Method and system for sliding door pattern cancellation in metal detection

Abstract

A method and system for reducing the signal interference effects of metal doors in a metal detection system. The system includes a transmitter operable to transmit an interrogation signal that is used to detect transitory metal objects within the detection region, a receiver operable to receive instantaneous signals that represent electromagnetic field disturbances during operation of the metal detection system and include electromagnetic field disturbances attributed to the movement of metal doors. The system also includes a metal detection module that determines a resulting waveform representing the difference between the instantaneous signals received during operation of the metal detection system and a recorded pattern of signals representing electromagnetic field disturbances caused by a pattern of movement of the metal doors in the detection region when a transitory metallic object is not present. The record pattern is canceled from the resulting waveform leaving only signals from transitory metal objects.