Minelab SD2200v2 Instruction Manual page 10

Page 16
5.2.8 Ground Balancing
Automatic ground balance is active whenever the detector is set in the
Tracking mode. In this mode, the detector continuously measures the effect
of ground mineralisation and automatically adjusts the ground balance to
compensate.
Introduction
The SD2200v2 can be operated with automatic ground balance (Tracking
mode) or with the ground balance fixed (Fixed mode).
When the Balance Mode switch is switched to Fixed mode, the ground
balance is held at its current level.
When switched from Fixed to Tracking mode, the detector begins to
automatically ground balance through a process of two stages. The first
stage is a very rapid adjustment to the ground mineralisation. This stage
lasts for five seconds after the switch is thrown. The second stage
continues to adjust to the ground mineralisation, but at a greatly reduced
speed. Adjustment continues for as long as the detector is kept in Tracking
mode.
It may be of use to repeat the ground balance function when ground
conditions change rapidly.
If the detector is switched to Fixed mode at any time, it will no longer adjust
itself to changes in soil mineralisation, but will stay fixed at the level it last
reached while in Tracking mode.
While in Tracking mode, the detector usually stops ground balancing when
it detects a target. However, a weak target signal may not be recognised
as a target and, if the coil is repeatedly passed over it, the target could be
tracked out. It is therefore recommended to switch from Tracking to Fixed
when pinpointing a potential target (see also Discrimination level control,
pages 21and 22).
For best results, use Tracking mode in areas with high ground noise. If the
ground mineralisation is only mild or with little variability, searching in Fixed
and regularly rebalancing when required can have advantages. People
who have used previous SD models must note that setting the Channel
switch does not affect the operation of the automatic ground balance.
The Minelab SD2200v2 Instruction Manual
Ground Balance Procedure
Ground balance both channels at once by setting the Channel switch to
Both. Move the coil up and down between 20mm and 100mm above the
ground, and while moving the coil, set the Balance Mode switch from Fixed
to Tracking. The fast ground balance lasts for only five seconds after
switching to Tracking. Therefore, it is important to be moving the coil as
the switch is thrown.
Figure 5 – Setting Ground Balance
Keep moving the coil until all ground noise has stopped. A persistent signal
probably indicates a target in the ground. In this case, move the coil to a
new location and repeat the procedure.
When there is no longer a change in the threshold while the coil is being
raised and lowered, the detector is said to be “ground balanced”.
Once the detector is ground balanced, you can then decide to detect in
either Tracking or Fixed mode. If the ground is mineralised or variable, use
Tracking. If the ground is very mild, use Fixed mode and switch back to
Tracking temporarily if the threshold becomes noisy. Do not test a target
by switching to Tracking when the coil is above it.
5.2.9 Iron Discrimination
Discrimination is the ability of a detector to distinguish between different
types of metal targets and to assist the operator in identifying a target.
Some goldfields are littered with “junk”, that is, metal objects which are of
little value and are an annoyance to detector operators. The SD2200v2 is
capable of rejecting a number of iron objects while still detecting
non-ferrous metals. The ability of the SD2200v2 to discriminate ferrous
targets means that while working these goldfields, much of the iron junk
can be ignored with little fear of ignoring valuable targets.
Page 17