Induction; Induction And Air-Coupling - RIDGID SeekTech SR-20 Operator's Manual

Induction

To induce a signal onto the target line, place the trans‑
mitter over and in line with the target line� The transmit‑
ter must be oriented with respect to the line, as shown
below, to operate properly (orientation is specific to the
transmitter model)�
The transmitter's internal transmitting antenna generates
a signal that energizes correctly oriented, nearby metal‑
lic objects�
To improve the circuit, ensure that both ends of the target
line are grounded and place the transmitter away from
other metallic conductors that may be nearby�
Note: For complete instructions on generating a locating
signal with a transmitter, please consult the operator's
manual for your line transmitter.
20 – English

Induction and Air-Coupling

WARNING
Air-coupling can lead to false locates.
With Induction, the transmitter broadcasts a signal in all
directions� If the receiver is too near to the transmitter,
the signal broadcast through the air will be stronger than
the signal from the target line underground� This is called
air‑coupling and it can prevent you from getting an accu‑
rate locate�
The impact of air‑coupling varies with each locate and
can occur at ranges greater than 20 m [70 ft] if the utili‑
ty is deep or poorly grounded� Very weak inductive cou‑
pling and deep utilities result in greater air‑coupling rang‑
es� Always confirm the detection of utilities and the depth
measurement readings by testing for air‑coupling� Read
the following sections for instructions on how to test for
air‑coupling�
Testing for Air-Coupling
When the receiver is severely air coupled it will warn you
by hiding the Tracing Line and Guidance Arrows� Even
if you see these displayed, the receiver may still be dis‑
playing results corrupted by air‑coupling� There are two
ways you can test for air‑coupling: the 45° tilt test and the
depth verification test�
To perform the 45° tilt test, follow these steps:
1� With the SR‑24 aligned with the target line, touch
the Lower Antenna to the ground and tilt the SR‑24
at a 45° angle toward the transmitter�
2� Note the depth�
3� With the Lower Antenna still touching the ground, tilt
the SR‑24 away from the transmitter at a 45° angle�
4� Note the depth�
If the tilted depth reading changes significantly compar‑
ing the two cases, air‑coupling is occurring�
Note: The depth reading will not be an accurate reading
of the target line's depth.