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or region. When a number of cables are damaged by a natural disaster, a whole country could be leſt without connectivity. For that reason, the data load has to be
spread across more than one cable, and the cables do not all land in the same location. Otherwise ‘it creates what is called a single point of failure, and that is kind of putting all your eggs in one basket’, says Eric Handa of AP Telecom. ‘You want to make sure you have diverse cables going to different locations, and that creates a mesh network, to make sure you are running at least three routes. Between New York and London, many cables go to many different locations, but in Jakarta, Indonesia, there are not a lot of options because the country doesn’t have a lot of cables.’ As cable operators worry about redundancy,
it is getting hard to recall that, only as recently as 1988, the first transatlantic submarine fibre-optic telephone cable – the TAT-8 – was laid down to connect the United States and Europe. Two years later, the North Pacific Cable System linked the USA and Japan. Today, it’s no longer distance that is the
issue, but speed and capacity. Te explosion of data traffic – driven by the internet; mobile and machine-to-machine computing; the surge in video applications; and the shiſt of enterprise computing to the cloud – is fuelling a demand for multi-terabit capacities from telecom providers. Besides transmission technology, the fibres
Inspecting fibre optic cables
there and do some additional burial work, burying that section of the cable into the seabed and protecting it,’ says Wilson. Burying the cables deeper is being made
The speed and power of the world’s underwater nervous system will become unrecognisable, compared to those pioneering days of the late 1980s
possible by the same ROV technology that helped to repair the fibre optic networks off the east coast of Japan. Te latest versions of these robots now can put down fibre optic cables at a depth of three metres into the seabed, in ocean depth up to 2,000m. And, as cable burials are getting deeper – and cables themselves are getting ever longer – their demand for power is surging, helped by the recent move from AC power to DC systems in some cable networks, says SMD’s Graeme Walker.
Staying connected
Driving this push for cable safety is the fact that submarine networks nowadays have become vital veins of the global economy, carrying huge amounts of system-critical data. In some cases, if there is no redundancy, the outage of one single cable could have dramatic consequences, such as data blackout for a city
26 FIBRE SYSTEMS Issue 1 • Autumn 2013
themselves are constantly evolving too, opening up new possibilities for submarine cable systems. For instance, Corning’s latest fibre systems, such as the Vascade EX2000 and EX3000, use new silica core technologies to achieve attenuation levels and very large effective areas. According to Chris Towery, manager at the High Data Rate Optical Fibers department at Corning, this will ‘significantly improve the design flexibility of submarine systems, enabling trans-Pacific distances at 100Gb/s and more with reasonable repeater spacing and high channel counts’. An additional benefit of silica core fibres compared to the silica-germania doped fibres of first-generation submarine systems, he says, is that ‘they have a nine per cent lower non-linear index of refraction and can reduce latency by 0.4 per cent, which may not sound like much, but we have been told by our customers that every microsecond counts’. Te speed and power of the world’s
underwater nervous system will become unrecognisable, compared to those pioneering days of the late 1980s.l
Global Marine Systems
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