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.)
9. Some objects will cause sharp static or "ticking" when
rejected. This is a perfectly normal response, with the SILENCER
switched OFF. When the SILENCER is switched on, these "ticking"
sounds are eliminated.
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