Rostelecom Gpon technology - what you need to know. How a fiber optic cable works How to build a fiber optic Internet

As you read this, terabytes of data are floating around the world, locked in glass threads stretched along the ocean floor. Reminds me of magic, but it's just advanced technology. Optical fiber is a technology that humanity owes to the naturalists of the 19th century. Observing rays of light on the surface of a pond, they suggested that light could be controlled, but that brilliant idea was only realized recently with the advent of sophisticated factories and a thorough study of the optical properties of materials.

Locked light

A copper twisted pair (like your internet cable) carries electrons in abundance. The current is transmitted through the conductor and carries with it information encoded in a sequence of pulses. Zeros and ones are a binary code that probably everyone has heard of. The optical signal conductor works on the same principle, but from a physics point of view, everything is much more complicated with it. There could be a half-hour lecture on quantum mechanics, and how many eminent physicists came to a dead end trying to understand the nature of light, but we will try to do without lengthy arguments.

It is enough to keep in mind that, like electrons, photons or light waves (in fact, in our context they are the same thing), can carry encoded information. For example, at airfields, in cases of radio communication failure, signals are transmitted to aircraft using directional searchlights. But this is a primitive method, and it only works at a line of sight distance. At the same time, optical fiber transmits light over kilometers and far from a straight path.

To achieve this effect, you could use mirrors. Actually, this is where the test engineers began their experiments. They covered metal pipes from the inside with a mirror layer and directed a beam of light inside. But not only that, such light guides were prohibitively expensive. The light was reflected repeatedly from their walls and gradually faded, lost strength and completely disappeared.

Mirrors were no good. It couldn't be any other way. Even the most expensive mirror is not perfect. Its reflection coefficient is less than 100% and after each fall on the mirror surface the light beam loses part of its energy, and in the closed volume of the light guide an innumerable number of such refractions occur.

This is where it’s time to remember the pond and those ancient studies that were based on observing the behavior of light in water. Imagine how a ray of the setting sun falls on the surface of the water, overcomes the boundary and heads down to the bottom of the pond.

Those readers who remember the school physics course probably already guess that light will change the direction of its movement. Part of the light will pass under the water, slightly changing the angle of its movement, and another insignificant part of the light will be reflected back into the sky, because “the angle of incidence is equal to the angle of reflection.” If you observe this phenomenon for a long time, one day you will notice that the light reflected from a mirror under water, at a certain angle, will not be able to escape outside - it will be reflected completely from the boundary of water and air, better than from any mirror. The point is not in water as such, but in the combination of two media with different optical properties - unequal refractive indices. To create a light trap, a minimal difference between them is sufficient.

Flexible light guides

The materials aren't that important. Physics experiments for children that demonstrate this effect often use water and a clear plastic tube. Such a light guide cannot transmit a light beam more than a couple of meters, but it looks beautiful. For the same reason, lamps and other decorative products often have plastic light guides in their design. But when it comes to transmitting information over many kilometers, special, ultra-pure materials are required, with a minimum of impurities and optical properties close to ideal.

In 1934, American Norman R. French patented a glass light guide that was supposed to provide telephone communications, but it didn’t really work. It took a lot of time to find a material that would meet the highest requirements for purity and transparency, to invent an optical fiber made of silicon dioxide - the purest quartz glass. To create a difference in refractive index in transparent silicon, they resort to tricks. The center of the transparent blank, which will turn into a wire, is left clean, while the outer layers are saturated with germanium - it changes the optical characteristics of the glass.

In this case, the blank is usually sintered from two pre-prepared glass tubes inserted into one another. But you can do the opposite by saturating the fiberglass core with germanium. More technologically advanced and high-quality glass fiber is obtained when glass tubes are filled from the inside with gas and wait until the germanium itself settles on the glass in a thin layer. The tube is then heated and stretched to a meter length. In this case, the cavity inside closes itself.

The resulting rod has a core with one refractive index and a cladding with other optical parameters. It will then be used for the manufacture of optical fiber. While the heavy workpiece, as thick as a hand, does not resemble a wire in any way, but quartz glass stretches well.

The prepared blank is raised to the height of a ten-meter tower, fixed on the top and heated evenly until its consistency resembles nougat. Then the thinnest thread begins to stretch from the glass blank under its own weight. On the way down, it cools and becomes flexible. It may seem strange, but ultra-thin glass bends very well.

The finished optical fiber, continuously flowing down, is dipped into a bath of liquid plastic, which forms a protective layer on the surface of the quartz, and then wound. This continues until the blank at the top of the tower is completely processed into a single thread of hundreds of kilometers of optical fiber.

From it, in turn, cables will be woven, containing from a couple to a couple of hundred individual glass fibers, reinforcing inserts, shielding layers and protective shells.

1. Axial rod.
2. Optical fiber.
3. Plastic protection for optical fibers.
4. Film with hydrophobic gel.
5. Polyethylene shell.
6. Reinforcement.
7. Outer polyethylene shell.

Connection with the speed of light

Home Internet in the post-Soviet space is often carried out over a two-core twisted pair cable with conductors one to two millimeters thick. The maximum for it is 100 megabits per second. This is enough for a couple of computers, but when the apartment contains a smart TV, a NAS that distributes torrents, a home server, several smartphones and smart devices from the world of the Internet of Things, even an eight-core wire is not enough. The limitations of the communication channel become apparent. As a rule, in the form of artifacts and stuttering movie characters on the TV screen, or lags in online games. Optical fiber with a thickness of 9 microns has 30 times greater bandwidth, not to mention the fact that there can be several such cores in the wire.

At the same time, it is more compact and weighs significantly less than conventional wires, which turns out to be a decisive advantage when laying trunk communication lines and planning urban communications.

Optical cables connect continents, cities and data centers. In Russia, the first such line appeared in Moscow. The first underwater optical cable ran between St. Petersburg and the Danish Aberslund. The fiber was then extended between businesses, government agencies and banks. In large cities, a scheme has become widespread in which optical communication lines are extended to individual apartment buildings, and, nevertheless, for the average consumer, optical fiber still remains exotic. We would be interested to know how many of our readers use it at home, because most apartments still have the good old twisted pair cable.

Optical fiber is not only expensive and difficult to produce. Its qualified service is even more expensive. You can't do without blue electrical tape here. When installing, quartz fibers must be spliced ​​in a special way, and fiber optic communication lines must be equipped with additional equipment.

Despite the fact that the difference in refractive indices in the core and cladding of the fiber in theory creates an ideal light guide, light launched through a quartz wire is still attenuated due to impurities contained in the glass. Alas, it is almost impossible to get rid of them completely. A dozen water molecules per kilometer of optical fiber is already enough to introduce errors into the signal and reduce the distance over which it can be transmitted.

Electrical engineers face a similar problem with conventional wires. The distance to which a signal can be sent via wire without problems is called the regeneration distance.

For a standard telephone cable it is equal to a kilometer, for a shielded cable - five. The fiber optic core holds light at a distance of up to several hundred kilometers, but in the end, the signal still has to be amplified and regenerated. Relatively cheap and simple amplifiers are installed on classical communication lines. For fiber optics, complex and highly technical units are required that use rare earth metals and infrared lasers.

A small section of specially prepared fiberglass is cut into the communication line. It is additionally saturated with atoms of erbium, a rare earth element used, among other things, in the nuclear industry. The erbium atoms in this section of the fiber are in an excited state due to additional pumping by light. Simply put, they are illuminated with a specially tuned laser. The signal passing through such an area of ​​​​the cable is amplified approximately twofold, since the erbium atoms, in response to the impact, emit light of the same wavelength as the incoming signal, and therefore retain the information encoded in it. After the amplifier, the optical signal can travel another hundred kilometers before the procedure needs to be repeated.

Such systems require trained specialists for maintenance and constant supervision, so the economic benefit of laying individual optical lines for specific subscribers remains questionable in most countries of the world. And yet, we all use fiberglass to convey messages. The entire modern Internet is based on this technology, and it is thanks to it that Internet broadcasts in ultra-high definition, video streaming, online games with minimal latency, instant communication with almost anywhere on the planet, and even mobile Internet have become possible. Yes, cell phone base stations are also connected by fiberglass.

Even though scientists are looking for new ways to build communication networks, we won't get anything more practical for a very long time. Experimental technologies make it possible to increase the information capacity of fiberglass by two to three times, ever thicker multi-core glass cables lie on the seabed between continents, but the fundamental limitations imposed by the speed of light locked in a quartz vein are unlikely to be overcome. The solution seems to be the abandonment of quartz and the limitations associated with it, the transmission of information using lasers, but this is only possible in a straight line. Consequently, transmitters will have to be placed in space or at least in the upper layers of the atmosphere. Similar experiments have attracted the attention of major corporations in recent years, but that's another story.

The most common types of fiber optic cable used in Ukraine were described. And today - a cross-section of the cable, and as the story progresses - some practical aspects of its installation.

We will not dwell on the detailed structure of all types of cable. Let's take some averaged standard OK:

1. Central (axial) element.
2. Optical fiber.
3. Plastic modules for optical fibers.
4. Film with hydrophobic gel.
5. Polyethylene shell.
6. Armor.
7. Outer polyethylene shell.

What does each layer represent when examined in detail?

Central (axial) element

Fiberglass rod with or without a polymer sheath. Main purpose - gives rigidity to the cable. Fiberglass rods without a sheath are bad because they easily break when bent and damage the optical fiber located around them.

Optical fiber

Optical fiber strands are most often 125 microns thick (about the size of a hair). They consist of a core (through which, in fact, the signal is transmitted) and a glass shell of a slightly different composition, which ensures complete refraction in the core.

In cable markings, the diameter of the core and sheath is indicated by numbers separated by a slash. For example: 9/125 - core 9 microns, shell - 125 microns.

The number of fibers in the cable varies from 2 to 144, this is also recorded by a number in the marking.

Depending on the thickness of the core, optical fiber is divided into single-mode(thin core) and multimode(larger diameter). Recently, multimode has been used less and less, so we will not dwell on it. We only note that it is intended for use over short distances. The sheathing of multimode cables and patch cords is usually done orange color(single mode - yellow).

In turn, single-mode optical fiber can be:

• Standard (marking SF, SM or SMF);
• With dispersion shifted ( DS, DSF);
• With non-zero biased variance ( NZ, NZDSF or NZDS).

In general terms, a fiber optic cable with shifted dispersion (including non-zero) is used over much longer distances than a regular one.

On top of the shell, the glass threads are varnished, and this microscopic layer also plays an important role. Optical fiber without a varnish coating is damaged, crumbles and breaks at the slightest impact. While in varnish insulation it can be twisted and subjected to some stress. In practice, fiber optic threads can withstand the weight of the cable on supports for weeks if all other power rods break during operation.

However, you should not place too much hope on the strength of the fibers - even varnished fibers break easily. Therefore, when installing optical networks, especially when repairing existing highways, extreme care is required.

Plastic modules for optical fibers

These are plastic shells, inside of which there is a bundle of fiber optic threads and a hydrophobic lubricant. A cable can contain either one such tube with optical fiber, or several (the latter is more common, especially if there are a lot of fibers). Modules perform function of protecting fibers from mechanical damage and along the way - their combination and marking (if there are several modules in the cable). However, you need to remember that the plastic module, when bent, breaks quite easily and breaks the fibers in it.

There is no single standard for color marking of modules and fibers, but each manufacturer attaches a passport to the cable drum in which this is indicated.

Film and polyethylene sheath

These are additional elements protecting fibers and modules from friction and moisture- some types of optical cable contain a hydrophobe under the film. The film on top can be additionally reinforced with interlacing threads and impregnated with a hydrophobic gel.

The plastic shell performs the same functions as the film, plus it serves as a layer between the armor and the modules. There are cable modifications where it is not present at all.

Armor

This can be either Kevlar armor (woven threads), or a ring of steel wires, or a sheet of corrugated steel:

• Kevlar used in those types of fiber optic cable where the metal content is unacceptable or where its weight needs to be reduced.
• Cable with steel wire armor designed for underground installation directly into the ground - durable armor protects against many damages, incl. from a shovel.
• Cable with corrugated armor laid in pipes or cable ducts, such armor can only protect against rodents.

Outer polyethylene shell

The first and practically the most important level of protection. Dense polyethylene is designed to withstand all the loads that fall on the cable, so if it is damaged, the risk of cable damage increases significantly. You need to make sure that the shell:

a) It was not damaged during installation - otherwise moisture that got inside will increase losses on the line;

b) During operation, it did not touch a tree, wall, corner or edge of a structure, etc., if there is a risk of friction in this place under wind and other loads.

In the modern world, it is necessary to transmit information efficiently and quickly. Today there is no more advanced and efficient method of data transmission than fiber optic cable. If anyone thinks that this is a unique development, then they are deeply mistaken. The first optical fibers appeared at the end of the last century, and work is still underway to develop this technology.

Today we already have a transmission material with unique properties. Its use has gained wide popularity. Information is of great importance nowadays. With its help we communicate, develop the economy and everyday life. The speed of information transfer must be high in order to ensure the necessary pace of modern life. Therefore, many Internet providers are now introducing fiber optic cable.

This type of conductor is designed only to transmit a pulse of light carrying part of the information. Therefore, it is used to transmit informative data, and not to connect power. Fiber optic cable makes it possible to increase speed several times compared to metal wires. During operation, it has no side effects, deterioration in quality over a distance, or overheating of the wire. The advantage of a cable based on optical fibers is that it cannot influence the transmitted signal, so it does not need a screen, and stray currents do not affect it.

Classification

Fiber optic cable differs greatly from twisted pair cable depending on the application and installation location. There are main types of cables based on optical fiber:

• For indoor installation.
• Installations in cable channels, without armor.
• Installations in cable ducts, armored.
• Laying in the ground.
• Suspended, without a cable.
• Suspended, with cable.
• For underwater installation.

Device

The simplest device has a fiber optic cable for indoor installation, as well as a conventional cable that does not have armor. The most complex design is for cables for underwater installation and for installation in the ground.

Indoor cable

Internal cables are divided into subscriber cables, for laying to the consumer, and distribution cables, for creating a network. Optics are carried out in cable channels and trays. Some varieties are laid along the facade of the building to the distribution box, or to the subscriber itself.

A fiber optic device for internal installation consists of an optical fiber, a special protective coating, and power elements, for example, a cable. Cables laid inside buildings are subject to fire safety requirements: resistance to combustion, low smoke emission. The cable sheath material is polyurethane rather than polyethylene. The cable should be light, thin and flexible. Many versions of fiber optic cable are lightweight and protected from moisture.

Indoors, the cable is usually laid over short distances, so there is no talk of signal attenuation and the impact on information transmission. In such cables the number of optical fibers is no more than twelve. There are also hybrid fiber optic cables that contain twisted pair.

Cable without armor for cable channels

Optics without armor are used for installation in cable ducts, provided that there are no mechanical influences from the outside. This cable design is used for tunnels and house collectors. It is laid in polyethylene pipes, manually or with a special winch. A special feature of this cable design is the presence of a hydrophobic filler, which guarantees normal operation in the cable channel and protects it from moisture.

Armored cable for cable ducts

Fiber optic cable with armor is used when there are external loads, for example, tensile stress. Armor is done in different ways. Armor in the form of a tape is used if there is no exposure to aggressive substances, in tunnels, etc. The armor structure consists of a steel pipe (corrugated or smooth), with a wall thickness of 0.25 mm. Corrugation is performed when it is one layer of cable protection. It protects the optical fiber from rodents and increases the flexibility of the cable. In conditions with a high risk of damage, wire armor is used, for example, at the bottom of a river, or in the ground.

Cable for laying in the ground

To install the cable in the ground, optical fiber with wire armor is used. Cables with tape armor, reinforced, can also be used, but they are not widely used. A cable laying machine is used to lay the optical fiber into the ground. If installation in the ground is carried out in cold weather at temperatures less than -10 degrees, then the cable is heated in advance.

For wet ground, a cable with a sealed optical fiber in a metal tube is used, and the wire armor is impregnated with a water-repellent compound. Specialists make calculations for cable laying. They determine permissible stretching, compressive loads, etc. Otherwise, after a certain time, the optical fibers will be damaged and the cable will become unusable.

Armor influences the amount of tensile load that can be allowed. Optical fiber with wire armor can withstand loads of up to 80 kN; with tape armor, the load can be no more than 2.7 kN.

Overhead fiber optic cable without armor

Such cables are installed on the supports of communication and power lines. This makes installation easier and more convenient than in the ground. There is an important limitation - during installation the temperature should not drop below -15 degrees. The cable cross-section is round. This reduces wind loads on the cable. The distance between supports should be no more than 100 meters. The design has a strength element in the form of fiberglass.

Thanks to the power element, the cable can withstand heavy loads directed along it. Strength elements in the form of aramid threads are used at distances between pillars of up to 1000 meters. The advantage of aramid threads, in addition to low weight and strength, is the dielectric properties of aramid. If lightning strikes the cable, there will be no damage.

The cores of overhead cables are divided according to their type into:

• A cable with a core in the form of a profile, the optical fiber is resistant to compression and stretching.
• A cable with twisted modules, optical fibers are laid freely, and has tensile strength.
• With an optical module, the core contains nothing except optical fiber. The disadvantage of this design is that it is inconvenient to identify the fibers. Advantage: small diameter, low cost.

Fiber optic cable with rope

Cable fiber is self-supporting. Such cables are used for laying over the air. The cable can be load-bearing or coiled. There are cable models in which the optical fiber is located inside a lightning protection cable. A cable reinforced with a profile core is quite efficient. The cable consists of a steel wire in a sheath. This sheath is connected to the cable braid. The free volume is filled with a hydrophobic substance. Such cables are laid with a distance between poles of no more than 70 meters. The limitation of the cable is the impossibility of laying it on the power supply line.

Cables with a rope for lightning protection are installed on high-voltage lines with fixation to grounding. Rope cable is used when there is a risk of damage by animals, or over long distances.

Fiber optic cable for underwater installation

This type of optical fiber is set apart from the rest because it is laid under special conditions. All submarine cables have armor, the design of which depends on the depth of installation and the topography of the bottom of the reservoir.

Some types of underwater optical fiber for armor design with:

• Single armor.
• Reinforced armor.
• Reinforced double armor.
• No reservation.

1› Polyethylene insulation.
2› Mylar covering.
3› Double wire armor.
4› Aluminum waterproofing.
5› Polycarbonate.
6› Central tube.
7› Hydrophobic filler.
8› Optical fiber.

The size of the armor does not depend on the depth of the gasket. Reinforcement protects the cable only from the inhabitants of the reservoir, anchors, and ships.

Fiber splicing

A special type of welding machine is used for welding. It contains a microscope, clamps for fixing fibers, arc welding, a heat-shrink chamber for heating the sleeves, and a microprocessor for control and monitoring.

Brief technical process for splicing fiber optics:

• Removing the shell with a stripper.
• Preparation for welding. Sleeves are put on the ends. The ends of the fibers are degreased with alcohol. The end of the fiber is cleaved with a special device at a certain angle. The fibers are placed in the apparatus.
• Welding. The fibers are aligned. With automatic control, the position of the fibers is set automatically. After confirmation from the welder, the fibers are welded by the machine. With manual control, all operations are carried out manually by a specialist. When welding, the fibers are melted by an electric arc and combined. Then the welded area is heated to avoid internal stress.
• Quality check. The automatic welding machine analyzes the image of the welding site using a microscope and determines the evaluation of the work. An accurate result is obtained using a reflectometer, which detects inhomogeneity and attenuation along the welding line.
• Treatment and protection of the welded area. The inserted sleeve is moved to welding and placed in the oven for heat shrinking for one minute. After this, the sleeve cools down, is placed in the protective plate of the coupling, and a spare optical fiber is applied.

Advantages of fiber optic cable

The main advantage of optical fiber is the increased speed of information transfer, virtually no signal attenuation (very low), and also the security of data transmission.

• It is impossible to connect to an optical line without sanctions. Whenever connected to the network, the optical fibers will be damaged.
• Electrical safety. It increases the popularity and scope of such cables. They are increasingly used in industry when there is a danger of explosions at work.
• Has good protection against interference of natural origin, electrical equipment, etc.

Broadband Internet is the general name for a whole group of modern high-speed technologies for constantly accessing the World Wide Web. Data is received and transmitted at the same high speed - up to hundreds of Mbit/s.

Thanks to broadband Internet, users have access to

digital TV services; IP telephony; possibility of cloud data storage and much more.

Internet service providers offer various types of broadband Internet access connections. All available varieties can be divided into two large groups:

fixed - based on wired connections; fiber optic - via optical communication lines; mobile - via wireless communication channels.

Broadband access over a leased line

The very first broadband technologies were based on Internet access via a digital leased line (DSL). Modern methods of digital signal processing can significantly increase the capacity of a telephone line, which has made the xDSL family of technologies one of the most widespread throughout the world.

The symbol "x" is used to represent the entire family of leased line access technologies, which differ in data transfer speed and line multiplexing method. They are designated by separate abbreviations - ADSL, HDSL, RADSL, SHDSL, VDSL.

In general, all xDSL technologies can be divided into two categories:

symmetrical - with the same speed of receiving and transmitting data; asymmetric - with a higher speed of receiving data from the network.

Symmetric technologies are used most often in the corporate sector, while asymmetric technologies are used for subscriber access.

High-speed fiber optic Internet access channels

Access to the Internet via an optical line is the most common and fastest option for broadband access, widely used in multi-apartment city buildings. Each entrance of the house is connected via a fiber optic switch to the provider, and a twisted pair cable is pulled to the end subscribers for connection to a router or directly to the computer’s network card. In this case, the access speed to the global network will not exceed 100 Mbit/s.

The highest speed connection is achieved when the subscriber also connects via a fiber optic cable, rather than the usual twisted pair copper cable. Fiber access allows you to provide connection speeds of up to 1 Gbit/s, which allows you to connect any types of services - Internet, digital TV, IP telephony.

Mobile broadband

Broadband Internet access through the mobile networks of 3G and 4G cellular operators is a popular service due to the large coverage area and the explosive proliferation of mobile gadgets.

3G technology today is already morally obsolete, but is used quite widely, since it is available on a significant part of the coverage of leading operators. To replace 3G, 4G technology is being actively introduced, allowing for significantly higher speeds. In metropolitan areas and large cities, providers are also developing the provision of Internet connections via WiMax, since most gadgets come with an already integrated WiFi module.

Many Internet users use optical fiber, but not all of them understand what it is and how information is transmitted?

Optical fiber, also known as optical fiber, is the fastest and easiest way to transmit data on the Internet. Such cables have their own special structure: they consist of many thin wires that are separated from each other by a special coating.
Each wire is a piece of light, and the light in turn transmits data. This cable is capable of transmitting data for both the Internet and TV and landline telephone.

That is why users of fiber optic networks often combine these services that are offered to them by the provider and connect a telephone, router, PC and other possible equipment to the network.

Fiber optics are often referred to as “Fibre-optic communications”. It allows you to transmit data using the best laser, and their transmission is possible over long distances at high speed.
Cables and their fibers have a very small diameter - fractions of an inch. The optical rays inside them carry data and pass through a special fiber core made of silicon.
Using such fiber, you can restore and set up a connection not only with any city, but also with other countries.

1. Internet (fiber optics)

Advantages of optical fiber:
- Optical fiber is a strong and durable material with a high throughput level. This is what allows the speed to “accelerate” to such a level.
- Safety. Using such a system will ensure maximum security when working with the network. Attackers cannot obtain your data, or almost impossible.
- The level of protection of such a cable is enormous, and it is also protected from various interferences with its operation.
- By connecting such a fiber, it becomes possible to organize a number of additional functions. Often such cables are used to install video surveillance systems and other security devices.

2. Optical fiber connection

The first thing you need to do is make sure that fiber optic is connected to your home. And then you will need to go to Rostelecom and ask to connect the service. But now you need to configure the connected equipment.

Setup Instructions:
- After the optical fiber has been installed, the entire base part is installed by specialists, the rest of the setup must be done by hand.