Nokta detectors Fors Tech - Manual (Page 18)

Metal detectors work on the principle of conductivity and all metals are conductive. On the
other hand, soil itself has a certain degree of conductive property. Under certain
conditions, the conductivity level of the soil may be very high. Soil and rocks have
magnetic properties as well as conductivity. For this reason, when searching in soil and
between rocks, in order for the detector not to give a target signal for the soil, the detector
should be able to eliminate the soil and minimize the effects of rocks while still detecting
real targets. Otherwise, false signals and noise may mislead the user and make it
impossible to find the target. The purpose of ground balancing is to eliminate these false
signals and noise.
When you sweep the search coil over the ground, you can see whether the ground balance
is adjusted properly or not. However, if the signals and noise continue when the coil is
raised up, you must consider the possibility of the electromagnetic waves in the
surrounding environment. Electromagnetic waves may result from power lines or from the
operation of electrical devices, radars, wireless radios, and even TVs. In such a case, first
make sure that the device is silent by making the sensitivity and threshold adjustments
and then ground balance.
GROUND BALANCE
If you want, you can use the ID Masking to ignore unwanted targets. The ID Masking
default value is set to 10. We recommend you to change this value according to the
type of target.
CONDUCTIVE GROUND (COG):
This is the special mode of FORS Tech designed for conductive ground (wet beach
sand, alkali sand etc.). What is special about this mode is that it will not react to iron or
similar targets within the same range and that the device will ground balance easily on
all types of ground. The reason for this is that while the device can ground balance
automatically between 40-90 in the other discrimination modes, it can ground
balance between 0-90 in this mode. This enables you to easily ground balance the
device on conductive ground where normally you can hardly ground balance or
cannot ground balance it at all.
Just like in the DI2 mode, in the COG mode, the device will produce a low tone for iron
and a single tone for all other metals which increases in pitch as the coil approaches
the target.
Different than the other modes, the ID Masking is preset to 40 to eliminate ferrous
metals or ground effects due to iron mineralization. If you are searching for ferrous
targets, you can use another mode or set the ID Masking value below 40.
Salty water or alkali ground are highly conductive due to high ionization and they
create iron effects on detectors. These effects can easily impair a detector's capability
of searching and detecting metals. Existence of iron elimination feature in a detector
can improve the situation but may not be sufficient.
FORS Tech Conductive Ground mode eliminates these effects and ground noise. What
you need to pay attention to when metal detecting on conductive ground are further
explained under SEARCHING IN SHALLOW WATER and ON THE BEACH (see page 27).
FORS / Page 16
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