White's Electronics, Inc.

Mark D Rowan

A metal detector employing static discrimination. Within the scope of the invention is a two-frequency method and apparatus for discriminating between metal objects and ground. Also within the scope of the invention is a three-frequency method and apparatus for discriminating between ferrous and non-ferrous metal objects. The methods and apparatus do not require movement of the search head of the metal detector.

Metal detector employing static discrimination

A method and apparatus for distinguishing metal objects employing multiple frequency interrogation. In one aspect, the method includes interrogating a target with at least two frequencies, obtaining respective response signals for the two frequencies, resolving the response signals into at least respective resistive component portions, comparing the magnitudes of at least two of the resistive component portions, selecting one response signal from among the response signals based on the comparison, and characterizing the target with the selected response signal. In other aspects, the method includes obtaining response data by interrogating the target at at least two frequencies, normalizing the response data and comparing the normalized response data. A signal is provided indicating the extent of any disagreement in the normalized response data.

Method and apparatus for distinguishing metal objects employing multiple frequency interrogation

A metal detector having a receive signal responsive to detected metal objects and having a display panel that can simultaneously display a plurality of phase angles associated with the receive signal. Additionally, the display panel can simultaneously display a second variable associated with the receive signal at each particular phase angle. The second variable is user selectable and can be either (1) a count of the number of times the signal amplitude exceeds a predetermined threshold level at a particular phase angle or (2) the signal amplitude when the signal is at a particular phase angle.

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Lebanon, OR, United States of America

Mark D Rowan