How Detectors Work; Target Id - Minelab X-terra 305 Instruction Manual

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how deteCtors worK

Metal detectors work due to the fact that
metal is conductive. Metal detectors create
an electromagnetic field, which penetrates
the ground.
When the coil senses a change in this field
(caused by a metal object) it sends a signal
back to the control box which then alerts the
operator. Metal detectors react to the size,
shape and composition of objects.
Typically, the larger the object, the deeper it
can be detected.
The X-Terra uses a single frequency (7.5kHz)
as the standard operating frequency. This
frequency has the ability to penetrate deep
into the ground.
The frequency of a detector is the number
of times a signal is transmitted into the
ground and received back, per second
(measured in Hertz - Hz).
The X-Terra has a number of different icons
that have been designed to best represent and
identify the metal objects in the ground.

Target ID

Buried metal objects are referred to as targets.
As the coil is passed over a target, it detects
its conductivity and displays this as a number.
Target Identification (ID) is used to distinguish
one type of metal target from another.
Target ID numbers range from –4 to 44 on
the X-Terra 305 and –9 to 48 on the X-Terra
505. Negative numbers represent ferrous
targets and positive numbers represent
nonferrous targets.
The last detected target ID stays on the
display until another target is detected. If the
detector passes over a target that it rejects, the
display will return to a blank detection screen
represented by 2 dashes.
target id
Depth indicator
A guide to how deep a
metal object is under the
Target ID
ground. The more arrows
The numeric identifier of
displayed, the deeper the
a particular metal object
object is likely to be from
underneath the ground.
the coil.
Discrimination segment
Another identifier of metal objects, each segment
refers to a certain type of metal signal. Segments
can be turned off (to accept targets) or turned on
(to reject targets) which in turn accepts or rejects
signals from the corresponding metal objects.
(A grey icon on the diagrams in this manual
represents a flashing icon on the detector.)
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