Subsurface discrimination using handheld electromagnetic induction sensors

The authors summarize the results of recent work on subsurface discrimination using the EM61-HH handheld electromagnetic induction (EMI) sensor. They compare the multiaxis EMI response of a variety of inert ordnance items with the response of ordnance fragments and scrap metal pieces recovered from firing ranges. The distributions of the eigenvalues of magnetic polarizability for the different classes of objects do not completely overlap, indicating that it should be possible to distinguish between the ordnance and at least some of the clutter. They also present results on how well this discrimination capability can be realized when the sensor is employed in an operationally interesting mode, e.g., swept around over the target