Air-Coupling - RIDGID SeekTech ST-305R Manual Del Operador

Air-Coupling

Any transmitter in Inductive Mode gener-
ates a field through the air around it; includ-
ing the ground underneath. If within air-cou-
pling range of the ST-305/R, the receiver
will measure this field instead of the target
conductor. Air-coupling will distort readings
and misconstrue the location of the target
conductor.
Air-coupling effects can dominate the re-
ceived signal over a wide range (great-
er than 20 m [70 ft]) if the induced utility is
deep and poorly grounded. Very weak in-
duction and deep utilities will result in great-
er air-coupling distances. Always confirm
the detection of utilities and the readings of
depth measurements.
Air-coupling does not depend on the output
power of the transmitter and cannot be re-
duced by turning down the power. Air-cou-
pling only depends on the ratio of the field
from the transmitter compared to the in-
duced field in the target utility.
The effect of air-coupling can vary continu-
ously so be aware of the difference between
the transmitter's field and the induced field
of the utility being traced. While both will
have the same frequency, the transmitter's
field is only strong enough to obscure the
utility's signal in the region around the trans-
mitter itself.
Be sure to look overhead for power lines
that could also confuse the locate.
16 – English – ST-305/R
Testing for Air-Coupling
To test for air-coupling, tilt the receiver at a
45 degree angle towards the ST-305/R and
ensure the lower antenna of the receiver
touches the ground. Afterwards, tilt the re-
ceiver 45 degrees away from the ST-305/R
and observe the depth reading. If the depth
reading changes significantly, air-coupling
may be affecting the accuracy of the locate.
Alternatively, test for air-coupling by stand-
ing 6 m [20 ft] away from the ST-305/R. With
the lower antenna on the ground, take note
of the indicated depth measurement on the
receiver. Raise the receiver vertically 45 cm
[18 in] and observe the change in the depth
indication. If the receiver only reads the con-
ductor, the depth should increase accord-
ingly. If the receiver is air-coupling, the depth
indication does not change by 45 cm [18 in],
but changes disproportionately.