Design and Development of an NQR-based explosive detection ...
Transcript of Design and Development of an NQR-based explosive detection ...
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Design and Development of an NQR-based
explosive detection system for humanitarian demining
Y. Otagaki, P. Farantatos, W. Rafique
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Outline
• Introduction to ACRA project
• Technology overview
• Integrated system specifications
• Principle of NQR
• Portable system
• Interference cancellation
• Conclusion
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1. Develop an NQR-based anti-vehicle mine (AVM) detector suitable for use and production in the humanitarian context 2. Develop methodology for using dialogue and data to direct NQR demining activities for maximum positive impact in the minimum possible time
Project - A Clear Road Ahead
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ACRA Team
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ACRA team at the Symposium
Dr Sarah Njeri Working in the African Leadership centre at King’s College London. Currently looking into the peace-building aspect of humanitarian demining
Dr Jamie Barras Working in the department of Informatics at King’s College London. He is the technical lead in the KCL NQR group.
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Mine Detection Technologies Overview
P. Farantatos
Method Range Cost ($) Problems
Metal detector <20 cm <5000 False alarms
Ground Penetrating Radar (GPR) <1 m <10000 False alarms, not for clay soil
Odor ~ cm <10000 Not sensitive enough, wind influence
Nuclear Quadrupole Resonance (NQR) ~ cm >10000 Weak signals
Nuclear Quadrupole Resonance (NQR):
• 14N (found in explosive materials: TNT, RDX) is particularly sensitive to NQR
• Detection specific to the explosive material, not the casing
• Current R&D focus on ameliorating detection strength
Detects explosive content
Detects … metal
Detects large underground anomalies
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NQR Detection System - Requirements
P. Farantatos
• Functional Requirements: Humanitarian Demining Setting
• Low-cost • Portability • Rugged design • Easy to assemble • Low-resource setting adaptable
• Engineering Requirements
• Low power consumption • Off-the-shelf components • Reproducible open-source design • Simple manufacturing specifications • Low-weight
• General technical Specifications for NQR-based explosives detection
• RF power driving circuit • Probe sensor transceiver • DSP RF noise cancellation
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NQR Detection System – Hardware Specs
P. Farantatos
Power Supply
Power Amplifier Spectrometer Probe Circuit Coil
Component Spec Engineering Requirements’ Conformance
Power Supply 12V batteries Low-cost, off-the-shelf available
Spectrometer FPGA-based Low-cost, small size, low-weight
Power Amplifier Class-D In-house design, >90% efficiency, small size, low power consumption, low-weight, low-cost open-source design
Coil Magnetic Loop Antenna Negligible material costs, simplified construction, low-weight, easily reproducible, high efficiency
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Coil Sensor: Electrically-Small Loop Antenna
P. Farantatos
Features Benefits
Hollow copper tube Negligible costs, easy DIY construction, high efficiency
Near-field operation Behaves as magnetic field probe
Diameter dimension Proportional to Anti-Vehicle Landmine size
Plastic encapsulation Suitable for durable operation on-the-field, configurable as an on-the-ground “mat” sensor
(Y. Sotiriou, 2018)
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Resonance freq≠Resonance freq
Ex. sound
Tuning fork
Resonance
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Resonance freq≠Resonance freq
Ex. sound
Tuning fork
Resonance
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Resonance freq≠Resonance freq
Ex. sound
Tuning fork
Resonance freq=Resonance freq
Resonance
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Resonance freq≠Resonance freq
Ex. sound
Tuning fork
Resonance freq=Resonance freq
Absorb
Resonance
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Resonance freq≠Resonance freq
Ex. sound
Tuning fork
Resonance freq=Resonance freq
Absorb Emit
Resonance
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Proton Neutron
AC magnetic
field
Nuclear
AC magnetic
field
Particular frequency
QR (Quadrupole resonance)
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NQR control unit
Transmitter receiver
unit
10 cm
Antenna
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FPGA
Receiver I-V
amplifier
AD
converter Post
amplifier
Cs
Cs’
Cp
Class-D amplifier
NQR control unit Transmitter receiver
unit Antenna
TR switch
Q switch
Power
supply
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FPGA
Receiver I-V
amplifier
AD
converter Post
amplifier
Cs
Cs’
Cp
Class-D amplifier
NQR control unit Transmitter receiver
unit Antenna
TR switch
Q switch
Power
supply
Transmission pulse
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FPGA
Receiver I-V
amplifier
AD
converter Post
amplifier
Cs
Cs’
Cp
Class-D amplifier
NQR control unit Transmitter receiver
unit Antenna
TR switch
Q switch
Power
supply
Transmission pulse
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FPGA
Receiver I-V
amplifier
AD
converter Post
amplifier
Cs
Cs’
Cp
Class-D amplifier
NQR control unit Transmitter receiver
unit Antenna
TR switch
Q switch
Power
supply
Transmission pulse
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FPGA
Receiver I-V
amplifier
AD
converter Post
amplifier
Cs
Cs’
Cp
Class-D amplifier
NQR control unit Transmitter receiver
unit Antenna
TR switch
Q switch
Power
supply
Transmission pulse
Sample
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FPGA
Receiver I-V
amplifier
AD
converter Post
amplifier
Cs
Cs’
Cp
Class-D amplifier
NQR control unit Transmitter receiver
unit Antenna
TR switch
Q switch
Power
supply
Transmission pulse
NQR
signal
Sample
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FPGA
Receiver I-V
amplifier
AD
converter Post
amplifier
Cs
Cs’
Cp
Class-D amplifier
NQR control unit Transmitter receiver
unit Antenna
TR switch
Q switch
Power
supply
Transmission pulse
NQR
signal
Sample
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FPGA
Receiver I-V
amplifier
AD
converter Post
amplifier
Cs
Cs’
Cp
Class-D amplifier
NQR control unit Transmitter receiver
unit Antenna
TR switch
Q switch
Power
supply
Transmission pulse
NQR
signal
Sample
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Where we were
35 kg
Mains powered
£35,000
Where we are
1 kg
Portable battery
£1,000
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Previous control unit
New control unit with a power
amplifier
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Control board
DE0-Nano Development and Education Board
(Altera corp.)
$79
Size:49*75.2mm
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Class D amp
(Z~1 ) Commercial amp
(Z=50 )
Power amplifier
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Class D amp
(Z~1 ) Commercial amp
(Z=50 )
x 1/10
Power amplifier
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Field test at Columbia
System for Ammonium nitrite
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• In NQR signal detection, interference can be a major hurdle in detecting the NQR from the signal of interest.
• Interference can be caused by several factors such as impurities in the NQR sample, due to detection hardware or the background environment.
• Main cause of the interference are signals due to radio transmission in the outdoor environment and it is difficult to shield against at it.
Interference Problem in NQR
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• In order to cancel the interference, we first divide the data into small parts, with each part containing a single echo, and then we performs interference cancellation for each part separately.
• It is done by setting a fixed threshold value which equals to twice the value of the average threshold spectrum intensity.
• This cancels all the interference frequency components whose spectrum intensities are higher than the threshold.
Interference Cancellation in NQR Signal
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Results for Interference Cancellation
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THANK YOU FOR YOUR ATTENTION!