Transatlantic communications cable
A transatlantic telecommunications cable is a submarine communications cable connecting one side of the Atlantic Ocean to the other. In the 19th and early 20th centuries each cable was a single wire. After mid-century, coaxial cable came into use, with amplifiers. Late in the century, all used optical fiber, and most now use optical amplifiers.
When the first transatlantic telegraph cable was laid in 1858 by Cyrus West Field, it operated for only three weeks; subsequent attempts in 1865 and 1866 were more successful.  Although a telephone cable was discussed starting in the 1920s,[ citation needed] to be practical it needed a number of technological advances which did not arrive until the 1940s.[ citation needed] Starting in 1927, transatlantic telephone service was radio-based. 
TAT-1 (Transatlantic No. 1) was the first transatlantic telephone cable system. It was laid between Gallanach Bay, near Oban, Scotland and Clarenville, Newfoundland between 1955 and 1956 by the cable ship Monarch.  It was inaugurated on September 25, 1956, initially carrying 36 telephone channels. In the first 24 hours of public service there were 588 London–U.S. calls and 119 from London to Canada. The capacity of the cable was soon increased to 48 channels. 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 was finally retired in 1978. Later coaxial cables, installed through the 1970s, used transistors and had higher bandwidth. The Moscow–Washington hotline was initially connected through this system.
All cables presently in service use fiber optic technology. Many cables terminate in Newfoundland and Ireland, which lie on the great circle route (the shortest route) from London, UK to New York City, USA.
There have been a succession of newer transatlantic cable systems. All recent systems have used fiber optic transmission, and a self-healing ring topology. Late in the 20th century, communications satellites lost most of their North Atlantic telephone traffic to these low cost, high capacity, low latency cables. This advantage only increases over time as tighter cables provide higher bandwidth – the 2012 generation of cables drop the transatlantic latency to under 60 milliseconds, according to Hibernia Atlantic, deploying such a cable that year.  
The TAT series of cables constitute a large percentage of all North Atlantic cables. All TAT cables are joint ventures between a number of telecommunications companies, e.g. British Telecom. CANTAT cables terminate in Canada rather than in the USA.
|Name||In service||Type||Initial channels||Final channels||Western end||Eastern end|
|TAT-8||1988–2002||Fiber-optic||40,000||–||New Jersey||England, France|
|TAT-9||1992–2004||Fiber-optic||80,000||–||New Jersey, Nova Scotia||Spain, France, England|
|TAT-10||1992–2003||Fiber-optic||2 × 565 Mbit/s||–||USA||Germany, Netherlands|
|TAT-11||1993–2003||Fiber-optic||2 × 565 Mbit/s||–||New Jersey||France|
|TAT-12/13||1996–2008||Fiber-optic||12 × 2.5 Gbit/s||–||USA × 2||England, France|
|TAT-14||2001–||Fiber-optic||3.2 Tbit/s||–||New Jersey × 2||England, France, Netherlands, Germany, Denmark|
|CANTAT-3||1994–2010||Fiber-optic||2 × 2.5 Gbit/s||Nova Scotia||Iceland, Faroe Islands, England, Denmark, Germany|
|PTAT-1||1989–2004||Fiber-optic||3 × 140 Mbit/s?||New Jersey & Bermuda||Ireland & England|
There are a number of private non-TAT cables.
|Cable name||Ready for service||Length||Landing points||Owner|
|Atlantis-2||February 2000||8,500 km||Carcavelos, PT; El Médano, ES- CN; Praia, CV; Dakar, SN; Fortaleza, BR- CE; Las Toninas, AR- B||various telecom operators|
|EulaLink||Q1 2018||5,900 km||Sines, PT; Fortaleza, BR- CE; Santos, BR- SP||Telebras, IslaLink|
|SAex||Q2 2018||13,050 km||Virginia Beach, US- VA; Jamestown, SH- HL; Yzerfontein, ZA- WC; Mtunzini, ZA- NL||SAEx International Ltd. (SimplCom South Africa)|
|SACS||Q3 2018||6,165 km||Fortaleza, BR- CE; Luanda, AO||Angola Cables|
|SAIL||Q4 2018||5,900 km||Fortaleza, BR- CE; Kribi, CM||Camtel, China Unicom|
- Guarnieri, M. (March 2014). "The Conquest of the Atlantic". IEEE Industrial Electronics Magazine. 8 (1): 53–55/67. doi: 10.1109/MIE.2014.2299492.
- Short-Wave System for Transatlantic Telephony, by Polkinghorn and Schlaack BSTJ, 1935
- "Being First Telephone Cable to Connect Hemispheres". Popular Mechanics, March 1954, p. 114.
- "Building Networks for High-Speed Stock Trading - WSJ.com". Online.wsj.com. October 9, 2011. Retrieved September 18, 2013.
- "The $300m cable that will save traders milliseconds". The Daily Telegraph. London. September 11, 2011. Retrieved September 18, 2013.
- "Angola Cables to build the world's first submarine cable across the South Atlantic: Press Releases - NEC".
- "16Tbit/s SAEx cable deal signed".
- "Hibernia Offers Cross-Atlantic 40G". Light Reading. August 13, 2009.
- "Submarine Cable Actions Taken PN". FCC. October 4, 2012.
- Sawers, Paul (April 24, 2019). "How Google is building its huge subsea cable infrastructure". VentureBeat. Archived from the original on April 26, 2019. Retrieved April 26, 2019.
- Li, Abner (April 5, 2019). "Google's Dunant trans-Atlantic cable will deliver record-breaking capacity w/ first use of SDM tech". 9to5Google. Archived from the original on April 25, 2019. Retrieved April 25, 2019.
- Hayes, Jeremiah (September 2008). "A history of transatlantic cables". IEEE Communications. 46 (9): 42–48. doi: 10.1109/MCOM.2008.4623705.
- Aronsson's Telecom History Timeline
- Timeline of Submarine Communications Cables, 1850–2016
- Submarine Cable Landings Worldwide