Equipment structure
The submarine optical cable is laid on the seabed with a wire bundle wrapped in an insulating sheath. The sea water can prevent the interference of external light and magnetic waves, so the signal-to-noise ratio of the submarine cable is relatively high; There is no time delay in communication; the design life of submarine optical cables is 25 years of continuous operation, while artificial satellites generally run out of fuel within 10 to 15 years.
The basic structure of submarine optical cable is: polyethylene layer, polyester resin or asphalt layer, steel strand layer, aluminum waterproof layer, polycarbonate layer, copper or aluminum pipe, paraffin, and alkane Layers, fiber bundles, etc.
The submarine optical cable system is mainly used to connect optical cables and the Internet. It is divided into two parts: onshore equipment and underwater equipment. The onshore equipment packs and transmits communication services such as voice, image, and data. The underwater equipment is responsible for the processing, sending and receiving of communication signals. Underwater equipment is divided into three parts: submarine fiber optic cable, repeater and "branch unit": the submarine fiber optic cable is the most important and most vulnerable part.
The structure of the deep-sea optical cable is more complicated: the optical fiber is set in the U-shaped groove plastic skeleton, and the groove is filled with grease or elastic plastic to form the core. The core is wrapped with high-strength steel wire. During the wrapping process, all gaps should be filled with waterproof material. Then a layer of copper tape is wrapped around the steel wire and the seam is welded to make the steel wire and the copper tube form a resistance Combination of compression and tension. A layer of polyethylene sheath is also added on the outside of the steel wire and copper pipe. Such a tight multi-layer structure is to protect the optical fiber, prevent breakage and prevent the intrusion of sea water. In areas where sharks are infested, an additional layer of polyethylene sheath is added to the outside of the submarine cable.
The structure of the submarine optical cable requires strong and light materials, but light metal aluminum cannot be used. Because aluminum and seawater will electrochemically react to produce hydrogen, hydrogen molecules will diffuse into the glass material of the optical fiber, making the optical fiber The loss becomes larger. Therefore, the submarine optical fiber cable must not only prevent hydrogen from being generated inside, but also prevent hydrogen from penetrating into the optical cable from the outside. For this reason, in the early 1990s, a carbon- or titanium-coated optical fiber was developed to prevent hydrogen penetration and chemical corrosion. The optical fiber connector is also required to be high-strength, requiring the connection to maintain the strength of the original optical fiber and the surface of the original optical fiber from damage.
Development history
Submarine optical cable communication has a history of more than 100 years.
In 1850, the Anglo-French Telegraph Company began to lay the world's first submarine cable between Britain and France, which could only send Morse telegraph codes.
The first submarine cable in the world was laid between Britain and France in 1850. John Watkins Brett's Anglo-French Telegraph Company opened a cable across the English Channel. The quality is poor and nothing else. Any guarantee. On November 13, 1851, the protected core, the real cable, was erected. In 1852, Great Britain and Ireland were connected together.
In 1852, the Submarine Telegraph Company first connected a cable from London to Paris. In 1853, England was added to the Netherlands by a cable across the North Sea. For the first time, a cable was used to connect London and Paris.
In 1858, Cyrus West Field (CyrusWestField), they persuaded the British Industrialist Fund for the first attempt to lay a transatlantic telegraph cable. From the beginning, and in operation, only 1 month. There have been many problems with this technology. Scientists tried to constantly try newer technologies in 1865 and 1866, and the Dadong Telegraph Bureau used more advanced technologies and produced the world's first successful transatlantic cable. This technology was completed in India in 1870.
In 1863, cables were connected from Mumbai to the Arabian Peninsula.
In 1866, Britain succeeded in laying the transatlantic submarine cable (TheAtlanticCable) between the United States and Britain, realizing the transatlantic telegraph communication between the European and American continents.
In 1876, after Bell invented the telephone, submarine cables had new functions, and the pace of large-scale laying of submarine cables in various countries accelerated.
China’s first submarine cable was the first governor of Taiwan during the Qing Dynasty, Liu Mingchuan. On behalf of Taiwan’s Tainan Anping to Penghu, it is 53 nautical miles long.
By 1888, a total of two water lines were erected. One was the 177-nautical-mile water line between Chuanshi Island in Fuzhou and Huwei (Freshwater) in Taiwan. It was mainly used by the Taiwan government to inform the Qing court of natural disasters in Taiwan. , Public security, finance, and business communications; the other is the 53-nautical-mile water line from Tainan Anping to Penghu. The mainland landing site of Chuanshidao in the sea off Fujian still exists, but the specific landing site of Taiwan’s Danshui is no longer available.
The global submarine communication cable was completed in 1902.
From 1902 to 1903, submarine cables connected to Hawaii from the continental United States, connected to Guam in 1902, and connected to the Philippines in 1903. In 1902, Canada, Australia, New Zealand and Fiji also completed the connection.
In 1987, the first submarine cable in Taiwan, China, was completed between Taiwan’s Freshwater and Nagasaki, Japan. (Disabled)
The international cable landing point is Yilan Toucheng, that is, the cable connects from the Toucheng of Yilan County to the United States, Japan, Northeast Asia, Southeast Asia, Australia, New Zealand, the Philippines and other places. Pingtung Fangshan is a cable connecting China, Ryukyu, Japan, South Korea, and Guam from Fangshan Township in Pingtung County to California and Oregon on the west coast of the United States.
In 1988, the first submarine cable in mainland China was completed in 1988, between Chuanshi Island in Fuzhou and Taiwan (freshwater), with a length of 177 nautical miles. (Disabled)
In 1988, a transoceanic submarine optical cable (TAT-8) system was laid between the United States, Britain and France, with a total length of 6,700 kilometers. This optical cable contains 3 pairs of optical fibers, each pair has a transmission rate of 280Mb/s, and the relay station distance is 67 kilometers. This is the first communication submarine cable across the Atlantic Ocean, marking the arrival of the era of submarine cable.
In 1989, the submarine optical cable (13,200 kilometers in length) across the Pacific was also successfully constructed. Since then, the submarine optical cable has replaced the coaxial cable in the field of intercontinental submarine cables that cross the ocean, and the intercontinental ocean is no longer laid submarine cable.
In the 1990s, submarine optical cables and satellite communications have become the main means of contemporary intercontinental communications.
From 1989 to the end of 1998, China successively participated in the construction and investment of 18 international submarine optical cables.
In December 1993, the first international submarine cable system to land in China was the China-Japan (C-J) submarine cable system.
In February 1996, the China-South Korea submarine optical cable was completed and opened, and landed in Qingdao, my country and Taian, South Korea, with a total length of 549 kilometers.
In November 1997, my country’s participation in the construction of the Global Submarine Optical Cable System (FLAG) was completed and put into operation. This is the first intercontinental optical cable system to land in my country. It is located in the United Kingdom, Egypt, India, and Thailand. , Japan and other 12 countries and regions landed, with a total length of more than 27,000 kilometers, of which the Chinese section is 622 kilometers.
On September 14, 2000, with the opening of the Asia-Europe submarine optical cable Shanghai landing station, China Telecom Corporation participated in the construction and connection of the Asia-Europe submarine optical fiber cable system connecting 33 countries and regions in Asia and Europe. After more than three years of construction, it was officially opened. Its completion marks that my country's international communications level has reached a new level.
On August 12, 2014, Google announced that it would cooperate with five other companies to build a US$300 million Pacific submarine optical cable system to help Asian users obtain faster internet speeds. This high-speed submarine cable called "FASTER" will connect two locations on the Japanese coastline with the West Coast cities of the United States, including Los Angeles, San Francisco, Portland and Seattle. The five companies cooperating with Google on this project include China Mobile, China Telecom, France GlobalTransit, Japan KDDI and Singapore Telecom. After the construction is completed, the bandwidth of this submarine optical cable will reach 60Tbps, which is about 10 million times the bandwidth of an ordinary cable modem.
Google also supports UNITY, another trans-Pacific submarine cable system connecting the United States and Japan. This system has been put into use in 2010. At that time, the bandwidth of the submarine optical cable was 7.68Tbps.
At the beginning of 2016, US military scientists are developing a fast-repairable submarine optical cable that can restore tactical military communications destroyed by opponents.
Main types
According to different marine environments and water depths
It can be divided into deep-sea optical cables and shallow-sea optical cables. Correspondingly, they appear as single-layer armor in the optical cable structure. Layer and double armor layer. In the product model representation method, DK is used for single-layer armor, and SK is used for double-layer armor. The specifications are expressed by the number and type of fibers.
According to the role and function, it can be divided into
submarine communication cable and submarine optical fiber cable. The former is mainly used for communication services, and the latter is mainly used for underwater transmission of high-power light energy.
Technical Principles
The networks of all countries in the world can be regarded as a large local area network. Submarine and land optical cables connect them to become the Internet. Optical cables are the "central nervous system" of the Internet. Almost the "brain" of the Internet. As the birthplace of the Internet, the United States is home to many Web and IM (such as MSN) servers. Out of the 13 root servers that resolve domain names in the world, 10 are in the United States. Log in to most .com and .net websites or send e-mails, data Almost you have to make a circle around the United States to reach your destination.
Submarine cables are maintained separately. For safety purposes, submarine cables also need to be maintained at ordinary times. If someone fished out the submarine cable and added optical fiber, the information could be stolen. If there is a war, someone may damage the fiber optic cable. Submarine cables are the best solution for communication. Other methods such as satellites and microwaves can be used as supplements, but they seem to be unable to replace submarine cables because their channels are limited. It is a way that allows the majority of users to communicate in a cheap way.
The remote power supply of the submarine cable system is very important, and the repeaters along the submarine cable rely on the remote power supply of the landing station. The digital repeater used in the submarine optical cable has many functions, and the power consumption is several times larger than that of the analog repeater of the submarine cable. The power supply requires high reliability and cannot be interrupted. Therefore, in areas where sharks are infested, two layers of steel tape and a layer of polyethylene outer sheath should be added to the outside of the submarine optical cable. Even with such tight protection, there were instances where the polyethylene insulators of deep-sea optical cables were bitten by sharks causing power failures in the late 1980s.
Main features
Compared with terrestrial optical cables, submarine optical cables have many advantages: First, they do not need to dig tunnels or use brackets for laying, so the investment is low and the construction speed is fast; The second is that except for the landing area, most of the cables are on the seabed at a certain depth, free from the destruction of the natural environment such as wind and waves and the interference of human production activities. Therefore, the cables are safe and stable, with strong anti-interference ability and good confidentiality performance.
Construction progress
Foreign
The Asia-Europe submarine optical cable system starts from the United Kingdom in the west, connects with France, Italy and other countries via the Mediterranean, and enters the Indian Ocean through the Red Sea to Singapore, and then Further east, through Malaysia, the Philippines, Vietnam, etc., reach China, and finally reach Japan and South Korea. It has a total length of 38,000 kilometers, connects 33 countries and regions, and has a total of 39 landing stations. The Asia-Europe submarine optical cable system has one landing station each in Shanghai and Shantou.
In 2020, NEC will complete the construction of the transatlantic submarine cable between Angola and Brazil.
China
As an important means of contemporary international communications, submarine optical cables undertake 90% of international communications services and are the main carrier of global information communications. It is also a new high-profit growth point for my country's optical fiber companies.
The biggest problem in the construction of my country's submarine cable system is the integration of the submarine cable system. The international market adopts the submarine cable construction mode of the cooperation of communication equipment general contractors, optical fiber cable manufacturers and construction units, while my country’s submarine cable construction adopts the segmentation mode. Cable manufacturing companies provide submarine cables and accessories, which are laid by the submarine cable construction unit, and then the owner or operator performs system integration. This model is not conducive to the integration of system integration capabilities, is not conducive to the formation of one or two submarine cable system integrators, and it is not conducive to the internationalization of China's submarine cable system.
The construction of large-scale submarine optical cables includes many aspects of contract management, risk aversion, etc., which should be an area that Chinese enterprises urgently need to upgrade.
The production technology of submarine optical cable mainly includes special optical fiber manufacturing for submarine cable, special laser welding stainless steel tube optical unit manufacturing for submarine cable, inner steel wire armor, seamless copper tube manufacturing, insulation layer extrusion, and outer layer. It is made of steel wire armor, outer layer PP rope and asphalt.
Huawei Marine, established in 2008, has participated in nearly 100 submarine optical cable laying or upgrading projects, and the company's global market share has increased from less than 5% to 20%. Two trans-Atlantic fiber optic cables have been upgraded in recent years: one from South Africa to the United Kingdom, and the other in the Bahamas and Azores.
On June 27, 2017, at the 2017 China Unicom International Partner Conference, China Unicom, Cameroon Telecom, and Huawei Marine jointly signed the South Atlantic International Submarine Cable (SAIL) construction agreement. The SAIL submarine cable is about 6000 kilometers long and has a design capacity of 32Tbit/s. After completion, it will connect the African continent and the American continent, becoming the submarine cable route between Africa and South America with the largest transmission capacity and the smallest delay, providing high-quality and reliable intercontinental Communication service.
As of June 2020, the overall layout of China Telecom International’s cloud resources has covered major cities along the "Silk Road Economic Belt" and "21st Century Maritime Silk Road". With the advent of the 5G era, China Telecom is fully launching 5G scale construction and strives to complete the construction of 250,000 base stations nationwide by 2020.
In August 2020, the Hainan Wenchang to Hong Kong submarine optical fiber cable project is progressing in an orderly manner. The entire submarine cable is 650 kilometers from Hong Kong to the Hainan Wenchang landing point. The entire approval has entered the middle and late stages. The entire submarine cable construction The cycle is about 3 months.
Related news
May 19, 2020 China Mobile International Limited (CMI), Facebook, South African telecom operator MTNGlobalConnect, French telecom operator Orange, Saudi Telecom, Egypt Telecom, Vodafone and West Indian Ocean Cable Corporation announced that they will cooperate to lay 2Africa submarine cables to serve the African continent and the Middle East, and connect them to other submarine cables via East Africa to further extend to Asia. The 2Africa submarine cable has a total length of 37,000 kilometers and will be one of the world's largest submarine cable projects when completed. It has 21 landing points in 16 countries in Africa, which will seamlessly connect Africa and Europe (to the east via Egypt) and the Middle East (via Saudi Arabia).
In July 2020, on the issue of building the first submarine optical cable connecting South America and the Asia-Pacific region, the Chilean government finally chose Japan’s plan to set the end point of the Asia-Pacific region in Australia and New Zealand instead of China's proposed setting is in Shanghai.
According to a report released by Technavio, an international market research organization, the global submarine optical cable market is expected to grow by USD 4.34 billion from 2020 to 2024, with a compound annual growth rate of over 15% during the period.
According to reports, Facebook and Google are planning to lay two submarine optical cables to connect the west coast of the United States with Singapore and Indonesia. Facebook said that the two optical cables are "Echo" and "BiFrost", which will increase the data capacity of the above-mentioned areas by 70% and will also improve the reliability of the Internet. Facebook will invest in both cables at the same time, while Google will only invest in Echo. The project is still subject to regulatory approval, so the cost of the project has not yet been disclosed.
Construction method
Design requirements
The submarine optical cable design must ensure that the optical fiber is not affected by external forces and the environment. The basic requirements are: it can adapt to submarine pressure, wear, Corrosion, biological and other environments; there is a suitable armor layer to prevent fishing boat trawling, anchors and sharks; when the optical cable is broken, the length of seawater infiltration into the optical cable is reduced as much as possible; it can prevent the hydrogen from penetrating into the optical cable from the outside and prevent the inside The generated hydrogen; has a low-resistance remote power supply circuit; can withstand the tension during laying and recycling; the service life is generally required to be more than 25 years.
The deep-sea (depth above 1000 meters) submarine optical cable adopts a steel-free armored structure, but the structure of the cable core and the strengthening member (usually the central steel wire) must be able to protect the optical fiber to prevent the high pressure of the seawater With high tension during laying and recycling. In order to prevent sharks from harming, two layers of steel tape should be spirally wrapped on the sheath of the deep-sea optical cable in the sea area where the sharks are infested, and a layer of polyethylene outer sheath should be squeezed.
The core structure of the shallow sea (within 1000 meters of water) submarine optical cable is the same as that of the deep sea optical cable, but the shallow sea optical cable must have a single-layer or double-layer steel wire armor. The number of armor layers and the outer diameter of the steel wire are determined according to the submarine environment, water depth, whether it can be buried, fishing, etc. of the submarine cable route.
Laying process
The submarine cable project is recognized as a complex and difficult large-scale project by countries all over the world. In shallow seas, if the water depth is less than 200 meters, cables are buried, while in deep seas, they are laid. Hydraulic jet burying is the main burying method. There are several rows of water spray holes at the bottom of the buried equipment, which are distributed in parallel on both sides. During operation, each hole sprays high-pressure water jets to the seabed at the same time to wash away the seabed sediment and form a submarine cable trench; there is a fairlead on the upper part of the equipment, It is used to guide the cable (optical cable) to the bottom of the submarine cable trench, and the trench is automatically filled in by the tide. The buried equipment is towed forward by the construction ship, and various instructions are given through the working cable. Cable laying machines generally do not have underwater burying equipment, and are laid on the surface of the seabed by the weight of the submarine cable.
The boat keeps driving forward, then rushes a trench with the underwater robot, puts the optical cable into it, and then flushes the sand back with the underwater robot, covers the optical cable, and then keeps moving forward, when it needs to be connected The connection is completed on the ship, then sealed, and then continue to be laid. The submarine optical cables are all optical fibers, and there are very few cables, and all the cables are buried in the soil. The underwater robot is to flush a trench and put it in and then bury the soil.
The underwater robot actually uses a high-pressure water pump to pressurize the water to a high pressure and spray it out, thereby rushing out of the trench. As for maintenance, there is no maintenance at all. Usually, there is no need for maintenance. You only need to check whether the optical cable is exposed on a regular basis with an underwater robot, and if there is, cover the mud. In addition, if it breaks, use the attenuation detector to measure it to get the specific position, and then go there to fish it, connect it or other methods, usually cut off all the damaged section and replace it with a new one.
Login location
Submarine optical cable is the backbone of the Internet. The number of optical cables represents whether a country is closely connected with the Internet.
Someone used Microsoft's Bing map and wikipedia data to create an interactive map of the world's submarine optical cable distribution.
There are only three submarine optical cable connection points in mainland China.
The first one is Qingdao (2 optical cables).
The second one is Shanghai (6 optical cables).
The third one is Shantou (3 optical cables).
Because of the overlap between optical cables, in fact, all channels between mainland China and the Internet are 3 entrances and 6 optical cables.
1.APCN2 (Asia Pacific No. 2) submarine optical cable
Bandwidth: 2.56Tbps
Length: 19000km
Passing area: Mainland China , Hong Kong, Taiwan, Japan, South Korea, Malaysia, Philippines.
Place of entry: Shantou, Shanghai.
2.CUCN (China-US) submarine optical cable
Bandwidth: 2.2Tbps
Length: 30000km
Passing area: Mainland China, Taiwan, Japan, South Korea, the United States.
Place of entry: Shantou, Shanghai.
3.SEA-ME-WE3 (Asia-Europe) submarine optical cable
Bandwidth: 960Gbps
Length: 39000km
Passing area: East Asia, Southeast Asia, Middle East, Western Europe.
Place of entry: Shantou, Shanghai.
4.EAC-C2C submarine optical cable
Bandwidth: 10.24Tbps
Length: 36800km
Passing area: Asia-Pacific region
Place of entry: Shanghai, Qingdao
5.FLAG submarine optical cable
Bandwidth: 10Gbps
Length: 27000km
Passing Region: Western Europe, Middle East, South Asia, East Asia
Place of entry: Shanghai
6. Trans-Pacific Express (TPE, Pan Pacific) submarine optical cable
Bandwidth: 5.12 Tbps
Length: 17700km
Passing area: Mainland China, Taiwan, South Korea, United States
Place of entry: Shanghai, Qingdao
as By comparison, Taiwan has 9 optical cables, Hong Kong and South Korea each have 11 optical cables, while Japan has at least 11 entrances and 15 optical cables.
Accident handling
Break
There are generally two main reasons for the break of a submarine cable. One is force majeure such as earthquakes and tsunamis, and the other is man-made causes. Once the cable is disconnected, it will not only have a huge impact on international communications, but the loss caused is even more incalculable.
Damage
Cables are often easily damaged by fishing trawlers, anchors, and even sharks. Cables are sometimes destroyed by enemy troops during wartime. The Great Newfoundland earthquake in 1929 caused a large-scale submarine collapse that caused damage to the transatlantic cable.
Once multiple submarine cables are damaged at the same time (such as earthquake damage), it may cause the interruption of regional Internet and long-distance telephone services, resulting in unpredictable losses. For example, the Hengchun earthquake in 2006 is just one example. .
To repair the deep cable, the damaged part is brought to the surface for repair. Cables in deep water belts must be cut off the damaged parts and brought to the surface for repair. The repaired parts will be longer than the original ones.
Some important cable lines near ports have established repair ships that specialize in repairing cables. Several restoration companies such as CSCyrusWestField have been established near Halifax, Nova Scotia. Some large telecom operators such as France Telecom and Japan Telecom have their own submarine cable ships.
Repair
Submarine fiber optic cables are usually buried at a depth of 1-2 meters under the seabed. Because the seabed is not very regular, the fiber optic cables will inevitably be exposed sometimes. Optical cables may be destroyed when fishing boats anchor or use trawl nets to fish. Therefore, the places where there are optical cables passing through the seabed are designated as no anchoring zones and no ships are allowed to dock. This principle is the same as that of optical cables on land. We often see signs like "There are optical cables underground, construction is forbidden" on the road. Submarine optical cables need to be protected, and technology needs to be strengthened to improve the tensile strength of the submarine cable itself.
The first step in the repair work is to find the breakpoint. Submarine cable engineers can find the approximate location of the breakpoint through telephone and Internet outages. The shore terminal can emit light pulses, and normal optical fibers can always transmit these pulses in the sea, but if the fiber is broken somewhere, the pulses will bounce back from that point, and the shore terminal can find the break point in this way. After that, new fiber optic cables need to be brought in by ships for repair, but the first step is to retrieve the broken fiber.
If the fiber optic cable is less than 2000 meters deep underwater, you can use a robot to salvage the fiber optic cable. Generally, it is located in the sea with a water depth of about 3000 meters to 4000 meters. Only one kind of grappling hook can be used. It takes more than 12 hours. After the broken fiber optic cable is caught on the ship, the cable needs to be added in the middle. This work is done by a highly professional technician.
1. After the robot dives into the water, it scans and detects the precise location of the damaged submarine optical cable.
2. The robot digs out the submarine optical cable buried in mud and cuts it with cable scissors. The rope was put down on the boat, and the robot was tied to one end of the optical cable, and then it was pulled out of the sea. At the same time, the robot installs a wireless transponder at the cut.
3. Use the same method to pull another piece of optical cable out of the sea. As with the maintenance of telephone lines, the instruments on the ship are connected to both ends of the optical cable, and the submarine optical cable landing station in two directions is used to detect which end of the optical cable is blocked. Afterwards, take back the longer part of the submarine cable with the blocked part and cut it off. The other section was fitted with a buoy and left to float on the sea temporarily.
4. Next, manually connect the spare submarine optical cable to the two breakpoints of the submarine optical cable. Connecting fiber optic cable connectors is a highly "technical content" job that is not competent for ordinary people. It must be a person who has undergone special and strict training and obtained a license from an international organization before it can be operated.
5. After the spare submarine optical cable is connected, after repeated tests, after the communication is normal, it will be thrown into the sea. At this time, the underwater robot is about to "fight" again: "flush" the repaired submarine optical cable, that is, use a high-pressure water gun to flush the silt on the seabed out of a trench, and "lay" the repaired submarine optical cable into it.
At the same time, severe weather such as strong winds and waves on the sea may slow down the restoration work.