On September 25, 1956, the modern era of telecommunications began with a phone call. Actually, it was 707 phone calls made between England and North America in the first day of operations of the new TAT-1 transatlantic telephone cable. Stretching between Newfoundland and Scotland, the TAT-1 extended over 1,950 nautical miles and used a series of 51 signal boosting repeaters to ensure a robust current throughout the length of the cable. It was the result of nearly a century of innovation, and was the first of many transatlantic cables that have made so much of our modern world possible.
TAT-1 was not the first transatlantic cable. In 1866, following several attempts and over a decade of development, the first transatlantic telegraph cable was brought online. It had taken so long because the team that developed it had to solve problems that no one had faced before: finding the most suitable underwater topography for laying a cable, shielding and insulating the currents on the wire from the capacitive effects of tons of seawater, and finding a ship and crew up to the task of laying thousands of miles of cable. After all this hard work, the result was underwhelming. At peak operations, the telegraph cable could transmit a maximum of 17 words per minute. And because bandwidth was so low and the cost to lay the cable so high. it was expensive to use. They charged $5 per word, meaning that to transmit this sentence would take over a minute and cost you $110. It was doubtful you could find anything important enough to say that would justify the cost.
With the advent of telephone technology, the desire to create a conduit for transatlantic communication grew. The largest problem was that of distance: electrical signal could only travel so far on copper wires before degrading and fading away to nothing. This was solved with the creation of signal repeaters that, when spaced out at intervals, could extend the range of a signal theoretically infinitely. This was before the development of the transistor, and so these repeaters were made from old-fashioned vacuum tubes, making the challenge that much trickier. The specifications demanded that the repeaters, of which there would end up being 51 along the course of the cable, would need to bend into the spool to fit on the deployment ship. With some masterful engineering, the specially-designed repeaters were made into a flexible length of eight feet long and not only met the needs of the project, but also lasted the lifetime of the cable without requiring maintenance. This was extraordinarily convenient given how hard it would be to replace a section of cable hundreds of miles from shore and two and a half miles underwater.
Compared to the unreliable and insecure radio service that came before it, TAT-1’s dedicated line between North America and Europe was a massive leap forward. It provided 36 separate channels for communications traffic, meaning it could handle 35 calls at once (one of the channels was reserved for telegraph communications. While it was still expensive to use, it provided a constant conduit for voice communications between the continents, and was even secure enough to afford it the distinguished responsibility of carrying the Moscow-Washington hotline between the famous red phones.
TAT-1 was the first of many undersea transatlantic cables. By 1963, TAT-3 was carrying 138 channels between New Jersey and the U.K., and by 1976 engineers had stretched copper wire as far it would go by running a cable between Rhode Island and France that carried 10,000 channels. TAT-8, laid in 1988, was the first of the fiber optic cables and carried 40,000 channels. Today, with advances in fiber optic technologies, undersea cables are still the fastest and most reliable method of communication around the globe. Even satellites can’t keep up. The most recently laid cables can handle 8 terabits of data each. To accomplish this, you would need to lay around 4 million TAT-1s. We’ve come a long way.
Note: In case you were wondering, it would have cost about $3,300 and taken 39 minutes to transcontinentally telegraph this story in 1866, not including this note.
