METAL DETECTION SYSTEM

摘要

A walk-through metal detection system (10) with split field generation coils (12) excited in phase to generate an electromagnetic field (24) having a substantially uniform vertical field density. A plurality of receive coils (28) are also provided, each receive coil connected to a separate detector circuit (30) for detecting disturbances in the generated field caused by the presence of metal objects. The signals (79, 100, 102) output from the detector circuits are processed to generate an output signal (G) indicative of the total metal mass detected within the generated electromagnetic field, or of the individual lumped metal mass(es) detected within the generated electromagnetic field. The output signal is compared to a threshold signal (H), and if greater than the treshold signal, then an illicit metal object is presumed to be present within the electromagnetic field and an alarm (34) is sounded. The approximate vertical and/or horizontal position of the detected metal object(s) may be determined from further processing (106, 110) of the detector circuit outputs.