Internet Infrastructure: Undersea Cables
When thinking about where the internet lives, it would be plausible to think it lies among high-tech satellites communicating around the world simultaneously – resembling something of a digital cloud. Instead, the internet does not resemble a cloud, but instead resides in a physical infrastructure in hundreds of cables snaking underground and along the bottom of the sea. In fact, overseas satellite links currently account for only roughly 2 percent of international traffic, while the remainder is carried by undersea cable (Source 1). The reliability of these cables is high, and the carrying capacity of undersea cables is multiple times higher than that of a satellite. As a result of their usefulness, they have become highly valued by the largest corporations and also national governments. The first undersea communication cables were laid in the 1850s by the British and were used for telegraphy purposes. For several decades scientists struggled with formidable electrical problems. For instance, undersea cables of the 19th century did not allow for amplifiers in the cables, so high voltages were used to combat the electrical resistance across the cables. This problem severely limited the cable’s bandwidth to 10-12 telegraph words per minute (2). The technology required to effectively communicate across bodies of water was not developed until the 1950s, when several scientists produced mathematical analysis for electrical signals based on their capacitance and resistance. Improvements surfaced as a result of research, and in the 1960s, transoceanic cables were laid that included a new technology called ‘frequency-multiplexed voice band signals.’ A high voltage was put into the cables and amplifiers were placed at intervals along the cable. Many of these cables can be used today, but the limited bandwidth makes them impractical. In the 1980s, fiber optic cables were developed and rapidly replaced older technologies. Modern...
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