Examine individual changes

'[[File:Submarine cable cross-section 3D plain.svg|right|thumb|300px|A [[cross section (geometry)|cross section]] of a modern submarine communications cable.<br /> 1 – [[Polyethylene]]<br /> 2 – [[BoPET|Mylar]] tape<br /> 3 – Stranded [[steel]] wires<br /> 4 – [[Aluminium]] water barrier<br /> 5 – [[Polycarbonate]]<br /> 6 – [[Copper]] or aluminium tube<br /> 7 – [[Petroleum jelly]]<br /> 8 – [[Optical fiber]]s]] [[File:France Telecom Marine Rene Descartes p1150247.jpg|thumb|Submarine cables are laid using special [[cable layer]] ships, such as the modern [[René Descartes (ship)|''René Descartes'']], operated by [[Orange Marine]].]] A '''submarine communications cable''' is a cable laid on the [[seabed|sea bed]] between land-based stations to carry [[telecommunication]] signals across stretches of ocean. The first submarine communications cables, laid in the 1850s, carried [[telegraphy]] traffic. Subsequent generations of cables carried [[telephone]] traffic, then [[data transmission|data communication]]s traffic. Modern cables use [[optical fiber]] technology to carry [[digital data]], which includes telephone, [[Internet]] and private data traffic. Modern cables are typically {{convert|69|mm}} in diameter and weigh around 10 kilograms per metre (7&nbsp;lb/ft), although thinner and lighter cables are used for deep-water sections.<ref>[http://image.guardian.co.uk/sys-images/Technology/Pix/pictures/2008/02/01/SeaCableHi.jpg "The internet's undersea world"]&nbsp;– annotated image, ''The Guardian''.</ref> As of 2010, submarine cables link all the world's [[continent]]s except [[Antarctica]]. <!-- this happened before 2010, can anyone find a reference for when exactly? 1880, Africa ISBN 0789001160 pp.43,50--> ==Early history: telegraph and coaxial cables== ===Trials=== After [[William Fothergill Cooke|William Cooke]] and [[Charles Wheatstone]] had introduced their working [[telegraphy|telegraph]] in 1839, the idea of a submarine line across the [[Atlantic Ocean]] began to be thought of as a possible triumph of the future. [[Samuel Morse]] proclaimed his faith in it as early as 1840, and in 1842, he submerged a wire, insulated with tarred [[hemp]] and [[Natural rubber|India rubber]],<ref>[http://www.globusz.com/ebooks/Telegraph/00000013.htm Heroes of the Telegraph&nbsp;– Chapter III.&nbsp;– Samuel Morse]{{Dead link|date=April 2010}}</ref><ref>{{cite web|url=http://inventors.about.com/library/inventors/bl_morse_timeline1.htm |title=Timeline&nbsp;– Biography of Samuel Morse |publisher=Inventors.about.com |date=2009-10-30 |accessdate=2010-04-25}}</ref> in the water of [[New York Harbor]], and telegraphed through it. The following autumn, Wheatstone performed a similar experiment in [[Swansea Bay]]. A good [[insulator (electrical)|insulator]] to cover the wire and prevent the electric current from leaking into the water was necessary for the success of a long submarine line. [[Natural rubber|India rubber]] had been tried by [[Moritz von Jacobi]], the [[Prussia]]n [[electrical engineering|electrical engineer]], as far back as the early 19th century. Another insulating gum which could be melted by heat and readily applied to wire made its appearance in 1842. [[Gutta-percha]], the adhesive juice of the ''[[Palaquium gutta]]'' tree, was introduced to Europe by [[William Montgomerie]], a [[Scotland|Scottish]] [[surgery|surgeon]] in the service of the [[East India Company|British East India Company]].<ref name=Haigh26>{{cite book|last=Haigh|first=K R|title=Cable Ships and Submarine Cables|year=1968|publisher=Adlard Coles Ltd|location=London|pages=26–27}}</ref> Twenty years earlier, he had seen whips made of it in [[Singapore]], and he believed that it would be useful in the fabrication of surgical apparatuses. [[Michael Faraday]] and Wheatstone soon discovered the merits of gutta-percha as an insulator, and in 1845, the latter suggested that it should be employed to cover the wire which was proposed to be laid from [[Dover]] to [[Calais]]. It was tried on a wire laid across the [[Rhine]] between [[Deutz, Cologne|Deutz]] and [[Cologne]].{{Citation needed|date=May 2013}} In 1849, [[Charles Vincent Walker|C.V. Walker]], electrician to the [[South Eastern Railway (UK)|South Eastern Railway]], submerged a two-mile wire coated with gutta-percha off the coast from Folkestone, which was tested successfully.<ref name=Haigh26/> ===The first commercial cables=== [[File:British & Irish Magnetic Telegraph Co. Limited 3 shilling stamp c. 1862 remaindered without control number.jpg|thumbnail|right|A [[telegraph stamp]] of the British & Irish Magnetic Telegraph Co. Limited (c. 1862).]] Having earlier obtained a concession from the French Government, in August 1850 [[John Watkins Brett]]'s [[Anglo-French Telegraph Company]] laid the first line across the [[English Channel]], using the converted [[tugboat|tug]] ''Goliath''. It was simply a copper wire coated with [[gutta-percha]], without any other protection, and was not successful.<ref name=Haigh192>{{cite book|last=Haigh|first=K R|title=Cable Ships and Submarine Cables|year=1968|publisher=Adlard Coles Ltd|location=London|pages=192–193}} The company is referred to as the English Channel Submarine Telegraph Company</ref> The experiment served to secure renewal of the concession, and in September 1851, a protected core, or true, cable was laid by the reconstituted [[Submarine Telegraph Company]] from a government hulk, the ''Blazer'', which was towed across the Channel.<ref name=Haigh192/><ref name=Brett>{{cite journal|last=Brett|first=John Watkins|title=On the Submarine Telegraph|journal=Royal Institution of Great Britain: Proceedings|date=March 18, 1857|volume=II, 1854-1858|url=http://www.atlantic-cable.com/Article/Brett/index.htm (transcript)|accessdate=17 May 2013}}</ref> In 1853 further successful cables were laid, linking Great Britain with [[Ireland]], [[Belgium]] and the [[Netherlands]], and crossing [[The Belts]] in [[Denmark]].<ref>{{cite book|last=Haigh|first=K R|title=Cable Ships and Submarine Cables|year=1968|publisher=Adlard Coles Ltd|location=London|page=361}}</ref> The British & Irish Magnetic Telegraph Company completed the first successful Irish link on May 23 between [[Portpatrick]] and [[Donaghadee]] using the [[collier (ship)|collier]] ''William Hutt''.<ref name=Haigh34>{{cite book|last=Haigh|first=K R|title=Cable Ships and Submarine Cables|year=1968|publisher=Adlard Coles Ltd|location=London|pages=34–36}}</ref> The same ship was used for the link from Dover to [[Ostend]] in Belgium, by the Submarine Telegraph Company.<ref name=Haigh192/> Meanwhile, the Electric & International Telegraph Company completed two cables across the [[North Sea]], from [[Orford Ness]] to [[Scheveningen]], The Netherlands. They were laid by the ''Monarch'', a [[paddle steamer]] which later became the first vessel with permanent cable-laying equipment.<ref>{{cite book|last=Haigh|first=K R|title=Cable Ships and Submarine Cables|year=1968|publisher=Adlard Coles Ltd|location=London|page=195}}</ref> ===Transatlantic telegraph cable=== {{Main|Transatlantic telegraph cable}} The first attempt at laying a [[transatlantic telegraph cable]] was promoted by [[Cyrus West Field]], who persuaded British industrialists to fund and lay one in 1858. However, the technology of the day was not capable of supporting the project; it was plagued with problems from the outset, and was in operation for only a month. Subsequent attempts in 1865 and 1866 with the world's largest steamship, the [[SS Great Eastern|SS ''Great Eastern'']], used a more advanced technology and produced the first successful transatlantic cable. The ''Great Eastern'' later went on to lay the first cable reaching to India from Aden, Yemen, in 1870. ===British dominance of early cable=== From the 1850s until 1911, British submarine cable systems dominated the most important market, the [[North Atlantic Ocean]]. The British had both supply side and demand side advantages. In terms of supply, Britain had entrepreneurs willing to put forth enormous amounts of capital necessary to build, lay and maintain these cables. In terms of demand, [[British Empire|Britain's vast colonial empire]] led to business for the cable companies from news agencies, trading and shipping companies, and the British government. Many of Britain's colonies had significant populations of European settlers, making news about them of interest to the general public in the home country. British officials believed that depending on telegraph lines that passed through non-British territory posed a security risk, as lines could be cut and messages could be interrupted during wartime. They sought the creation of a worldwide network within the empire, which became known as the [[All Red Line]], and conversely prepared strategies to quickly interrupt enemy communications.<ref name="kennedy197110">{{cite journal | url=http://www.jstor.org/stable/563928 | title=Imperial Cable Communications and Strategy, 1870-1914 | author=Kennedy, P. M. | journal=The English Historical Review |date=October 1971 | volume=86 | issue=341 | pages=728–752}}</ref> Britain's very first action after declaring war on Germany in World War I was to have the cable ship ''Alert'' (not the CS ''[[Telconia]]'' as frequently reported)<ref>Rhodri Jeffreys-Jones, ''In Spies We Trust: The Story of Western Intelligence'', page 43, Oxford University Press, 2013 ISBN 0199580979.</ref> cut the five cables linking Germany with France, Spain and the Azores, and through them, North America.<ref>Jonathan Reed Winkler, ''Nexus: Strategic Communications and American Security in World War I'', pages 5-6, 289, Harvard University Press, 2008 ISBN 0674033906.</ref> Thereafter the only way Germany could communicate was by wireless, and that meant that [[Room 40]] could listen in. The submarine cables were an economic boon to trading companies because owners of ships could communicate with captains when they reached their destination on the other side of the ocean and even give directions as to where to go next to pick up more cargo based on reported pricing and supply information. The British government had obvious uses for the cables in maintaining administrative communications with governors throughout its empire as well as in engaging other nations diplomatically and communicating with its military units in wartime. The geographic location of British territory was also an advantage as it included both Ireland on the east side of the Atlantic ocean and Newfoundland in North America on the west side, making for the shortest route across the ocean, which reduced costs significantly. A few facts put this dominance of the industry in perspective. In 1896, there were thirty cable laying ships in the world and twenty-four of them were owned by British companies. In 1892, British companies owned and operated two-thirds of the world's cables and by 1923, their share was still 42.7 percent.<ref>Headrick, D.R., & Griset, P. (2001). Submarine telegraph cables: business and politics, 1838-1939. The Business History Review, 75(3), 543-578.</ref> During [[World War I]], Britain's telegraph communications were almost completely uninterrupted, while it was able to quickly cut Germany's cables worldwide.{{r|kennedy197110}} ===Cable to India, Singapore, Far East and Australia=== [[File:1901 Eastern Telegraph cables.png|thumb|300px|Eastern Telegraph Company network in 1901]] Throughout the 1860s and 70's, British cable expanded eastward, into the Mediterranean Sea and the Indian Ocean. An 1863 cable to [[Bombay]], India (now [[Mumbai]]) provided a crucial link to [[Saudi Arabia]].<ref>{{cite news|url=http://www.telegraphindia.com/1080203/jsp/frontpage/story_8856997.jsp |title=The Telegraph&nbsp;– Calcutta (Kolkata) &#124; Frontpage &#124; Third cable cut, but India's safe |publisher=Telegraphindia.com |date=2008-02-03 |accessdate=2010-04-25}}</ref> In 1870, Bombay was linked to London via submarine cable in a combined operation by four cable companies, at the behest of the British Government. In 1872, these four companies were combined to form the mammoth globespanning [[Cable & Wireless plc|Eastern Telegraph Company]], owned by [[John Pender]]. A spin-off from Eastern Telegraph Company was a second sister company, the Eastern Extension, China and Australasia Telegraph Company, commonly known simply as "the Extension". In 1872, Australia was linked by cable to Bombay via Singapore and China and in 1876, the cable linked the British Empire from London to New Zealand.<ref>''Landing the New Zealand cable'', pg 3, [[The Nelson Mail|The Colonist]], 19 February 1876</ref> ===Submarine cables across the Pacific=== The first trans-pacific cables were completed in 1902–03, linking the US mainland to Hawaii in 1902 and Guam to the Philippines in 1903.<ref>{{cite web|url=http://www.brainyhistory.com/events/1903/july_4_1903_69271.html |title=Pacific Cable (SF, Hawaii, Guam, Phil) opens, President TR sends message July 4 in History |publisher=Brainyhistory.com |date=1903-07-04 |accessdate=2010-04-25}}</ref> Canada, Australia, New Zealand and Fiji were also linked in 1902.<ref>{{cite web|url=http://geo.international.gc.ca/asia/australia/relations/history-en.asp |title=Australia :: Canada-Australia Relations :: History |publisher=Geo.international.gc.ca |date= |accessdate=2010-04-25}}</ref> 88 years later, the [[NPC (cable system)|North Pacific Cable system]] was the first regenerative ([[repeater]]ed) system to completely cross the Pacific from the US mainland to Japan. The US portion of NPC was manufactured in Portland, Oregon, from 1989 to 1991 at STC Submarine Systems, and later Alcatel Submarine Networks. The system was laid by Cable & Wireless Marine on the ''[[Cable Ship|CS]] Cable Venture'' in 1991. ===Construction=== Transatlantic cables of the 19th century consisted of an outer layer of iron and later steel wire, wrapping India rubber, wrapping gutta-percha, which surrounded a multi-stranded copper wire at the core. The portions closest to each shore landing had additional protective armor wires. [[Gutta-percha]], a natural polymer similar to rubber, had nearly ideal properties for insulating submarine cables, with the exception of a rather high [[dielectric]] constant which made cable [[capacitance]] high. Gutta-percha was not replaced as a cable insulation until [[polyethylene]] was introduced in the 1930s. In the 1920s, the American military experimented with rubber-insulated cables as an alternative to gutta-percha, since American interests controlled significant supplies of rubber but no gutta-percha manufacturers. ===Bandwidth problems=== Early long-distance submarine telegraph cables exhibited formidable electrical problems. Unlike modern cables, the technology of the 19th century did not allow for in-line [[repeater]] [[amplifier]]s in the cable. Large [[voltage]]s were used to attempt to overcome the [[electrical resistance]] of their tremendous length but the cables' distributed [[capacitance]] and [[inductance]] combined to distort the telegraph pulses in the line, reducing the cable's [[Bandwidth (signal processing)|bandwidth]], severely limiting the [[Bit rate|data rate]] for telegraph operation to 10–12 [[words per minute]]. As early as 1823,{{Citation needed|reason=one of the refs in Ronalds' article says he thought his telegraph was instantaneous|date=June 2009}} [[Francis Ronalds]] had observed that electric signals were retarded in passing through an insulated wire or core laid underground, and the same effect was noticed by [[Latimer Clark]] (1853) on cores immersed in water, and particularly on the lengthy cable between England and The Hague. [[Michael Faraday]] showed that the effect was caused by capacitance between the wire and the [[ground (electricity)|earth]] (or water) surrounding it. Faraday had noticed that when a wire is charged from a battery (for example when pressing a telegraph key), the [[electric charge]] in the wire induces an opposite charge in the water as it travels along. In 1831, Faraday described this effect in what is now referred to as [[Faraday's law of induction]]. As the two charges attract each other, the exciting charge is retarded. The core acts as a [[capacitor]] distributed along the length of the cable which, coupled with the resistance and [[inductance]] of the cable limits the speed at which a [[Signalling (telecommunication)|signal]] travels through the [[electrical conduction|conductor]] of the cable. Early cable designs failed to analyze these effects correctly. Famously, [[E.O.W. Whitehouse]] had dismissed the problems and insisted that a transatlantic cable was feasible. When he subsequently became electrician of the [[Atlantic Telegraph Company]], he became involved in a public dispute with [[William Thomson, 1st Baron Kelvin|William Thomson]]. Whitehouse believed that, with enough voltage, any cable could be driven. Because of the excessive voltages recommended by Whitehouse, Cyrus West Field's first transatlantic cable never worked reliably, and eventually [[short circuit]]ed to the ocean when Whitehouse increased the voltage beyond the cable design limit. Thomson designed a complex electric-field generator that minimized current by [[resonance|resonating]] the cable, and a sensitive light-beam [[mirror galvanometer]] for detecting the faint telegraph signals. Thomson became wealthy on the royalties of these, and several related inventions. Thomson was elevated to [[Lord Kelvin]] for his contributions in this area, chiefly an accurate [[mathematical model]] of the cable, which permitted design of the equipment for accurate telegraphy. The effects of [[atmospheric electricity]] and the [[geomagnetic field]] on submarine cables also motivated many of the [[International Geophysical Year|early polar expeditions]]. Thomson had produced a mathematical analysis of propagation of electrical signals into telegraph cables based on their capacitance and resistance, but since long submarine cables operated at slow rates, he did not include the effects of inductance. By the 1890s, [[Oliver Heaviside]] had produced the modern general form of the [[telegrapher's equations]] which included the effects of inductance and which were essential to extending the theory of [[transmission line]]s to higher [[frequencies]] required for high-speed data and voice. ===Transatlantic telephony=== [[File:Submarine Telephone Cables PICT8182 1.JPG|thumb|right|Five submarine communication cables crossing the Scottish shore at Scad Head on [[Hoy]], [[Orkney]].]] While laying a transatlantic telephone cable was seriously considered from the 1920s, the technology required for economically feasible telecommunications was not developed until the 1940s. A first attempt to lay a [[pupinize]]d telephone cable failed in the early 1930s due to the [[Great Depression]]. In 1942, [[Siemens Brothers]] of [[New Charlton]], London in conjunction with the [[United Kingdom]] [[National Physical Laboratory, UK|National Physical Laboratory]], adapted submarine communications cable technology to create the world's first submarine oil pipeline in [[Operation Pluto]] during [[World War II]]. [[TAT-1]] (Transatlantic No. 1) was the first [[transatlantic telephone cable]] system. Between 1955 and 1956, cable was laid between Gallanach Bay, near [[Oban]], Scotland and [[Clarenville, Newfoundland and Labrador]]. It was inaugurated on September 25, 1956, initially carrying 36 telephone channels. In the 1960s, transoceanic cables were [[coaxial cable]]s that transmitted [[frequency-division multiplexing|frequency-multiplexed voiceband signals]]. A high voltage direct current on the inner conductor powered repeaters (two-way amplifiers placed at intervals along the cable). The first-generation repeaters remain among the most reliable [[vacuum tube]] amplifiers ever designed.<ref>{{cite web |url=http://www.iscpc.org/information/Timeline_History.htm |title=Learn About Submarine Cables |publisher=International Submarine Cable Protection Committee}}. From this page: In 1966, after ten years of service, the 1608 tubes in the repeaters had not suffered a single failure. In fact, after more than 100 million tube-hours over all, AT&T undersea repeaters were without failure.</ref> Later ones were transistorized. Many of these cables are still usable, but have been abandoned because their capacity is too small to be commercially viable. Some have been used as scientific instruments to measure earthquake waves and other geomagnetic events.<ref>{{cite web |url=http://www.whoi.edu/science/GG/DSO/H2O/EOSarticle/H2O_article_revised_9.pdf |title=The Hawaii-2 Observatory (H2O) |author=Butler, R., A. D. Chave, F. K. Duennebier, D. R. Yoerger, R. Petitt, D. Harris, F.B. Wooding, A. D. Bowen, J. Bailey, J. Jolly, E. Hobart, J. A. Hildebrand, A. H. Dodeman|format=PDF}}</ref> ==Modern history== ===Optical telephone cables=== [[File:Submarine cable repeater.png|300px|thumb|Diagram of an optical submarine cable repeater.]] In the 1980s, [[optical fiber|fiber optic cables]] were developed. The first transatlantic telephone cable to use optical fiber was [[TAT-8]], which went into operation in 1988. A fiber-optic cable comprises multiple pairs of fibers. Each pair has one fiber in each direction. TAT-8 had two operational pairs and one backup pair. Modern optical fiber repeaters use a solid-state [[optical amplifier]], usually an [[Optical amplifier#Doped fiber amplifiers|Erbium-doped fiber amplifier]]. Each repeater contains separate equipment for each fiber. These comprise signal reforming, error measurement and controls. A solid-state laser dispatches the signal into the next length of fiber. The solid-state laser excites a short length of doped fiber that itself acts as a laser amplifier. As the light passes through the fiber, it is amplified. This system also permits [[wavelength-division multiplexing]], which dramatically increases the capacity of the fiber. Repeaters are powered by a constant direct current passed down the conductor near the center of the cable, so all repeaters in a cable are in series. Power feed equipment is installed at the terminal stations. Typically both ends share the current generation with one end providing a positive voltage and the other a negative voltage. A [[virtual ground|virtual earth]] point exists roughly halfway along the cable under normal operation. The amplifiers or repeaters derive their power from the potential difference across them. The optic fiber used in undersea cables is chosen for its exceptional clarity, permitting runs of more than 100 kilometers between repeaters to minimize the number of amplifiers and the distortion they cause. The rising demand for these fiber-optic cables outpaced the capacity of providers such as AT&T. Having to shift traffic to satellites resulted in poorer quality signals. To address this issue, AT&T had to improve its cable laying abilities. It invested $100 million in producing two specialized fiber-optic cable laying vessels. These included laboratories in the ships for splicing cable and testing its electrical properties. Such field monitoring is important because the glass of fiber-optic cable is less malleable than the copper cable that had been formerly used. The ships are equipped with [[Bow thruster|thrusters]] that increase maneuverability. This capability is important because fiber-optic cable must be laid straight from the stern (another factor copper cable laying ships did not have to contend with).<ref>Bradsher, K. (1990, August 15). New fiber-optic cable will expand calls abroad, and defy sharks. The New York Times, D7</ref> Originally, submarine cables were simple point-to-point connections. With the development of [[submarine branching unit]]s (SBUs), more than one destination could be served by a single ''cable system''. Modern cable systems now usually have their fibers arranged in a [[self-healing ring]] to increase their redundancy, with the submarine sections following different paths on the ocean floor. One driver for this development was that the capacity of cable systems had become so large that it was not possible to completely back-up a cable system with satellite capacity, so it became necessary to provide sufficient terrestrial back-up capability. Not all telecommunications organizations wish to take advantage of this capability, so modern cable systems may have dual [[Cable landing point|landing points]] in some countries (where back-up capability is required) and only single landing points in other countries where back-up capability is either not required, the capacity to the country is small enough to be backed up by other means, or having back-up is regarded as too expensive. A further redundant-path development over and above the self-healing rings approach is the "Mesh Network" whereby fast switching equipment is used to transfer services between network paths with little to no effect on higher-level protocols if a path becomes inoperable. As more paths become available to use between two points, the less likely it is that one or two simultaneous failures will prevent end-to-end service. As of 2012, operators had "successfully demonstrated long-term, error-free transmission at 100&nbsp;Gbps across Atlantic Ocean" routes of up to {{convert|6000|km|-2|abbr=on}},<ref>{{cite web|url=http://www.submarinenetworks.com/systems/trans-atlantic/hibernia-atlantic/hibernia-atlantic-trials-100g-transatlantic |title=Submarine Cable Networks&nbsp;– Hibernia Atlantic Trials the First 100G Transatlantic |publisher=Submarinenetworks.com |date= |accessdate=2012-08-15}}</ref> meaning a typical cable can move tens of [[terabits]] per second overseas. Speeds improved rapidly in the last few years, with 40&nbsp;Gbit/s having been offered on that route only three years earlier in August 2009.<ref>{{cite web|url=http://www.lightreading.com/document.asp?doc_id=180473 |title=Light Reading Europe&nbsp;– Optical Networking&nbsp;– Hibernia Offers Cross-Atlantic 40G&nbsp;– Telecom News Wire |publisher=Lightreading.com |date= |accessdate=2012-08-15}}</ref> Switching and all-by-sea routing commonly increases the distance and thus the round trip latency by more than 50%. For example, the round trip delay (RTD) or latency of the fastest transatlantic connections is under 60&nbsp;ms, close to the theoretical maximum for an all-sea route. While in theory, a [[great circle route]] between London and New York City is only {{convert|5600|km|-2|abbr=on}},<ref>{{cite web|url=http://www.gcmap.com/mapui?P=NYC-LCY&DU=km |title=Great Circle Mapper |publisher=Gcmap.com |date= |accessdate=2012-08-15}}</ref> this requires several land masses ([[Ireland]], [[Newfoundland (island)|Newfoundland]], [[Prince Edward Island]] and the isthmus connecting [[New Brunswick]] to [[Nova Scotia]]) to be traversed, as well as the extremely tidal [[Bay of Fundy]] and a land route along [[Massachusetts]]' north shore from [[Gloucester]] to [[Boston]] and through fairly built up areas to [[Manhattan]] itself. In theory, using this partly land route could result in round trip times below 40&nbsp;ms, not counting switching. Along routes with less land in the way, speeds can approach [[speed of light]] minimums in the long term. ===Importance of submarine cables=== As of 2006, overseas satellite links accounted for only 1 percent of international traffic, while the remainder was carried by undersea cable. The reliability of submarine cables is high, especially when (as noted above) multiple paths are available in the event of a cable break. Also, the total carrying capacity of submarine cables is in the [[terabits]] per second, while satellites typically offer only [[megabits]] per second and display higher [[Latency (engineering)|latency]]. However, a typical multi-terabit, transoceanic submarine cable system costs several hundred million dollars to construct.<ref>{{cite news |url=http://www.wired.com/epicenter/2008/02/googles-submari/ |title=Google's Submarine Cable Plans Get Official |author=Gardiner, Bryan|format=PDF |work=Wired |date=2008-02-25}}</ref> As a result of these cables' cost and usefulness, they are highly valued not only by the corporations building and operating them for profit, but also by national governments. For instance, the [[Australian government]] considers its submarine cable systems to be "vital to the national economy". Accordingly, the [[Australian Communications and Media Authority]] (ACMA) has created protection zones that restrict activities that could potentially damage cables linking Australia to the rest of the world. The ACMA also regulates all projects to install new submarine cables.<ref>[http://www.acma.gov.au/WEB/STANDARD/1001/pc=PC_100223] Australian Communications and Media Authority. (2010, February 5). Submarine telecommunications cables.</ref> ===Investment in and financing of submarine cables=== Almost all fiber optic cables from TAT-8 in 1988 until approximately 1997 were constructed by "consortia" of operators. For example, TAT-8 counted 35 participants including most major international carriers at the time such as [[AT&T Corporation]].<ref>{{citation|journal=The Rotarian|title=Talking the Light Fantastic|author=Dunn, John|date=March 1987}}</ref> Two privately financed, non-consortium cables were constructed in the late 1990s, which preceded a massive, speculative rush to construct privately financed cables that peaked in more than $22 billion worth of investment between 1999 and 2001. This was followed by the bankruptcy and reorganization of cable operators such as [[Global Crossing]], [[360networks]], [[Fiber-Optic Link Around the Globe|FLAG]], [[Worldcom]], and Asia Global Crossing. There has been an increasing tendency in recent years to expand submarine cable capacity in the [[Pacific Ocean]] (the previous bias always having been to lay communications cable across the Atlantic Ocean which separates the United States and Europe). For example, between 1998 and 2003, approximately 70% of undersea fiber-optic cable was laid in the Pacific. This is in part a response to the emerging significance of Asian markets in the global economy.<ref>Lindstrom, A. (1999, January 1). Taming the terrors of the deep. America's Network, 103(1), 5-16.</ref> [[File:Cable map18.svg|thumb|right|alt=Modern fiber-optic cable around Africa's coast.|A map of active and anticipated submarine communications cables servicing the African continent.]] Although much of the investment in submarine cables has been directed toward developed markets such as the transatlantic and transpacific routes, in recent years there has been an increased effort to expand the submarine cable network to serve the developing world. For instance, in July 2009, an underwater fiber optic cable line plugged [[East Africa]] into the broader Internet. The company that provided this new cable was [[SEACOM (African cable system)|SEACOM]], which is 75% owned by Africans.<ref>[http://www.seacom.mu/index2.asp] SEACOM (2010)</ref> The project was delayed by a month due to increased [[piracy]] along the coast.<ref>{{cite news |url=http://www.cnn.com/2009/TECH/07/22/seacom.on/index.html |title=Cable makes big promises for African Internet|author=McCarthy, Diane | work=CNN | date=2009-07-27}}</ref> ===Antarctica=== Antarctica is the only continent yet to be reached by a submarine telecommunications cable. All phone, video, and e-mail traffic must be relayed to the rest of the world via [[satellite]], which is still quite unreliable. Bases on the continent itself are able to communicate with one another via [[radio]], but this is only a local network. To be a viable alternative, a fiber-optic cable would have to be able to withstand temperatures of −80˚ C as well as massive strain from ice flowing up to 10 meters per year. Thus, plugging into the larger Internet backbone with the high bandwidth afforded by fiber-optic cable is still an as yet infeasible economic and technical challenge in the Antarctic.<ref>{{Citation |last=Conti |first=Juan Pablo |date=2009-12-05 |url=http://eandt.theiet.org/magazine/2009/21/frozen-out-of-broadband.cfm |title=Frozen out of broadband |journal=Engineering & Technology |volume=4 |number=21 |pages=34–36 |issn=1750-9645}}</ref> ==Cable repair== Cables can be broken by [[trawling|fishing trawlers]], anchors, earthquakes, [[turbidity current]]s, and even shark bites.<ref name="dangerstocables">{{cite news |last=Tanner |first=John C. |title=2,000 Meters Under the Sea |date=1 June 2001 |work=America's Network |publisher=bnet.com |url=http://findarticles.com/p/articles/mi_m0DUJ/is_9_105/ai_n27568414/ |accessdate=9 August 2009 }}</ref> Based on surveying breaks in the Atlantic Ocean and the Caribbean Sea, it was found that between 1959 and 1996, fewer than 9% were due to natural events. In response to this threat to the communications network, the practice of cable burial has developed. The average incidence of cable faults was 3.7 per {{convert|1000|km|-1|abbr=on}} per year from 1959 to 1979. That rate was reduced to 0.44 faults per 1000&nbsp;km per year after 1985, due to widespread burial of cable starting in 1980.<ref>[http://www.scig.net/Section07b.pdf] Shapiro, S., Murray, J.G., Gleason, R.F., Barnes, S.R., Eales, B.A., & Woodward, P.R. (1987). Threats to submarine cables.</ref> Still, cable breaks are by no means a thing of the past, with more than 50 repairs a year in the Atlantic alone,<ref>{{cite news | url = http://www.technologyreview.com/Infotech/20152/?a=f | date = February 5, 2008 | title = Analyzing the Internet Collapse: Multiple fiber cuts to undersea cables show the fragility of the Internet at its choke points. | author = John Borland | work = Technology Review }}</ref> and significant breaks in [[2006 Hengchun earthquake#Disruption in communications|2006]], [[2008 submarine cable disruption|2008]], and 2009. The propensity for fishing trawler nets to cause cable faults may well have been exploited during the [[Cold War]]. For example, in February 1959, a series of 12 breaks occurred in five American trans-Atlantic communications cables. In response, a United States naval vessel, the [[USS Roy O. Hale (DE-336)|U.S.S. ''Roy O. Hale'']], detained and investigated the Soviet trawler ''Novorosiysk''. A review of the ship's log indicated it had been in the region of each of the cables when they broke. Broken sections of cable were also found on the deck of the ''Novorosiysk''. It appeared that the cables had been dragged along by the ship's nets, and then cut once they were pulled up onto the deck to release the nets. The Soviet Union's stance on the investigation was that it was unjustified, but the United States cited the [[Convention for the Protection of Submarine Telegraph Cables]] of 1884 to which Russia had signed (prior to the formation of the Soviet Union) as evidence of violation of international protocol.<ref>The Embassy of the United States of America. (1959, March 24). U.S. note to Soviet Union on breaks in trans-Atlantic cables. The New York Times, 10.</ref> Shore stations can locate a break in a cable by electrical measurements, such as through [[spread-spectrum time-domain reflectometry]] (SSTDR). SSTDR is a type of time-domain reflectometry that can be used in live environments very quickly. Presently, SSTDR can collect a complete data set in 20&nbsp;ms.<ref>Smith, Paul, Furse, Cynthia, Safavi, Mehdi, and Lo, Chet. "Feasibility of [http://livewiretest.com/analysis-of-spread-spectrum-time-domain-reflectometry-for-wire-fault-location/ Spread Spectrum Sensors for Location of Arcs on Live Wires] Spread Spectrum Sensors for Location of Arcs on Live Wires." IEEE Sensors Journal. December, 2005. {{WebCite|url=http://www.webcitation.org/5wQrUbdfD|date =2011-02-11}}</ref> Spread spectrum signals are sent down the wire and then the reflected signal is observed. It is then correlated with the copy of the sent signal and algorithms are applied to the shape and timing of the signals to locate the break. A cable repair ship will be sent to the location to drop a marker buoy near the break. Several types of [[grapple (tool)|grapples]] are used depending on the situation. If the sea bed in question is sandy, a grapple with rigid prongs is used to plough under the surface and catch the cable. If the cable is on a rocky sea surface, the grapple is more flexible, with hooks along its length so that it can adjust to the changing surface.<ref>[http://books.google.com/books?id=TuQDAAAAMBAJ&pg=PA621#v=onepage&q&f=true "When the ocean floor quakes"] ''Popular Mechanics'', '''vol.53''', no.4, pp.618-622, April 1930, {{ISSN|0032-4558}}, pg 621: various drawing and cutaways of cable repair ship equipment and operations</ref> In especially deep water, the cable may not be strong enough to lift as a single unit, so a special grapple that cuts the cable soon after it has been hooked is used and only one length of cable is brought to the surface at a time, whereupon a new section is spliced in.<ref>Clarke, A.C. (1959). Voice across the sea. New York, N.Y.: Harper & Row, Publishers, Inc.. p. 113</ref> The repaired cable is longer than the original, so the excess is deliberately laid in a 'U' shape on the seabed. A [[submersible]] can be used to repair cables that lie in shallower waters. A number of ports near important cable routes became homes to specialised cable repair ships. [[Halifax Regional Municipality|Halifax]], [[Nova Scotia]] was home to a half dozen such vessels for most of the 20th century including long-lived vessels such as the [[Cable Ship|CS]] ''Cyrus West Field'', CS ''Minia'' and ''[[CS Mackay-Bennett]]''. The latter two were contracted to recover victims from the [[sinking of the RMS Titanic|sinking of the RMS ''Titanic'']]. The crews of these vessels developed many new techniques and devices to repair and improve cable laying, such as the "[[Pipe-and-cable-laying plough|plough]]". ==Intelligence gathering== Underwater cables, which cannot be kept under constant surveillance, have tempted intelligence-gathering organizations since the late 19th century. Frequently at the beginning of wars, nations have cut the cables of the other sides to redirect the information flow into cables that were being monitored. The most ambitious efforts occurred in [[World War I]], when British and German forces systematically attempted to destroy the others' worldwide communications systems by cutting their cables with surface ships or submarines.<ref>Jonathan Reed Winkler, Nexus: Strategic Communications and American Security in World War I (Cambridge, MA: [[Harvard University Press]], 2008)</ref> During the [[Cold War]], the [[United States Navy]] and [[National Security Agency]] (NSA) succeeded in placing wire taps on Soviet underwater communication lines in [[Operation Ivy Bells]]. ==Environmental impact== The main point of interaction of cables with marine life is in the [[benthic zone]] of the oceans where the majority of cable lies. Recent studies (in 2003 and 2006) have indicated that cables pose minimal impacts on life in these environments. In sampling sediment cores around cables and in areas removed from cables, there were few statistically significant differences in organism diversity or abundance. The main difference was that the cables provided an attachment point for anemones that typically could not grow in soft sediment areas. Data from 1877 to 1955 showed a total of 16 cable faults caused by the entanglement of various [[whales]], but such deadly entanglements have entirely ceased after the transition from telegraph cables to coaxial cables and then fiber-optic cables (the new cables are better designed in terms of torsional balance so that they have less of a tendency to coil).<ref>[http://www.iscpc.org/publications/ICPC-UNEP_Report.pdf] Carter, L., Burnett, D., Drew, S., Marle, G., Hagadorn, L., Bartlett-McNeil D., & Irvine N. (2009, December). Submarine cables and the oceans: connecting the world. p. 31</ref> ==Notable events== The [[1929 Grand Banks earthquake|Newfoundland earthquake of 1929]] broke a series of trans-Atlantic cables by triggering a massive undersea mudslide. The sequence of breaks helped scientists chart the progress of the mudslide.{{Citation needed|date=August 2013}} In July 2005, a portion of the [[SEA-ME-WE 3 (cable system)|SEA-ME-WE 3]] submarine cable located {{convert|35|km|0}} south of [[Karachi]] that provided [[Pakistan]]'s major outer communications became defective, disrupting almost all of Pakistan's communications with the rest of the world, and affecting approximately 10 million Internet users.<ref>{{cite web|url=http://pakistantimes.net/2005/07/06/top5.htm |title=Top Story: Standby Net arrangements terminated in Pakistan |publisher=Pakistan Times |date= |accessdate=2010-04-25}}</ref><ref>{{cite news|url=http://www.smh.com.au/news/breaking/communication-breakdown-in-pakistan/2005/06/29/1119724673577.html?from=moreStories |title=Communication breakdown in Pakistan&nbsp;– Breaking&nbsp;– Technology |publisher=smh.com.au |date= 2005-06-29|accessdate=2010-04-25}}</ref><ref>{{cite news|author=PTI, Jun 28, 2005, 08.06pm IST |url=http://articles.timesofindia.indiatimes.com/2005-06-28/pakistan/27867464_1_submarine-cable-ptcl-karachi |title=Pakistan cut off from the world-Pakistan-World-The Times of India |publisher=The Times of India |date=2005-06-28 |accessdate=2010-04-25}}</ref> On 26 December 2006, the [[2006 Hengchun earthquake]] rendered numerous cables between [[Taiwan]] and [[Philippines]] inoperable.{{Citation needed|date=August 2013}} In March 2007, [[piracy|pirates]] stole an {{convert|11|km|0|adj=on}} section of the [[T-V-H (cable system)|T-V-H]] submarine cable that connected [[Thailand]], [[Vietnam]], and [[Hong Kong]], affecting Vietnam's Internet users with far slower speeds. The thieves attempted to sell the 100 tons of cable as scrap.<ref>{{cite web|url=http://www.lirneasia.net/2007/06/vietnams-submarine-cable-lost-and-found/ |title=Vietnam's submarine cable 'lost' and 'found' at LIRNEasia |publisher=Lirneasia.net |date= |accessdate=2010-04-25}}</ref><!-- This needs putting somewhere else...: Cable theft is becoming a more frequent problem worldwide.<ref>http://www.icf.at/en/6050/cable_theft.html</ref><ref>http://goliath.ecnext.com/comsite5/bin/pdinventory.pl?pdlanding=1&referid=2750&item_id=0199-6695504</ref><ref>http://www.highbeam.com/doc/1G1-169826537.html</ref>--> The [[2008 submarine cable disruption]] was a series of cable outages, two of the three [[Suez Canal]] cables, two disruptions in the Persian Gulf, and one in Malaysia. It caused massive communications disruptions to [[India]] and the [[Middle East]].<ref>{{cite web|author=5:47 p.m. ET |url=http://www.msnbc.msn.com/id/22938899/ |title=Finger-thin undersea cables tie world together&nbsp;– Internet&nbsp;– MSNBC.com |publisher=MSNBC |date=2008-01-31 |accessdate=2010-04-25}}</ref><ref>{{cite web|url=http://www.asiamedia.ucla.edu/article-southasia.asp?parentid=86456 |title=AsiaMedia :: Bangladesh: Submarine cable snapped in Egypt |publisher=Asiamedia.ucla.edu |date=2008-01-31 |accessdate=2010-04-25}}</ref> In April 2010, the undersea cable [[SEA-ME-WE 4 (cable system)|SEA-ME-WE 4]] was under an outage. The South East Asia–Middle East–Western Europe 4 (SEA-ME-WE 4) submarine communications cable system, which connects South East Asia and Europe, was reportedly cut in three places, off Palermo, Italy.{{Citation needed|date=August 2013}} The [[2011 Tōhoku earthquake and tsunami]] damaged a number of undersea cables that make landings in Japan, including:<ref>{{cite web|author=10:34 a.m. PT |url=http://gigaom.com/broadband/in-japan-many-under-sea-cables-are-damaged/ |title=In Japan, Many Undersea Cables Are Damaged|publisher=gigaom|date=2011-03-14|accessdate=2011-03-16}}</ref> * [[APCN 2 (cable system)|APCN-2]], an intra-Asian cable that forms a ring linking China, Hong Kong, Japan, the Republic of Korea, Malaysia, the Philippines, Singapore, and Taiwan * Pacific Crossing West and Pacific Crossing North * Segments of the [[EAC-C2C (cable system)|East Asia Crossing network]] (reported by [[PacNet]]) * A segment of the [[Japan-US (cable system)|Japan-U.S. Cable Network]] (reported by [[Korea Telecom]]) * [[PC-1]] submarine cable system (reported by [[Nippon Telegraph and Telephone|NTT]]) In February 2012, breaks in the [[EASSy]] and [[TEAMS (cable system)|TEAMS]] cables disconnected about half of the networks in Kenya and Uganda from the global Internet.<ref>See [[TEAMS (cable system)]] article.</ref> In March 2013, the [[SEA-ME-WE 4|SEA-ME-WE-4]] connection from France to Singapore was cut by divers near Egypt.<ref name="cw2010327">Kirk, Jeremy (2013-03-27). Sabotage suspected in Egypt submarine cable cut. ComputerWorld, 27 March 2013. Retrieved from http://www.computerworld.com/s/article/9237946/Sabotage_suspected_in_Egypt_submarine_cable_cut.</ref> ==See also== * [[List of domestic submarine communications cables]] * [[List of international submarine communications cables]] * [[Transatlantic communications cable]] * [[Loading coil#Loaded submarine cable|Loaded submarine cable]] ==References== {{Reflist|2}} ==External links== {{Commons category|Undersea telecommunications}} * [http://www.suboptic.org/uploads/Subtelforum%202nd%20Annual%20Industry%20Report.pdf Free Submarine Telecoms Industry report] * [http://www.iscpc.org/ The International Cable Protection Committee]&nbsp;– includes a register of submarine cables worldwide (though not always updated as often as one might hope) * [http://www.atlantic-cable.com/Cables/CableTimeLine/index.htm Timeline of Submarine Communications Cables, 1850-2010] * [http://www.kisca.org.uk/ Kingfisher Information Service&nbsp;– Cable Awareness; UK Fisherman's Submarine Cable Awareness site] * [http://www.sigcables.com/cgi-bin/index.pl France Telecom's Fishermen's/Submarine Cable Information] * [http://www.ofcc.com/ Oregon Fisherman's Cable Committee] * [http://www.kidorf.com/ Website with comprehensive list of cable landing sites and suppliers globally] (contains many duplicates and incomplete data) * [http://www.suboptic.org/ SubOptic]&nbsp;– the industry's major conference, held every 3 years * [http://www.subtelforum.com/ Submarine Telecoms Forum]&nbsp;– a trade magazine dedicated to the submarine cable industry ===Articles=== * [http://www.atlantic-cable.com/Article/WireRope/wirerope.htm History of the Atlantic Cable & Submarine Telegraphy&nbsp;– Wire Rope and the Submarine Cable Industry] * [http://www.wired.com/wired/archive/4.12/ffglass.html Mother Earth Mother Board&nbsp;– Wired article by Neal Stephenson about submarine cables] * [http://www.nature.com/nature/journal/v290/n5805/abs/290392a0.html Nature article&nbsp;– Geomagnetic induction on a transatlantic communications cable] * [http://www.europhysicsnews.com/full/30/article2/article2.html Hunt, Bruce J. ''Lord Cable''. Europhysics News (2004), Vol. 35 No 6.] * [http://www.hup.harvard.edu/catalog/WINNEX.html Winkler, Jonathan Reed. Nexus: Strategic Communications and American Security in World War I. (Cambridge, MA: Harvard University Press, 2008)] Account of how U.S. government discovered strategic significance of communications lines, including submarine cables, during World War I. * [http://www1.alcatel-lucent.com/submarine/how/index.htm Animations from Alcatel showing how submarine cables are installed and repaired] * [http://news.bbc.co.uk/2/hi/technology/7228315.stm Work begins to repair severed net] ===Maps=== {{Commons category|Maps of submarine communication cables}} * [http://www.submarinecablemap.com/ TeleGeography Interactive Cable Map] Comprehensive online submarine cable map displaying cable routes, landing points, owners, length, ready-for-service (RFS) date, and website. * [http://www.cablemap.info/ Greg's Cable Map] Google map display of submarine cables with downloadable KML data. * [http://eyeball-series.org/cable-eyeball.htm Map and Satellite views of US landing sites for transatlantic cables] * [http://eyeball-series.org/cablew-eyeball.htm Map and Satellite views of US landing sites for transpacific cables] * [http://image.guardian.co.uk/sys-images/Technology/Pix/pictures/2008/02/01/SeaCableHi.jpg World map of submarine cables from the ''Guardian'' originally from TeleGeography] * [http://www.kisca.org.uk/charts.htm Positions and Route information of Submarine Cables in the Seas Around the UK] {{Telephony}} {{Telecommunications}} {{DEFAULTSORT:Submarine Communications Cable}} [[Category:Coastal construction]] [[Category:Submarine communications cables|*]] [[Category:Telecommunications equipment]] [[Category:History of telecommunications]] [[ka:წყალქვეშა საკომუნიკაციო კაბელი]] [[no:Sjøkabel]]'