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Metal Detecting Theory
How a Metal Detector Works
Metal detectors work by creating a magnetic field which stimulates electric currents in metal objects.
the metal detector measures the changes in the magnetic field caused by the currents. by analysing
the strength and timing of the currents the metal detector can estimate the depth and the type of
metal in a target.
the EVO6000 shows the depth on the right side of the display and the type of metal as a target id on
the large digits in the centre of the screen. the
setting (
SENSITIVITY
) is used to filter
out weak signals which might be noise.
the volume of the low pitch tone the evo6000 makes when it detects iron targets is controlled by the
IRON VOL
). if you are not interested in digging iron targets, set the
iron volume
setting (
IRON VOL
) low. Using an
iron volume
setting (
IRON VOL
) of zero will mute iron targets
entirely.
the EVO6000 lets you assign different tones to different target ids using the
setting (
DISCRIM
). the volume of the medium pitch tone that the EVO6000 makes when it detects
targets with target ids above iron, but below the
discrimination level
(
DISCRIM
) is controlled by the
(
DISC VOL
). if you want to focus on targets with higher target ids, set the
discriminate volume
(
DISC VOL
) low.
Ground Signals
The ground can also cause changes to the magnetic field. the effect of the ground on the magnetic
field changes with the level of mineralisation of the soil and on how close the ground is to the metal
detector
search head
. metal detectors use timing information and the rate of change of the magnetic
field to eliminate the ground signal.
The EVO6000 can automatically track and eliminate the ground signal (
TRACKING
). you can also set
the ground level yourself (
GROUND
) or have the EVO6000 calculate a ground setting for you to use
(
AUTOSET
). To help you spot when ground conditions have changed, the EVO6000 will tell you if the
tracking value it would have used is different from the ground level you have set.
Detection Modes
Metal detectors working in
monitor the instantaneous changes in the magnetic field as
they pass over a target. motion mode is easier to use and set up because it is less sensitive to changes
in ground conditions. in motion mode a detector will detect a target only when the
search head
is
moving. even small movements of the
search head
are enough to make motion mode work.
measure the level of the magnetic field relative to a
baseline
level. the
baseline
level
has to be reset when ground conditions change or in the presence of multiple targets.
Non-
motion modes
can find deep targets and do not require you to move the
search head
.
Non-motion
modes
are great for pin pointing targets and on sites where it is difficult to swing the search head.