Teledyne 440, Системное руководство, Страница: 40 / 256

3 – Physical Installation
3-8 © Teledyne TSS DPN 402196 Issue 4.1
must make certain that they do not obstruct or interfere with camera and lighting systems,
scanning sonar systems, or other forward-looking sensors and probes.
NOTE
You must stow manipulator arms securely while you survey with the 440 System.
Any free movement in the manipulators might cause unexpected changes in the
background signal that could affect or invalidate survey data.
If you have to use the manipulators during a survey, you must check the back-
ground compensation immediately after you have stowed the manipulator arms.
❐
Rear Mounting
Rear mounting of the coil array avoids interference with manipulator arms, camera and lighting
installations, etc. However, in this position the coils could detect the trailing ROV umbilical and
show it as a false target. If this happens, your survey results will include errors of indeterminate
size.
If you must mount the coils at the rear of the ROV, arrange to monitor them with a video camera so
that you may detect and correct this condition if it occurs.
3. Height of Coils
Ideally, you should mount the search-coils so that they are no lower than 0.1m above the lowest point
on the ROV. This position is a compromise between the need to mount them low down to extend their
operating range, and the need to protect them from damage by maintaining a safe distance from the
seabed.
There is a danger that signal saturation may occur when a large target is very close to the coil array.
When surveying such a target therefore, select a higher mounting position on the ROV.
Make certain you mount the coils so they are parallel with the horizontal axis of the ROV. The System
measures the distance from the coil centres to the target, and these measurements would contain
errors if the coils were not horizontal. Be particularly careful if your system uses rams to lower and
deploy the coil array after you have launched the ROV.
3.1.3.3 Coil Assembly and Installation
You must use the correct non-conductive mounting components supplied with the 440 System to fix the
search-coils to the ROV frame. These mounting components include six pre-drilled cast nylon beams
and nylon threaded stud, nuts and washers.
When assembled, the nylon components should support the search-coils rigidly in position. You may
degrade System performance if you have to cut or modify the mounting components to establish a
successful installation.
IMPORTANT
Apart from relevant components of the 440 sub-sea installation, do not place any
conductive material, however small or apparently insignificant, any closer to the
search-coils than 0.75m. Note that, to the 440 System, a conductive bolt near the
coils can look like a target at 1 metre range.