In discrimination modes, positive hot rocks will give a typical metal sound again. Negative
hot rocks will not give any sound in these modes (except for occasional false signals).
Therefore, while searching in the field, you can decide by listening to the warning tones
emitted by the device. If you get a metal tone, it means that you have either detected a
metal or a positive hot rock. If you get a strong signal and a stable ID, you can determine
whether it is a hot rock or a metal by looking at the ID. Please keep in mind though weaker
signals tend to give different IDs and metals under rocks may produce different metal
signals. Consequently, digging up a target signal is the best option.
If you are using the discrimination modes and know the IDs of the hot rocks around you, you
can use ID masking to eliminate these rocks. However, this may not be sufficient to avoid all
rock signals. The device may still receive signals from rocks because soil and hot rocks
together will form a combined effect and generate a different ID than those of rocks.
When the ground tracking is active, the device may give a warning tone and ID when it
passes over a hot rock because the effect of the hot rock will be different than the
ground's. If you sweep the search coil over the rock, ground tracking will automatically
adjust the setting and the warning tone/ID will either disappear or diminish significantly.
Because there is a slight delay in ground tracking, you may hear a strong signal at the first
one or two sweeps until the setting is adjusted. Then the sound will get weaker and
disappear. This will not happen with metal targets because metals will prevent the device
from ground balancing. Therefore, in ground tracking, if you are getting a constant signal
over a target after repeated sweeps, there is a high possibility that the target is a metal.
Moving from over a hot rock back to soil, the device may give signals to the ground for a
few sweeps until the ground balance setting is updated again. This is normal and should
not mislead you.
Under normal circumstances, ground tracking should not be used for elimination of hot
rocks. It is recommended for use in areas with changing soil types.
It is a hard task for average or simple detectors to find metals under rocks. These detectors will
generally miss the metals and thus make them available for you and protected from others.
For this reason, a missed target by another detector makes you lucky for reading this manual
and using the FORS CoRe.
A well adjusted FORS CoRe will increase your chance of finding metals under hot rocks. The
combined effect of a metal and a hot rock is less than the metal's effect by itself and the
received ID will be different than the metal's expected ID. The ID will be a combination of the
rock's and metal's and based on how small the metal is compared to the rock, it will be closer
to the rock's ID. You should always keep in mind that metals under hot rocks will never appear
with their own metal ID. For example; gold under a brick may generate an iron tone and ID
instead of gold.
EFFECTS OF HOT ROCKS IN GROUND TRACKING
METALS UNDER HOT ROCKS
FORS / Page 27
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NOKTA DETECTORS
HOT ROCKS and SEARCHING IN ROCKY AREAS
