Phase angle based EMI object discrimination and analysis of data from a commercial differential two frequency system

摘要

The EPFL the VUB have been investigating the response of metal detectors within the framework of humanitarian demining research activities, in particular frequency domain systems. A simple cricuit model has been looked at first, followed by the analysis of a more complete model. As has also been stessed before, this analysis indicates the possibility of identifying some metallic objects. In addition, the phase shift of the received signal turns out to be a continuous, monotonically decreasing function of the object size; thisleads to the idea of imaposing a "phase threshold" in order to reduce the amount of detected clutter. This discrimination-based approach is less ambitious than object identification, but is likely to be more robust and to work when looking for metalic objects of a certain size, e.g. non minimum-metal mines or UXO.