Garrett Metal Detectors Metal Detectors GTAx 550 - Manual (Page 33)

There are two ways to set discrimination.
First method: Press the (+) and (-) touchpads to
position the blinking Upper Scale cursor above
the Lower Scale segment corresponding to the
particular target to be detected or ignored. If the
segment is displayed, that particular target will
be detected. If you wish to reject that type of
target, press the ACCEPT/REJECT touchpad. The
segment will disappear, creating a reject notch. If
the Lower Scale segment is not displayed, press the
ACCEPT/REJECT touchpad to illuminate it, creating
an accept notch, and your GTAx 550 will begin
detecting targets represented by that segment.
Second method: Pass the searchcoil over an
object to be accepted or rejected as a target or pass
the particular target across the face of the coil about
two inches from its surface. Check to make certain
there is an appropriate cursor on the Upper Scale of
the Graphic Display. Then press ACCEPT/REJECT
depending upon your discrimination choice for this
specific target.