Multi-Sensor Measurements for the Detection of Buried Targets
Waymond R. Scott, Jr. and James McClellanSchool of Electrical and Computer Engineering
Georgia Institute of TechnologyAtlanta, GA 30332-0250
MURI Review 1-13-05 Scott/McClellan, Georgia Tech 2
Outline
IntroductionThree Sensor ExperimentMulti-static RadarAccomplishments/Plans
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Multi-Sensor Cooperation/Adaptation
GPR
EMI
Seismic
Imaging
SigProc
Imaging
Features
Features
Features
DecisionProcess
ExploitCorrelation & Sensitivity
Feedback
Feedback
Controls
Controls
Controls
Controls
Controls
ControlsFrequency BandwidthFocusingRemote ImagingMeasurement Spacing
Frequency BandwidthMeasurement Spacing
Frequency BandwidthArray Elements UsedMeasurement Spacing
MURI Review 1-13-05 Scott/McClellan, Georgia Tech 4
Experimental Test BedDevelop a set of experiments to investigate the potential of multi-modal processing
Landmine (Three sensors/six modes)EMIGPR
• Bi-Static• Multi-Static
Seismic• Unfocused• Focused• Remote Detection
Buried Structure (Two sensors/four modes)GPR
• Bi-Static• Multi-Static
Seismic• Bi-Static• Multi-Static
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Outline
IntroductionThree-Sensor ExperimentMulti-static RadarAccomplishments/Plans
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Diagram of the Laboratory Model
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Three Sensor Experiment
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Three Sensor Experiment
Experimental Scenario #16 Mines> 20 Clutter objectsRelatively uniform distribution
Experimental Scenario #27 Mines> 25 Clutter objectsNon-uniform distribution
Experimental Scenario #3Non-uniform distribution of 7 Mines (2 AT, 5 AP) and 57 clutter objectsRock field surrounding AP mine and canAP mines and clutter objects grouped around and on top of AT mines
MURI Review 1-13-05 Scott/McClellan, Georgia Tech 9
Burial Scenario #1
1.8m by 1.8m Scan Region
Rocks (3 and4 cm deep)
Dry Sand(5cm deep)
MINESVS-2.2
(7cm deep)
TS-50(1.5cm deep)
w/ Nail
M-14(0.5cm deep)
VS-50(1cm deep)
PFM-1(1.5 cm deep)
VS-1.6(6.5cm deep)
SeismicSources
Cans (3 and2.5 cm deep)
AssortedMetal Clutter (2 to 4 cm deep)
Shells(4cm deep)
ThreadedRod(3.5cm deep)
Penny(5.5cm deep)
Nails(4cm deep)
Ball Bearing(3.5cm deep)
Shells(5.5cm deep)
MURI Review 1-13-05 Scott/McClellan, Georgia Tech 10
Comparison of ImagesSeismic Sensor
Image 30 dB Scale
GPR Sensor Energy Image of Migrated
Data (25 dB scale)
EMI SensorImage ( 90 dB scale)
MURI Review 1-13-05 Scott/McClellan, Georgia Tech 11
Outline
IntroductionThree-Sensor ExperimentMulti-static RadarAccomplishments/Plans
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Antenna & Array Assembly
Absorber
switch
Port-2 In
Port-1 In
Port-1 Out
Port-2 Out
Rx-4Rx-3Rx-2Rx-1Tx-1Tx-2
48cm 12 12 12 12
Heat-sealable plastic sheet
Resistively-Loaded Vee
Styrofoam
Double-Y balun
FR-4 Support Panel
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GPR Array
Receiving antenna
y = +48cm
y = 0
y = -12cm
y = -24cm
y = -36cm
y = -48cm
synthetic array at y = 0
Transmitting antenna
We can obtain 192cm-wide synthetic array aperture by using reciprocity and synthesizing the scans at 6 positions
Physical array
MURI Review 1-13-05 Scott/McClellan, Georgia Tech 14
3D ExperimentsFree Space (calibration)
Spheres, Mines, Shapes, and No targetBuried targets (with clean surface and with surface covered by rocks)
No TargetsGrid of spheres (calibration)Grid of mines and clutterBuried structure
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Free Space Target Measurements -Setup
36.5cm
73 cm
xy
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Free Space Target Measurements -Targets
GT Plywood (38.5 x 46.5 x 1.84 cm)
11cm Shotput
1” Metal Sphere
TS-50
VS 1.6
MURI Review 1-13-05 Scott/McClellan, Georgia Tech 17
H-Plane Cut at x = 0cm; 11cm Metal Sphere at 25.5cm from Radar
Free Space Target Measurements -Results
-90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90
-90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90
0
2
4
6
8
10
t, ns
ec
0
2
4
6
8
10
t, ns
ec
R1 T1 R2 T1 R3 T1 R4 T1
R1 T2 R2 T2 R3 T2 R4 T2
0 dB
-20
-10
-30
-40
0 dB
-20
-10
-30
-40
rel. max.
rel. max.
MURI Review 1-13-05 Scott/McClellan, Georgia Tech 18
Comparison of the R1 – T1 Responses from Targets - H-Plane Cut at x = 0cm
Free Space Target Measurements -Results
-90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90
0
2
4
6
8
10
t, ns
ec
11cm Shotput 1” Metal Sphere VS 1.6-50 dB
-70
-60
-80
-90
-90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90
0
2
4
6
8
10
t, ns
ec
TS-50 GT Plywood No Target-50 dB
-70
-60
-80
-90
MURI Review 1-13-05 Scott/McClellan, Georgia Tech 19
VS 1.6 Mines11
-50 0 50
-50
0
50-25
-20
-15
-10
-5
s21
-50 0 50
-50
0
50-25
-20
-15
-10
-5
s31
-50 0 50
-50
0
50-25
-20
-15
-10
-5
s41
-50 0 50
-50
0
50-25
-20
-15
-10
-5
s12
-50 0 50
-50
0
50-25
-20
-15
-10
-5
s22
-50 0 50
-50
0
50-20
-15
-10
-5
s32
-50 0 50
-50
0
50-20
-15
-10
-5
s42
-50 0 50
-50
0
50 -20
-15
-10
-5
Coherent Sum of All TR Pairs
-80 -60 -40 -20 0 20 40 60 80
-80
-60
-40
-20
0
20
40
60
80
-25
-20
-15
-10
-5
MURI Review 1-13-05 Scott/McClellan, Georgia Tech 20
3D Experiments
Free Space (calibration)Spheres, Mines, Shapes, and No target
Buried targets (with clean surface and with surface covered by rocks)
No TargetsGrid of spheres (calibration)Grid of mines and clutterBuried structure
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Buried Target Measurements -Setup
With-Rock ScanClean Scan
Antenna height = 10cm from the surface of the ground
Scan region: 180cm x 180cm square
Rock coverage: 240cm x 340cm
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Metal SpheresTarget Locations & Depths
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LandminesTarget Locations & Depths
2D-plane cuts for the display of the
results
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x = 0cm-cut
Landmines
-90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90
-90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90
0
2
4
6
8
10
t, ns
ec
0
2
4
6
8
10
t, ns
ec
R1 T1 R3 T1 R2 T2 R4 T2
R1 T1 R3 T1 R2 T2 R4 T2
0 dB
-20
-10
-30
-40
0 dB
-20
-10
-30
-40
rel. max.
rel. max.
Clean Scan
With-Rock Scan
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Buried StructureTarget Location & Depth
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x = 0cm-cut
Buried Structure
-90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90
-90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90 -90 -45 0y, cm
45 90
0
2
4
6
8
10
t, ns
ec
0
2
4
6
8
10
t, ns
ec
R1 T1 R3 T1 R2 T2 R4 T2
R1 T1 R3 T1 R2 T2 R4 T2
0 dB
-20
-10
-30
-40
0 dB
-20
-10
-30
-40
rel. max.
rel. max.
Clean Scan
With-Rock Scan
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Buried Structure (Rocks)
Energy Sum of All TR Pairs
-80 -60 -40 -20 0 20 40 60 80
-80
-60
-40
-20
0
20
40
60
80 -45
-40
-35
-30
-25
-20
-15
-10
-5
Raw Data Energy Images for TR pairs
R1T1
-50 0 50
-50
0
50-25
-20
-15
-10
-5
R2T1
-50 0 50
-50
0
50-25
-20
-15
-10
-5
R3T1
-50 0 50
-50
0
50-25
-20
-15
-10
-5
R4T1
-50 0 50
-50
0
50-25
-20
-15
-10
-5
R1T2
-50 0 50
-50
0
50-25
-20
-15
-10
-5
R2T2
-50 0 50
-50
0
50-25
-20
-15
-10
-5
R3T2
-50 0 50
-50
0
50-25
-20
-15
-10
-5
R4T2
-50 0 50
-50
0
50
-25
-20
-15
-10
-5
MURI Review 1-13-05 Scott/McClellan, Georgia Tech 28
AccomplishmentsDeveloped three sensor experiment to study multimodal processing
Developed new metal detector and a radarInvestigated three burial scenariosShowed responses for all the sensors over a variety of targetsDemonstrated possible feature for multimodal/cooperative processingDeveloped new 3D quadtree strategy for GPR data
Developed seismic experiments, models, and processing Improved experimental measurement by incorporating a Wiener filter Demonstrated reverse-time focusing and corresponding enhancement of mine signatureDemonstrated imaging on numerical and experimental data from a clean and a cluttered environmentModified time-reverse imaging algorithms to include near field DOA and range estimates. The algorithms are verified for both numerical and experimental data with and without clutter.Modified wideband RELAX and CLEAN algorithms for the case of passive buried targets. The algorithms are verified for both numerical and experimental data with and without clutter. Used RELAX imaging to locate targets with cumulative maneuvering receivers.Developed a vector signal modeling algorithm based on IQML (Iterative Quadratic maximum Likelihood) to estimate the two-dimensional ω-k spectrum for multi-channel seismic data.
Developed multi-static radarDemonstrated radar operation with and without clutter objects for four scenarios
Buried structuresDeveloped numerical model for a buried structureDemonstrated two possible configurations for a sensorMade measurement using multi-static radar
MURI Review 1-13-05 Scott/McClellan, Georgia Tech 29
PlansThree sensor experiment (Landmine)
Incorporate reverse-time focusing and imagingIncorporate multi-static radarMore burial scenarios based on inputs from the signal processors
More/Stronger clutterDistribution of targets and clutterClose proximity between clutter and targets
Look for more connections between the sensor responses that can be exploited for multimodal/cooperative imaging/inversion/detection algorithms
Imaging/inversion/detection algorithmsExtend 3-D quadtree algorithm to multi-static GPR data.Investigate the use of reverse-time ideas to characterize the inhomogeneity of the groundInvestigate the time reverse imaging algorithm for multi-static GPR data.Investigate the CLEAN and RELAX algorithms for target imaging from reflected data in the presence of forward waves with limited number of receivers.Investigate joint imaging algorithms for GPR and seismic data.
Buried StructuresExperiments with multi-static radarDevelop joint seismic/radar experimentSignal Processing
