Discrimination
Discrimination is the ability of metal detectors to discriminate or suppress individual detector targets based on the so-called imprinted area and electrical conductivity of the metal from which the target is made.
In single frequency metal detectors, the discrimination of the target is achieved by measuring the phase shift between the transmit and receive coil signals induced by the detected target.
For multi-frequency detectors, this measurement is made for each operating frequency and then the measurements from each frequency are compared and evaluated using a specially designed algorithm. As a result, multi-frequency metal detectors provide noticeably more accurate results even for deeper targets in difficult soilconditions than single frequency metal detectors
In digital metal detectors, this value is then displayed on the display as a numerical target ID.
Targets made of more conductive metals or targets with a larger imprinted area then come out with higher ID numbers than targets made of lower conductivity metals or with a smaller imprinted area. Discrimination can then be used to suppress or tonally discriminate between ranges of ID numbers according to user preference.
Two types of discrimination are generally used:
- Basic: The metal detector detects only targets enabled by discrimination, other targets are not detected at all.
- Tonal: The metal detector detects all metals, but assigns different pitches to them based on their properties.
In most modern detectors, these two types of discrimination can be combined.