Options and Upgrades
4.14 Option 043, Coax to Fiber-Optic Interface Unit
4.14.1 Introduction
The SeaBat 8101 Sonar Head uplinks data to the Sonar Processor via a co-axial
cable embedded in the standard 25 meter head to processor cable. This length
can be increased to a maximum of 150 meters by making compensating circuit
adjustments in the Sonar Processor. Option 043 allows the use of a fiber-optic
cable which provides a far greater length. Fiber-optic interfaces are typically used
with ROV installations where the head to processor cable is first terminated on
the vehicle.
This option requires no modification to the sonar head but does require modifica-
tion to the circuitry of the sonar processor. In addition, the sonar head to sonar
processor cable will require a change in termination dictated by the specifics of
the customer's installation.
For systems that already have Option 043 modifications to the sonar processor,
the co-ax to fiber-optic interface unit alone can be procured as Option 043A.
4.14.2 Installation
The fiber optic interface unit (Figure 25) consists of a coax to fiber converter box.
The standard head to processor cable must be reterminated within the ROV. The
normal coaxial uplink is redirected to the coax to fiber-optic interface unit which
will be located in the general vicinity of the sonar head on the ROV. The optical
output of the interface unit must be coupled to the fiber-optic cable in the ROV's
umbilical cable. At the topside end, the fiber-optic cable is sent directly to either
the FO1 or FO2 connectors on the rear panel of the sonar processor. The 8101
system must be configured to look for the uplink at the selected fiber-optic port.
See Paragraph 3.9.1, for information on selecting the correct uplink port.
4.14.3 Application
Due to the high frequency digital uplink employed by the SeaBat 81xx series sys-
tems, uplink cable length is generally limited to 150 meters of coaxial cable. For
installations where cable lengths in excess of this length are required, such as
ROV installations, Option 043 should be used.
The Coax to Fiber-Optic Interface Unit is designed to fit into an ROV junction
box. The unit requires 24 VDC operating power which must be supplied from the
ROV. Analog co-axial input is made via a standard 75 ohm BNC connector and
the optical output uses as ST type 62.5/125 nm fiber. See Table 9 and Table 10
for additional specifications.
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SeaBat 8101 Operator's Manual
4-14
Version 3.02
