Recent work in context-dependent processing for buried threat detection has revealed the potential of exploiting correlated environmental parameters in ground-penetrating radar (GPR) imaging, detection and discrimination, as well as data fusion approaches. In order to fully understand the physical phenomenology and develop performance predictions, we need to correlate measurable environmental parameters to GPR performance. We focus on hydro-meteorological and hydrogeologic properties such as temperature, humidity, soil water matric potential, soil water content, and sediment density and texture to understand the hydrogeophysical relationships and methods to incorporate them into optimal experimental design and data processing. Varying levels of data and information quality are assessed to quantify the sensitivity of GPR acquisition and processing methods to environmental contextual information. Both numerical modeling and experimental data collection are used to evaluate soil water controls on three-dimensional electromagnetic wave propagation. We present the analysis of experimental data collected in a new instrumented test bed facility constructed for assessing various configurations of air- or ground-coupled GPR systems. We assess factors such volume integration scale, measurement scaling and accuracy of the various hydro-electromagnetic sensing methods in terms of understanding multi-static radar angular illumination and imaging performance.
We recently developed a new, man-portable, electromagnetic induction (EMI) sensor designed to detect and classify small, unexploded sub-munitions and discriminate them from non-hazardous debris. The ability to distinguish innocuous metal clutter from potentially hazardous unexploded ordnance (UXO) and other explosive remnants of war (ERW) before excavation can significantly accelerate land reclamation efforts by eliminating time spent removing harmless scrap metal. The EMI sensor employs a multi-axis transmitter and receiver configuration to produce data sufficient for anomaly discrimination. A real-time data inversion routine produces intrinsic and extrinsic anomaly features describing the polarizability, location, and orientation of the anomaly under test. We discuss data acquisition and post-processing software development, and results from laboratory and field tests demonstrating the discrimination capability of the system. Data acquisition and real-time processing emphasize ease-of-use, quality control (QC), and display of discrimination results. Integration of the QC and discrimination methods into the data acquisition software reduces the time required between sensor data collection and the final anomaly discrimination result. The system supports multiple concepts of operations (CONOPs) including: 1) a non-GPS cued configuration in which detected anomalies are discriminated and excavated immediately following the anomaly survey; 2) GPS integration to survey multiple anomalies to produce a prioritized dig list with global anomaly locations; and 3) a dynamic mapping configuration supporting detection followed by discrimination and excavation of targets of interest.
The implementation of new advanced electromagnetic induction (EMI) sensor surveys at sites containing unexploded
ordnance (UXO) and explosive remnants of war (ERW) is an effective method for accurate mapping and for discriminating
clutter from targets of interest. We present development and integration of a next generation advanced EMI sensor onto a
cart-based sensing platform to combine the mapping capability of previous digital geophysical survey instruments with
the high-resolution discrimination capability of advanced characterization arrays. The EMI sensor employs a multi-axis
receiver configuration to produce data sufficient for anomaly discrimination. We discuss platform design and
development, data acquisition and post-processing software development, and results from field tests demonstrating the
detection and discrimination capability of the cart-based system. Platform development and design focused on navigation
and EMI sensor integration onto a custom, low-noise, metal-free platform. Data acquisition is via an Android application
with emphasis on ease-of-use and real-time quality control (QC) of collected data. Post-processing methods emphasize
QC, inversion-based anomaly location estimation, and automated or supervised polarizability-based discrimination
methods to produce a prioritized dig list. Integration of the detection, clutter rejection and QC methods into the post-processing
software module reduces the time required between sensor data collection and generation of a prioritized dig
list. System concept of operations (CONOPs), data collection, QC, data processing procedures, and performance against
various clutter objects and targets of interest will also be discussed.
Standard protocol for detection and classification of Unexploded Ordnance (UXO) comprises a two-step process that includes an initial digital geophysical mapping (DGM) survey to detect magnetic field anomalies followed by a cued survey at each anomaly location that enables classification of these anomalies. The initial DGM survey is typically performed using a low resolution single axis electromagnetic induction (EMI) sensor while the follow-up cued survey requires revisiting each anomaly location with a multi-axis high resolution EMI sensor. The DGM survey comprises data collection in tightly spaced transects over the entire survey area. Once data collection in this area is complete, a threshold analysis is applied to the resulting magnetic field anomaly map to identify anomalies corresponding to potential targets of interest (TOI). The cued sensor is deployed in static mode where this higher resolution sensor is placed over the location of each anomaly to record a number of soundings that may be stacked and averaged to produce low noise data. These data are of sufficient quality to subsequently classify the object as either TOI or clutter. While this approach has demonstrated success in producing effective classification of UXO, conducting successive surveys is time consuming. Additionally, the low resolution of the initial DGM survey often produces errors in the target picking process that results in poor placement of the cued sensor and often requires several revisits to the anomaly location to ensure adequate characterization of the target space. We present data and test results from an advanced multi-axis EMI sensor optimized to provide both detection and classification from a single survey. We demonstrate how the large volume of data from this sensor may be used to produce effective detection and classification decisions while only requiring one survey of the munitions response area.
KEYWORDS: Sensors, Electromagnetic coupling, Target detection, Magnetism, Data acquisition, Explosives, Receivers, Signal to noise ratio, Neodymium, Signal detection
The remediation of explosive remnants of war (ERW) and associated unexploded ordnance (UXO) has seen improvements through the injection of modern technological advances and streamlined standard operating procedures. However, reliable and cost-effective detection and geophysical mapping of sites contaminated with UXO such as cluster munitions, abandoned ordnance, and improvised explosive devices rely on the ability to discriminate hazardous items from metallic clutter. In addition to anthropogenic clutter, handheld and vehicle-based metal detector systems are plagued by natural geologic and environmental noise in many post conflict areas. We present new and advanced electromagnetic induction (EMI) technologies including man-portable and towed EMI arrays and associated data processing software. While these systems feature vastly different form factors and transmit-receive configurations, they all exhibit several fundamental traits that enable successful classification of EMI anomalies. Specifically, multidirectional sampling of scattered magnetic fields from targets and corresponding high volume of unique data provide rich information for extracting useful classification features for clutter rejection analysis. The quality of classification features depends largely on the extent to which the data resolve unique physics-based parameters. To date, most of the advanced sensors enable high quality inversion by producing data that are extremely rich in spatial content through multi-angle illumination and multi-point reception.
KEYWORDS: Electromagnetic coupling, Data modeling, Target detection, Magnetism, Data processing, Transmitters, Sensors, Detection and tracking algorithms, Systems modeling, Polarizability
One of the most challenging aspects of survey data processing is target selection. The fundamental input for the classification is dynamic data collected along survey lines. These data are different from the static data obtained in cued mode and used for target classification. Survey data are typically collected using just one transmitter loop (the Z-axis loop) and feature short data point collection times and short decay transience. The collection intervals for each data point are typically 0.1 s, and the signal repetition rates are typically 90 or 270 Hz (in other words, the transient decay times are 2.7 ms or 0.9 ms). Reliable classification requires multiple side/angle illumination; i.e., to conduct reliable classification it is necessary to combine and jointly invert multiple data points. However, picking data points that provide optimal information for classifying targets is a difficult task. The traditional method plots signal amplitudes on a 2D map and picks peaks of signal level without properly accounting for the underlying physics. In this paper, the joint diagonalization is applied to survey data sets to improve data pre-processing and target picking. The JD technique is an EMI data analysis and target classification technique and is applicable for all next-generation multi-static array EMI sensors. The method extracts multi-static response data matrix eigenvalues. The eigenvalues are main characteristics of the data. Recent studies have demonstrated that the method has great potential to quickly estimate the number of potential targets and moreover classify these targets at the data pre-processing stage, in real time and without the need for a forward model. Another advantage of JD is that it provides the ability to separate signal from noise making it possible to de-noise data without distorting the signal due to the targets. In this paper the JD technique is used to process dynamic data collected at South West Proving Ground and Aberdeen Proving Ground (APG) sites using the 2 × 2 TEMTADS and OPTEMA systems, respectively. The joint eigenvalues are extracted as functions of time for each data point and summed/stacked together before being used to create detection maps. Once targets are detected, a set of data is chosen for each anomaly and inverted using the ortho-normalized volume magnetic source technique.
Land reclamation efforts in post-conflict regions are often hampered by the presence of Unexploded Ordnance (UXO) or other Explosive Remnants of War (ERW). Surface geophysical methods, such as Electromagnetic Induction (EMI) and magnetometry, are typically applied to screen rehabilitation areas for UXO prior to excavation; however, the prevalence of innocuous magnetic clutter related to indigenous scrap, fragmentation, or geology can severely impede the progress and efficiency of these remediation efforts. Additionally, the variability in surface conditions and local topography necessitates the development of sensor technologies that can be applied to a range of sites including those that prohibit the use of vehicle-mounted or large array systems. We present a man-portable EMI sensor known as the Electromagnetic Packable Technology (EMPACT) system that features a multi-axis sensor configuration in a compact form factor. The system is designed for operation in challenging site conditions and can be used in low ground-standoff modes to detect small and low-metal content objects. The EMPACT acquires high spatial density, multi-axis data that enable high resolution of small objects. This high density data can also be used to provide characterization of target physical features, such as size, material content, and shape. We summarize the development of this system for humanitarian demining operations and present results from preliminary system evaluations against a range of target types. Specifically, we assess the general detection capabilities of the EMPACT system and we evaluate the potential for target classification based on analysis of data and target model features.
Detection and discrimination of unexploded ordnance (UXO) in areas of prior conflict is of high importance to the international community and the United States government. For humanitarian applications, sensors and processing methods need to be robust, reliable, and easy to train and implement using indigenous UXO removal personnel. This paper describes system characterization, system testing, and a continental United States (CONUS) Operational Field Evaluations (OFE) of the PAC-MAG man-portable UXO detection system. System testing occurred at a government test facility in June, 2010 and December, 2011 and the OFE occurred at the same location in June, 2012. NVESD and White River Technologies personnel were present for all testing and evaluation. The PAC-MAG system is a manportable magnetometer array for the detection and characterization of ferrous UXO. System hardware includes four Cesium vapor magnetometers for detection, a Real-time Kinematic Global Position System (RTK-GPS) for sensor positioning, an electronics module for merging array data and WiFi communications and a tablet computer for transmitting and logging data. An odometer, or “hipchain” encoder, provides position information in GPS-denied areas. System software elements include data logging software and post-processing software for detection and characterization of ferrous anomalies. The output of the post-processing software is a dig list containing locations of potential UXO(s), formatted for import into the system GPS equipment for reacquisition of anomalies. Results from system characterization and the OFE will be described.
This paper illustrates the discrimination performance of a set of advanced models at an actual UXO live site. The suite of
methods, which combines the orthonormalized volume magnetic source (ONVMS) model, a data-preprocessing
technique based on joint diagonalization (JD), and differential evolution (DE) minimization, among others, was tested at
the former Camp Beale in California. The data for the study were collected independently by two UXO production teams
from Parsons and CH2M HILL using the MetalMapper (MM) sensor in cued mode; each set of data was also processed
independently. Initially all data were inverted using a multi-target version of the combined ONVMS-DE algorithm,
which provided intrinsic parameters (the total ONVMS amplitudes) that were then used to perform classification after
having been inspected by an expert. Classification of the Parsons data was conducted by a Sky Research production team
using a fingerprinting approach; analysis of the CH2M HILL data was performed by a Sky/Dartmouth R&D team using
unsupervised clustering. During the classification stage the analysts requested the ground truth for selected anomalies
typical of the different clusters; this was then used to classify them using a probability function. This paper reviews the
data inversion, processing, and discrimination schemes involving the advanced EMI methods and presents the
classification results obtained for both the CH2M HILL and the Parsons data. Independent scoring by the Institute for
Defense Analyses reveals superb all-around classification performance.
This paper presents an active source Electromagnetic Induction (EMI) sensor that offers extended detection ranges (>
2m) with minimal sensitivity to magnetic geology. The Ultra Deep Search (ULTRA) EMI system employs a large (20 -
40m), stationary, surface-laid transmitter loop that produces a relatively uniform magnetic field within the search region.
This primary field decays slowly with depth due to the non-dipolar nature of the field within the search volume. An
array of 3-axis receiver cubes measures the time derivative of secondary field decays produced by subsurface metallic
objects. The large-loop transmitter combined with the vector sensing induction coil receivers produces a deep search
capability that remains robust in environments containing highly magnetic soils. In this paper, we assess the general
detection capabilities of the ULTRA system and present data collected over a set of standardized UXO targets.
Additionally, we evaluate the potential for target feature extraction through dipole fit analysis of several data sets.
KEYWORDS: Magnetometers, Global Positioning System, Magnetism, Magnetic sensors, Sensors, Data acquisition, Land mines, Standards development, Target detection, Data processing
Detection and discrimination of unexploded ordnance (UXO) in areas of prior conflict is of high importance to the
international community and the United States government. For humanitarian applications, sensors and processing
methods need to be robust, reliable, and easy to train and implement using indigenous UXO removal personnel. This
paper focuses on magnetometer sensing techniques, processing, and operation for UXO detection and discrimination
applications. Specifically, we discuss the collection, processing, and discrimination of data collected using the PACMAG
man-portable system consisting of arrays of sensitive total-field magnetometers, global positioning (GPS)
combined with digital odometers, and a data acquisition system. We outline preliminary standard operating procedures
for optimal collection of UXO-induced magnetic fields and associated position data using either a GPS, or odometer
when surveying in GPS-denied areas. Processing techniques such as gridding and filtering, target picking, and
discrimination lead to estimates of target size and location. Emphasis is placed on simplifying the production of
magnetometer hardware and software for use by minimally-trained personnel with no advanced knowledge of magnetic
sensing and geophysics.
KEYWORDS: Magnetism, Sensors, Data modeling, Data acquisition, Electromagnetic coupling, Signal to noise ratio, Mathematical modeling, Data centers, Electromagnetism, Detection and tracking algorithms
The challenges associated with removing UXO and explosive remnants of war have led to a variety of methods for
detection and discrimination of buried metallic objects using time-domain electromagnetic induction (EMI). Recent
work has shown that parameters recovered from physics-based inversions can discriminate and classify buried ordnance
from non-ordnance. We present results of applying advanced processing to data from a dynamically repositioned multiaxis
EMI instrument. Data are collected using an adaptive sampling process to find the center of the anomaly and collect
minimal data while maintaining model fidelity. An ortho-normalized volume magnetic source (ONVMS) model is used
to resolve various targets at different depths. The ONVMS model is a generalized volume dipole model, with the single
dipole model being a special limiting case. Using the ONVMS model, an object's response to a sensor's primary
magnetic field is modeled mathematically by a set of equivalent magnetic dipoles distributed inside a volume containing
the object. We assess the utility and veracity of the dynamic sampling strategy coupled with the ONVMS model on data
acquired over a set of calibration and simulant targets. Rapid target characterization codes are aggregated into a software
package with particular focus on ease of use for non-expert users.
Because the recovery of underwater munitions is many times more expensive than recovering the same items on dry
land, there is a continuing need to advance marine geophysical characterization methods. To efficiently and reliably
conduct surveying in marine environments, low-noise geophysical sensors are being configured to operate close to the
sea bottom. We describe systems that are deployed from surface vessels via rigid or flexible tow cables or mounted
directly to submersible platforms such as unmanned underwater vehicles. Development and testing of a towed
configuration has led to a 4 meter wide hydrodynamically stable tow wing with an instrumented top-side assembly
mounted on the stern of a surface survey vessel. An integrated positioning system combined with an instrumented cable
management system, vessel and wing attitude and wing depth measurements to provide sub-meter positional accuracy in
up to 25 meter water depths and within 1 to 2 meters of the seafloor. We present the results of data collected during an
instrument validation survey over a series of targets emplaced at measured locations. Performance of the system was
validated through analyses of data collected at varying speeds, headings, and height above the seafloor. Implementation
of the system during live-site operations has demonstrated its capability to survey hundreds of acres of marine or
lacustrine environment. Unique deployment concepts that utilize new miniaturized and very low noise sensors show
promise for expanding the applicability of magnetic sensing at marine sites.
The Nemesis detection system has been developed to provide an efficient and reliable unmanned, multi-sensor, groundbased
platform to detect and mark landmines. The detection system consists of two detection sensor arrays: a Ground
Penetrating Synthetic Aperture Radar (GPSAR) developed by Planning Systems, Inc. (PSI) and an electromagnetic
induction (EMI) sensor array developed by Minelab Electronics, PTY. Limited. Under direction of the Night Vision and
Electronic Sensors Directorate (NVESD), overseas testing was performed at Kampong Chhnang Test Center (KCTC),
Cambodia, from May 12-30, 2008. Test objectives included: evaluation of detection performance, demonstration of
real-time visualization and alarm generation, and evaluation of system operational efficiency. Testing was performed on
five sensor test lanes, each consisting of a unique soil mixture and three off-road lanes which include curves,
overgrowth, potholes, and non-uniform lane geometry. In this paper, we outline the test objectives, procedures, results,
and lessons learned from overseas testing. We also describe the current state of the system, and plans for future
enhancements and modifications including clutter rejection and feature-level fusion.
Both force protection and humanitarian demining missions require efficient and reliable detection and discrimination of
buried anti-tank and anti-personnel landmines. Widely varying surface and subsurface conditions, mine types and
placement, as well as environmental regimes challenge the robustness of the automatic target recognition process. In
this paper we present applications created for the U.S. Army Nemesis detection platform. Nemesis is an unmanned
rubber-tracked vehicle-based system designed to eradicate a wide variety of anti-tank and anti-personnel landmines for
humanitarian demining missions. The detection system integrates advanced ground penetrating synthetic aperture radar
(GPSAR) and electromagnetic induction (EMI) arrays, highly accurate global and local positioning, and on-board target
detection/classification software on the front loader of a semi-autonomous UGV. An automated procedure is developed
to estimate the soil's dielectric constant using surface reflections from the ground penetrating radar. The results have
implications not only for calibration of system data acquisition parameters, but also for user awareness and tuning of
automatic target recognition detection and discrimination algorithms.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.