Subsea Cables & Internet Infrastructure

A fibre optic subsea cable is encased in a polyethylene sheath. Most damage due to fishing trawlers, current abrasion, and anchors occurs in water depths 1,000 meters or less. Hence cables laid or buried in shallow waters are usually single or double armored to protect them. The armor consists of galvanized or stainless steel wires wrapped around the white polyethylene layer. Galvanized steel wire has a zinc coat that resists salt water corrosion. While armor does protect against abrasion and small mechanical forces, it is not strong to prevent the cable being torn by sea floor trawler net or a dropped or moving anchor.

TAT-1 was the first Trans-Atlantic cable intended to carry voice traffic. Up to that point the only telephony across the ocean was short wave radio. These first generation vacuum tubes regenerated the electrical signals used for communication. These vacuum tubes could only regenerate in one direction. Hence TAT-1 was a two cable system. The vacuum tubes were amazingly reliable with none of the 51 repeaters on each of the two cables comprising TAT-1 failing during its long operational life span. The cable introduced two other innovations, namely polyethylene to protect the cable and a coaxial cable design. Polyethylene replaced gutta-perch, a tree rubber product.