Discrimination Points - Fisher 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 searchcoil 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 searchcoil (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
searchcoil 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 normal
response indicating that the powerful discrimination
circuitry is doing its job.
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