Patent ID: 7088103

Claim:
A metal detector, comprising: a transmitting module for transmitting a time-varying electromagnetic wave to the target; a receiving module for receiving said wave as modified by the target; an analyzing module for determining a phase delay of the modified said wave, comparing said phase delay to a selected discrimination level defining first and second discrimination regions, and defining, in a normal mode of operation of the metal detector where said phase delay is in said first discrimination region, an “accept” state of the metal detector wherein the metal detector reports a characterization of the target to a user and, where said phase delay is in said second discrimination region, a “reject” state of the metal detector wherein the metal detector does not report a characterization of the target to the user; and an exception space circuit cooperating with said analyzing module for causing, in a selectable exception space mode of operation of the metal detector where said phase delay falls within a first selected range within said first discrimination region, the metal detector to be placed in said “reject” state.