User's Manual

Locating
Effects of Depth, Pitch, and Topography on Distance
Between FLP and RLP
Because of the transmitter’s field shape, the deeper the transmitter is, the further apart the FLP and RLP
will be. The distance between the FLP and RLP with respect to the location of the LL is also a function of
the transmitter pitch and the topography. (For more information on these topics, please see Appendix B:
Projected Versus Actual Depth and Fore/Aft Offset.)
When the transmitter pitch is negative, the FLP will be further from the LL than the RLP (see figure
below). When the transmitter pitch is positive, the RLP will be further from the LL than the FLP. If the
ground surface or topography slopes significantly, the locations of the FLP and RLP will also be affected
with respect to the LL even though the transmitter itself is level.
RLP
LL
RLP
FLP
Ground
Bird's Eye View
(Looking Down)
Side View
Axis Line
LL
Drill
Drill
Surface of
FLP
Transmitter (Negative
or Downward Pitch)
Transmitter (Negative
or Downward Pitch)
Effect of Pitch on Distance Between FLP, RLP, and LL
Note how the RLP and FLP are at different distances from the LL when the transmitter is at
a negative pitch (compare with figure on previous page in which transmitter is level).
It is possible to calculate depth (as a comparison to the receiver’s depth reading) using the distance
between the locate points and pitch. For additional information, please see Appendix C: Calculating
Depth Based on Distance Between FLP and RLP.
It is also possible to track the locate line when walk-over locating is not feasible, such as when surface
obstructions or interference occur. For more information about this feature, called off-track locating, see
“Off-Track Locating” at the end of the Lo
cating section.
DigiTrak
®
LT2™ Operator’s Manual 45