
A – Operating Theory
DPN 402197 © TSS (International) Ltd Page 7 of 10
Figure A–7: Target location using two coil pairs
The 350 System uses an array of two coil pairs to determine the position of the target
cable. Figure A–7 shows this situation.
The SEP measures the strength of signals simultaneously on each of the four chan-
nels v
x1
/v
z1
and v
x2
/v
z2
and determines the target location by triangulation. The SEP
extracts the co-ordinates for lateral offset and vertical range, and transmits these
through the umbilical to the SDC.
A.4.2 Forward Search Mode
If the 350 System receives input from an altimeter, it can use this information to esti-
mate the range to a tone-carrying cable that lies along an intersecting course ahead
of the ROV.
You may find this facility useful if you are searching for a target in the survey area.
You may use the display to steer the ROV towards the expected position of the target
at a near-perpendicular angle and then switch to the run mode to steer a course along
the target.
Figure A–8: Forward Range Calculation
When operating in the Forward Search mode, the 350 System uses signals from the
vertical and the fore-aft coils.
Signals from the relevant coil pair allow the 350 System to determine the search
angle
φ
to the target cable in the same way as described in sub-section A.4.1 above.
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