3M 2550 Manuale Utente

78-9000-0192-2 Rev C

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.