Page 16
The Minelab SD2200v2
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
t o
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.
Instruction Manual
Page 17
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.
