The first submarine cable was laid between Britain and France in 1850, crossing the English Channel. The first transatlantic submarine cable successfully connected the United Kingdom and the United States on August 16, 1858. It was the first time that Queen Victoria sent a congratulatory message to US President Buchanan via a submarine cable. It was finally built after several years of investment by American industrialist Cyrus Field with millions of dollars!
The first submarine optical cable was laid in 1988, connecting Europe and America across the Atlantic Ocean. Up to now, the total length of submarine optical cables has exceeded 900,000 kilometers, which is equivalent to 22.5 circles around the equator. These submarine optical cables have undertaken 90% of the world's transnational data transmission tasks.
Question 1: There is already satellite communication, why do we still use submarine optical cables?
I believe that many friends have this problem. Since the first satellite was launched in 1957, humans have launched tens of thousands of man-made objects into low-Earth orbit, and there are still thousands of satellites in normal operation. Can three satellites above the equator connect the whole world, and why do we need submarine optical cables? The answer to
is also very simple. The capacity is not enough. For example, the communication capacity of the Shishi No.12 communication satellite launched on the night of December 27, 2019 can reach about 10G in both directions, and it is also China's most advanced communication satellite! In fact, the link of 10G or so, just find an ordinary computer room is a lot of 10G SFP modules!
Therefore, from the point of view of the 10G fiber optic cable, this satellite is simply weak. It is only suitable for high-value, high real-time and difficult to cover areas with fiber optic cables and ground base stations. Therefore, at this stage, submarine fiber optic cables still occupy 90% of countries. % Of transnational communications business!
Question 2: How is the submarine optical cable laid?
’s early method of laying submarine cables was to dig in shallow waters. In deep seas, they were basically dropped directly. The natural weight of the cables would be located on the seabed along the seabed terrain. Of course, this method is not very safe because of whales or other large ones passing by. Animals will encounter or even bite, but after the growth of various attachments, there will be no problems, but many shellfish will secrete corrosive substances to erode the cable.
Later cables and optical cables have special submarine laying robots, which will dig a trench on the seabed. According to our country’s requirements, it is at least 3 meters for offshore operations, but the requirements around the world are somewhat different. For example, Hong Kong, China requires 5 meters. , Special areas even require 10 meters, and repeaters are needed every certain distance!
However, in deep seas or deep seas, which cannot be reached by underwater robots, it is laid directly. Simply put, survey the seabed terrain, try to avoid areas with unstable terrain, avoid trenches, etc., and directly discard the cable. Under the sea!
Question 3: How does the submarine optical cable cross the trench?
There are also high mountains and ditches on the sea floor. For example, the Mariana Trench is even more than 11 kilometers deep, which is even more exaggerated than the 8848 of Mount Everest. Therefore, some friends think that when the submarine optical cable encounters such a deep trench, it is directly "overhead" the cable. Yes, this is actually a misunderstanding, because the "overhead" method will cause marine plankton to grow on the cable, heavier and heavier, and may eventually break!
and the "overhead" method is also easy to be caught by an intruded submarine. Of course, it is also easy for large marine creatures such as whales or king squid to hit, even if it does not break, it will cause serious impact! Therefore, no matter how deep the trench is, the submarine cable must be placed next to the seabed. Of course, it will try to avoid the type of trench that crosses the abyss. Of course, it must also avoid fish reefs and coral reefs, but if it can’t be avoided, try to avoid submarine cliffs. Find a flat place to cross the trench!
Question 4: Are the thickness of submarine optical cables the same? How thick are they? The protection of
submarine optical cable is a bit exaggerated, with multiple layers of high-strength steel wire braided mesh wrapping the metal casing in the middle, The inside of the cable is protected by a detailed thin fiber optic cable, the diameter of the general submarine fiber optic cable is usually about 69 mm, the weight per meter is as high as 10 kg, and the design life is 25 years!
is different from what you think is that the fiber optic cables in the deep sea area are different in thickness from those in the shallow sea area. Because there is no interference in the fiber optic cables in the deep sea area, ordinary ships cannot reach the anchor, and large fish can hardly reach the deep seabed. It is an undisturbed world, so the fiber optic cable in the deep sea area can be thinner, but the fiber optic cable in the shallow sea area is not. It must be stupid and thick!
Question 4: What should I do if the optical cable is disconnected by the earthquake and the ship? One problem that
submarine cables and optical cables must face is that the cables or optical cables may be interrupted due to earthquakes or submarine cliff collapses, or the ship may hang up and hang up, and the submarine may hang up, and even deliberately damage and cause breakage! Of course, the legendary submarine optical cable eavesdropping is based on the principle of light leakage of bent optical cables. Now some anti-eavesdropping optical cables have broken before bending and light leakage. This is a digression.
In addition, since both cables and optical cables need repeaters to maintain long distances to ensure signal strength, generally optical cables need to be relayed for tens of kilometers, but now they can generally achieve 100 kilometers without relay, or low-loss large effective area optical fiber can Up to 400 kilometers without relay, but the Pacific Ocean is tens of thousands of kilometers, it must be relayed, so a power supply conductor layer is set in the optical cable, usually a copper tube in the middle! The power supply voltage of
is between thousands of volts and tens of thousands of volts. The repeater obtains power from these power sources, and then relays the signal in the optical cable to make the transmission distance farther, so more interesting things happen! For example, in the late 1980s, there was a case where the polyethylene insulator of a deep-sea optical cable was bitten by a shark and caused a power supply failure!
On March 26, 2001, the international communication cable located on the seabed off the Yangtze River estuary was pulled twice by the anchor of a sail fishing boat, causing network interruptions in China, the United States, Europe, Asia, China and Japan, and the total loss of the two accidents Over 100 million U.S. dollars
In October 2003, a fishing boat was pulled when anchored, causing the submarine optical cable to Chongming Island to be accidentally broken. This accident caused at least 30,000 cable TV subscribers on Chongming Island to block the signal reception, which lasted for nearly 4 days!
The Bashi Strait earthquake in southern Hengchun, Taiwan on December 26, 2006 caused minor losses on land, but caused many optical cables under the sea to be interrupted, resulting in the disruption of Internet and international telephone services in East Asia, and the impact on the economy and society was extremely serious. The Telecommunications Union (ITU) has identified it as a modern new type of disaster, which will comprehensively improve the seismic standards of submarine cables!
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In January 2020, the Falcon fiber optic cable connecting Muscat and the port of Suez was broken by the anchor of a large ship, causing at least 6 days of Internet interruption in Yemen, which also affected Saudi Arabia and Kuwait , Qatar, Sudan and Ethiopia’s Internet, these regional diversions are affected!
There are 3 landing points for submarine optical cables in mainland my country, namely Qingdao (2 optical cables), Shanghai (6 optical cables), and Shantou (3 optical cables). The shallow sea area of the optical cable is the hardest hit area, while the deeper sea area is mostly caused by power failure caused by shark bites, or because of geological changes, communication on the earth is actually very fragile, but fortunately, submarine cables have been formed. In a large and complex network, most of the broken areas can be bypassed by routing without losing contact completely.
