27
This result can also occur midway between the ground spike and a fault and when the A-
frame is exactly perpendicular to the fault. There is a return field around the Transmitter
ground spike. As you move toward the fault, the bars and the Active numerical number will
decrease until you reach the midpoint between the fault and ground spikes. At the half
waypoint between the fault and ground spike, the signal strength is at it is absolute lowest. At
this point the bar graph and Active display will show zero and the arrows become erratic.
To determine if you are midway between faults or directly over a fault, move the A-Frame
further from the Transmitter and measure again. If the arrows tell you to continue in this
direction, the zero point was a midpoint. If the arrows tell you to return toward the
Transmitter, the zero point was a fault. As you continue, they will increase until you reach
the fault.
Nearly 70% of the signal exists within the last 1/3 of the distance between the ground spike
and the fault. The amount of signal measured and displayed by the A-Frame is proportional
to the number of field lines in
Figure 5-2
between the A-Frame spikes. Thus, the maximum
signal point occurs when one A-Frame spike is directly above the fault.
One can learn what to expect the A-Frame response at the fault will be by probing around the
ground point. As shown in
Figure 5-2
, the signal pattern around the fault and ground point is
identical (if there are no nearby conductors). This means that the A-Frame will react the
same way around the fault as at the ground point.
As you move toward the fault, the bars and the Active numerical display will decrease until
you reach the midpoint between the fault and ground spike. As you continue, they will
increase until you reach the fault.
