Table of Contents
Advertisement
5.3 Route location methods
1.The Maximum method
This method consists of positioning the electromagnetic sensor in the direction of the
magnetic field created by the utility radiation (fig.4.3). EMD antenna must be positioned
horizontally and the sensor placed in a plane perpendicular to the cable route. In this case the
maximum signal level is observed when the sensor antenna passes directly above the utility
line. The maximum method is intended
for a quick route location. Flat peaks of
the signal level curve do not allow for
high location accuracy, but enables a
quick route location.
The Maximum method
2. The Minimum method
When the EMD antenna in a vertical (transport) position is placed directly above the route
the signal is at its lowest level fig. 4.4. As the distance from the point directly above the pipeline
increases, the signal level first rises sharply then slowly decreases. This is the minimum method,
which is used to determine a more precise
route location (after quick route tracing
using maximum method.
The Minimum method
8. Set the required gain factor of filtered signal to
«×1/2/4/8», by pressing buttons ▲/▼
9. Commence detection or tracing according to
the method set in p.4.3, avoiding prolonged input/
output overloads
Horizontal
position
Vertical
position
14
Fig. 5.3
Fig. 5.4
Advertisement
Table of Contents
