Schonstedt Instrument GA-52Cx, Instruction Manual, Page: 6 / 17

- 6 -
If you are looking for a corner marker and detect two or more signals in the same general area,
raise the locator several inches above the ground or decrease the gain setting. Any signal that
disappears when the locator is held higher or the gain is decreased is probably coming from a
smaller target. As shown in Figure 6, the signal from a rusty bolt or other small item decreases
faster with distance than the signal from a larger target, such as an 18-inch length of 3/4 inch
rebar that can be located at depths up to 9 feet.
Figure 6: Raising the Locator Eliminates Unwanted Signals
Strongly Magnetized Markers
A strongly magnetized marker at or
near the surface may provide location
information that is misleading.
The heavy line in Figure 7 represents
the variations in tone frequencies
when the locator is moved over the
marker. When moving the instrument
from A to B, the frequency of the tone
increases and then decreases suddenly
at B. From just beyond B the
frequency of the tone increases
sharply, becomes very high directly
over the marker and decrease just
before reaching C. From C to D the
pattern is the reverse of that from A to
B. It is obvious that the locator must
enter the B-C region. Otherwise the
marker might be assumed to be
between A and B, or C and D.
Figure 7: Signal Pattern from a
Strongly Magnetized Marker
This phenomenon is explained by the fact that the locator is 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 high frequency is produced at these points.