Fisher 1225-X - Manual (Page 8)

8. Some objects will cause sharp static or “ticking”
when rejected. This is a perfectly normal response
indicating that the powerful discrimination circuitry
of the 1225-X is doing the job.
9. Large pieces of trash such as beer cans or jar lids
may sound like a good target no matter what you
do. With a little practice however, you will be able
to tell the difference between a large target and a
small coin-sized object.
10. The following chart shows some different target
responses you may expect at different levels of
discrimination. Note that as you increase the
discrimination level, you progressively eliminate more
targets including some good ones, such as nickels
and gold rings.
DISCRIMINATION POINTS
Figure 4. Discrimination. Typical 1225-X audion responses for 2-inch deep
targets with search coil sweeping 1 to 2 inches above ground.
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Note: The discrimination levels shown are typical values only and
may vary from detector to detector.