Control Box
The control box encloses the electronic circuitry of the detector. The
control box originates the TX (transmit) signals sent by the coil and
interprets the RX (receive) signals detected by the coil. All user selectable
functions (knobs & switches) are located on the front and rear panels of
the control box.
Discrimination
The ability of a metal detector to estimate if a located target is made from
ferrous metal (iron or steel) or non-ferrous metal (non-magnetic).
Double-D Coils
Double D coils are coils that have two windings of wire that overlap in the
shape of two D's (one reversed). The characteristics of a Double D coil
are stability, especially in heavily mineralized ground, good depth and
sensitivity and a very thorough search pattern.
Electromagnetic
Commonly called the 'signal from the coil'. An electromagnetic field is
Field
generated within the wire windings of the search coil and this field is
pulsed or sent into the ground. The presence of a metal target in the
ground will disturb the pattern of this field and this disturbance is
registered by the receive system of the detector and indicated to the
operator by an audible target signal "beep".
False Signal
False signals are signals, which sound similar to target signals but are
caused by other factors. Common causes for false signals are incorrect
ground balance, hot rocks, signals caused by knocking the coil on
obstacles, etc. With experience, the operator will learn methods to
minimise false signals and to hear subtle differences between target
signals and false signals.
Ferrous Metals
Metals composed of or containing iron. A ferrous item is one, which is
attracted to a magnet and is predominantly or completely made of iron
or steel.
Ground Balance
The ability of the metal detector to compensate for the effects of ground
mineralization. The GP 3500 has "automatic ground balance". When it is
used in Tracking mode it continually compensates for changes in the
ground mineralization.
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Halo Effect
After a metal object has remained undisturbed in the soil for a
considerable amount of time, a diffusion occurs around the object.
This has the effect of the object appearing to the detector to be
a larger size.
Hot Rocks
A hot rock is an individual rock which has a particularly high
degree of mineralization as compared to the average ground
around it. Due to this high difference, the detector does not have
the opportunity to ground balance on the individual rock so
therefore gives a false signal.
Interference
Electricity or radio waves in the area being detected can cause
instability or chattering of the detectors threshold. The types of
interference commonly occur due to power lines, underground
cables, radar, other detectors or climatic conditions like
thunderstorms.
Mineralization
Most ground contains certain minerals, which can cause false
Ground
signals to be given by a detector. Heavily mineralized ground
requires different ground processing than does neutral or lightly
mineralized ground (see Ground Balance).
Ground containing heavy salt concentrations require entirely
different processing again (sea salt).
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 tend to be cone shaped.
Non - Ferrous
Metals not containing significant levels of iron. Non-ferrous
Metal
s
metals are non-magnetic such as Gold, Silver, Copper, Brass,
Lead or Aluminium.
Pinpoint
The method of locating 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
RX 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.
glossary of common terms
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GP 3500
www.minelab.com
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