Identifying Target Signals - Minelab GP 3000 Instruction Manual

IDENTIFYING TARGET SIGNALS

Metallic targets will usually give a 'solid' sounding signal when the coil is swept across
the object from any direction. Ground noises usually give a broad uneven signal when
the coil is swept from different directions. A metallic target generally produces a short,
sharp and mostly symmetrical signal.
If you are not sure if the sound is ground noise or a target signal,
you need to investigate.
Scrape a shallow hole about 70-100mm deep over the suspected
target. Sweep the coil over the hole at the original ground level.
Do not dip the coil into the hole. If the signal has decreased in
volume or is less defined, it is probably ground noise.
If the signal remains the same or becomes louder, it is likely a metallic
target. If you are still not sure, make the hole deeper and repeat the
process. You may also notice that mineral noises are often experienced
from one direction only, on the return swing it is
no longer there.
A 'halo effect', which may be built up around a buried metal object,
makes the object appear to be larger to the detector than it actually is.
This will be reduced once the target is disturbed from its position in the
ground (e.g. a small object, detected at a substantial depth, may be
more difficult to detect once recovered from the ground. If the object is
reburied, the 'halo effect' will disappear).
HINT Do not try to eliminate what might appear to be a faint, isolated
ground noise by balancing the detector because you may be 'balancing
out' the target response from a deeply buried metallic target.
IDENTIFYING TARGET SIGNALS
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