3M 2550 Cable Box User Manual


 
78-9000-0192-2 Rev C 31
E. Directional Null (DirNull)
TRACE [2] + Mode [SK] + DirNull [SK Toggle]
or Menu/OK [5] + Cable/Pipe [SK] + Mode [SK] + DirNull [SK Toggle]
In Directional Null mode, as the operator approaches the cable or pipe, the numerical
Signal Strength [9] ([8] for 2550 locator) will increase then fall sharply as the receiver
crosses the target cable or pipe. The Bar Graph [11] ([10] for 2550 locator) fills from
both sides toward the middle and the receiver speaker volume decreases. As the antenna
moves off the target path, the Bar Graph [11] ([10] for 2550 locator) opens, the Signal
Strength [9] ([8] for 2550 locator) increases, and the speaker volume increases. Gain
adjust is automatic in Directional Null mode.
The center of the DirNull display provides a ‘compass view' of the target path. An arrow
will point toward the location of the cable/pipe in 45-degree steps. A solid line will
appear over the cable/pipe, indicating its orientation to the receiver handle.
For example:
Figure 1: If the target path is to the right of the
receiver, and running parallel to the operator, the
right arrow will display.
Figure 2: If the target path is to the left and in front
of the operator (not running parallel to the receiver)
the arrow will point toward the top left side of
the display.
Figure 3: When the receiver crosses the target path,
a solid line will appear, instead of arrows, indicating
the target path and its orientation to the receiver
handle.
Before marking target path, always use Directional Peak (Dir Pk), Special Peak (Spl Pk)
or Trace View (T-View) mode to verify location.