Pinpointing - CDI CD42-STS User Manual

CD42-STS Subsea Diver/ROV Pig Location and Tracking System
Pinpointing a Stationary Pig
Once the approximate location of a stationary pig is known, a more
precise method known as "pinpointing" can be used to further increase
the location accuracy. With the pinpointing method, the antenna of
the CD42-STS is rotated to be perpendicular to the pipeline rather than
parallel. Once rotated, the operator looks for the minimum ("null") signal
rather than the maximum.
A 3-D representation of the signal "null" is shown here:
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