TAT-1

History

The first transatlantic telegraph cable had been laid in 1858 (see Cyrus West Field). It only operated for a month, but was replaced with a successful connection in 1866. (about US$45, or roughly $550 in 2010 dollars) for three minutes and handling around 300,000 calls a year. Although a telephone cable was discussed at that time, it was not practical until a number of technological advances arrived in the 1940s.

The developments that made TAT-1 possible were coaxial cable, polyethylene insulation (replacing gutta-percha), very reliable vacuum tubes for the submerged repeaters, and a general improvement in carrier equipment. Transistors were not used, being a recent invention of unknown longevity.

The agreement to make the connection was announced by the Postmaster General on December 1, 1953. The project was a joint one between the General Post Office of the UK, the American Telephone and Telegraph company, and the Canadian Overseas Telecommunications Corporation. The share split in the scheme was 40% British, 50% American, and 10% Canadian. The total cost was about £120 million.

There were to be two main cables, one for each direction of transmission. Each cable was produced and laid in three sections, two shallow-water armored sections, and one continuous central section 1500 nmi long. The electronic repeaters were designed by the Bell Telephone Laboratories of the United States and they were inserted into the cable at 37 nmi intervals – for a total of 51 repeaters in the central section. The armored cables were manufactured southeast of London, at a factory in Erith, Kent, owned by Submarine Cables Ltd. (owned jointly by Siemens Brothers & Co, Ltd, and The Telegraph Construction & Maintenance Company, Ltd).

The cables were laid over the summers of 1955 and 1956, with the majority of the work done by the cable ship HMTS Monarch. At the land-end in Gallanach Bay near Oban, Scotland, the cable was connected to coaxial (and then 24-circuit carrier lines) carrying the transatlantic circuits via Glasgow and Inverness to the International Exchange at Faraday Building in London. At the cable landing point in Newfoundland the cable joined at Clarenville, then crossed the 300 mi Cabot Strait by another submarine cable to Sydney Mines, Nova Scotia. From there the communications traffic was routed to the US border by a microwave radio relay link, and in Brunswick, Maine, the route joined the main US network and branched to Montreal to connect with the Canadian network.

Opened on September 25, 1956, TAT-1 carried 588 London–US calls and 119 London–Canada calls in the first 24 hours of public service.

The original 36 channels were 4 kHz bandwidth. The increase to 48 channels was accomplished by narrowing the bandwidth to 3 kHz. Later, an additional three channels were added by use of C carrier equipment. Time-assignment speech interpolation (TASI) was implemented on the TAT-1 cable in June 1960 and effectively increased the cable's capacity from 37 (out of 51 available channels) to 72 speech circuits.

TAT-1 carried the Moscow–Washington hotline between the American and Soviet heads of state, although using a teleprinter rather than voice calls as written communications were regarded as less likely to be misinterpreted. The link became operational on 13 July 1963 and was principally motivated as a result of the Cuban Missile Crisis where it took the US, for example, nearly 12 hours to receive and decode the initial settlement message that contained approx. 3,000 words. By the time the message was decoded and interpreted, and an answer had been prepared, another, more aggressive message had been received.{{Cite web | access-date = 2016-02-27

In May 1957, TAT-1 was used to transmit a concert by the singer and civil rights activist Paul Robeson, performing in New York, to St Pancras Town Hall in London.{{Cite web | access-date = 2016-02-27 | access-date = 2016-02-27

After the success of TAT-1, a number of other TAT cables were laid, and TAT-1 was retired in 1978.

The TAT-1 was named an IEEE milestone in 2006.

References

References

1. "Specimen of the first transatlantic telephone cable, 1956". The Science Museum.
2. Bill Burns. "History of the Atlantic Cable & Undersea Communications". Atlantic-Cable.com.
3. Bill Ray. (14 October 2013). "TAT-1: Call the cable guy, all I see is a beautiful beach".
4. "First transatlantic telegraph cable completed". A&E Television Networks, LLC.
5. "Global Telephone Calls For All".
6. Mattingley, F.. (January 1957). "Manufacture of Submarine Cable at Ocean Works, Erith". [[The Post Office Electrical Engineers' Journal]].
7. (September 19, 1961). "Overall Characteristics of a TASI System".
8. "Hidden Histories of the Information Age: TAT-1".
9. "Paul Robeson, Treorchy Male Voice Choir – Transatlantic Exchange".
10. (5 October 1957). "Robeson sings to miners- by cable". Western Mail.
11. "Milestones:The First Submarine Transatlantic Telephone Cable System (TAT-1), 1956". IEEE.