Identification of metallic mine-like objects using low frequency magnetic fields

This paper addresses the issue of identifying conducting objects based on their response to low frequency magnetic fields; an area of research referred to as magnetic singularity identification (MSI). Real-time identification was carried out on several simple geometries. The low frequency transfer function of these objects was measured for both cardinal and arbitrary orientations of the magnetic field with respect to the planes of symmetry of the objects (i.e., different polarizations). Distinct negative real axis poles (singularities) associated with each object form the basis for their real-time identification algorithm. Recognizing this identification problem as one of inference from incomplete information, a generalized likelihood ratio test (GLRT) is presented as a solution to the M-ary hypothesis testing problem of interest. Best performance of their GLRT classification scheme, measured through Monte Carlo simulation and presented in terms of percent correct identification versus SNR, was obtained with a single pole per object orientation.