Minelab GPX 6000 User Manual page 21

Double‑D Modes
Double‑D Modes manage noise from EMI or conductive (salty) ground when using the
GPX 14™ Double‑D coil� These modes are only available when a Double‑D coil is in use�
A Double‑D coil has characteristics that allow it to cancel out EMI and conductive (salt) signals� A Double‑D coil contains two
back‑to‑back 'D' shaped copper wire windings that overlap in the centre of the coil�
The GPX 6000™ can sense targets in each of these two windings� EMI, conductive (salt) signals, and targets all produce
a different response in each winding that can then be compared� EMI signals produce mostly identical responses in each
winding because they are from distant sources� Salty soil is effectively a large and relatively uniform noise source, hence it
produces a larger signal in one specific winding (the transmit winding)� In comparison, gold nuggets produce a very different
response in each winding as the coil moves over them� The signal from the nugget varies depending on the detector swing as
well as the nugget depth�
By subtracting the response from these two windings in different proportions, the detector effectively minimises the
response from distant EMI or conductive (salty) ground� This subtraction also affects target responses� The response from
deeper nuggets is reduced, while shallower nuggets are mostly unaffected� This means that a Double‑D coil can be set to
optimally cancel either EMI or conductive (salty) ground� Sensitivity to shallow targets will still be quite good in either case
but deep targets will be more difficult to detect�
Set the Double‑D Mode
START `
1. Press the Noise Cancel button
for at least 2.5 seconds.
Choosing the Right Double‑D Mode
EMI Cancel (default): use when noise is caused by atmospheric interference�
EMI is noise that is present when holding the coil stationary�
Conductive Ground Cancel: use when noise is caused by interference from conductive (salty) soils� Conductivity is the
cause of noise that is present when raising and lowering the coil in the air between knee and shoulder height above
the ground�
Double‑D Mode Guide
EMI Cancel (default)
Reduces the effect of EMI�
Use when detecting:
` Near power‑lines
` In stormy weather
` Close to other detectors
CONTENTS
Long press the Noise Cancel button for at least 2�5 seconds to
(Default)
toggle between the two Double‑D modes�
The icon for the currently enabled Double‑D mode is displayed�
Long press for at
least 2�5 s
Conductive Ground Cancel
Reduces the effect of conductive (salty) soils�
Use when detecting:
` In large open gold fields with conductive (salty) soil
` In wet ground
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