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1998 due to its obsolete terminal transmission technology. Pieces of the decommissioned Gemini cable were

recovered and redeployed (along with the original repeaters) for three re-lay projects connecting Bermuda, Tortola and Jamaica to the United States (Figure 3). Although the Gemini cable system had been originally designed for operation at 4 x 2.5Gb/s, new line terminal equipment was installed that supported 16 x 10 Gb/s on each of the two fibre pairs, thus providing additional capacity for future expansion. Additional pieces of the Gemini system were

redeployed in a separate project on the east side of the Atlantic Ocean. Completed in 2006, project HUGO connected the island of Guernsey to mainland Britain and France. HUGO had initially been an unrepeatered system (with the original Gemini repeaters taken off), but had become limited by the relatively high loss of the cable. Te recent upgrade of the HUGO system wet plant represents another type of cable recovery and re-lay project with the insertion by Xtera of Raman-based optical repeater to remove these loss limitations. Te marine operations required for the insertion of the repeaters were similar to those carried out for a

simple cable repair. Tis wet upgrade demonstrates that new technologies can be used to extend the capacity and working life of redeployed systems. Another recent cable re-lay project using the

redundant Rioja 1 cable was carried out by BT in 2014 to improve connectivity to the Isles of Scilly. Te 939km cable between Porthcurno, Cornwall, and Santander, Spain, had remained unused on the seabed of the Atlantic Ocean since it was taken out of service in 2006. Te cable was cut at two points in the Atlantic – about 100km and 15km from Land’s End. Te 85km cable section recovered from the seabed was landed at Portcressa beach on the Isles of Scilly in July 2014, re-laid back to the UK mainland and then reconnected to the original cable approximately 15km offshore.

Conclusion Tere are many compelling reasons to use recovered cables around the world. Compared with new builds, cable re-lay offers the following

potential advantages: l


It can be significantly quicker to get the system up and running with funding in place.

In some cases, savings close to 50 per cent can be seen when compared with new build.


Tere are massive environmental savings of up to 95 per cent.

Recovering a decommissioned cable system with the objective of building a new system in another location is a challenging endeavour requiring additional skills beyond those needed for standard new builds with brand new wet plant direct from the factory. Also, the commercial benefits that the purchasers can expect from the cable redeployment is strongly influenced by a number of factors, including the original marine installation of the cable to be recovered, the relative locations of existing and new systems, and project design requirements. As such, re-lay project assessment can only be carried out on a case-by-case basis, and will require a high level of expertise in order to correctly identify, quantify and optimise all the factors impacting the project cost and performance.l

Bertrand Clesca is head of global marketing for Xtera and is based in Paris, France

Further reading ‘Twenty thousand leagues under the sea: A life cycle assessment of fibre optic submarine cable systems’,Craig Donovan – KTH, Stockholm, Sweden, October 2009.

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