Topside Fibre Mux

The Fathom Systems Topside Fibre Multiplexer enables the iBIS to provide communication routing and redundancy with divers and the diving bell.

One of the main technical advantages of the iBIS SDC package over conventional bell control systems is the provision of superior video, voice communications and data links between the SDC and surface – by the use of optical fibres.

The use of optical fibres for underwater video and telemetry is now a well-proven technology, with significant advantages over ‘copper’ hard-wired systems (i.e. systems using multiple electrical signal and power cables).  The main advantage is that the datalink is essentially loss-less (signals transmitted into one end of the link reappear at the opposite end without loss or degradation).

The iBIS uses two separate optical fibres in the main bell umbilical, with each fibre having its own dedicated multiplexer unit at each end of the link.  The two SDC multiplexers are located inside the SDC Mux pod and the two topside multiplexers are inside the topside Multiplexer rack.

In order to provide a fault tolerant system, there are copper wire backup links in the main bell umbilical for diver’s voice communications and serial telemetry to the SDC Mux pod and diver monitoring acquisition unit.  Failover to these links is either automatic or manual.

The main function of the topside fibre optic multiplexer is to convert the conventional copper signals to the two optical fibre signals that are transmitted to the SDC over the two singlemode optical fibres.  This conversion process involves isolation, signal switching, level adjustment/balancing and buffering/amplification.