View source for TAT-1

==History==
[[File:TAT 1 cable.JPG|thumb|right|A section of TAT 1 cable with the layers successively stripped back]]
The first [[transatlantic telegraph cable]] had been laid in 1858 (see [[Cyrus West Field]]).<ref name=History>{{cite web |url=http://www.history.com/this-day-in-history/first-transatlantic-telegraph-cable-completed |title=First transatlantic telegraph cable completed |website=History.com |publisher=A&E Television Networks, LLC |access-date=4 June 2015}}</ref>  It only operated for a month, but was replaced with a successful connection in 1866.<ref name=History/>  A radio-based transatlantic telephone service was started in 1927, charging £9<ref>{{cite web |url=https://blog.sciencemuseum.org.uk/global-telephone-calls-for-all/|title=Global Telephone Calls For All| website=www.blog.sciencemuseum.org.uk |access-date=4 June 2015}}</ref> (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 tube]]s for the submerged [[repeater]]s, and a general improvement in [[carrier wave|carrier]] equipment. [[Transistor]]s 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 [[AT&T Corporation|American Telephone and Telegraph]] company, and the [[VSNL International Canada|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 {{convert|1500|nmi|km}} long. The electronic repeaters were designed by the [[Bell Telephone Laboratories]] of the United States and they were inserted into the cable at {{convert|37|nmi|km|adj=on}} 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|Siemens Brothers & Co, Ltd]], and The Telegraph Construction & Maintenance Company, Ltd).<ref>{{cite journal | author=Mattingley, F. | title=Manufacture of Submarine Cable at Ocean Works, Erith | journal=[[The Post Office Electrical Engineers' Journal]] | volume=49 | issue=4 | page=308 |date=January 1957 }}</ref>

The cables were laid over the summers of 1955 and 1956, with the majority of the work done by the [[cable ship]] [[CS Monarch (1945)|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 {{convert|300|mi|km|adj=on}} [[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&nbsp;kHz [[Voice frequency|bandwidth]]. The increase to 48 channels was accomplished by narrowing the bandwidth to 3&nbsp;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.<ref>{{Cite web|url = http://www.ascend.com/bstj/vol41-1962/articles/bstj41-4-1439.pdf|archive-url = https://web.archive.org/web/20141014155952/http://www.ascend.com/bstj/vol41-1962/articles/bstj41-4-1439.pdf|url-status = dead|archive-date = October 14, 2014|title = Overall Characteristics of a TASI System|date = September 19, 1961|access-date = 8 October 2014}}</ref>

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.<ref name="BBC: Hidden Histories of the Information Age 5 January 2016">{{cite episode| title= Hidden Histories of the Information Age: TAT-1| series= Hidden Histories of the Information Age | credits= Presenters: [[Aleks Krotoski]] | station= [[BBC Radio 4]]| url= http://www.bbc.co.uk/programmes/b04m3bcc| airdate= 5 January 2016| minutes= 11:45 }}</ref> 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.<ref>{{Cite web
| url = http://www.cryptomuseum.com/crypto/hotline/index.htm
| title = Washington Moscow Hotline
| website = cryptomuseum.com
| access-date = 2016-02-27
}}</ref>

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 [[Camden Town Hall|St Pancras Town Hall]] in London.<ref>{{Cite web
| url = http://www.bbc.co.uk/programmes/b04m3bcc
| title = Tat-1, Hidden Histories of the Information Age - BBC Radio 4
| website = BBC
| access-date = 2016-02-27
}}</ref> Due to [[McCarthyism]], Robeson's passport had been withdrawn by the United States authorities in 1950. Unable to accept numerous invitations to perform abroad, he stated, "We have to learn the hard way that there is another way to sing."<ref>{{Cite web
| url = http://www2.warwick.ac.uk/services/library/mrc/explorefurther/images/robeson/
| title = Let Robeson Sing
| website = www2.warwick.ac.uk
| access-date = 2016-02-27
}}</ref> The 15 minute connection, which required a music-quality circuit, cost £300 (~£6,500 as of 2015). Robeson performed this way again in October 1957 when he linked up to the [[Grand Pavilion, Porthcawl]], Wales, fulfilling an invitation to the [[eisteddfod]] there. A 10-inch record featuring selections from the event, entitled ''Transatlantic Exchange'', was issued by South Wales area of the [[National Union of Mineworkers (Great Britain)|National Union of Mineworkers]] as a fundraiser and protest at Robeson's treatment.<ref>{{cite web |title=Paul Robeson, Treorchy Male Voice Choir – Transatlantic Exchange |url=https://www.discogs.com/release/9834205-Paul-Robeson-Treorchy-Male-Voice-Choir-Transatlantic-Exchange/image/SW1hZ2U6MjcwNzIzNjg= |website=Discogs |access-date=17 January 2022}}</ref><ref name="Western Mail">{{cite journal |title=Robeson sings to miners- by cable |journal=Western Mail |date=5 October 1957 |page=2 |url=https://www.britishnewspaperarchive.co.uk/viewer/bl/0000104/19571005/031/0002 |access-date=17 January 2022}}</ref>

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

[[File:2024-09-03 Kerrera IEEE Milestone 02.jpg|thumb|IEEE Milestone plaque for the first submarine transatlantic telephone cable system]]
The TAT-1 was named an [[List of IEEE milestones|IEEE milestone]] in 2006.<ref>{{cite web |url=http://www.ieeeghn.org/wiki/index.php/Milestones:The_First_Submarine_Transatlantic_Telephone_Cable_System_%28TAT-1%29,_1956 |title=Milestones:The First Submarine Transatlantic Telephone Cable System (TAT-1), 1956 |work=IEEE Global History Network |publisher=IEEE |access-date=3 August 2011}}</ref>