Physical properties, such as soil moisture, magnetic susceptibility and electrical conductivity (... more Physical properties, such as soil moisture, magnetic susceptibility and electrical conductivity (EC) are sources of signal interference for many landmine detectors. Soil EC mechanisms and their relationship to moisture are being studied to increase the soil EC prediction accuracy by radar remote sensing, airborne and ground electromagnetic (EM) methods. This is required for effective detection operations in problematic regions of
ABSTRACT Defence R&D Canada (DRDC), an agency within the Department of National Defence, ... more ABSTRACT Defence R&D Canada (DRDC), an agency within the Department of National Defence, has been conducting research and development (R&D) on the detection of landmines for countermine operations and of unexploded ordnance (UXO) for range clearance since 1975. The Canadian Centre for Mine Action Technologies (CCMAT), located at DRDC Suffield, was formed in 1998 to carry out R&D related to humanitarian demining. The lead group responsible for formulating and executing both countermine and humanitarian R&D programs in detection is the Threat Detection Group at DRDC Suffield. This paper describes R&D for both programs under the major headings of remote minefield detection, close-in scanning detection, confirmation detection and teleoperated systems. Among DRDC's achievements in landmine and UXO detection R&D are pioneering work in electromagnetic and magnetic identification and classification; the first military-fielded multisensor, teleoperated vehicle-mounted landmine detection system; pioneering use of confirmation detectors for multisensor landmine detection systems; the first fielded thermal neutron activation landmine confirmation sensor; the first detection of landmines using a real-time hyperspectral imager; electrical impedance imaging detection of landmines and UXO and a unique neutron backscatter landmine imager.
Symposium on Antenna Technology and Applied Electromagnetics, Aug 1, 1988
Experiment· were conducted to measure the response characteristic· of a detector system consistin... more Experiment· were conducted to measure the response characteristic· of a detector system consisting of an array of two electromagnetic pulse induction tensor·. Laboratory data for three object : (1)a ıteel sphere (2) a steel prolate spheroid and (3) an 81 mm mortar casing are presented in order to discuss how the response of an object varies with its depth, orientation and lateral offset from coil centres. Relevance of these result· to developing algorithms for location of metallic objects are also pointed out. Finally, data obtained from a scan over buried targets are presented to illustrate a practical application.
1990 Symposium on Antenna Technology and Applied Electromagnetics, 1990
A simple model is used to explain spatial response characteristics of an electromagnetic inductio... more A simple model is used to explain spatial response characteristics of an electromagnetic induction detector as it scans over a metallic object. The technique is illustrated with numerical and experimental data for two mechanically identical prolate spheroids, one made of steel and the other of aluminium. Some basic differences in the response characteristics of a permeable and a non-permeable object are pointed out and explained.
1988 Symposium on Antenna Technology and Applied Electromagnetics, 1988
The static magnetic dipole inversion problem is related to the problem of location and identifica... more The static magnetic dipole inversion problem is related to the problem of location and identification of compact ferrous objects. It is shown that the inversion of the dipole field or gradient is a necessary first step toward determining object location and identity. Several recursive and nonrecursive methods of determining dipole moment and location from field or gradient measurements are described and compared. It is shown that given dipole moment estimates, it is possible to determine the identity of the dipole source in practical situations by pattern recognition.
1990 Symposium on Antenna Technology and Applied Electromagnetics, 1990
Location and identification of compact ferrous objects is of major concern for detection of vehic... more Location and identification of compact ferrous objects is of major concern for detection of vehicles, submarines, achaeological objects, buried or hidden explosive objects, geological ore inclusions and inclusions in the human body. In principle, measurement of the spatial variation of the magnetostatic field associated with a compact ferrous object may be used to locate and identify the object and considerable success has been achieved in this area [1].
An automated system which measures, coherently averages, and stores time domain electromagnetic i... more An automated system which measures, coherently averages, and stores time domain electromagnetic induction responses of conductive objects and allows on-line analysis of the data is described. The sensor portion of the system consists of a set of coils, transmit and receive circuitry situated in a remote nonmetallic laboratory. The circuitry is controlled by a specialized high-speed data-acquisition system which communicates, through a microcomputer, with a distant mainframe computer. Advanced inductive load switching techniques are employed and errors due to temperature variations in the coils are minimized by suitable sensor design. The user can change date-collection parameters, such as pulse length, dwell time, and transmitter waveform shape, under program control to tailor the system to a particular application. The design also allows for easy replacement of the sensor elements; i.e., coils, receive and transmit circuitry as different applications require. This flexibility allows the system to be readily adapted for research in a number of areas that rely on measurement of electromagnetic induction responses. A typical response may be obtained in less than 1 min. The minimum time resolution of the system is 4 μs. Noise levels of 3 to 5 mV standard deviation are obtainable for 500 averages. Data are presented to demonstrate the capabilities of the system.
Detection and Remediation Technologies for Mines and Minelike Targets IX, 2004
Physical properties, such as soil moisture, magnetic susceptibility and electrical conductivity (... more Physical properties, such as soil moisture, magnetic susceptibility and electrical conductivity (EC) are sources of signal interference for many landmine detectors. Soil EC mechanisms and their relationship to moisture are being studied to increase the soil EC prediction accuracy by radar remote sensing, airborne and ground electromagnetic (EM) methods. This is required for effective detection operations in problematic regions of
The Improved Landmine Detector Project ILDP was initiated in Autumn 1994 to develop a prototype t... more The Improved Landmine Detector Project ILDP was initiated in Autumn 1994 to develop a prototype teleoperated vehicle mounted mine detector for low metal content and nonmetallic mines to meet the Canadian requirements for rear area mine clearance in combat situations and peacekeeping on roads and tracks. The relatively relaxed requirements, such as low speed and reduced detectability of completely nonmetallic mines, greatly increase the likelihood of success. The ILDP system consists of a unique teleoperated vehicle carrying a forward looking infrared imager, a 3 m wide down-looking highly sensitive electromagnetic induction detector and a 3 m wide down-looking ground probing radar, which all scan the ground in front of the vehicle. Scanning sensor information is combined using a suite of navigation sensors and custom designed navigation, spatial correspondence and data fusion algorithms. Suspect targets are then con rmed by a thermal neutron analysis detector. A key element to the success of the system is the combination of sensor information. This requires coordinated communication between the sensors and navigation system and well designed sensor co-registration, spatial correspondence and data fusion methodologies. These complex tasks are discussed in detail. The advanced development model was completed in October 1997 and testing and improvements are ongoing. Results of system performance during extensive eld trials are presented. A follow-on project has been initiated to build four to six production units for the Canadian Forces by the year 2000.
1988 IEEE AP-S. International Symposium, Antennas and Propagation
Low-frequency transient response is often used to detect or identify buried objects. At sufficien... more Low-frequency transient response is often used to detect or identify buried objects. At sufficiently low frequencies, the signal penetration in the ground is high and the air-earth interface has a negligible effect on the return response. The use of an exciting current loop also minimizes the ground conductivity effect. These properties are used to develop an efficient numerical method to
IEEE Transactions on Geoscience and Remote Sensing, 1991
An efficient numerical technique is presented for electromagnetic scattering in the near-field zo... more An efficient numerical technique is presented for electromagnetic scattering in the near-field zone by three-dimensional permeable conducting objects excited by a loop antenna. The impedance boundary conditions are used to simplify the formulation and reduce the computation time and memory. Numerical results are presented to illustrate the dependence of the scattered field on the physical characteristics of the scatterer and
... a part of some multisensor military systems [6], the detection of antipersonnel land-mines co... more ... a part of some multisensor military systems [6], the detection of antipersonnel land-mines continues ... Manufacturers of detectors could also use such information in improving their detectors. ... In the following we present some issues, specific to the humanitarian demining problem ...
... targets, such as larger pieces of scrap, loops of wire, metal anti-vehicle mines or ... the f... more ... targets, such as larger pieces of scrap, loops of wire, metal anti-vehicle mines or ... the feasibility of applying a thermal infrared (TIR) hyperspectral imager for land-mine detection was ... However, TIR hyperspectral imagers suitable for landmine detection are very scarce, the only ...
IEEE Transactions on Pattern Analysis and Machine Intelligence, 1984
with probability greater than 1-4/Mb 2. Since 8 was arbitrary, for M sufficiently large d is arbi... more with probability greater than 1-4/Mb 2. Since 8 was arbitrary, for M sufficiently large d is arbitrarily close to d with probability arbitrarily close to 1. So d is a consistent estimate. Q.E.D. Corollary: The estimate d as given by (5.4
This paper discusses methods of location and identification of compact metallic and ferrous objec... more This paper discusses methods of location and identification of compact metallic and ferrous objects using magnetometers and electromagnetic pulse induction. To date, no commercially available systems exist which can explicitly and accurately estimate the location of a compact ferrous or metallic object and identify it reliably. Self-contained systems which could do so in real-time would represent a significant advance in the state-of-the-art.
Physical properties, such as soil moisture, magnetic susceptibility and electrical conductivity (... more Physical properties, such as soil moisture, magnetic susceptibility and electrical conductivity (EC) are sources of signal interference for many landmine detectors. Soil EC mechanisms and their relationship to moisture are being studied to increase the soil EC prediction accuracy by radar remote sensing, airborne and ground electromagnetic (EM) methods. This is required for effective detection operations in problematic regions of
ABSTRACT Defence R&D Canada (DRDC), an agency within the Department of National Defence, ... more ABSTRACT Defence R&D Canada (DRDC), an agency within the Department of National Defence, has been conducting research and development (R&D) on the detection of landmines for countermine operations and of unexploded ordnance (UXO) for range clearance since 1975. The Canadian Centre for Mine Action Technologies (CCMAT), located at DRDC Suffield, was formed in 1998 to carry out R&D related to humanitarian demining. The lead group responsible for formulating and executing both countermine and humanitarian R&D programs in detection is the Threat Detection Group at DRDC Suffield. This paper describes R&D for both programs under the major headings of remote minefield detection, close-in scanning detection, confirmation detection and teleoperated systems. Among DRDC's achievements in landmine and UXO detection R&D are pioneering work in electromagnetic and magnetic identification and classification; the first military-fielded multisensor, teleoperated vehicle-mounted landmine detection system; pioneering use of confirmation detectors for multisensor landmine detection systems; the first fielded thermal neutron activation landmine confirmation sensor; the first detection of landmines using a real-time hyperspectral imager; electrical impedance imaging detection of landmines and UXO and a unique neutron backscatter landmine imager.
Symposium on Antenna Technology and Applied Electromagnetics, Aug 1, 1988
Experiment· were conducted to measure the response characteristic· of a detector system consistin... more Experiment· were conducted to measure the response characteristic· of a detector system consisting of an array of two electromagnetic pulse induction tensor·. Laboratory data for three object : (1)a ıteel sphere (2) a steel prolate spheroid and (3) an 81 mm mortar casing are presented in order to discuss how the response of an object varies with its depth, orientation and lateral offset from coil centres. Relevance of these result· to developing algorithms for location of metallic objects are also pointed out. Finally, data obtained from a scan over buried targets are presented to illustrate a practical application.
1990 Symposium on Antenna Technology and Applied Electromagnetics, 1990
A simple model is used to explain spatial response characteristics of an electromagnetic inductio... more A simple model is used to explain spatial response characteristics of an electromagnetic induction detector as it scans over a metallic object. The technique is illustrated with numerical and experimental data for two mechanically identical prolate spheroids, one made of steel and the other of aluminium. Some basic differences in the response characteristics of a permeable and a non-permeable object are pointed out and explained.
1988 Symposium on Antenna Technology and Applied Electromagnetics, 1988
The static magnetic dipole inversion problem is related to the problem of location and identifica... more The static magnetic dipole inversion problem is related to the problem of location and identification of compact ferrous objects. It is shown that the inversion of the dipole field or gradient is a necessary first step toward determining object location and identity. Several recursive and nonrecursive methods of determining dipole moment and location from field or gradient measurements are described and compared. It is shown that given dipole moment estimates, it is possible to determine the identity of the dipole source in practical situations by pattern recognition.
1990 Symposium on Antenna Technology and Applied Electromagnetics, 1990
Location and identification of compact ferrous objects is of major concern for detection of vehic... more Location and identification of compact ferrous objects is of major concern for detection of vehicles, submarines, achaeological objects, buried or hidden explosive objects, geological ore inclusions and inclusions in the human body. In principle, measurement of the spatial variation of the magnetostatic field associated with a compact ferrous object may be used to locate and identify the object and considerable success has been achieved in this area [1].
An automated system which measures, coherently averages, and stores time domain electromagnetic i... more An automated system which measures, coherently averages, and stores time domain electromagnetic induction responses of conductive objects and allows on-line analysis of the data is described. The sensor portion of the system consists of a set of coils, transmit and receive circuitry situated in a remote nonmetallic laboratory. The circuitry is controlled by a specialized high-speed data-acquisition system which communicates, through a microcomputer, with a distant mainframe computer. Advanced inductive load switching techniques are employed and errors due to temperature variations in the coils are minimized by suitable sensor design. The user can change date-collection parameters, such as pulse length, dwell time, and transmitter waveform shape, under program control to tailor the system to a particular application. The design also allows for easy replacement of the sensor elements; i.e., coils, receive and transmit circuitry as different applications require. This flexibility allows the system to be readily adapted for research in a number of areas that rely on measurement of electromagnetic induction responses. A typical response may be obtained in less than 1 min. The minimum time resolution of the system is 4 μs. Noise levels of 3 to 5 mV standard deviation are obtainable for 500 averages. Data are presented to demonstrate the capabilities of the system.
Detection and Remediation Technologies for Mines and Minelike Targets IX, 2004
Physical properties, such as soil moisture, magnetic susceptibility and electrical conductivity (... more Physical properties, such as soil moisture, magnetic susceptibility and electrical conductivity (EC) are sources of signal interference for many landmine detectors. Soil EC mechanisms and their relationship to moisture are being studied to increase the soil EC prediction accuracy by radar remote sensing, airborne and ground electromagnetic (EM) methods. This is required for effective detection operations in problematic regions of
The Improved Landmine Detector Project ILDP was initiated in Autumn 1994 to develop a prototype t... more The Improved Landmine Detector Project ILDP was initiated in Autumn 1994 to develop a prototype teleoperated vehicle mounted mine detector for low metal content and nonmetallic mines to meet the Canadian requirements for rear area mine clearance in combat situations and peacekeeping on roads and tracks. The relatively relaxed requirements, such as low speed and reduced detectability of completely nonmetallic mines, greatly increase the likelihood of success. The ILDP system consists of a unique teleoperated vehicle carrying a forward looking infrared imager, a 3 m wide down-looking highly sensitive electromagnetic induction detector and a 3 m wide down-looking ground probing radar, which all scan the ground in front of the vehicle. Scanning sensor information is combined using a suite of navigation sensors and custom designed navigation, spatial correspondence and data fusion algorithms. Suspect targets are then con rmed by a thermal neutron analysis detector. A key element to the success of the system is the combination of sensor information. This requires coordinated communication between the sensors and navigation system and well designed sensor co-registration, spatial correspondence and data fusion methodologies. These complex tasks are discussed in detail. The advanced development model was completed in October 1997 and testing and improvements are ongoing. Results of system performance during extensive eld trials are presented. A follow-on project has been initiated to build four to six production units for the Canadian Forces by the year 2000.
1988 IEEE AP-S. International Symposium, Antennas and Propagation
Low-frequency transient response is often used to detect or identify buried objects. At sufficien... more Low-frequency transient response is often used to detect or identify buried objects. At sufficiently low frequencies, the signal penetration in the ground is high and the air-earth interface has a negligible effect on the return response. The use of an exciting current loop also minimizes the ground conductivity effect. These properties are used to develop an efficient numerical method to
IEEE Transactions on Geoscience and Remote Sensing, 1991
An efficient numerical technique is presented for electromagnetic scattering in the near-field zo... more An efficient numerical technique is presented for electromagnetic scattering in the near-field zone by three-dimensional permeable conducting objects excited by a loop antenna. The impedance boundary conditions are used to simplify the formulation and reduce the computation time and memory. Numerical results are presented to illustrate the dependence of the scattered field on the physical characteristics of the scatterer and
... a part of some multisensor military systems [6], the detection of antipersonnel land-mines co... more ... a part of some multisensor military systems [6], the detection of antipersonnel land-mines continues ... Manufacturers of detectors could also use such information in improving their detectors. ... In the following we present some issues, specific to the humanitarian demining problem ...
... targets, such as larger pieces of scrap, loops of wire, metal anti-vehicle mines or ... the f... more ... targets, such as larger pieces of scrap, loops of wire, metal anti-vehicle mines or ... the feasibility of applying a thermal infrared (TIR) hyperspectral imager for land-mine detection was ... However, TIR hyperspectral imagers suitable for landmine detection are very scarce, the only ...
IEEE Transactions on Pattern Analysis and Machine Intelligence, 1984
with probability greater than 1-4/Mb 2. Since 8 was arbitrary, for M sufficiently large d is arbi... more with probability greater than 1-4/Mb 2. Since 8 was arbitrary, for M sufficiently large d is arbitrarily close to d with probability arbitrarily close to 1. So d is a consistent estimate. Q.E.D. Corollary: The estimate d as given by (5.4
This paper discusses methods of location and identification of compact metallic and ferrous objec... more This paper discusses methods of location and identification of compact metallic and ferrous objects using magnetometers and electromagnetic pulse induction. To date, no commercially available systems exist which can explicitly and accurately estimate the location of a compact ferrous or metallic object and identify it reliably. Self-contained systems which could do so in real-time would represent a significant advance in the state-of-the-art.
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Papers by Yogadhish Das