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Sometimes it may not be possible to remove the effects of
interference completely by using the Tune control alone.
Once the detector has been tuned for a particular location, it should
not require readjustment unless conditions change or new
interference is introduced, e.g. other detectors being used in the
same area. If the interference persists after tuning, consider using
the Rx switch set to Cancel position.
Boost (Shallow/N/Deep)
Boost selects the type of processing and filtering applied to the
detector signals.
•
N (Normal) may be used for general detecting conditions. This
does not boost any signals.
•
Shallow boosts signals from small targets close to the surface.
This makes faint target signals easier to hear. This setting may
also boost any ground noise, therefore Shallow is well suited
for 'quiet' ground conditions.
•
Deep may be used when searching for large targets at depth.
This smooths the threshold and target signals from small targets,
making small changes in threshold easier to hear.
Selection of the more suitable position should be after considering
both target size/depth and ground conditions.
NOTE
When Boost is changed, Threshold may also need to
be adjusted.
External amplifiers may be used in addition to the Boost switch,
provided that they have loudness limiters built in. This prevents loud
signals becoming unpleasant or dangerous to the user's hearing.
D E TA I L E D O P E R AT I N G I N S T R U C T I O N S
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B A L A N C I N G
GROUND BALANCING
The ground contains not only sand, but also many different chemicals,
minerals and salts. These extra materials are referred to as ground
mineralisation.
This ground mineralisation may often produce a sound from the detector,
known as 'ground noise'.
The ‘GP extreme’ has the ability to cancel out the effects of ground
mineralisation. This minimises ground noise and retains maximum
sensitivity to metal targets. Cancelling the effects of ground mineralisation
is referred to as 'ground balancing'. This ensures that target signals from
objects, such as gold, are not confused with interfering ground noise.
The ‘GP extreme’ has automatic ground balancing. This continually
adjusts to minimise the effects of ground mineralisation when Balance is
set to Tracking.
The ‘GP extreme’ may be operated with fixed ground balance or
automatic ground balance.
•
When Balance is set to Fixed, the ground balance remains at
the current level.
•
When Balance is changed from Fixed to Tracking, the detector
begins to automatically ground balance through a two stage process.
The first stage is a very rapid adjustment to the ground
mineralisation. This lasts for 5 sec. so coil movement should be at the
same time as Balance is changed from Fixed to Tracking.
The second stage continues to adjust to the ground mineralisation,
but at a greatly reduced speed.
This adjustment continues all the time that Balance is set to Tracking.
While in Tracking mode, the detector usually stops ground balancing
when a target signal is detected. However, a weak target response
may not be recognised as a target if the coil is repeatedly passed
over an object, it may be 'balanced out'. For this reason Balance
should be changed to Fixed when pinpointing a target.
HINTS
• Use ‘Tracking’ in areas with
high ground noise for best results.
If ‘Balance’ is changed to ‘Fixed’,
the detector will no longer adjust
to changes in ground
mineralisation, but will stay fixed at
the level previously calculated
while in ‘Tracking’ mode.
• Change from ‘Tracking’ to ‘Fixed’
when pinpointing a potential
target.
NOTE
The Level Adjust control also
effects the Tracking mode by
altering the detectors perception of
what is ground noise and what is a
weak target (see pages 37 and 38).
