Transoceanic Submarine Communication Cables
Hello again, Habr.
Yesterday, I published a material on Google’s own fiber optic communication cable laying on the bottom of the Pacific Ocean, which will connect the company's data centers in Oregon, USA, with Japan. It would seem that this is a huge project worth $ 300 million and a length of 10,000 km. However, if you dig a little deeper it becomes clear that this project is outstanding only because it will be done by one media giant for personal use. The entire planet is already tightly entangled with communication cables and there are much more of them under water than it seems at first glance. Interested in this topic, I prepared a general education material for curious.
The practice of laying a cable across the ocean dates back to the XIX century. According to Wikipedia , the first attempts to connect the two continents by wire connection were made in 1847. It was not until August 5, 1858, that the United Kingdom and the United States were successfully connected with the transatlantic telegraph cable, but the connection was lost in September. It is assumed that the cause of the steel cable waterproofing violation and its subsequent corrosion and breakage. The stable connection between the Old and the New Worlds was established only in 1866. In 1870 a cable was laid to India, which made it possible to link directly London and Bombay. Some of the best minds and industrialists of the time were involved in these projects: William Thomson (future great Lord Kelvin), Charles Wheatstone, the Siemens brothers. As you can see, almost 150 years ago, people were actively engaged in the creation of thousands of kilometers of communication lines. And this progress, of course, did not stop. However, telephone communication with America was established only in 1956, and the work lasted for almost 10 years. Details about the laying of the first transatlantic telegraph and telephone cable can be found in Arthur Clarke’s book Voice Across the Ocean .
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Of undoubted interest is the direct device of the cable, which will work at a depth of 5-8 kilometers inclusive.
It should be understood that the deep-sea cable should have the following basic characteristics:
The working part of the cable we are considering, in the big case, is no different from ordinary optics. The whole essence of deep-sea cables lies in protecting this very working part and maximizing its service life, as can be seen from the schematic figure on the right. Let's sort out the order of all the structural elements.
Polyethylene is the outer traditional insulation layer of the cable. This material is an excellent choice for direct contact with water, as it has the following properties:
Resistant to water, does not react with alkalis of any concentration, with solutions of neutral, acidic and basic salts, organic and inorganic acids, even with concentrated sulfuric acid.
Oceans contain, in fact, all the elements of the periodic table, and water is a universal solvent. The use of such a common chemical. the industry of the material as polyethylene is logical and justified, since, first of all, engineers had to eliminate the reaction of cable and water, thus avoiding its destruction under the influence of the environment. Polyethylene was used as an insulating material during the laying of the first intercontinental telephone lines in the middle of the 20th century.
However, due to its porous structure, polyethylene cannot provide complete waterproofing of the cable, so we move on to the next layer.
Mylar film is a synthetic material based on polyethylene terephthalate . It has the following properties:
It has no smell, taste. Transparent, chemically inactive, with high barrier properties (including many aggressive media), resistant to rupture (10 times stronger than polyethylene), wear and impact. Mylar (or in the USSR Lavsan) is widely used in industry, packaging, textiles, and the space industry. They even make tents from it. However, the use of this material is limited to multilayer films due to shrinkage during heat sealing.
After a layer of Mylar film, you can meet the reinforcement of a cable of various capacities, depending on the declared characteristics of the product and its intended purpose. Mainly used is a powerful steel sheath to give the cable sufficient rigidity and strength, as well as to counter the aggressive mechanical effects from outside. According to some data, wandering in the network, EMR outgoing from the cables can lure sharks, which gnaw through the cables. Also at great depths, the cable just keeps on the bottom, without digging a trench and fishing vessels can hook it with their gear. To protect against such effects, the cable is reinforced with steel braid. The steel wire used in reinforcement is pre-galvanized. Cable reinforcement can occur in several layers. The main task of the manufacturer during this operation is the uniformity of effort during the winding of steel wire. When double reinforcement winding occurs in different directions. If the balance is not observed during this operation, the cable may spontaneously twist into a spiral, forming loops.
As a result of these activities, the mass per kilometer can reach several tons. “Why not light and durable aluminum?” - many will ask. The problem is that in air, aluminum has a resistant oxide film, but when in contact with seawater, this metal can enter into an intense chemical reaction with the displacement of hydrogen ions, which have a detrimental effect on the part of the cable for which everything was started - the optical fiber. Therefore use steel.
Aluminum water barrier , or a layer of aluminum polyethylene is used as another layer of waterproofing and cable shielding. Alumopolyethylene is a combination of aluminum foil and plastic film, interconnected by an adhesive layer. Sizing can be both one-sided and two-sided. On the scale of the whole structure, alumopolyethylene looks almost imperceptible. The thickness of the film may vary from manufacturer to manufacturer, but, for example, one of the manufacturers in the Russian Federation has a thickness of the final product of 0.15-0.2 mm with one-sided sizing.
The polycarbonate layer is again used to reinforce the structure. Lightweight, durable and resistant to pressure and shock, the material is widely used in everyday products, for example, in bicycle and motorcycle helmets, also used as a material in the manufacture of lenses, CDs and lighting products, sheet version is used in construction as a light transmitting material. It has a high coefficient of thermal expansion . Application it was found in the manufacture of cables.
Copper or aluminum tube is part of the cable core and serves to shield it. Directly in this design are placed other copper tubes with fiber inside. Depending on the design of the cable, the tubes may be several and they can be intertwined with each other in various ways. Below are four examples of cable core organization:
Laying the fiber in copper tubes that are filled with a hydrophobic thixotropic gel, and metal structural elements are used to organize remote power supply of intermediate regenerators - devices that restore the shape of an optical pulse, which, undergoing propagation through the fiber, undergoes distortion.
In a cut, something like this is obtained:
A feature of the production of optical deep-sea cables is that it is most often located near the ports, as close as possible to the seashore. One of the main reasons for this placement is that the linear kilometer of the cable can reach a mass of several tons, and to reduce the required number of splices during the installation process, the manufacturer strives to make the cable as long as possible. The usual length for such a cable is 4 km, which can result in approximately 15 tons of mass. As can be understood from the above, the transportation of such a deep-water OK bay is not the simplest logistical task for land transport. Wooden drums that are usual for winding cables do not withstand the masses described earlier and for transporting OK on land, for example, you have to lay out the entire construction length “figure eight” on paired railway platforms in order not to damage the optical fiber inside the structure.
It would seem that having such a powerful-looking product you can load it onto ships and dump it into the sea abyss. The reality is a bit different. Cable routing is a long and laborious process. The route should be, of course, cost-effective and safe, since the use of various cable protection methods leads to an increase in the cost of the project and increases its payback period. In the case of cable laying between different countries, it is necessary to obtain a permit to use the coastal waters of a particular country, it is necessary to obtain all the necessary permits and licenses to conduct cable laying operations. After geological exploration, assessment of seismic activity in the region, volcanism, the likelihood of underwater landslides and other natural disasters in the region where the work will be carried out and, subsequently, lay the cable. The forecasts of meteorologists also play an important role so that the deadlines for work are not disrupted. During the geological survey route takes into account a wide range of parameters: depth, bottom topology, soil density, the presence of foreign objects such as boulders, or sunken ships. A possible deviation from the original route is also estimated, i.e. possible extension of the cable and increase the cost and duration of work. Only after all the necessary preparatory work has been completed can the cable be loaded onto the ships and the installation begins.
Actually, the process of laying out the gif becomes very clear.
Laying of fiber optic cable on the sea / ocean floor runs continuously from point A to point B. The cable is placed in the bay on the ships and transported to the place of descent to the bottom. These bays look like this:
If you think that it is too small, then pay attention to this photo:
After the ship leaves the sea, only the technical side of the process remains. The team of pavers with the help of special machines unwinds the cable with a certain speed and, maintaining the necessary cable tension due to the ship’s movement, moves along a previously laid route.
It looks like this:
In case of any problems, breaks, or damage to the cable, special anchors are provided that allow you to lift it to the surface and repair the problematic section of the line.
And, as a result, thanks to all this, we can look at photos and videos of cats from around the world on the Internet with comfort and at high speed.
In the comments to the article on the Google project, the user Lux_In_Tenebris provided a list of interesting literature on this topic , maybe someone will come in handy.
Also, the user YoMan provided a link to the video about the cable ship “Tyco Resolute”, thank you.
http://youtu.be/GAmSfd01_6I
Yesterday, I published a material on Google’s own fiber optic communication cable laying on the bottom of the Pacific Ocean, which will connect the company's data centers in Oregon, USA, with Japan. It would seem that this is a huge project worth $ 300 million and a length of 10,000 km. However, if you dig a little deeper it becomes clear that this project is outstanding only because it will be done by one media giant for personal use. The entire planet is already tightly entangled with communication cables and there are much more of them under water than it seems at first glance. Interested in this topic, I prepared a general education material for curious.
The origins of intercontinental communication
The practice of laying a cable across the ocean dates back to the XIX century. According to Wikipedia , the first attempts to connect the two continents by wire connection were made in 1847. It was not until August 5, 1858, that the United Kingdom and the United States were successfully connected with the transatlantic telegraph cable, but the connection was lost in September. It is assumed that the cause of the steel cable waterproofing violation and its subsequent corrosion and breakage. The stable connection between the Old and the New Worlds was established only in 1866. In 1870 a cable was laid to India, which made it possible to link directly London and Bombay. Some of the best minds and industrialists of the time were involved in these projects: William Thomson (future great Lord Kelvin), Charles Wheatstone, the Siemens brothers. As you can see, almost 150 years ago, people were actively engaged in the creation of thousands of kilometers of communication lines. And this progress, of course, did not stop. However, telephone communication with America was established only in 1956, and the work lasted for almost 10 years. Details about the laying of the first transatlantic telegraph and telephone cable can be found in Arthur Clarke’s book Voice Across the Ocean .
')
Cable device
Of undoubted interest is the direct device of the cable, which will work at a depth of 5-8 kilometers inclusive.
It should be understood that the deep-sea cable should have the following basic characteristics:
- Durability
- Be waterproof (suddenly!)
- To withstand the enormous pressure of water masses on themselves
- Have sufficient strength for installation and operation.
- Cable materials should be selected so that during mechanical changes (cable stretching during operation / laying, for example), its performance does not change
The working part of the cable we are considering, in the big case, is no different from ordinary optics. The whole essence of deep-sea cables lies in protecting this very working part and maximizing its service life, as can be seen from the schematic figure on the right. Let's sort out the order of all the structural elements.Polyethylene is the outer traditional insulation layer of the cable. This material is an excellent choice for direct contact with water, as it has the following properties:
Resistant to water, does not react with alkalis of any concentration, with solutions of neutral, acidic and basic salts, organic and inorganic acids, even with concentrated sulfuric acid.
Oceans contain, in fact, all the elements of the periodic table, and water is a universal solvent. The use of such a common chemical. the industry of the material as polyethylene is logical and justified, since, first of all, engineers had to eliminate the reaction of cable and water, thus avoiding its destruction under the influence of the environment. Polyethylene was used as an insulating material during the laying of the first intercontinental telephone lines in the middle of the 20th century.
However, due to its porous structure, polyethylene cannot provide complete waterproofing of the cable, so we move on to the next layer.
Mylar film is a synthetic material based on polyethylene terephthalate . It has the following properties:
It has no smell, taste. Transparent, chemically inactive, with high barrier properties (including many aggressive media), resistant to rupture (10 times stronger than polyethylene), wear and impact. Mylar (or in the USSR Lavsan) is widely used in industry, packaging, textiles, and the space industry. They even make tents from it. However, the use of this material is limited to multilayer films due to shrinkage during heat sealing.
After a layer of Mylar film, you can meet the reinforcement of a cable of various capacities, depending on the declared characteristics of the product and its intended purpose. Mainly used is a powerful steel sheath to give the cable sufficient rigidity and strength, as well as to counter the aggressive mechanical effects from outside. According to some data, wandering in the network, EMR outgoing from the cables can lure sharks, which gnaw through the cables. Also at great depths, the cable just keeps on the bottom, without digging a trench and fishing vessels can hook it with their gear. To protect against such effects, the cable is reinforced with steel braid. The steel wire used in reinforcement is pre-galvanized. Cable reinforcement can occur in several layers. The main task of the manufacturer during this operation is the uniformity of effort during the winding of steel wire. When double reinforcement winding occurs in different directions. If the balance is not observed during this operation, the cable may spontaneously twist into a spiral, forming loops.
As a result of these activities, the mass per kilometer can reach several tons. “Why not light and durable aluminum?” - many will ask. The problem is that in air, aluminum has a resistant oxide film, but when in contact with seawater, this metal can enter into an intense chemical reaction with the displacement of hydrogen ions, which have a detrimental effect on the part of the cable for which everything was started - the optical fiber. Therefore use steel.
Aluminum water barrier , or a layer of aluminum polyethylene is used as another layer of waterproofing and cable shielding. Alumopolyethylene is a combination of aluminum foil and plastic film, interconnected by an adhesive layer. Sizing can be both one-sided and two-sided. On the scale of the whole structure, alumopolyethylene looks almost imperceptible. The thickness of the film may vary from manufacturer to manufacturer, but, for example, one of the manufacturers in the Russian Federation has a thickness of the final product of 0.15-0.2 mm with one-sided sizing.
The polycarbonate layer is again used to reinforce the structure. Lightweight, durable and resistant to pressure and shock, the material is widely used in everyday products, for example, in bicycle and motorcycle helmets, also used as a material in the manufacture of lenses, CDs and lighting products, sheet version is used in construction as a light transmitting material. It has a high coefficient of thermal expansion . Application it was found in the manufacture of cables.
Copper or aluminum tube is part of the cable core and serves to shield it. Directly in this design are placed other copper tubes with fiber inside. Depending on the design of the cable, the tubes may be several and they can be intertwined with each other in various ways. Below are four examples of cable core organization:
Laying the fiber in copper tubes that are filled with a hydrophobic thixotropic gel, and metal structural elements are used to organize remote power supply of intermediate regenerators - devices that restore the shape of an optical pulse, which, undergoing propagation through the fiber, undergoes distortion.
In a cut, something like this is obtained:
Cable production
A feature of the production of optical deep-sea cables is that it is most often located near the ports, as close as possible to the seashore. One of the main reasons for this placement is that the linear kilometer of the cable can reach a mass of several tons, and to reduce the required number of splices during the installation process, the manufacturer strives to make the cable as long as possible. The usual length for such a cable is 4 km, which can result in approximately 15 tons of mass. As can be understood from the above, the transportation of such a deep-water OK bay is not the simplest logistical task for land transport. Wooden drums that are usual for winding cables do not withstand the masses described earlier and for transporting OK on land, for example, you have to lay out the entire construction length “figure eight” on paired railway platforms in order not to damage the optical fiber inside the structure.
Cable laying
It would seem that having such a powerful-looking product you can load it onto ships and dump it into the sea abyss. The reality is a bit different. Cable routing is a long and laborious process. The route should be, of course, cost-effective and safe, since the use of various cable protection methods leads to an increase in the cost of the project and increases its payback period. In the case of cable laying between different countries, it is necessary to obtain a permit to use the coastal waters of a particular country, it is necessary to obtain all the necessary permits and licenses to conduct cable laying operations. After geological exploration, assessment of seismic activity in the region, volcanism, the likelihood of underwater landslides and other natural disasters in the region where the work will be carried out and, subsequently, lay the cable. The forecasts of meteorologists also play an important role so that the deadlines for work are not disrupted. During the geological survey route takes into account a wide range of parameters: depth, bottom topology, soil density, the presence of foreign objects such as boulders, or sunken ships. A possible deviation from the original route is also estimated, i.e. possible extension of the cable and increase the cost and duration of work. Only after all the necessary preparatory work has been completed can the cable be loaded onto the ships and the installation begins.
Actually, the process of laying out the gif becomes very clear.
Laying of fiber optic cable on the sea / ocean floor runs continuously from point A to point B. The cable is placed in the bay on the ships and transported to the place of descent to the bottom. These bays look like this:
If you think that it is too small, then pay attention to this photo:
After the ship leaves the sea, only the technical side of the process remains. The team of pavers with the help of special machines unwinds the cable with a certain speed and, maintaining the necessary cable tension due to the ship’s movement, moves along a previously laid route.
It looks like this:
In case of any problems, breaks, or damage to the cable, special anchors are provided that allow you to lift it to the surface and repair the problematic section of the line.
And, as a result, thanks to all this, we can look at photos and videos of cats from around the world on the Internet with comfort and at high speed.
In the comments to the article on the Google project, the user Lux_In_Tenebris provided a list of interesting literature on this topic , maybe someone will come in handy.
Also, the user YoMan provided a link to the video about the cable ship “Tyco Resolute”, thank you.
http://youtu.be/GAmSfd01_6I
Dear readers. The article is exclusively educational. If you have something to say on this topic, add or correct - I will be only too happy. Report in the LAN, or comments.
Source: https://habr.com/ru/post/228415/
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