Table of Contents
Advertisement
coming from a shallow target. The signal from a rusty bolt or other small item (see Figure 9.) is much
weaker than the signal from a larger target such as a 18-inch length of 3/4 rebar which can be located at
depths up to 7 feet.
+ or -
Figure 9. Decreasing 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 10 represents the increase and decrease in the audio and bar graph (XTd model
only) 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, peaks directly over the marker and
then decreases 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.
Figure 10. Signal Pattern from a Strongly Magnetized Marker
AUDIO SIGNAL HIGHER ABOVE GROUND
AUDIO SIGNAL CLOSE TO GROUND
Audio Signal
B
A
0
+ or -
+ or -
- 8 -
+ or -
C
0
D
+ or -
IRON PIPE
Advertisement
Table of Contents
