AQUAREOS: The Story So Far

If we look at the procedure for humanitarian mine clearance we see that, once the ground is prepared, the process has two steps: 1) target location; and 2) confirmation that the target is a buried landmine.  Target location is accomplished by some form of remote sensing – a metal detector swept over the ground, or a dog doing a search etc; while confirmation that the target is a buried landmine generally involves direct contact with the target – the so-called “prodding and excavation” procedure.  There are new sensors, and combinations of sensors (e.g. MINEHOUND – MD+GPR) that allow, or aim to allow, for remote sensing for confirmation that the target is a buried landmine – when you consider that there may be 1000 false alarms for

every mine found it is easy to see why this is so: it removes the need to investigate every target located, saving a lot of time.

One technique being considered for confirming the target is a landmine is Quadrupole Resonance (QR), its great advantage being it directly detects the chemical signature of the explosive content of the mine.  As a radiofrequency technique, QR lends itself to remote sensing.  However, as a near-field method (frequencies for nitrogen QR range from 0 – 5.5 MHz) there is considerable signal attenuation with increasing separation between the sensor and the target (i.e the deeper the mine, the weaker the signal).  There is equally, a great deal of RF power attenuation for the same reason, meaning that considerable RF power is needed to “reach” buried mines.  In combination with the already-weak QR response, these factors represent a considerable challenge for the implementation of QR as a remote sensor for confirming that a target is a buried mine.  Our AQUAREOS project is designed to meet that challenge, using a combination of novel hardware design and advanced signal processing in a rugged, simple-to-use package.

Progress across the first six months of the project has been good.  A proof of concept AQUAREOS quadrupole resonance mine sensor device has been constructed and mounted on an all-terrain cart.  The proof of concept device uses a digital spectrometer platform with a class A/B RF power amplifier, both powered by a single rechargeable battery with ca 4 hours of battery life.  Control of the device can be via either a laptop/ tablet, or via the controls on the handle.  In addition to be operated from the cart, the device is inside a weatherproof carry case that suspends from the shoulder by a strap.  This is to test portability.  Output is a simple yes/no for the presence of the explosive being searched for indicated both by lights on the handle and on the laptop/tablet display.  Right now the signal processing algorithm uses primarily the signal intensity for discrimination, but this will be refined as the project progresses. 

This proof of concept device is used primarily for optimisation of the CONOPS (concept of operation).  In the next stage of the project, this aspect of the work will focus on the design and construction of the second-generation device with upgraded RF power in a smaller package. Jamie Barras.

Jamie Barras (http://nms.kcl.ac.uk/core/?page_id=895) is the leader of the Quadrupole Resonance Group within the Department of Informatics, King’s College London.  The AQUAREOS team thank Find A Better Way (http://www.findabetterway.org.uk/) for funding this work.

Further Reading

1.  J. Barras, M. J. Gaskell, N. Hunt, R. I. Jenkinson, K. R. Mann, D. A. G. Pedder, G. N. Shilstone and J. A. S. Smith, Detection of Ammonium Nitrate inside vehicles by nuclear quadrupole resonance, Applied Magnetic Resonance 2004, 25, 411 – 434.

2.    A. N. Garroway, M. L. Buess, J. B. Miller, B. H. Suits, A. D. Hibbs, G. A. Barrall, R. Matthews and L. J. Burnett, Remote Sensing by Nuclear Quadrupole Resonance, IEEE Trans Geo. Remote Sens. 2001, 39, 1108 – 1118.