Discrimination Points - Fisher Labs 1280-X Aquanaut Operating Manual

DISCRIMINATION POINTS

By adjusting the DISCRIMINATION control you will be able to ignore
(or "reject") small pieces of metallic trash and ground minerals
while detecting valuable targets. The lowest setting at which an
object is rejected is referred to as the object's "discrimination
point". Discrimination points are determined by such factors as
size, shape, depth, type of metal and ground mineralization.
1. Scatter some sample targets such as coins, pull
tabs and small pieces of foil on the ground 1 to 2
feet apart.
2. Turn the SENSITIVITY control to 9.*
3. Turn the DISCRIMINATION control to zero.
4. Put the headset on and turn the POWER ON-OFF/
VOLUME control to about 6.
5. Hold the search coil about 2 inches above and
parallel to the ground. Move it slowly over the
samples and note the sharp loud response as you
pass over each one. Keep in mind that the 1280-X
is a motion detector and responds only when the
search coil (or the target) is moving.
6. Increase the DISCRIMINATION control to a setting
of 3 and again pass over the targets. Repeat this
process at settings of 4,5,6 and so on to 10. You will
note that as you increase the level of discrimination,
the 1280-X will reject some targets and continue to
respond to others. You have now determined the
discrimination points for the rejected objects. For
example, the small nail discrimination point may be
at 4 and the pull tab discrimination point at 6.
7. Some objects such as shallow bottle caps, bent
pull tabs or trash less than 2 inches from the coil
may be difficult to reject. The 1280-X will instead
respond with a strong broken signal which will usually
disappear if the search coil is raised slightly. (The
strong signal of a good target will just get weaker
when the coil is raised.)
8. The 1280-X will remain silent when some objects are
rejected, however other objects may "snap, crackle
and pop" as they are rejected. This is a perfectly
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respond with a strong broken signal which will
usually disappear if the coil is speeded up or raised
slightly.
9. If you hear two beeps very close together and
can't find anything under either one, you're probably
over a nail or some other elonggated ferrous object.
But a coin on edge will give the same response and
there's lots of coins on edge down there. In either
case, the target will be between the beeps or, if you
sweep at right angles to your original direction, you'll
receive a single beep directly over the target.
10. You may hear some static at a sensitivity level
of 10. This is normal, how ever if it is too loud or
annoying, reduce the sensitivity level to about 8 or
9, just enough to eliminate most of the static.
11. When in doubt about the probable identity, dig
it up.
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