General Machine Products RD7000 Traceable Rod Detection - Manual (Page 18)

12 RD7000 Operation Manual
Section 4. – Locating cables and pipes
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.
To select null mode:
Press and release the key to switch the
receiver on.
Press the antenna key until the null mode icon
is 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 receiver will indicate
line position but not its orientation.
4.1.3 Peak/Null mode
Peak/Null mode give you the advantages associated with
these modes simultaneously.
Use the proportional arrows to place the receiver 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
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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 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 cannot be disabled
using the menu.
In peak mode the following indicators are displayed by the
LCD:
Depth.
Current.
Signal strength.
To select a peak mode:
Press and release the key to switch the
receiver on.
Press the antenna key until the peak mode icon
is displayed on the LCD.
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