landmines are affecting the lives and livelihood of millions of people around the world

8/2/2019 Landmines Are Affecting the Lives and Livelihood of Millions of People Around the World

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Landmines are affecting

the lives and livelihoodof millions of peoplearound the world. Thevideo impulse groundpenetratingradar system fordetection for small andshallow buried objectshas been developed.The hardwarecombines commercially

available componentswith componentsspecially developed ormodified for being usedin the system. The GPRsystem has beendesired to measureaccuratelyelectromagnetic fieldbackscattered fromsubsurface targets inorder to allow

identification ofdetected targetsthrough the solution ofthe inverse scatteringproblem. The GPR hasbeen tested in differentenvironmentalconditions and hasproved its ability todetect small andshallow buried targets.

INTRODUCTIONLandmines andunexploded ordnance(UXO) are a legacy ofwar, insurrection, andguerilla activity.Landmines kill andmaim approximately26,000 people annually.


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In Cambodia, wholeareas of arable landcannot be farmed dueto the threat oflandmines. United Na-tions relief operationsare made more difficultand dangerous due tothe mining of roads.Current deminingtechniques are heavilyreliant on metaldetectors andprodders.

Technologies areused for landmine

detection are:a. Metal detectors---capable of finding evenlow-metal contentmines in mineralizedsoils.b. Nuclear magneticresonance, fast neutronactivation and thermalneutron activation.c. Thermal imaging andelectro-optical sensors--- detect evidence ofburied objects.d. Biological sensorssuch as dogs, pigs,bees and birds.e. Chemical sensorssuch as thermalfluorescence--- detectairborne andwaterborne presence ofexplosive vapors.

. In this discussion, wewill concentrateon Ground PenetratingRadar (GPR). This ultrawide band radarprovides centimeterresolution to locate


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even small targets.There are two distincttypes of GPR, time-domain and frequencydomain. Time domainor impulse GPRtransmites discretepulses of nanosecondduration anddigitizes the returns atGHz sample rates.Frequency domainGPR systems transmitsingle frequencieseither uniquely, as aseries of frequencysteps, or as a chirp.

The amplitude andphase of the returnsignal is measured. Theresulting data isconverted to the timedomain. GPR operatesby detecting thedielectric contrasts inthe soils, which allows itto locate even nonmetallic minesIn this discussion wedeal with buried anti-tank (AT) and anti-personnel (AP)landmines whichrequire close approachor contact to activate.AT mines range fromabout 15 to 35 cm insize. They are typicallyburied up to 40cmdeep, but they can also

be deployed on thesurface of a road toblock a column ofmachinery. AP minesrange from about 5 to15cm in size. AT mineswhich are designed toimpede the progress of


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destroy vehicles andAP mines which aredesigned to kill andmaim people.

HARDWAREDESCRIPTIONThe impulse GPRsystem developed inthe InternationalResearch Centre forTelecommunications-transmission and Radar(IRCTR). Impulse GPRsystem comprises aImpulsegenerator, Transmitter,

Receiver, Pulseextender, A/Dconverter, Processorand Visual display.

IMPULSEGENERATORThe pulsegenerator delivered bySATIS Co. produces0.8 ns monocyclepulses. The uniquefeature of this generatoris its small trailingoscillations, which arebelow 2.4% ofmaximum amplitudeduring the first 2 ns andbelow 0.5% afterwards.The advantage of amonocycle incomparison with amono pulse is that the

frequency spectrum ofthe first one decreasesto zero at lowfrequencies, whichcannot be efficientlytransmitted via theantenna system, whilethe frequency spectrum


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of the second one hasa global maximumthere. As a result, themagnitude of the fieldradiated by an antennasystem fed by amonocycle isconsiderably larger thanthe magnitude of thefield radiated by theantenna system fed bya monopulse with thesame magnitude.

The generator spectrumcovers a widefrequency band from

500MHz till 2GHz on3dB level. Atfrequencies below1GHz, attenuationlosses in the ground aresmall and considerablepenetration depth canbe achieved. However,landmines detectionrequires down-rangeresolution of the orderof several centimeters,which can be achievedusing frequenciesabove 1GHz. It wasfound experimentallythat the 0.8nsmonocycle satisfiespenetration andresolutionrequirements. Thisoutput signal from 0.8nsgenerator is shown in

figure. The spectrum ofthis pulse has amaximum atfrequencies where theattenuation losses inthe ground start toincrease. So thespectral content of the


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monocycle below thismaximum penetratesdeep into the groundand the spectral contentabove this maximumprovides sufficientdown-range resolution.ANTENNA SYSTEMThe antenna system isone of the most criticalparts of GPR system,because itsperformance dependsstrongly on the antennasystem. The antennasystem should satisfy anumber of demands.

The antenna systemcontains transmitter andreceiver. The transmitantenna should:Radiate short ultra-wideband (UWB) pulse withsmall ringing.Radiate electromagnetic energy withina narrow cone in orderto filter out undesirableback scattering fromsurrounding objects.Produce an optimalfootprint on the groundsurface and below it.The waveform of theradiated field on thesurface and in theground should be thesame.The waveform of theradiated field in the

ground should notdepend on type of theground.

The receiver antennashould:Allow time windowing to


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isolate the direct airwave from the groundreflection.Provide sufficientsensitivity in order toreceive very weakfields.Receive the field in alocal point; effectiveaperture should not belarger than 1cm2.Be elevated at least10cm above the groundsurface.Additionally a possibilityto measuresimultaneously

backscattered field intwo orthogonalpolarizations isdesirable.PULSE EXTENDERPulse extender willamplify the groundreflection signal up tothe maximum levelacquired by A/Dconverter.A/D CONVERTERThe transmitter sendsout a series ofelectromagnetic pulsesthen listens with thereceiver connected tohigh speed samplerwhich in turn feeds A/DConverter. A dielectricanomaly in the soil maycause the signal to bereflected back to a

separate receiverantenna. Thisinformation is convertedfrom nanoseconds tomilliseconds so that itmay be digitized by aconventional A/Dconverter for


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processing and display.The center frequencyand band width of thetransmitted pulse canbe varied by changingthe antenna and arechosen with respect tothe required depth ofpenetration, soil typeand size of the object tobe detected. In thisexperiment, we usedantennas with a centerfrequency 1.4GHz and80% band width. Theprecision of samplingconverter is sufficiently

high to do accuratemeasurements ofscattered transient field.This A/D converter 12bit accuracy. Thisprovides 66 dB lineardynamic ranges. A/Dconverter converts thesignal into digital signalwhich passes to theprocessor.PROCESSORA/Dconverter converts thesignal into digital signalwhich passes to theprocessor. Processorfilters the signal. Thissignal shows presenceor absence of surrogatemine in the soil.Processor allowspassing the presence of

mine detecting signal.Processor selects themine detecting signaland passes to thevisual display.VISUAL DISPLAYVisual display helps tosee the range of


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targets. It displays theexact position oflandmine.SENSORSEMPLOYED

If all mines were casedor had substantialmetallic content, all thatwould be required fordetection are metaldetectors. Thewidespread use ofplastic landminesnecessitatesdevelopment anddeployment of

additional detectiontechnologies. Becausethere is no such thingas a plastic detector,other sensors attemptto exploit ancillarydisturbances in thebackground, such asthermal, chemical, ordielectric.GROUNDPENETRATINGRADARBecause of the difficultydetecting the tinyamounts of metal in aplastic landmine with ametal detector,technologydevelopment has beenfunded in other areas.Ground penetratingradar (GPR) has been

used for nearly 70years for a variety ofgeophysical subsurfaceimaging applicationsincluding utility mappingand hazardous wastecontainer location andhas been actively


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applied to the problemof landmine detectionfor nearly 20 years.When parameters suchas frequency range,antenna size, antennaseparation, and systemtiming are optimized fordetection of mine-sizedobjects in the nearsubsurface, GPR isquite effective indetecting both metaland plastic landmines ina variety of soils. Thedepth of penetration isa function of both the

frequency rangeproduced and the soilattenuation. Lowerfrequency componentspenetrate further, but itis a higher-frequencycomponent that isnecessary to image andresolve smaller targets.Both impulse- basedand swept frequencyGPR systems havebeen employed inArmy-sponsoredresearch programs.Generally a system witha bandwidth of roughly1 to 4GHz is effectivefor detection oflandmines.Ultimately, GPR imagesthe dielectric propertiesof the soils, and any

discontinuities appearas a signal. If soil wereperfectly homogeneous,a discontinuity causedby a land mine wouldstand out as ananomaly against thebackground.


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Unfortunately, evenunder near-ideal testtrack conditions, soilitself is a remarkablyinhomogeneousmedium, and falsealarms are easilygenerated from thebackground itself .Because of this,automatic targetrecognition (ATR)algorithms employed byimpulse-based GPRsystems typicallycalculate and removebackground and try to

detect the hyperbolicsignatures that arecharacteristic in sizeand shape of landminetargets in GEO-CENTERS 400 Seriesenergy in focusingground penetratingradar (EFGPR), weemploy a fuzzy logic-based algorithm thatuse prototypes, orfeature sets, forlandmines, andprototypes than toclutter. At each locationin a data set, we lookinside a neighborhoodof adjacent points,extract a feature set,and calculate if thefeatures set is closer tothe mine prototypes

.The output is a planview of the confidence,at each point along atest lane, that there is alade mine .A blobdetector then runs onthis confidence planeview, outputting target


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reports when a blob isof an appropriate sizeand shape.

Although GPR hasbeen shown to beeffective on the testtrack against a varietyof land mines in a rangeof soil conditions, it istechnologically complex. The weight and powerrequirements are notoverwhelming, but theymake GPR most easilydeployed on a vehicular

platform .ThroughNVESD at Fort Belvoir,the U.S Army isdeploying GPR in avariety of hand heldand vehicular land minedetection technologydevelopment programs.OVERVIEW OF THESYSTEM

A series ofmeasurements hasbeen taken using a setof targets buried in thevarious types of soil. AnFR-127-MSCB impulseground penetratingradar (ImGPR) systemdeveloped by theCommonwealthScientific and Industrial

Research Organization(CSIRO), Australia, hasbeen used for thesemeasurements. Thesystem collects 127returns, orsurroundings, persecond, each


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composed of 512samples with 12 bitaccuracy. The soundingrange may vary from 4ns to 32ns. The GPRsystem uses bistaticbow-tie antennas whichtransmit wideband,ultrashort durationpulses.

The GPR unit issuspended above theground surface at aheight of between 0.5to 2cm. Its motion iscontrolled by a stepper

motor unit runningalong a track at aconstant velocity asshown in fig.4. Sincethe motion of the GPRis controlled by astepper motor, withconstant speed,running on a straighttrack, these samplescorresponds todistances from startingpoint of the run.

GPR images thedielectric properties ofthe soil and anydiscontinuities appearas a signal. If the soilwere perfectlyhomogeneous adiscontinuity caused bya land mine would

stand out as ananomaly against thebackground. Automatictargets recognition(ATR) algorithmsemployed by impulsebased GPR system.


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The measurementsform a two dimensionalmatrix, referred to as aradargram or B scanand A scan are used forvisual inspection of dataon the acquisitioncomputer and inlaboratory analysis.A SCANImpulse GPR producesmeasurements ofelectromagnetic fieldscattered from thesubsurface. This isdetecting the graph asshown in figure.

A scan is a method fordetecting the presenceand absence ofsurrogate mine in claysoil. Theelectromagnetic field isscattered by the GPR.Scattering pulses aredetecting by the graph.This graph is AmplitudeVs Time. This graph ishelpful to find thelandmine and is usedfor visual inspection.The normal pulses areshowing the absence ofmines. The amplitude ofthe pulses are large ascompared to other area.This shows thepresence of mine. Sowe can detect thepresence of mine in that

clay soil.A scans in the presence(dashed) and absence(solid) of a surrogatemine in clay soil.B SCANA scan shows thepresence of mine but


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we cannot expect theexact target. Thisproblem is solving in Bscan. B scan orRadargram is used tovisualize the target ofsurrogate mine. Asample radargram isshown in figure. Thisshowing the targets atapproximately 55 cmand 100 cm. B scancalculating the distancefrom the soil to themine. In this sampleradargram showing theexact position.

A scan and B scan isused for laboratoryanalysis. A return at acertain position alongthe distance axis iscalled an A scan. Bscan is a graph which isTime delay VsDistance. So B scanhelps to calculate thepenetration length. Thisgraph helps to calculatethe distance fromground to the mine.

DEPLOYMENTPLATFORM

US army handheldstandoff mine detectionsystem that is a selfpropelled cart with GPRsystem. As

technologicaldevelopment for landmine detection tends tobe a vehicular basedsystem. This vehicularbased system is shownin figure. 7.


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self propelled cartwith GPR systemThis vehicle is selfpropelled so it can usein war places. This is avehicular based systembecause vehicle cancarry the weight andsupply the power. Thisdoes not mean, though,that handheld systemsare limited to metaldetectors. There areplatforms that aresmaller than fullvehicles but larger thanman deployable

devices. This vehiclecomprises a pulsegenerator, transmitter,receiver, pulseextender, A / Dconverter, processorand a visual display.This vehicle is passingthrough the soil, thepulse generatorproduces pulses andthe transmittertransmits this signal tothe ground. The soilcontain the land mine,the receiver receivesthe ground reflectingsignal. The A / Dconverter converts thesignal nanoseconds tomilliseconds. Thissignal is digital signaland this signal amplifies

and filtering by theprocessor. The signalcontains presence ofland mine, passes tothe visual display. Thisvisual display helps todisplay the exact targetof land mine. This helps


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to calculate thedistance from the soil tothe mine. This systemis very useful to the warplaces. This vehicle isself propelled so it canmake easy detection.TESTING ANDEVALUATIONThe U.S Army performsobjective blind andscored testing at theirtesting facilities, whichinclude carefullyconstructed mine lines.In this testing andevaluation environment,

land mines are live(filed with explosive)because certaindetection technologiessuch as QuadropleResonance rely ondetection of the actualexplosive charge.However, on this testlines, the mines areunfused and thus donot detonate if they arerun over by detectionsystem. Dirt and gravellanes are maintained.Typically, the lanes arevery smooth, largelyfree of bumps andditches that wouldcause the sensor arraysto maintain aninconsistent sensorheight that would

substantially affect dataquality. Off-road lanesare also used. They arenot as pristine as dirt orgravel lanes but are stilla substantially morecontrolled environmentthan a Jeep train


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through the KhyberPass.Each lane has anassociated calibrationlanes where the groundtruth is known andcontactors may run andrerun their system toiteratively optimizedetection performance.GPR systems typicallyneed calibration ortiming alignment, andinfrared camerasgenerally need boresighting. The featureextraction and ATR

algorithms on theindividual sensorsubsystems usuallyneed to be tweaked tomaximize the detectionrate and minimize thefalse alarm rate for theparticular environment.This can entailadjusting detectionthresholds ordetermining optimumblob sizes. Whenacceptableperformance isachieved on thecalibration lane, thecontractor is ready torun the blind, scoredsection of the lane.

ADVANTAGES

GPR has accuratemeasurements.GPR locates even smalltargets.It has been wellfounded by thedefense.GPR operates by


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detecting the dielectricsoils which allows it tolocate even no metallicmines.Biological sensors canonly operate for limitedperiods, but in GPR hasno such limits.GPR has been tested indifferent environmentalconditions.DISADVANTAGESThe sensor such asGPR is larger andheavier.GPR is more powerhungry.

GPR can suffer fallsalarm rates as high asmetal detectors.CONCLUSIONImpulse GPR system isusing for detecting anti-tank and anti-personalmines. Anti-tank minesare using for destroyingthe vehicles and anti-personal mines, whichare designed to kill andmaim people. Currently,very little technology isused in real-worlddemining activities.Active programs by theU.S Army in both landmine detection sensordevelopment andsystems integration areevaluating newtechnologies,

incrementally improvingexisting technologies,increasing theprobability of detection,reducing the false alarmrate, and planning outuseable deploymentscenarios. Through


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Reference:http://seminarprojects.com/Thread-landmine-detection-using-impulse-ground-

penetrating-radar--5548#ixzz1rSFDbNw8
http://seminarprojects.com/Thread-landmine-detection-using-impulse-ground-penetrating-radar--5548#ixzz1rSFDbNw8http://seminarprojects.com/Thread-landmine-detection-using-impulse-ground-penetrating-radar--5548#ixzz1rSFDbNw8http://seminarprojects.com/Thread-landmine-detection-using-impulse-ground-penetrating-radar--5548#ixzz1rSFDbNw8http://seminarprojects.com/Thread-landmine-detection-using-impulse-ground-penetrating-radar--5548#ixzz1rSFDbNw8http://seminarprojects.com/Thread-landmine-detection-using-impulse-ground-penetrating-radar--5548#ixzz1rSFDbNw8http://seminarprojects.com/Thread-landmine-detection-using-impulse-ground-penetrating-radar--5548#ixzz1rSFDbNw8

landmines are affecting the lives and livelihood of millions of people around the world

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