How it works: undersea internet fiber optic cables

Date:20 January 2020 Author: Leila Stein Tags:, , ,

South Africa is currently experiencing really slow internet speeds as a result of multiple undersea fiber optic cables that broke down last week. One of these cables that have since broken, the West Africa Cable System (WACS) arrived in South Africa in 2011 and in 2016 neighbourhoods across the country started getting cables laid so they could access this much-improved internet. fiber optics supplied internet improved speeds and was cheaper than the previous ADSL lines used by most households and businesses.

But how exactly do these cables work to deliver us the high-speed internet?

They transmit light

The fibre optic cables are used to transmit a signal as a pulse of light along a medium. This signal carries the data which we upload and download every time we go online.

They are made of glass

The “fibre” in a fibre-optic cable are actually made of thin glass which has lasers on one end and receptors on the other. This glass core is surrounded by glass cladding which ensures light that “escapes” is guided back along the fiber. This is protected by a cladding and either PVC or metal to protect the fiber from the water.

They lie on the ocean floor

The cables are laid directly on the ocean floor, with those closest to the shore being buried for their protection. The area where the cable will lie is mapped to avoid any areas of particular danger to the cable like fault lines.

They are sometimes faulty

While the current faults are quite shocking as more than one cable line has gone down, and bad weather in the Cape has stopped the ship meaning to go fix it from leaving the harbour, breaks in the lines are quite common. The reason this doesn’t usually cause problems is because network providers spread their capacity across multiple cables, to make sure there is a backup if one breaks. Major factors contributing to cable breaks include fishing vessels dragging their anchors across the ocean floor and environmental factors like earthquakes.

Image: Screenshot/ Submarine cable map


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