Extended-Range Positioning System Based on Foreign-Object Detection

Systems and methods are described for an extended-range positioning system based on foreign-object detection (FOD). In particular, a power-transfer apparatus is disclosed that includes a coil and a foreign-object-detection (FOD) system. The coil is configured to generate a magnetic field based on an electric current running through the coil for transferring power to a receiver device. the FOD system includes a plurality of FOD sense loops, FOD circuitry, and active-beacon receive circuitry. The FOD sense loops detect metal objects within the magnetic field based on changes to an electrical characteristic(s) of one or more of the FOD sense loops. The FOD circuitry processes a modulation pattern of the electrical characteristic(s) of the one or more FOD sense loops and provides first positioning information. The active-beacon receive circuitry processes induced voltage in at least two sense loops to provide second positioning information.