92-568: Asia Pacific Gateway (APG) is a submarine communications cable system that connects Mainland China , Hong Kong , Japan , South Korea , Malaysia , Taiwan , Thailand , Vietnam and Singapore . It will be about 10,400 kilometres (6,500 mi) long. The capacity will be 54.8 terabits per second. The APG cable consortium includes Facebook , CAT Telecom , China Telecom , China Mobile International, China Unicom , Chunghwa Telecom , KT Corporation , LG Uplus , NTT Communications, StarHub , Global Transit, Viettel and VNPT . The APG cable system
184-413: 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
276-453: A gain of +33dBm, however again the amount of power that can be fed into the fiber is limited. In single carrier configurations the dominating limitation is self phase modulation induced by the Kerr effect which limits the amplification to +18 dBm per fiber. In WDM configurations the limitation due to crossphase modulation becomes predominant instead. Optical pre-amplifiers are often used to negate
368-421: A handful of hours. 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,
460-687: A machine in 1837 for covering wires with silk or cotton thread that he developed into a wire wrapping capability for submarine cable with a factory in 1857 that became W.T. Henley's Telegraph Works Co., Ltd. The India Rubber, Gutta Percha and Telegraph Works Company , established by the Silver family and giving that name to a section of London , furnished cores to Henley's as well as eventually making and laying finished cable. In 1870 William Hooper established Hooper's Telegraph Works to manufacture his patented vulcanized rubber core, at first to furnish other makers of finished cable, that began to compete with
552-428: A public dispute with William Thomson . Whitehouse believed that, with enough voltage, any cable could be driven. Thomson believed that his law of squares showed that retardation could not be overcome by a higher voltage. His recommendation was a larger cable. Because of the excessive voltages recommended by Whitehouse, Cyrus West Field's first transatlantic cable never worked reliably, and eventually short circuited to
644-415: A pump laser light to be transmitted alongside the data carried by the cable; the pump light and the data are often transmitted in physically separate fibers. The ROPA contains a doped fiber that uses the pump light (often a 1480 nm laser light) to amplify the data signals carried on the rest of the fibers. WDM or wavelength division multiplexing was first implemented in submarine fiber optic cables from
736-408: A single fiber using wavelength division multiplexing (WDM), which allows for multiple optical carrier channels to be transmitted through a single fiber, each carrying its own information. WDM is limited by the optical bandwidth of the amplifiers used to transmit data through the cable and by the spacing between the frequencies of the optical carriers; however this minimum spacing is also limited, with
828-407: A solid-state optical amplifier , usually an erbium-doped fiber amplifier (EDFA). 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
920-405: A submarine cable can have a major impact in its capacity. SDM is combined with DWDM to improve capacity. The open cable concept allows for the design of a submarine cable independently of the transponders that will be used to transmit data through the cable. SLTE (Submarine Line Terminal Equipment) has transponders and a ROADM ( Reconfigurable optical add-drop multiplexer ) used for handling
1012-481: A typical multi-terabit, transoceanic submarine cable system costs several hundred million dollars to construct. 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,
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#17327872485501104-470: A wire, insulated with tarred hemp and India rubber , 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 to cover the wire and prevent the electric current from leaking into the water was necessary for the success of a long submarine line. India rubber had been tried by Moritz von Jacobi ,
1196-470: Is a natural rubber obtained from the sap of certain trees growing in the Far East. It hardens on exposure to air, but has the useful property of being thermoplastic . It can be moulded to a new shape after boiling in water and will reharden when cool. It is credited with being the first plastic available to manufacturing industry. Montgomerie is sometimes credited with discovering the substance. He
1288-480: Is either not required, the capacity to the country is small enough to be backed up by other means, or having backup 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, it
1380-590: Is less likely 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 Gbps across Atlantic Ocean" routes of up to 6,000 km (3,700 mi), meaning a typical cable can move tens of terabits per second overseas. Speeds improved rapidly in the previous few years, with 40 Gbit/s having been offered on that route only three years earlier in August 2009. Switching and all-by-sea routing commonly increases
1472-595: Is limited, although this has increased over the years; in 2014 unrepeated cables of up to 380 kilometres (240 mi) in length were in service; however these require unpowered repeaters to be positioned every 100 km. 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 lower-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
1564-449: Is responsible for it coming into widespread use, but it had in fact been known for some time by a few natives who used it to make handles for parangs (Malayan machetes ) and other items. However, it was not widely known, even amongst native Malays . Montgomerie said that most people he showed it to could not recognise it. It had even made its way to Europe, but again, was not widely known. Montgomerie's discovery began in 1822 when he
1656-694: Is too small to be commercially viable. Some have been used as scientific instruments to measure earthquake waves and other geomagnetic events. In 1942, Siemens Brothers of New Charlton , London, in conjunction with the United Kingdom National Physical Laboratory , adapted submarine communications cable technology to create the world's first submarine oil pipeline in Operation Pluto during World War II . Active fiber-optic cables may be useful in detecting seismic events which alter cable polarization. In
1748-552: 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. Submarine cables are important to the modern military as well as private enterprise. The US military , for example, uses the submarine cable network for data transfer from conflict zones to command staff in
1840-743: The Crimean War various forms of telegraphy played a major role; this was a first. At the start of the campaign there was a telegraph link at Bucharest connected to London. In the winter of 1854 the French extended the telegraph link to the Black Sea coast. In April 1855 the British laid an underwater cable from Varna to the Crimean peninsula so that news of the Crimean War could reach London in
1932-698: The North Pacific Cable system was the first regenerative system (i.e., with repeaters ) 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 CS Cable Venture . Transatlantic cables of
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#17327872485502024-758: The Prussian 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 Scottish surgeon in the service of the British East India Company . Twenty years earlier, Montgomerie had seen whips made of gutta-percha in Singapore , and he believed that it would be useful in
2116-533: The Rhine between Deutz and Cologne . In 1849, Charles Vincent Walker , electrician to the South Eastern Railway , submerged 3 km (2 mi) of wire coated with gutta-percha off the coast from Folkestone , which was tested successfully. In August 1850, having earlier obtained a concession from the French government, John Watkins Brett 's English Channel Submarine Telegraph Company laid
2208-753: The SS Great Eastern , used a more advanced technology and produced the first successful transatlantic cable. Great Eastern later went on to lay the first cable reaching to India from Aden, Yemen, in 1870. 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, Britain's vast colonial empire led to business for
2300-469: The steel wire armouring gave pests a route to eat their way in. Damaged armouring, which was not uncommon, also provided an entrance. Cases of sharks biting cables and attacks by sawfish have been recorded. In one case in 1873, a whale damaged the Persian Gulf Cable between Karachi and Gwadar . The whale was apparently attempting to use the cable to clean off barnacles at a point where
2392-443: The 1980s, 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. Except for very short lines, fiber-optic submarine cables include repeaters at regular intervals. Modern optical fiber repeaters use
2484-422: The 1990s to the 2000s, followed by DWDM or dense wavelength division mulltiplexing around 2007. Each fiber can carry 30 wavelengths at a time. SDM or spatial division multiplexing submarine cables have at least 12 fiber pairs which is an increase from the maximum of 8 pairs found in conventional submarine cables, and submarine cables with up to 24 fiber pairs have been deployed. The type of modulation employed in
2576-509: 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 armour 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. William Thomas Henley had developed
2668-492: The 20th Regiment of Bengal Native Infantry with the rank of Assistant Surgeon. Upon his arrival, he took over as senior surgeon of Singapore from a more junior officer, and was given the rank of acting Surgeon. In 1827, Montgomerie was posted back to Bengal . In 1835, the medical department headquarters was moved from Penang to Singapore, whereupon Montgomerie was made the head. He retired to England in January 1844. He
2760-615: The Singapore botanical experimental gardens and at his personal estate in Singapore. The latter never became economically viable, but he received a Society of Arts gold medal for nutmeg cultivation. He was also responsible for building the first lunatic asylum in Singapore. Montgomerie died at Barrackpore in India a few years after taking part in the Second Anglo-Burmese War as Superintendent Surgeon. Montgomerie
2852-623: The US mainland to Hawaii in 1902 and Guam to the Philippines in 1903. Canada, Australia, New Zealand and Fiji were also linked in 1902 with the trans-Pacific segment of the All Red Line . Japan was connected into the system in 1906. Service beyond Midway Atoll was abandoned in 1941 due to World War II, but the remainder stayed in operation until 1951 when the FCC gave permission to cease operations. The first trans-Pacific telephone cable
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2944-523: The United States. Interruption of the cable network during intense operations could have direct consequences for the military on the ground. 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 . Two privately financed, non-consortium cables were constructed in
3036-466: 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
3128-456: The cable descended over a steep drop. The unfortunate whale got its tail entangled in loops of cable and drowned. The cable repair ship Amber Witch was only able to winch up the cable with difficulty, weighed down as it was with the dead whale's body. 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 amplifiers in
3220-442: 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 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
3312-510: The cable. Large voltages 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 , severely limiting the data rate for telegraph operation to 10–12 words per minute . As early as 1816, Francis Ronalds had observed that electric signals were slowed in passing through an insulated wire or core laid underground, and outlined
3404-549: 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
3496-401: The cause to be induction, using the analogy of a long Leyden jar . 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 earth (or water) surrounding it. Faraday had noticed that when a wire is charged from
3588-623: 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. 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) cut the five cables linking Germany with France, Spain and the Azores, and through them, North America. Thereafter,
3680-440: The current at 10,000VDC is up to 1,650mA. Hence the total amount of power sent into the cable is often up to 16.5 kW. The optic fiber used in undersea cables is chosen for its exceptional clarity, permitting runs of more than 100 kilometres (62 mi) between repeaters to minimize the number of amplifiers and the distortion they cause. Unrepeated cables are cheaper than repeated cables and their maximum transmission distance
3772-434: The current generation with one end providing a positive voltage and the other a negative voltage. A 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 voltage passed down the cable is often anywhere from 3000 to 15,000VDC at a current of up to 1,100mA, with the current increasing with decreasing voltage;
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3864-402: The data traffic that is crossing oceans is carried by undersea cables. 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 1,000 megabits per second and display higher latency . However,
3956-511: The deep-sea sections which comprise the majority of the run, although larger and heavier cables are used for shallow-water sections near shore. After William Cooke and Charles Wheatstone had introduced their working 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
4048-412: The development of submarine branching units (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 reason for this development was that the capacity of cable systems had become so large that it
4140-438: 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 ms, close to the theoretical optimum for an all-sea route. While in theory, a great circle route (GCP) between London and New York City is only 5,600 km (3,500 mi), this requires several land masses ( Ireland , Newfoundland , Prince Edward Island and
4232-400: 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 lines to the higher frequencies required for high-speed data and voice. While laying a transatlantic telephone cable was seriously considered from the 1920s,
4324-415: The fabrication of surgical apparatus. 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 . In 1847 William Siemens , then an officer in the army of Prussia, laid the first successful underwater cable using gutta percha insulation, across
4416-444: The fiber, it is amplified. This system also permits wavelength-division multiplexing , which dramatically increases the capacity of the fiber. EDFA amplifiers were first used in submarine cables in 1995. Repeaters are powered by a constant direct current passed down the conductor near the centre 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
4508-552: The first instant telecommunications links between continents, such as the first transatlantic telegraph cable which became operational on 16 August 1858. Submarine cables first connected all the world's continents (except Antarctica ) when Java was connected to Darwin, Northern Territory , Australia, in 1871 in anticipation of the completion of the Australian Overland Telegraph Line in 1872 connecting to Adelaide, South Australia and thence to
4600-545: The first line across the English Channel , using the converted tugboat Goliath . It was simply a copper wire coated with gutta-percha , without any other protection, and was not successful. However, 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 , Blazer , which
4692-494: The founder of Singapore, and William Farquhar , who was stabbed by a would-be assassin in 1823. Farquhar had expressed concern over Montgomerie's youth when he arrived in Singapore in 1819. Montgomerie was very young at this point, even younger than the Sub-assistant Surgeon from whom he took over and was now in charge. If anything happened to Farquhar, Montgomerie would have been left in charge of Singapore as
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#17327872485504784-520: The government land leasing arrangements were not favourable in Singapore, and discouraged farming. He compared this to Ceylon (now known as Sri Lanka , but at the time a British possession) where land could be bought outright. In 1842, Montgomerie sent a box of nutmeg and mace to the Society of Arts (later to become the Royal Society) for which he was awarded a gold medal. Gutta-percha
4876-451: The government spice plantations had been neglected. The clove crop had been destroyed by blight , but since the nutmeg trees still looked healthy, Montgomerie decided to start his own plantation with seeds procured from Penang. He believed that enough nutmeg could be grown in Singapore to supply the entire British Empire by 1850, and that the price could be driven down to something affordable by ordinary people. However, he complained that
4968-415: The gutta-percha cores. The company later expanded into complete cable manufacture and cable laying, including the building of the first cable ship specifically designed to lay transatlantic cables. Gutta-percha and rubber were not replaced as a cable insulation until polyethylene was introduced in the 1930s. Even then, the material was only available to the military and the first submarine cable using it
5060-452: 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 partial land route could result in round trip times below 40 ms (which is the speed of light minimum time), and not counting switching. Along routes with less land in
5152-431: 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 , FLAG , Worldcom , and Asia Global Crossing. Tata Communications ' Global Network (TGN) is the only wholly owned fiber network circling
5244-716: The link from Dover to Ostend in Belgium, by the Submarine Telegraph Company. Meanwhile, the Electric & International Telegraph Company completed two cables across the North Sea , from Orford Ness to Scheveningen , the Netherlands. These cables were laid by Monarch , a paddle steamer which later became the first vessel with permanent cable-laying equipment. In 1858, the steamship Elba
5336-698: The mammoth globe-spanning 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. The first trans-Pacific cables providing telegraph service were completed in 1902 and 1903, linking
5428-549: The minimum spacing often being 50 GHz (0.4 nm). The use of WDM can reduce the maximum length of the cable although this can be overcome by designing equipment with this in mind. Optical post amplifiers, used to increase the strength of the signal generated by the optical transmitter often use a diode-pumped erbium-doped fiber laser. The diode is often a high power 980 or 1480 nm laser diode. This setup allows for an amplification of up to +24dBm in an affordable manner. Using an erbium-ytterbium doped fiber instead allows for
5520-456: The most important application was as an electrical insulator. This was essential for the worldwide telegraph network as it made possible the transatlantic telegraph cable and other links across oceans. No better material was available until the invention of polyethylene in the 1930s. It was the custom in Singapore to house ' lunatics ' in the jail. Natives and Chinese were confined in this way, while Europeans enjoyed better treatment. It
5612-490: The next most senior official. Farquhar wrote to Calcutta asking them to put alternative arrangements in place. In Singapore, Montgomerie was appointed a magistrate in 1819, head of the botanical experimental gardens in 1823 (where he concentrated on cultivating spices ), and sheriff in 1837. Montgomerie keenly pursued agriculture in Singapore. He owned the 32-acre (13 ha) Duxton Hill estate for most of his time there, but never succeeded in making it profitable. It
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#17327872485505704-474: The ocean when Whitehouse increased the voltage beyond the cable design limit. Thomson designed a complex electric-field generator that minimized current by 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
5796-444: The ocean, which reduced costs significantly. A few facts put this dominance of the industry in perspective. In 1896, there were 30 cable-laying ships in the world, 24 of which 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. During World War I , Britain's telegraph communications were almost completely uninterrupted, while it
5888-418: The only way Germany could communicate was by wireless, and that meant that Room 40 could listen in. The submarine cables were an economic benefit to trading companies, because owners of ships could communicate with captains when they reached their destination and give directions as to where to go next to pick up cargo based on reported pricing and supply information. The British government had obvious uses for
5980-435: The other pumping them at 1450 nm. Launching a pump frequency (pump laser light) at a power of just one watt leads to an increase in reach of 45 km or a 6-fold increase in capacity. Another way to increase the reach of a cable is by using unpowered repeaters called remote optical pre-amplifiers (ROPAs); these still make a cable count as unrepeatered since the repeaters do not require electrical power but they do require
6072-541: The planet. William Montgomerie William Montgomerie (1797–1856) was a Scottish military doctor with the East India Company , and later head of the medical department at Singapore . He is best known for promoting the use of gutta-percha in Europe. This material was an important natural rubber that made submarine telegraph cables possible. Montgomerie was involved in spice cultivation as head of
6164-488: The resistance and inductance of the cable, limits the speed at which a signal travels through the conductor of the cable. Early cable designs failed to analyse these effects correctly. Famously, E.O.W. Whitehouse had dismissed the problems and insisted that a transatlantic cable was feasible. When he subsequently became chief electrician of the Atlantic Telegraph Company , he became involved in
6256-478: The rest of Australia. Subsequent generations of cables carried telephone traffic, then data communications traffic. These early cables used copper wires in their cores, but modern cables use optical fiber technology to carry digital data , which includes telephone, Internet and private data traffic. Modern cables are typically about 25 mm (1 in) in diameter and weigh around 1.4 tonnes per kilometre (2.5 short tons per mile; 2.2 long tons per mile) for
6348-414: The sap by tapping but did not think it would be possible to persuade the native collectors to use this slower, but more sustainable method. Besides its use for making medical instruments, Montgomerie proposed several other uses, including as a dental filling (for which it is still used ). Numerous other applications were quickly found for the new material, including a much improved golf ball. However,
6440-537: 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 thrusters that increase maneuverability. This capability is important because fiber-optic cable must be laid straight from the stern, which was another factor that copper-cable-laying ships did not have to contend with. Originally, submarine cables were simple point-to-point connections. With
6532-569: The signals in the cable via software control. The ROADM is used to improve the reliability of the cable by allowing it to operate even if it has faults. This equipment is located inside a cable landing station (CLS). C-OTDR (Coherent Optical Time Domain Reflectometry) is used in submarine cables to detect the location of cable faults. The wet plant of a submarine cable comprises the cable itself, branching units, repeaters and possibly OADMs ( Optical add-drop multiplexers ). Currently 99% of
6624-613: The technology required for economically feasible telecommunications was not developed until the 1940s. A first attempt to lay a " pupinized " telephone cable—one with loading coils added at regular intervals—failed in the early 1930s due to the Great Depression . 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 , in Canada. It
6716-441: The thermal noise of the receiver. Pumping the pre-amplifier with a 980 nm laser leads to a noise of at most 3.5 dB, with a noise of 5 dB usually obtained with a 1480 nm laser. The noise has to be filtered using optical filters. Raman amplification can be used to extend the reach or the capacity of an unrepeatered cable, by launching 2 frequencies into a single fiber; one carrying data signals at 1550 nm, and
6808-633: The time were easily damaged by solvents and could not withstand the tropical climate. Montgomerie sent samples to the Calcutta Medical Board with a recommendation for its medical use. The board agreed with him and requested that he obtain as much as possible. Montgomerie also sent samples to the Royal Asiatic Society in London in 1843. He began an investigation into how widespread the tree was. He discovered that it
6900-504: The vegetation by the port's first Master Attendant . On seeing the strange inscription, they refused to carry on. Montgomerie commented "it was a pity that those who afterwards authorised the destruction of the ancient relic were not themselves prevented by some such wholesome superstition." Montgomerie was the head of the Singapore Yacht Club when it formed in 1826. Meetings were held in his house. The game of fives
6992-517: The way, round trip times can approach speed of light minimums in the long term. The type of optical fiber used in unrepeated and very long cables is often PCSF (pure silica core) due to its low loss of 0.172 dB per kilometer when carrying a 1550 nm wavelength laser light. The large chromatic dispersion of PCSF means that its use requires transmission and receiving equipment designed with this in mind; this property can also be used to reduce interference when transmitting multiple channels through
7084-656: Was able to quickly cut Germany's cables worldwide. Throughout the 1860s and 1870s, British cable expanded eastward, into the Mediterranean Sea and the Indian Ocean. An 1863 cable to Bombay (now Mumbai ), India, provided a crucial link to Saudi Arabia . 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
7176-601: Was accepted and the asylum was built. Montgomerie played a minor role in recovering pieces of the Singapore Stone after it was demolished by explosives in 1843. The stone was a large rock in the Singapore River bearing an ancient and undeciphered inscription. It was destroyed by the Settlement Engineer to clear the river channel. Montgomerie had intended to set up a Singapore museum, but
7268-652: Was born in Scotland in 1797. In 1827, he married Elizabeth Graham in Calcutta . A son is mentioned in a newspaper article. His brother was Major-General Sir P. Montgomerie of the Madras Artillery who fought in the First Opium War . In 1818, Montgomerie became a medical officer with the East India Company and was posted to India. In May 1819, he was posted to Singapore with the 2nd Battalion of
7360-548: Was inaugurated on September 25, 1956, initially carrying 36 telephone channels. In the 1960s, transoceanic cables were coaxial cables that transmitted 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. Later ones were transistorized. Many of these cables are still usable, but have been abandoned because their capacity
7452-797: Was laid from Hawaii to Japan in 1964, with an extension from Guam to The Philippines. Also in 1964, the Commonwealth Pacific Cable System (COMPAC), with 80 telephone channel capacity, opened for traffic from Sydney to Vancouver, and in 1967, the South East Asia Commonwealth (SEACOM) system, with 160 telephone channel capacity, opened for traffic. This system used microwave radio from Sydney to Cairns (Queensland), cable running from Cairns to Madang ( Papua New Guinea ), Guam , Hong Kong , Kota Kinabalu (capital of Sabah , Malaysia), Singapore , then overland by microwave radio to Kuala Lumpur . In 1991,
7544-659: Was not laid until 1945 during World War II across the English Channel . 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 did not have easy access to gutta-percha manufacturers. The 1926 development by John T. Blake of deproteinized rubber improved the impermeability of cables to water. Many early cables suffered from attack by sea life. The insulation could be eaten, for instance, by species of Teredo (shipworm) and Xylophaga . Hemp laid between
7636-471: Was not only found in Singapore, but all over the Malaysian peninsular and the islands of Indonesia and appeared to be plentiful. However, as early as 1846 Montgomerie was expressing fears that supplies would dry up due to the destructive method of harvesting and large quantities being produced. Trees were cut down and the bark stripped to get to the sap. Montgomerie believed that it was possible to harvest
7728-425: Was not possible to completely back up a cable system with satellite capacity, so it became necessary to provide sufficient terrestrial backup capability. Not all telecommunications organizations wish to take advantage of this capability, so modern cable systems may have dual landing points in some countries (where back-up capability is required) and only single landing points in other countries where back-up capability
7820-467: Was part of Montgomerie's duties to visit the jail daily to attend to their needs. There had been public disquiet about the lack of proper facilities, but nothing was done until 1840 when one mentally ill inmate murdered another. Montgomerie was tasked with investigating and making recommendations. He recommended a purpose-built lunatic asylum and submitted plans and costings. He rejected an alternative idea of sending patients to India. Montgomerie's plan
7912-483: Was recalled to Bengal some years later as Garrison Surgeon at Fort William, Calcutta , and was Superintendent Surgeon in the field during the Second Anglo-Burmese War (1852–1853). He died of cholera at Barrackpore , India, on 21 March 1856 and was buried in Fort William. While he was stationed at Singapore, Montgomerie was usually the doctor attending Singapore's leaders. These included Stamford Raffles ,
8004-420: Was scheduled to be ready for service in 2016. It will have cable landing points at: Submarine communications cable A submarine communications cable is a cable laid on the seabed between land-based stations to carry telecommunication signals across stretches of ocean and sea. The first submarine communications cables were laid beginning in the 1850s and carried telegraphy traffic, establishing
8096-578: Was shown a different natural rubber, gutta girek , and was told of the existence of a harder material, gutta percha . However, he could not obtain a sample at the time and did not get another opportunity until 1842 after he returned to Singapore. In that year a Malay showed him a parang with a gutta-percha handle. Montgomerie purchased the item and requested that more of the substance be provided. After experimentation, he concluded that its thermoplastic properties would be ideal for making many surgical instruments. The natural rubbers used for this purpose at
8188-616: Was sold after his death and briefly renamed "Woodsville". The area is now built-up and the name has reverted to Duxton Hill, a name also preserved in Duxton Road. The primary crop grown was sugar, but later he planted nutmeg trees. The estate was bounded by a river where Montgomerie had a large watermill . A short distance from the mill, the Serangoon Road crosses the river on a crossing known as Montgomerie's Bridge. On his return to Singapore in 1835, Montgomerie found that
8280-568: Was towed across the Channel. In 1853, more successful cables were laid, linking Great Britain with Ireland , Belgium , and the Netherlands , and crossing The Belts in Denmark . The British & Irish Magnetic Telegraph Company completed the first successful Irish link on May 23 between Portpatrick and Donaghadee using the collier William Hutt . The same ship was used for
8372-634: Was unable to do so. Instead, he sent the pieces he recovered to the Asiatic Society museum in Calcutta around 1848. In 1918, some of the fragments recovered by Montgomerie were returned to Singapore on extended loan and are now in the National Museum of Singapore . The destruction of the stone horrified many of the colony's officials. One described it as vandalism. The stone was first discovered by Bengali sailors tasked with clearing
8464-477: Was used to lay a telegraph cable from Jersey to Guernsey , on to Alderney and then to Weymouth , the cable being completed successfully in September of that year. Problems soon developed with eleven breaks occurring by 1860 due to storms, tidal and sand movements, and wear on rocks. A report to the Institution of Civil Engineers in 1860 set out the problems to assist in future cable-laying operations. In
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