Glossary Of Terms - Minelab GPX-4500 Instruction Manual

Glossary of Terms

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Hot Rock
An individual rock which has a high
degree of mineralisation in comparison
to the surrounding ground around it.
Due to this difference the detector does
not have the opportunity to Ground
Balance to the individual hot rock so
therefore gives a false signal. The signal
will diminish rapidly by increasing the
coil height above the hot rock.
Interference
Electricity or radio waves in the area
being detected can cause instability
or chattering of the Threshold.
Interference commonly occurs due to
power lines, underground cables, radar,
other detectors or climatic conditions
like thunderstorms.
Mineralisation
Most ground contains some minerals,
which can cause false ground signals
to be detected. Heavily mineralised
ground requires different detector
processing than does neutral or lightly
mineralised ground. Ground containing
heavy salt concentrations require
entirely different processing again.
Monoloop Coils
Monoloop coils are the style of coil
where the multiple strands of wire are
wound in a single loop around the
circumference of the coil. The field of
search of Monoloop coils tends to be
cone shaped. They provide greater
depth and sensitivity compared to a
Double-D coil of equivalent size in low-
medium mineralisation.
Non-Ferrous Metals
Metals which do not contain significant
levels of iron. Non-magnetic metals
such as Gold, Silver, Copper, Brass, Lead
or Aluminium.
Pinpoint
The method for determining the
precise location of a target prior to
digging. Pinpointing uses the design
of the search coil windings to
determine the exact position of the
detected target.
Rx (Receive)
Refers to the response, or
electromagnetic field, which is received
back by the coil and is used by the
control box circuitry to detect a metal
item in the ground.
Salt Mineralisation
Salt content in the ground causes a
negative (–) response rather than the
positive (+) response of laterite soils.
A large salt content in the ground will
have a different effect on the detector
than other types of mineralisation.
Therefore the detector needs to
use different filtering techniques to
overcome this effect.
Search Coil
The search coil is the circular plate
which is swept across the ground
surface during detecting. It transmits
electromagnetic signals into the
ground and receives the response.
Search Pattern
The search pattern is the area of ground
underneath the coil which is being
scanned. Depending on the style of
coil (Double-D or Monoloop) and the
Coil/Rx setting being used (Double-
D/Monoloop/Cancel), different coils
will have a different shaped area being
covered by each sweep.
Threshold
The continuous audible level of sound
emitted by the detector is referred to
as the Threshold. Threshold can be set
anywhere between silent and loud;
but a soft audible level is
normally suggested.
Target Signal
This is a change in the tone (pitch)
and volume of the Threshold
when a target is detected and not
discriminated (rejected).
Tracking
The function of automatic Ground
Balance where the detector makes
continuous adjustments to the Ground
Balance to compensate for changes in
the mineralisation of the ground.
Tx (Transmit)
This refers to the transmit signals or
electromagnetic pulses, sent into the
ground by the coil.
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