Comms & Optical Fibre Junction Box
The Comms & Optical Fibre Junction Box (COFJB) is fitted to the outside of the SDC.
The COFJB is oil-filled and pressure-compensated to ambient seawater pressure by means of an oil-filled bladder compensator unit mounted slightly below the COFJB. This provides a small overpressure of the compensating oil. The oil used inside the COFJB is standard mineral hydraulic oil.
The COFJB provides a convenient method of terminating the screened-twisted pair cables in the umbilical and the single-mode fibre-optic cables. In addition to terminating the umbilical cables, there is a diver voice comms changeover module inside the COFJB. This module allows the system to ‘fail-safe’ to a direct copper connection of diver voice comms to the surface equipment (in the event of a failure in the fibre-optic based diver voice communications). Under normal operating conditions, this module routes diver voice comms signals to the fibre-optic comms link in the SDC Mux pod.