EECS 826 – InSAR and Applications Utilizing SAR Systems for Landmine Detection EECS 826 Jason...

EECS 826 – InSAR and Applications

Utilizing SAR Systems for Landmine Detection

EECS 826Jason Kieffaber

April 28, 2009

EECS826 – SAR Systems for Landmine Detection

Overview

Agenda• Overview• GPR and UWB Basics

• GPR Basics• UWB Basics• UWB GPR Systems

• Current Systems • Rail-GPSAR• BoomSAR• REMIDS

• Summary• Questions and References


Overview

Background (Costs)• 110 Million deployed

• 60+ countries• 100+ Million awaiting deployment

• Deployment cost: $3-$30• Clearing cost: $300-$1000• 2000 people/month (mostly civilians)• Survivor costs: $5000• Viable for at least 50 years• 1100 years to clear


Overview

Background (Land Mines)• Anti-Tank Landmines

• Buried• Larger/Uniform• War-time Use

• Anti-Personnel Landmines• Surface Placement• Foliage Cover• Smaller/Less Uniform• Civilian Use/Targets


Overview

Background (Clearing)• War-Time

• Military Focus• Anti-Tank Emphasis• Forward Looking• Speed

• Post-War• Humanitarian Focus• Anti-Personnel • Longer Time-Scale

• Removal vs. Intentional Detonation


GPR and UWB Basics

Ground Penetrating and Ultra Wide-Band RADAR• GPR Basics

• Acquisition Platform• Propagation• Target Recognition

• UWB Basics• Frequency and Bandwidth

• GPR UWB Systems Summary


GPR and UWB Basics

Acquisition Platform• Common GPR Methodology

• Reflection Seismology• Antenna/Ground Coupled• Time Consuming• Dangerous for Mines


GPR and UWB Basics

Acquisition Platform (Ground Based)• Near-Earth

• Metal Detector Coupled• Vehicle Mounted

• Forward Looking• Boom Mounted

• Negatives• Still Dangerous• Incomplete Coverage• Real-Time Requirements• No Ground Contact• Time Consuming (False Positives)


GPR and UWB Basics

Acquisition Platform (Airborne)• Common SAR Methods

• Safe (Generally)• Real-Time Not Required• Faster/More Coverage• Accessibility• Post Analyze False Targets

• Negatives• Fewer Samples• No Ground Contact


GPR and UWB Basics

Propagation• Multiple Reflection Boundaries• Homogeneous Assumption

• Air/Ground Boundary• Ground/Target Boundary• Uniform Soil Type

• Reality• Air/Foliage Boundary• Air/Ground Boundary• Ground/Ground Boundary• Ground/Target Boundary• Generally Non-Uniform Soil


GPR and UWB Basics

Propagation (Soil Dielectrics)• Index of Refraction Tied to Dielectric Constant

• Permeability: µr ≈ 1• Permittivity/Dielectric Constant εr

• Dielectric Constant Depends on Moisture

• Snell’s Law

• Moisture Content Depends on Soil Type• Permeability ≈ 1 (Most Soil)• Complex Relationship• Could be Multiple Boundaries


GPR and UWB Basics

Propagation (Solutions)• Traditional GPR

• Extensive Operator Training• Small Areas, Near Constant Soil Characteristics

• Non-Traditional Options • Remove/Compensate for Boundary Changes

• Air/Ground Relatively Easy, Others Complex• Usually Post-Processing

• Simple Migration Compensation• Complex Dielectric Modeling• Algorithmic Training


GPR and UWB Basics

Propagation (Migration Compensation) [McClellan et. al.]

• Conventional Focusing Techniques Inadequate• Multipath Issues• Non-Hyperbolic Response

• Post Filter Differently• 2-D FIR Filter• Simple Model• Successive Focus Steps


GPR and UWB Basics

Propagation (Modeling) [Jin, Zhou, et. al.]

• ψt = Real{θ t}• Incident Electric Field at Z

• Transmission Factors

• Geometry

COMPLEX!


GPR and UWB Basics

Propagation (Training)• Training

• Apply a Suite of Algorithmic Processes• Requires Post Processing• Requires Multiple/Varying Passes

• Multiple Simple Migration Passes• Index of Complex Soil Dielectrics

• Time and Processing Intensive• Not Applicable for Real Time Applications• Still More Art Than Science


GPR and UWB Basics

Target Recognition• False Positives

• Single Biggest Problem• Rock vs. Junk vs. Bush vs. Mine• Conservative Estimate of 10:1• Wasted Time

• Target Recognition/ROI Identification Improvements• Interference Suppression• Symmetry Recognition• ESD Recognition• Simple Training Methodology


GPR and UWB Basics

Target Recognition (Interference) [Zhang, Song, et. al.]

• Radio Frequency Interference (RFI)• With Small Sample Size, Cannot Accurately Estimate• No Estimation, No Compensation

• Enlarge Sample Size• 2-D Fourier (If Band-limited)• Fan Shaped Regions of Validity• Provides Superior Rejection

• If Band-limited, Can Achieve Better RFI Rejection


GPR and UWB Basics

Target Recognition (Symmetry) [Carin, Ressler, et. al.]

• Assumptions• Device is Symmetrical• Body of Revolution• Primary Axis Perpendicular to Surface• Assumes Uniform Device Conductivity

• Multiple 3-D Algorithms Available• Classic Model – Physical Optics • Method of Moments

• Effective for Buried and Surface Placement


GPR and UWB Basics

Target Recognition (Physical Optics)• Apply Incident Field/Ray Instead of Total Field

• Apply at Multiple Sample Points• Accurate for Small Scatter Relative to Field

• Accurate for Ideal Surfaces• Simple Model• Born Approximation


GPR and UWB Basics

Target Recognition (Method of Moments)• More Accurate Estimation/Modeling

• Also Sample/Phenomenological Based• Polarized Wave-front Analysis

• A) Diffraction (Front)• B) Diffraction (Back)• C) Reverberation• D) Creeping-Wave Circumnavigation• E) Diffraction (Bottom)• F) Diffraction (Multiple)


GPR and UWB Basics

Target Recognition (ESD/Spectral) [Ho, Carin, et. al.]

• Analysis of the Spectral Properties of the Mine• Similar to Propagation Analysis • Works for Metal and Plastic Mines

• Provided Sufficient Dielectric Contrast• Resistant to Differences in Soil Dielectrics• Utilizes 3-D FDTD (Finite-Difference Time Domain)

• Baseline• Builds Database from Measured Models

• d (data) = g (ground bounce) + s (landmine scatter) + w (noise)

• Same Drawbacks as Propagation Analysis


GPR and UWB Basics

Target Recognition (ESD/Spectral)


GPR and UWB Basics

Target Recognition (Training and Detection)• Example Process:

• SVM: Support Vector Machine (Machine Learning)• PCA: Principle Component Analysis

• Effect to be Matched (ESD, Dielectrics, Etc.)


GPR and UWB Basics

Frequency and Bandwidth (Needs)• Surface and Buried Mines

• Foliage AND Ground Penetration• Resilient to Clutter• Band-limited• Frequency Tradeoff

• Higher Frequency = Better Resolution• Lower Frequency = Deeper Ground Penetration

Depth of Penetration

Optimal Frequency

Applications

0-1.5 ft (0-0.5 m)

1600 MHzStructural Concrete,

Roadways, Bridge Decks

0-3 ft (0-1 m)

900 MHz Concrete, Shallow Soils, Archaeology

0-12 ft (0-9 m)

400 MHzShallow Geology, Utilities,

UST's, Archaeology


GPR and UWB Basics

Frequency and Bandwidth (Ultra Wide-Band)• Ultra Wide-Band Definition

• Bandwidth Must be 25% of the Center Frequency

• Band-Limited• Resistant to Clutter Interference• Resistant to Radio Interference• Relatively Low Power• UWB is a Solid Solution


GPR and UWB Basics

Frequency and Bandwidth (Specifics)• GPR Desirable Specifics

• Approximately 1 GHz Center Frequency• Range From 0.1 GHz to 3 GHz• Penetration Depth of Approximately 1 Meter• Effective for Most Mine Types

• Approximately 1 GHz Bandwidth• Range From 0.5 GHz to 2 GHz• 100% BW (UWB)• Effective for Power, SNR, and Clutter Rejection

• Short Pulse (Nanoseconds) Duration


GPR and UWB Basics

GPR UWB Systems Summary• Platform

•Normally Airborne, UWB, Short Pulse• System Training

• Dielectric Soil, Spectral, Discrimination Factors• Image Acquisition

• SAR, Desired System Parameters• Prescreening Stage

• Ground/Air Boundary Rejection, Soil Assumptions• Target Discrimination

• Migration, Clutter Rejection, Target Matching


Current Systems

Current Systems• Rail-GPSAR• BoomSAR• REMIDS• Other Areas of Development


Current Systems

Rail-GPSAR


Current Systems

Rail-GPSAR (Description)• Experimental Landmine Detection System• Rail/Trolley Mounted (24m long, 3.4m high)• 1 TX, 1 RX TEM Horn Antenna (VV/HH Polarization)• Geodimeter Calibrated• Strip-Map, Side-Looking SAR (200 m2)• Image Formation (Constant Integral Angle Back)• Short Pulse UWB • 10 GHz Sampling• Forward Speed of 5cm/s• Center Frequency: 0.3 GHz – 1.9 GHz• Average Power 50 mW


Current Systems

Rail-GPSAR (Block Diagram)


Current Systems

Rail-GPSAR (RFI Suppression)


Current Systems

Rail-GPSAR

(PCA/SVM)


Current Systems

BoomSAR (Description)• Research on FOPEN and GPEN (Phenomenology)• Army Research Laboratory – SAR on a Boom• Built in 1995 – Aberdeen and Yuma Proving Grounds• JLG Boom (1000 pounds, 45m maximum)• Low Speed – 1 km/hr• Geodimeter Calibrated• 2 TX, 2 RX TEM Horn Antennas (VV, HH, VH, HV)• Center Frequency 0.04 GHz - 2 GHz • 2 GHz Sampling• Average Power 1.5 W• UWB Short Pulse• 300 m Range Swath Width• 128 Burst/Second/Polarization


Current Systems

BoomSAR (Block Diagram)


Current Systems

BoomSAR (Example Image)


Current Systems

REMIDS


Current Systems

REMIDS (Description)• Remote Minefield Detection System• Endfire/Forward Looking UWB SAR and Infrared Camera• UK Ministry of Defense (2002)• 80 m Test Track/5 Soil Types• 1 TX, 2 RX Endfire (not Broadside) Antennas

• Left/Right Ambiguity (As Tested)• Degraded Resolution• Aperture Vertically Limited (Not Horizontally)

• 3 GHz Bandwidth (1.5 GHz Center) – Short Pulse• 10 GHz Sampling• Offline Analysis


Current Systems

REMIDS (System Overview)


Overview

REMIDS (Test Track – Thales/Paris)


Overview

REMIDS (Sample Image)


Current Systems

REMIDS (System Diagram)


Current Systems

Other Areas of Development [Optional]• Submerged/Underwater Mines

• Significance• SAR Research/MISE Program

Ultra Wideband Radar Images of the Surface Disturbance Produced by a Submerged, Mine-Like Object. [Sletten]

• Moving Targets • Foliage Penetration• Change Detection

Single-Channel UWB SAR Ground Moving Targets Detection Method Using Change Detection BasedOn Single-Pass Sub-Aperture Images [Zhou, et. al.]


Summary

Agenda:• History and Background• GPR and UWB Basics

• GPR Basics• UWB Basics• UWB GPR Systems

• Current Systems • Rail-GPSAR• BoomSAR• REMIDS


Questions

QUESTIONS?


References• [1] Zhou, Hong, et. al. “Single Channel UWB SAR Ground Moving Targets Detection Method Using Change Detection Based on Single-Pass Sub-Aperture Images” Synthetic Aperture Radar, 2007, APSAR (2007): 266-270.

• [2] Sletten, M.A. “Ultra Wideband Radar Images of the Surface Disturbance Produced by a Submerged, Mine-Like Object.” Geoscience and Remote Sensing 38.6 (2000): 2506-2514.

• [3] Cooper, P. et. al. “Ultra Wideband Endfire Synthetic Aperture Radar for Landmine Detection.” Geoscience and Remote Sensing Symposium (2003).

• [4] Tian, Jin, et. al. “Ultrawideband Synthethic Aperture Radar Landmine Detection.” Geoscience and Remote Sensing 45.11.1(2007): 3561-3573.

• [5] Chant, I.J., et.al. “Overview of Current Radar Land Mine Detection Research at the Defence Science and Technology Organisation, Salisbury, South Austrailia.” Detection fo Abandonded Land Mines: EUREL Conf (Publ. No 431) (1996): 138-142.

• [6] Ressler, M. A. “The Army Research Laboratory Ultra Wideband BoomSAR.” Geoscience and Remote Sensing Symposium 3 (1996): 1886-1888.

• [7] Tian, Jin, et. al. “Ultra-wide Band SAR Subsurface Metallic Landmine Images: Simulation and Measurement.” Intl. Conf. on Radar (2006): 1-4.

• [8] Zhang, Han-hua, et. al. “A Rail-Mounted UWB SAR Landmines Detection System: Rail-GPSAR.” Intl. Conf. on Radar (2006): 5-9.


References• [9] Ho, K.C., et. al. “An Investigation of Using the Spectral Characteristics From Ground Penetrating Radar for Landmine/Clutter Discrimination” Geoscience and Remote Sensing 46.4 (2008): 1177-1191.

• [10] Ressler, M.A., et. al. “Ultra Wideband Radar Images of the Surface Disturbance Produced by a Submerged, Mine-Like Object.” Geoscience and Remote Sensing 35.3 (1997): 762-772.

• [11] McClellan, J.H., et. al. “Migration of Underground Targets in UWB-SAR Systems.” Intl. Conf. Image Processing 1 (2000): 713-716.

• Wikipedia. “Ultra Wideband”, “SAR”, “Endfire”, “BoomSAR”, “Ground Penetrating”, et.al. www.wikipedia.org

• Taylor, James D., “Introduction to Ultra-Wideband Radar Systems”. 1995 • Images:

•http://newsgrist.typepad.com/underbelly/images/landmine2005sm_1.jpg•http://www.state.gov/img/09/30573/090123_fs_demolition_300_1.jpg•http://en.wikipedia.org/wiki/File:Mine_(AWM_304925).jpg•http://www.geocities.com/nhfortress/Towers/mine.jpg•http://upload.wikimedia.org/wikipedia/commons/0/0c/TC24_Italian_landmine_cutaway.png•http://www1.american.edu/TED/ice/images4/ek_landmine.jpg•http://library.thinkquest.org/C008616/site/pics/Landmine.jpg•http://www.betterworldtg.com/en/Stepping_On_Landmine__291w.jpg•http://www.it.uu.se/research/syscon/signalprocessing/topics/NQR/Landmine.jpg

EECS 826 – InSAR and Applications Utilizing SAR Systems for Landmine Detection EECS 826 Jason...

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