Indeed, within the same sweep of just one metre, a considerable variety
of ground events may be encountered, ranging from one extreme to
the other (values between 70 and 90): hot rocks, brick, slag, pottery
interspersed with soil that is neutral or characterised by diverse mineralisation.
This may be to such an extent that any mean value would be meaningless.
You must then determine an acceptable level of rejection for the
groundbased on your own experience of the site, your detection methods
and the interference that you are prepared to tolerate.
Always return to manual mode at level 90 in the event of
interference, or use the pumping mode to adjust the settings over the
ground zone that seems the most heavily mineralised.
Low ground balance levels also generate the clearest signals on
certain irons that are already dicult to eliminate.
With some digital detectors on the market, you will note that when
the ground balance settings are low – either in Manual, Pumping or
Tracking mode – hot rocks do not register, as they have been
somewhat ‘notched’ or inhibited. This trick gives you good stability
regardless of the ground rejection level, however it also deprives you of
the benets of a well-adjusted ground balance, and worse, gives you
the impression that your settings are well congured.
Very often the deepest targets in magnetic soil are identied with
a signature similar to that of hot rocks, and are therefore detected poorly
with this kind of device (as they are ‘notched’).
Dēus on the contrary gives you full control over the ground settings.
When you lower the ground balance (87-85-82 etc.) you fully accept hot
rocks, which is the only way to obtain real gains in terms of penetration
on certain magnetic soils.
This mode is not available in Beach mode, in wet areas, as the
Pumping mode is more eective.
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