Discrimination Points - Fisher M-SCOPE 1236-X2 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 its "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 1236-X2 on by turning the VOLUME control clockwise
to 5.
3. Set the SENSITIVITY Control to 8.
4. Set the FREQUENCY Control to 0.
5. Set the DISC control to the IRON present position.
6. Hold the search coil in the air, away from any metal objects, and
check the batteries as explained in the Control Functions section.
(See SENSITIVITY, p. 9.)
7. 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 1236-
X2 is a motion detector in the DISC mode and responds only when
the search coil (or the target) is moving.
7. Increase the DISC 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 1236-X2 rejects some targets and continues 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 3 and the pull tab discrimination point at 7.
8. 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
1236-X2 will instead respond with a strong broken signal, which will
usually disappear if the search coil is raised slightly. (whereas, the
strong signal of a good target will usually get weaker when the
search coil is raised.)
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PINPOINTING IN MOTION SEARCH MODE
Pinpointing in the Search Mode will take a little practice, but you
may find that for most targets it's even quicker than the No-Motion
Pinpointing Mode. Simply use the same procedure as in steps 2
through 5 on p. 14. The only difference will be that when you stop
the coil over the target you will lose the audio signal. You must
keep the coil moving at least slightly to determine the location of
the strongest signal before you stop it.
1. For very strong signals, you may improve your
motion mode pinpointing accuracy by adding one
or more of the following steps:
a. Lift the coil until the signal is just barely heard.
b. Reduce the sensitivity level.
c. Increase the discrimination level.
d. Rest the coil on the ground and move it back
and forth very slowly.
2. For very weak signals try the following:
a. Move the coil closer to the ground.
b. Increase the sensitivity level.
c. Decrease the discrimination level.
d. Speed up the sweep rate slightly.
1. Minimum Depth
a. Very slow or very fast sweep speed.
b. Discrimination set at 10.
2. Good Depth
a. Moderate sweep speed.
1
b. Discrimination set at 5.
2
3. Maximum Depth
3
4
a. Moderate sweep speed.
b. Discrimination set at 10.
Figure 9. Search coil
detection pattern
4. Missed target
NOTE:
Many targets within the range of your 1236-X2 will not be
detected unless you closely overlap your swings.
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