Understanding Sondes And The Scout; Appendix A - RIDGID Scout Operator's Manual

Scout™ Sonde and Line Locator

Appendix A

Understanding Sondes
and The Scout
Electrical fields emitted by buried objects can be of two
types; the first type, is emitted by long conductors such
as energized wires, inspection camera push cables or
pipes. These objects produce a long cylindrical field
and this is often referred to as "Line" tracing.
Figure 1 – The field emitted by a charged line.
(Passive, AC Tracing is just a special case where the
line is "energized" with electrical power.)
The second type, sondes, (also called transmitters,
beacons, or active duct probes) emit a differently shaped
field and the Scout is programmed to measure and dis-
play this type of field. The more complex field shape of
a sonde, is called a dipole field, and is the same as that
produced by a bar magnet and our planet Earth.
Figure 2 – The dipole field emitted by a sonde.
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In fact, if the Earth were turned on its side, its magnetic
field would look a lot like the field from a sonde.
Figure 3
As a locator, the Scout can measure the shape (angle) of
the field lines from a sonde and identify distinct charac-
teristics of these lines. Three important characteristics are
the two POLES and the EQUATOR. At the Poles the
angle of the signal is 90 degrees (vertical). At the Equator
it is 0 (horizontal). Poles are distinct points in space,
while the Equator wraps completely around the sonde.
Since these distinct characteristics are constant, they can
be used to accurately pinpoint the location of the sonde.
Ground
Figure 4
Poles usually occur where conventional locators would
experience "nulls", the dead spots that occur when the
signal passes through their antennas vertically. The dif-
ference is that Scout can "see" the Poles ("nulls") and
show you where they are, even when you're not directly
over them, and no matter how Scout's antennas are
aligned with the signal. This is one reason why locating
with Scout is so much easier than with conventional lo-
cators.
If vertical the sonde is located at the point where the
Equator passes directly between the two Poles.
Ridge Tool Company
Pole Pole