DCI DigiTrak Mark III, Operator'S Manual

Page: 63 / 92

®
Locating
Field Strength:
100%
0%
Field Strength:
100%
0%
Parallel Field Lines and Antenna Perpendicular Field Lines and Antenna
Orientation of Field Lines with Respect to Antennas
>>>>>
>>>>>>>>>>
>
>>>>>>>>>>>>>
>
Field Strength:
50%
50%
Vertical Field Lines at FNLP and RNLP
Front and Rear
Negative Locate Points
If the field line is vertical with respect to the antennas,
each antenna will read 50% of the signal (figure). This
occurs at two locations: one behind the transmitter,
known as the rear negative locate point (RNLP), and one
in front of the transmitter, known as the front negative
locate point (FNLP). Each of these locations is a specific
point that is independent of the transmitter’s signal
strength. Both the rear and front negative locate points
are important to accurately locating the transmitter, but
the FNLP is used more frequently. The FNLP is also
used to aid against oversteering.
>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>
Field Strength:
50%
50%
Horizontal Field Lines at PLL
Positive Locate Line
Above Transmitter
When the field line is horizontal with respect to the
antennas, each antenna will read 50% of the field strength
at that point. This location is directly above the transmitter
and is referred to as the positive locate line (PLL). The
transmitter’s exact lateral location below the PLL can be
determined either by using the FNLP and RNLP or by
finding the peak signal. However, locating the trans-
mitter’s position below ground using the peak signal is not
encouraged due to its susceptibility to interference
potentials.
DigiTrak
®
Mark III Operator’s Manual 55