation through the nightand in poor weather conditions.

The integrated Digital Signal Processingcircuits in Blighter provide most of theradar processing functions performed byremote ‘Plot Extractor’ systems in otherradars. The process of plot extractiondramatically reduces the data bandwidthsuch that instead of needing to distributeraw radar video with a bandwidthrequirement of 10 to 20MHz, Blighter’sprocessed Plot output is a mere 10kbits/s.

This narrow band data requirementenables simple, low cost and low latencydistribution via many communicationsystems. Typically a simple Ethernetconnection may be used, over copper orfibre, to carry multiple Blighter radarchannels. But for remote operation, meshradio systems, point-to-point microwavelinks or even Sat Comm can be used. Ifvideo from camera systems is requiredthen Blighter’s data channel will piggy-back on the video data channelconsuming just a small percentage of thebandwidth required for camera video.

Compact size

Unlike conventional surveillance systems,Blighter’s Ku Band PESA technologymeans that it is incredibly compact insize. The main radar unit containing PESAe-scan modules, Transmitter, Receiver,Waveform Generator, Signal Processorand PSU is contained in a single unitabout the size as a large briefcase. Avariety of antennas attach to the front ofthe radar unit depending on coveragerequired, but even the antennas arenarrower than the radar unit at about0.5m.

For many remote radar sites, especiallytemporary ones, Blighter’s compact sizeand light weight means that it can behand-carried and installed without anylifting gear or specialist transport.Furthermore, it can if required be

Combination of the Blighter B202 Mk 2 portable ground surveillance radar and Liteye’sAquila PTZ thermal surveillance system provides a virtual fortress around VIPs

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mounted temporarily on tripods or othertemporary structures.

As Blighter scans, it uses its PESA, Dopplerand FMCW technology to immediatelydetect potential intruders and show themon an overlay map. As well as predictingthe position of the target throughextrapolation of the target’s heading andspeed, the BlighterView HMI 2 commandand control software platform alsorecords all historical target data.

Doppler radar, camera…actionAlmost every security radar systemrequires the interaction of a camerasystem in order to observe the objectinitially detected by the radar. Blighter isno exception, it provides early warning ofintruders over long ranges and potentiallythousands of square kilometres.Additionally it attempts to classify thetarget by assessing its key radarcharacteristics - the radar cross sectionalarea and Doppler velocity.

Although this target classification helpsthe BlighterView HMI 2 to filter differentclasses of target, every operator wants tosee the intruder with their own eyes.BlighterView HMI 2 includes an extensivelong-range camera control panel with lotsof functionality to provide automatic,semi-automatic and manually initiatedcueing of the camera system to observethe target or targets of interest.

Typical ‘cameras’ include multi-sensorelectro-optic camera systems includingdaylight colour, night time thermalimager, often a wide field-of-view‘context’ camera and sometimes a LaserRange Finder (LRF), though this is lessnecessary with the radar alreadyproviding accurate range measurement.Each alert zone can be configured to cuea selected camera either to a fixed pointin the zone, the target position in that

zone, or to initiate auto-tracking. Somecamera systems include a video trackingcapability, which BlighterView HMI 2supports.

Key markets

Blighter ITAR-free PESA radars pluscameras, thermal imagers, trackers andsoftware solutions are used worldwide incommercial, government and defencemarkets in area and asset protection fornational border security, homelandsecurity, critical infrastructure protectionsuch as airports, coastal surveillance, andin military applications.

Blighter’s B400 series long range radarshave been operational in South Korea forsome years providing a persistentsurveillance capability along the KoreanDemilitarised Zone (DMZ), a buffer zonewhich runs 250km across the Koreanpeninsula and separates North and SouthKorea. The region is considered one of theworld’s most mountainous areas withenvironmental extremes of -30ºC inwinter and a humid +40ºC in summer.The Blighter radars work 24 hours a day,365 days a year, monitoring the 4km-wideDMZ for any human, vehicle or low-flyingaircraft incursions.

Blighter PESA radars are particularly wellsuited to border security applications dueto their long-range detection capability(10m to 2km in steps up to 32km), 20ºwide elevation beam and their ability todetect very small and slow targets even incluttered environments.

Borders and coastlines

The inherent modularity of Blighter’sPESA radar technology makes it relativelystraightforward to tailor the coretechnology to different markets or toaddress specific surveillance situations.For example, at this year’s Eurosatory inParis, the company will unveil BlighterScout, a rapid deployment radar camerasystem for border security hotspots andother similar security applications.

Blighter Scout is a lightweight e-scan radarand camera surveillance system featuringthe Blighter Revolution 360 PESA radar, lowlight camera, thermal imaging system andan integrated radar tracker. It’s is designed

BlighterView HMI 2.0 Screen Snapshot – Satellite Map – Zoomed Out

Plextek Blighter B442 E scan radar.


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for mounting on vehicle and trailer mastsfor field deployment in just minutes.

Blighter Scout provides a low cost andlightweight mobile surveillance capabilityfor situations where fixed towers areprohibitively expensive, impractical tobuild or simply ineffective due to theterrain or environment. It enablessecurity forces to deploy a surveillanceplatform to exactly where it’s needed.For example, to monitor a hot spot on anextensive border or to follow intruderroutes as they adapt to the seasons or inreaction to ground interdiction.

Blighter Scout can be supplied in apalletised form complete with a standardtelescopic mast ready to slide onto theback of a standard 4x4 pickup truck orother surveillance vehicles/trailers. Thecomplete system requires only a singlemast as the electro-optic platform ismounted on top with the radar rotatingaround the mast section directly below it.

The radar can detect a walking person at7.4 km (4.6 miles) or a large movingvehicle at 22 km (13.7 miles) and then cuethe camera system to follow and identifytargets. With its wide 20-degreecontinuous elevation beam coverage –which can be increased to 40-degrees viaa simple built-in manual tilt control –Blighter Scout can operate in hilly ormountainous areas scanning hill tops and

valleys in a single sweep.

Blighter Scout integrates with a range ofelectro-optic camera systems. Thestandard complementary system forBlighter Scout is Chess Dynamics’Hawkeye electro-optic platform featuringthe Piranha MRTV or LRTV high sensitivitycolour daylight TV cameras and a PiranhaTV wide field of view context camera –with an option for cooled or uncooledthermal imagers.

Similarly, Blighter has recently enhancedits B400 series PESA radars by adding a sea

clutter filter for coastal and harboursecurity applications. This filter enablesBlighter’s Doppler signal processing unitto uniquely filter out sea wave clutterreturns in both velocity and amplitude.The Blighter coastal surveillance radar isoptimised to detect small and slowmoving targets under poor environmentalconditions.

Blighter Surveillance Systems will beexhibiting at Eurosatory in Paris, Franceon 16-20 June (Hall 5, Stand K511) and atDVD, Millbrook Proving Ground,Millbrook, UK on 25-26 June (Stand SP49).

PESA Technology gives Blighter Radar the Edge

Blighter B422 E-scan Radar and Liteye Aquila Daytime and Thermal Camera System at Airport

There are several products in the Blighter radar family:

l the ‘B202 Mk 2’ is a medium range (0-8km), lightweight, man-portable and/orvehicle-mobile radar capable of electronically scanning 90°.

l the B303 is a medium range (0-8km) compact mobile radar suited to mounting on amast on vehicles or trailers. The 180° electronic scanning of the B303 provides acost effective 360° solution using just two units back-to-back.

l the B400 series radars are for long range (0-2, 5, 8, 16 or 32km), fixed or mobileinstallations on towers, buildings or other pieces of fixed infrastructure. The B400series radar is a modular design allowing from 90° of electronic scanning on theB402 up to a full 360° on a B442 radar.

l Blighter Revolution 360 radar is a low cost, lightweight vehicle-mobile radar foruse on vehicle masts and trailer masts. Uses a single B400 series radar unit. Optionwith integrated electro-optic system is called Blighter Scout.


pesa technology gives blighter radar the edge

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