Patent ID: 6791329
Filing Date: 2004-09-14
Classification: G01V

Abstract:
A metal detector system comprising:a chassis for supporting electromagnetic sensor components above a medium, said chassis having first and second ends; a first transmitter coil attached to said chassis for inducing an electromagnetic field in the medium beneath said chassis; a first receiver coil attached to said first end of said chassis for receiving electromagnetic signals from objects in the medium beneath said chassis, said first receiver coil having an output; a second receiver coil attached to said second end of said chassis for receiving electromagnetic signals from objects in the medium beneath said chassis, said second receiver coil having an output; a propulsion system attached to said chassis between said first and second receiver coils, whereby an electromagnetic interference signal emanating from said propulsion system is received at a nominally equal magnitude by each of said first and second receiver coils; signal processing components operatively connected to said outputs of said first and second receiver coils for adding or subtracting said outputs of said first and second receiver coils, whereby said interference signal emanating from said propulsion system and received by said first and second receiver coils is nulled; a data acquisition system operatively connected to said signal processing components; and a computer usable medium having computer readable program code means embodied therein, operatively connected to said data acquisition system, for comparing a signature signal from said data acquisition system with a library of signature signals stored on said computer usable medium, whereby a signature signal from an object or void in the medium beneath said chassis is compared with said library of signature signals from objects of interest such as landmines.