Figure 3-4: Coil Separation Distance - Teledyne 440 System Manual

Separation
(0.75 - 1.2m)
Non metallic
coil support
Buoyancy
aid
Coils
Height of

Figure 3-4: Coil separation distance

Small ROVs will tend to generate a comparatively weak background signal. This allows you to mount
the coils closer to the ROV body.
Larger ROVs would generate a stronger background signal. To avoid this having too great an effect on
System operation, you should mount the coils farther from the body of a large ROV. This requirement
should not present a problem because larger ROVs usually possess greater manoeuvring power, and
so will be able to overcome the additional manoeuvring resistance caused by the coil mounting
position.
The separation distance should be such that the background compensation signal
for any channel does not exceed 1000µV for standard coil values and 7500µV for
early coil values – see section 6.2.2.3 "Background Compensation" on page 6-22
for a description of background compensation. For most installations, a coil sepa-
ration distance of between 0.75 and 1.2 metres will usually achieve this.
Loose metalwork on the ROV can cause changing eddy currents and hence
changing background compensation levels as the vehicle lifts of the seabed. This
is easily mistaken for a problem with the seawater rejection. It is best cured by
moving the coils further away from the ROV. Fixing any loose metalwork securely
and ensuring a good earth connection (at seawater potential) to the SEP may also
help.
2. Coil mounting position
❐ Front Mounting
Based upon considerable field experience, Teledyne TSS recommends a front-
mounting location for the coils of the 440 System. This is both effective and practi-
cal for the majority of installations.
The preferred position to mount the coil array is on the front of the ROV. This will help the pilot to
follow the most effective course along the target by using the DeepView for Windows Run Window.
It will also reduce the risk of an umbilical snag. With coils mounted on the front of the ROV you
DPN 402196 Issue 4.1
ROV
coils
© Teledyne TSS
3 – Physical Installation
NOTE
NOTE
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