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E limination of C lutter through S ignal P rocessing for L andmine / O rdnance D etection (ECSPLOD)

E limination of C lutter through S ignal P rocessing for L andmine / O rdnance D etection (ECSPLOD). Gabriel Ford Aniket Hirebet Vasileios T. Nasis Norman Butler Advisor: Dr. Athina Petropulu May 29, 2002. Nic Dunlop. What are landmines?. Buried explosive devices.

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E limination of C lutter through S ignal P rocessing for L andmine / O rdnance D etection (ECSPLOD)

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  1. Elimination of Clutter through Signal Processing for Landmine / Ordnance Detection(ECSPLOD) • Gabriel Ford • Aniket Hirebet • Vasileios T. Nasis • Norman Butler • Advisor: • Dr. Athina Petropulu May 29, 2002 Nic Dunlop

  2. What are landmines? • Buried explosive devices. • Triggered by pressure or tripwire. • Types • Anti-personnel • Anti-tank • Cost 3 dollars to purchase. • Cost 1000 dollars to remove. Nic Dunlop

  3. The Human Toll • Over 110 million mines are scattered across the world. • 500 people are killed or injured every week by triggering landmines. • 80% of the victims are civilians. Nic Dunlop

  4. Why Metal Detectors Fail • Only effective when locating mines with substantial metal content. • Modern anti-personnel mines are made of plastics and contain dielectric explosives. National Defense Magazine

  5. Preprocessing Preprocessing Detection Classification Ground Penetrating Radar (GPR) DeTec - EPFL DeTec - EPFL • Ground Penetrating Radar (GPR) can detect all types of landmines, including modern plastic mines. • Our project focuses on preprocessing to improve landmine detection.

  6. Experimental Setup • Ground Penetrating Radar (GPR) data was collected by DeTeC with a commercial SPRscan system. DeTec - EPFL • Mines were buried in the center of a scanning pattern. • Each line in the scanning pattern represents a separate B-scan.

  7. GPR Data: A-scans and B-scans • The received signal at any measurement point is called an A-scan. A-scan • A B-scan is a collection of A-scans recorded along a scanning line. • The vertical (time) axis corresponds to depth. • A B-scan represents a vertical slice of the ground. B-scan – Composed of A-scans

  8. The Problem: Signal Clutter • GPR images are marred by a high degree of clutter. • For homogeneous media, the clutter varies little over a B-scan. • As a result, the mine signal is still evident. PFM-1 Mine in SAND • For non-homogeneous media, the clutter is more random. • In this case, the mine signal is highly obscured. ? PFM-1 Mine in SOIL

  9. c b Signal Clutter Defined w • A-scan Model: • w = c + b + s + e • The received signal w: • c:antenna cross-talk • b:ground bounce • s:target signal • e: measurement noise e Rx Tx c b s • Clutter is due primarily to ground bounce and antenna cross-talk.

  10. Clutter Reduction • Common clutter reduction methods include: • subtracting a signal measured in the absence of a target • subtracting a moving average estimate of the background • ensemble mean subtraction • These procedures are ineffective for the general case of mines buried in non-homogeneous media. • We have developed ECSPLOD to specifically overcome this problem

  11. d = s+n y + e x = n’ SUM Adaptive Filter - x = n’ d = s+n x = n’ d = s+n x = n’ d = s+n x = n’ d = s+n x = n’ d = s+n x = n’ d = s+n x = n’ d = s+n Method of Solution • ECSPLOD extends mean subtractionwithadaptivefiltering for interference cancellation. • ECSPLOD updates the adaptive filter input signal to compensate for variation in clutter properties. Mine Response

  12. Plastic Mine in Sand – Mean Subtraction Raw Data Mean Subtraction

  13. Plastic Mine in Soil – Mean Subtraction Raw Data Mean Subtraction

  14. Plastic Mine in Soil: Moving Average Subtraction vs. ECSPLOD MA ECSPLOD-KALMAN ECSPLOD-NLMS

  15. Summary–ECSPLOD Raw Data Mean Subtraction ECSPLOD - NLMS

  16. Raw Data Moving Average Subtraction ECSPLODNLMS ECSPLODKalman Plastic Mine in Soil – Detection

  17. Detection Evaluation – ROC Curves PFM - 1 in Soil, NLMS Type 72 in Soil, NLMS

  18. Economic Summary • Out of pocket costs were under $500 (reference material and printing costs) • Cost in private sector summarized below:

  19. Summary and Conclusions • The Problem: • There is a need for a reliable demining technology • Metal detectors do not work on all types of mines • Ground Penetrating Data is suitable for all types of mines • But GPR is plagued with the problem of excessive signal clutter

  20. The Solution: Mean Subtraction only works in homogeneous media Moving Average Subtraction shows some improvement ECSPLOD utilizes Mean Subtraction followed by Adaptive Filtering ROCs and visual comparisons show that ECSPLOD works Summary and Conclusions

  21. Before After Questions and Comments ECSPLOD Special thanks to: Athina Petropulu Moshe Kam Brian Kravitz Wayne Hill Maja Bystrom

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