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Section 4 – Locating cables and pipes
This section introduces the principals and techniques of
locating buried cable and pipe utilities with the RD7000+
system. For more information on the theory of cable
and pipe location, please refer to "ABC & XYZ of locating
buried pipes and cables", which is available from
www.radiodetection.com
4.1 Antenna modes
The RD7000+ system supports three antenna modes to
suit your particular application or the local environment.
These modes are:
•
Peak mode (all models)
•
Null mode (TL and PL models only).
•
Peak/Null mode (all models).
4.1.1 Peak mode
Peak mode provides the most sensitive and accurate
mode for location and depth measurement. It provides
a sharp peak response with a corresponding small
decrease in sensitivity. Peak mode is always enabled
unless an alternative mode is selected using the menu.
In peak mode the following indicators are displayed by
the LCD:
•
Depth.
•
Current.
•
Signal strength.
•
Compass.
To select a peak mode:
1.
Press and release the
locator on.
2.
Press the antenna key until the peak mode icon
is displayed on the LCD.
4.1.2 Null mode
Null mode is used to verify a locate signal in environments
with limited or no electromagnetic distortion.
In null mode the following indicators are displayed by
the LCD:
•
Signal strength.
•
Right and left arrows.
•
Compass.
12 RD7000+ Operation Manual
key to switch the
To select null mode:
1.
Press and release the
locator on.
2.
Press the antenna key until the null mode icon
displayed on the LCD.
Null mode gives a null response when it is directly over
the line. The sharp, null response is easier to use than
the peak response but is vulnerable to interference and
should not be used for locating, except in areas where
there is no interference present (See 4.1.3 Combined
Peak/Null mode). In null mode, the locator will indicate
line position but not its orientation.
4.1.3 Combined Peak/Null mode
Peak/Null mode give you the advantages associated with
these modes simultaneously.
Use the proportional arrows to place the locator above
the NULL point. If the peak response is not at a maximum
then this is evidence of a distorted field. If the peak
response is at its maximum level where the NULL point is
located then there is no or very limited distortion present.
In Peak/Null mode the following indicators are displayed
by the LCD:
•
Proportional right and left arrows.
•
Signal strength.
•
Current
•
Depth
•
Compass
To select Peak/Null mode:
1.
Press and release the
locator on.
2.
Press the antenna key until the Peak/Null mode icon
is displayed on the LCD.
4.2 Compass
The LCD compass provides a visual indication of the
direction of the target cable, pipe or sonde. The compass
is available when locating active frequencies as well as
CATV and CPS passive frequencies. The compass is
unavailable when the locator is set to detect passive Power
and Radio signals.
key to switch the
is
key to switch the
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