Product Manual

9
If you are looking for a corner marker and detect two or three signals in the same general
vicinity, raise the locator several inches above the ground, or decrease the gain setting before
you get a shovel. Any signal that disappears when the locator is held higher, or the gain is
decreased, is probably coming from a smaller target. The signal from a rusty bolt or other
small item (see Figure 13) is much weaker than the signal from a larger target, such as an 18-
inch length of 3/4 inch rebar which can be located at depths up to 10 feet.
Figure 13: Decreasing the gain eliminates unwanted signals.
Strongly Magnetized Markers
A strongly magnetized marker at or near the surface provides a weaker indication on both
sides of the marker that could be mistaken for the marker.
The heavy line in Figure 14 represents the increase and decrease in the audio and bar graph
indications as you move the locator over a marker. Between points A and B the signals
increase slightly and then decrease. Just beyond B the signals increase rapidly, peak directly
over the marker and then decrease at point C. From C to D the signals increase and
decrease again. So if you do not
move the locator completely
across the marker you might
assume that the weaker indication
on either side of the marker is its
location. The two weaker
indications occur because the
locator is extremely sensitive to
the magnetic field components
parallel to its long axis. At points
B and C the field is perpendicular
to the locator so no significant
audio or bar graph indications are
produced at these points.
Figure 14: Signal Pattern from a Strongly Magnetized Marker