CASR

Canadian
American
Strategic
Review

Canadian Forces Landmine Detection and Mineclearing  —  November 2004 ILDS  —  the Improved Landmine Detection System : A Quick Summary of the Mine Detection Systems Behind the CF’s Remote ILDS Part 2:  Background on Canadian Forces Remotely-Operated Landmine Detection. Magnets and Neutrons: A Summary of ILDS Mine Detection Sensor Technologies The ‘Improved Landmine Detection System’ uses four distinct sensor technologies: metal detection, infrared thermal imaging , ground-penetrating radar , and  ‘TNA’ or thermal neutron activation detection.  Each of  these ILDS sensor technologies (and their application to the Protection Vehicle (PV) or Remote Detection Vehicle (RDV) is described below. [The disruptive action of the PV’s mine plough (Surface Munitions Clearing Device) was described in  Part 1:  Vehicle Types and Vehicular Operations]. Metal Detectors  –  Magnetic Signature Duplicator and Minimum Metal Detector Two types of metal detectors are employed by ILDS. The tracked PV uses mine plough-mounted Magnetic Signature Duplicators. The MSD can locate magnetic influence mines (ie: mines – usually anti-tank types – with fuses activated by magnetic influences such as vehicles). The small, wheeled RDV (left) has an rack- mounted Minimum Metal Detector. As suggested by its name, the MMD is designed to detect ‘minimum metal content’ mines (such mines have plastic cases and parts but even stainless steel parts can be difficult to detect). The MMD uses electromagnetic induction to detect the smallest metal parts in fuses, fasteners, and other tiny components within a plastic-cased mine (which might elude conventional hand-held metal detectors such as the CF’s AN-19/2 set).  The MMD’s electromagnetic induction (EMI) array (developed for ILDS by Schiebel Systems Ltd. Canada) uses 24 overlapping transmit/receive coil pairs. To be effective, the detector must pass as close as possible to the surface (hence the adjustable MMD rack arms). The MMD covers a sweep path of 3m, the same width as the RDV. Metallic debris in the soil can trigger false alarm  –  one reason that the metal detectors need ‘back up’. Forward-Looking Infrared Cameras  –  the ‘IR’  or  Thermal  Imagers Infrared sensors have wide military application, making use of their ability to generate thermal images. However, ‘IR’ imagers have a very specific application for mine detection. Both mines themselves and the action of burying mines effects the thermal properties of soil. This is due to changes in soil density, mines being denser than soil while the earth disturbed while burying that mine will be much less dense than all the surrounding soil. Success in detecting thermal anomalies will depend partly upon soil type and density as well as ambient temperature, and length of time since landmines were laid. The size and type of mine are also factors.  ILDS uses the commercially-available Agema 1000 infrared imaging camera (which has a 8-14 micrometer wavelength band.) Ground-Penetrating Radar  ( GPR,  also referred to as ‘Ground-Probing Radar’ ) Radar signals are reflected by denser, buried objects. Due to its higher density, a mine has a different radar signature than the soil [1] that surrounds it. An RDV uses three GPR modules ( 3 radome divisions are just visible at left) each made up of multiple send/receive antennae. Together, this GPR array (which is fixed 70 cm above the surface of the soil) covers a 3m swath. The ground-penetrating radar chosen for ILDS is made by ELTA Electronics, Israel. This GPR “is a continuous wave, frequency modulated and ultra-wide band (1-3 Ghz) radar... designed to operate at speeds up to 4 km/hr and to detect antitank landmines to 30 cm in depth”. The GPR will also detect buried anti-personnel mines, improvised explosive devices, or other ‘unexploded ordnance’ regardless of their metal content. RDV’s  Nitrogen ‘Sniffer’  —  the  Thermal Neutron Activation  (TNA)  Detector In simple terms, TNA detects unnaturally-high nitrogen levels [2] in soil which confirms the presence of explosives. And confirming the findings of  ILDS’s others sensors is the whole point behind TNA. How the system does this is rather complex. ‘Slow’ (ie: low kinetic energy) neutrons are injected into the soil.  Measuring the energy levels of  returned electromagnetic radiation allows TNA to detect the presence of nitrogen (and to quantify it) in an irradiated sample. Since the TNA detector is the final of ILDS’s four sensor types, it is appropriate that the system is mount on the tail arm of the RDV alongside that vehicle’s mine-marking system. The ILDS TNA sensor was built by SAIC Canada and Bubble Technologies. [1] Soil is dielectric (ie: it allows radar signals to pass through uninterrupted).  Denser materials reflect the signals.  Thus, ground-penetating radar can detect  buried mines. [2]  Naturally-occurring nitrogen in soil makes up a percentage-by-weight of 0.1% on average. Nitrogen content in explosives can have a percentage-by-weight of 18-38%.