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COUNCILS ABOUT IDENTIFICATION OF
TYPES OF OBJECTS
In the course of detecting you will notice those objects that are located close to the
coil can complicate the ability of the detector to ID these properly either with audio or visual
indications. This effect is the so called near zone. Just a person cannot see a small object
brought too close to the eyes the detector also cannot “see’ these near zone objects clearly.
In these cases it is recommended to lift the coil and re scan the object. This will also allow
the hodograph to fit within the the screen and not travel outside of the display area. The
goal is to try and keep the hodograph of the detected object within the confines of the
screen and also to reduce the effects of ground minerals on the hodograph when held to
near the ground.
While using your detector you may notice that large ferrous objects, due to their
size and shape, can appear as a possible coin. How can we properly identify these
erroneous targets?
First of all the audio from these large ferrous targets will also sound “large” and
lifting the coil even 40cm off of the ground the audio will not significantly diminish.
Obviously then this is not a coin.
Secondly, as it was already noted, large ferrous targets often times will have
large distinct loop shape to the hodograph. However if the target is large and the coil is
too close then the signal will leave the screen (see below) and may appear as a coin.
This will often times confuse users new to the detector. See the comments in fig. 36.
Here part of the ferrous signal
“loop” has left the screen and
may now appear as a coin
signal due to the clipping of the
displayed signal.
The same target signal but this time
with the coil raised enough to allow the
entire signal to be displayed properly
without any clipping. Clearly the object
is iron.
Fig. 36
Observing the above drawing we can clearly see the advantage to raising the
coil on certain large or shallow objects in order to keep the signal within the screen.
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