Thursday, September 16, 2010

Metal Detectors Glossary III

Head:    head is a commonly used synonym for search coil.
Masking:   masking occurs when ground minerals or buried objects interfere with the detection of a legitimate find, resulting in a mixed signal. This is also called "nulled out."
Matrix:   matrix refers to the total detection area covered by a search coil's electromagnetic field. (Though if you ever say "What is the matrix?," don't blame us if you wake up and find yourself talking to Laurence Fishburne.)
Negative Ground:   if a metal detector has a preset ground balance, then negative ground, i.e. ground that has more non-conductive minerals and fewer conductive minerals, will cause a negative or nulling effect. In other words, negative ground may cause metal detectors to ignore more signal than is necessary.
Neutral Ground:   neutral ground is soil that contains neither conductive nor non-conductive minerals.
Notch:   notch filtering or notch discrimination is used to create a range of accepted and rejected targets. Setting the notch level to discriminate against certain objects means tuning out or blocking a particular frequency band. This is called notch reject. Conversely, creating a notch window of accepted frequencies is called notch accept.
Null:   when a metal or coin detector coil passes over targets that have been discriminated against or are outside of the accepted notch window, a detector's threshold audio will go quiet or drop momentarily, i.e. go null.
Pinpointing:    pinpointing refers to the act of determining the precise location of a target. This can be accomplished by manually "detuning" a metal detector, or adjusting it to be less sensitive, and then sweeping the target response area again. Because the detector is less sensitive after detuning, an audio signal should provide a more exact location due to the strength of the signal.
Positive Ground:   positive ground is soil that contains a high amount of conductive minerals. Positive ground results in too many signals, which can make it difficult or impossible for a metal detectorist to find legitimate targets. This often occurs on wet beaches, due to their high salt content.
Prospecting:   prospecting means treasure hunting or going metal detecting in search of gold, silver, or valuables.

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