Minelab SD2200v2 Instruction Manual page 11

Page 18 The Minelab SD2200v2 Instruction Manual Page 19
Iron Discrimination Switch
The main means of iron discrimination of the SD2200v2 is the ‘blanking’
(silencing) of the threshold which occurs when the detector determines a
target is of ferrous metal (magnetic). This form of iron discrimination
operates when the Iron Discrimination switch is in the Disc position and
the detector is fitted with the supplied 11” Double ‘D’ wound coil.
Targets must produce sufficiently strong signals for the SD2200v2 to
successfully discriminate iron objects. Fortunately, most iron junk is located
near the surface and much of it can produce the required signal strength.
Note: When used in Disc mode, deeper or small targets, whether ferrous
or non-ferrous, will produce the normal target audio signal.
When the SD2200v2 is operated in the Disc + ID mode, the same audio
blanking will operate as it did in Disc for strong signals. However, there is
an additional mode of iron discrimination which can operate with weaker
signals. In this case, the detector will jump into the ID audio signal mode.
In Disc + ID mode, the operator needs to monitor the pitch of the signal as
the coil is swept over the buried metal target. Most ferrous targets will
produce a changing pitch signal as the coil is moved back and forth across
the target. Non-ferrous targets will produce a signal with a steadier pitch.
Some ferrous targets, particularly thin nail-like targets, can also produce
steady pitches just like non-ferrous targets. Some gold will also produce a
variable pitch, particularly specimen gold or gold containing a matrix of
quartz and/or ironstone. Therefore, only signals with highly variable pitch
can be trusted to indicating ferrous targets in the +ID mode.
The +ID target mode of recognition requires a lot of operator experience. It
is recommended that the operator investigate most targets detected in the
+ID mode and learn to distinguish the signals.
The audio blanking on ferrous targets is the most useful form of
discrimination. This will only operate if a Double “D” coil is used.
The central position of the Iron Discrimination switch activates the All Metal
mode. There is no discrimination in this mode. Targets will cause pitch
and volume of signals to vary, but these variations convey no consistent
information about the type of metal.
Figure 6 - Discrimination Levels