Ground Cancelation - Fisher F44 Owner's Manual

WHAT IS GROUND CANCELATION?

GROUND CANCELATION

Why do I need to cancel out the ground?
All soils contain minerals. Signals from ground minerals are often tens or
hundreds of times as strong as the signal from a buried metal object. The
magnetism of iron minerals, found in nearly all soils, causes one type of
interfering signal. Dissolved mineral salts, found in some soils, are electrically
conductive, causing another type of interfering signal.
Ground Cancelation is the process by which the metal detector cancels the
unwanted signals coming from the ground minerals while still detecting the
signals from buried metal objects. This is accomplished by matching the
detector's Ground setting to the Phase of the ground signal.
When the detector is calibrated to the soil, the result will be deeper target
detection, quieter operation and more accurate target identification.
The most accurate GROUND value is the value displayed when "pumping" the
searchcoil over the ground in an area free of metal.
Ground Grab
®
This control allows you to set the detector's internal ground setting equal to the
Phase of the ground you are searching over.
Press-and-hold
ground value and store it in the detector.
In order to calibrate the detector to the most accurate ground value, pump the
searchcoil up and down over the ground while standing in one place over a patch
of ground free of metal.
1. Press-and-hold
2. Start with searchcoil 6" above the ground; lower it to about 1" from the
ground.
3. Continue the pumping motion up and down until the 2-digit number
stabilizes and remains a constant value.
4. At the point where the 2-digit number stops changing, the detector has
correctly measured the ground Phase.
5. Release
value displayed.
During GROUND GRAB, the detector jumps into ALL METAL operation.
The sound you hear is the sound of the ground.
6. Note: GROUND GRAB
conductive soils, such as a wet salt water beach. Automatic balancing is not
possible in soils with ground values less than 40. The screen will display "--
" and an alarm will sound if over metal or in ground with a value less than 40.
Computerized Ground Cancelation:
to invoke automatic ground cancelation. This will "grab" the
.
to set the detector's internal ground setting equal to the last
will not automatically balance over highly
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