Patent ID: 8207731

Claim:
A metal detector adapted to transport a product through a region intersecting an electromagnetic field, comprising: (a) at least one coil residing within the electromagnetic field, the coil generating a signal in response to a disturbance of the electromagnetic field; (b) an infeed sensor, the infeed sensor detecting entry of each product into the region intersecting the electromagnetic field and generating an infeed output signal in response thereto; (c) an analog to digital converter, the analog to digital converter receiving the signal and generating a plurality of output signals, comprising; i) a first output signal, the first output signal representing a reactive component of the signal generated by the coil; and ii) a second output signal, the second output signal representing a resistive component of the signal generated by the coil; (d) a reactive component learn memory, the reactive component learn memory receiving the first output signal and generating a reactive component reference signal in response thereto; and (e) a reactive component synchronization processor, the reactive component synchronization processor receiving the infeed sensor output signal and the reactive component reference signal, the reactive component synchronization processor subtracting the reactive component reference signal from a reactive signal generated by a product being inspected by the metal detector so as to generate a subtracted reactive component signal having a substantially reduced product effect.