| 摘要 |
A metal detector having a plurality of phase delay discrimination regions with corresponding selectable exception spaces therein. A metal detector for indicating the presence of a metal target, 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 the phase delay of the modified said wave and providing a characterization to a user of the target based on said phase delay, said analyzing module being further adapted in a normal mode of operation of the metal detector to report said characterization to the user in a circumstance (a) wherein said phase delay exceeds a predetermined discrimination level and to not report said characterization to the user in a circumstance (b) wherein said phase delay does not exceed said discrimination level, and an exception space circuit cooperating with said analyzing module for comparing said phase delay with a limited range of one or more predetermined values for said phase delay and, in a first exception space mode of operation of the metal detector, causing said analyzing module to not report said characterization in said circumstance (a) when said range of values exceeds said discrimination level and, in a second exception space mode of operation of the metal detector, report said characterization in circumstance (b) wherein said range of values does not exceed said discrimination level, is provided.
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