Nokta detectors Fors CoRe - Manual (Page 17)

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 CoRe 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.
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 CoRe 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 28).
FORS / Page 16
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