9
Figure 4-4: Two Readings of Target Depth
4.2
Typical Signatures and Operating Hints
You can develop a good sense of target depth by taking two readings from a target – one with the
instrument tip at the ground surface, and one with the end of the 880B four to twelve inches above the
ground. The response to a shallow target diminishes more rapidly than that of a deeper target. See Figure
4-4.
Once a target depth has been estimated, a rough idea of its size can be gauged by the amount of sensitivity
setting needed to read “25” on the meter.
Long and narrow targets provide the greatest response when the instrument is parallel to the target. See
Figure 4-5.
The following figures illustrate typical responses to various objects.
Figure 4-5: Dip Slightly and Move Slowly Across Target
