The idea to transfer data over an electrical network appeared several decades ago. Back in the 30s of the last century, experiments were carried out in Russia and Germany on the use of power lines for transmitting information. However, until the end of the 90s, the technology found very limited applications. It was mainly used to equip high-voltage power lines with HF communication channels to transmit control information for technical services at a low (2.4 Kbps) speed.

A particular interest in the possibility of transmitting information over a power network arose with the development of the Internet. To provide Internet access to the general population, it was necessary to connect the provider's points of presence to the homes or offices of clients, most of which do not have a high-speed access channel similar to that of the provider. Moreover, in order to lay such a cable, each client will have to pay a considerable sum. And if corporate users can often afford to connect using expensive technology, then for home users, of which there are much more, this is absolutely unacceptable. The challenge was therefore to develop an affordable last mile technology that would reliably connect the provider and its customers.

Dozens of companies have worked in this direction, investing hundreds of millions of dollars in technologies ranging from xDSL, coaxial television cables, wireless radio access to data transmission via satellite.

Many technologies relied on using existing infrastructure - telephone lines, cable TV networks, etc. - to access the Internet. However, it is obvious that in terms of the prevalence and availability of ready-made infrastructure, no other can compare with the power grid. There are power outlets in every home, even in the most remote corners of the world.

In the 90s, a number of research works on high-speed data transmission over the power network, during which some problems were identified: the wiring is characterized by a high level of noise, rapid attenuation of the high-frequency signal, a change in the communication parameters of the line depending on the current load. Over time, these difficulties were overcome. In the process of developing more advanced methods for modulating signals, technologies for high-speed Internet access using the power grid were created.

The pioneer in this area was the British company Nor.Web, which together with by United Utilities has developed Digital Power Line (DPL) technology that allows voice and data packets to be transmitted over simple 120/220 V electrical networks.

In 1997, the first experiment was carried out, and two years later the technology was tested in Manchester and Milan. However, the results were unsuccessful and Nor.Web stopped researching. Inhomogeneity of the transmission medium and the lack of an element base and uniform standard led to the fact that Digital Powerline technology did not find commercial use.

Following DPL, solutions from German companies appeared: Bewag patented a telecommunications development that allows data transmission over electrical wires, Veba achieved an increase in the speed of data transmission over power networks, but the Israeli company Main.net (www.mainnet-plc .com). Its PLC (Powerline Communications) technology has become widespread.

PLC equipment provides both data and voice (VoIP) transmission. The data transfer rate can range from 2 to 10 Mbps.

PLC technology is based on signal frequency division, in which a high-speed data stream is divided into several low-speed streams, transmitted at separate subcarriers, and then combined into one signal.

The main price competitor for electrical access is the Asymmetrical Digital Subscriber Lines (ADSL). However, it should be noted that asymmetric channels are not suitable for solving all problems, for example, they are not suitable for dynamic online games, where the return traffic is large enough.

PLC services such as high speed Internet are now available in a number of European countries. For example, in Germany the service is offered in several cities under different trade marks: Vype (www.vype.de); Piper-Net (www.piper-net.de) and PowerKom (www.drewag.de); in Austria under the Speed-Web trademark (www.linzag.net); in Sweden the service is provided under the ENkom brand (www.enkom.nu); in the Netherlands under the name Digistroom (www.digistroom.nl); in Scotland - Broadband (www.hydro.co.uk/broadband).

This promising technology has attracted the interest of such powerful players in the telecommunications market as Motorola, Cisco Systems, Intel, Hewlett-Packard, Panasonic, Sharp and others. For example, Motorola, together with Phonex Broadband and Sonicblue, have successfully tested the method of transmitting music files over the power grid. In order to avoid negative factors of competition, several large telecommunications companies have united in an alliance (it is called the HomePlug Alliance) with the aim of joint research and practical testing, as well as the adoption of a single standard for data transmission over power supply systems.

Attractiveness of PLC technology for energy companies

For energy companies, PLC technology is beneficial for the following reasons:

Opens the way to new markets as it transforms power lines into a data network;

Allows you to offer customers such popular services as high-speed Internet access, telephony, etc.;

Does not require a frequency resource and appropriate licenses;

Inexpensive equipment provides low initial investment and the possibility of a phased increase in capacity;

It allows us to offer new types of services without significant capital investments, since the power grid equipment already has a large number of users, a developed infrastructure for building a customer support system, repair services, etc.;

Provides energy and municipal companies with the ability to permanently remotely monitor all parameters of consumption of electricity, water, gas, heat and transactions for payment for any type of service.

High speed internet access

The cost of implementing the last mile technology consists of the cost of the linear infrastructure (approximately 60-80% of the total cost), the cost of equipment (20-30%) and the cost of design, preparatory engineering works, etc. (10-20%). The widespread prevalence of electrical networks of 0.2-0.4 kV, the absence of the need for expensive work on laying trenches and punching walls for laying cables stimulate an increased interest in them as a data transmission medium. An example of a high-speed Internet connection is the technology of the Swiss company Ascom, which is a leader in the production of communication systems and networks based on PLC technology. The company offers an end-to-end solution in which the power cables supplying the building serve as the “last mile” of data transmission, and the electrical wiring inside the building acts as the “last inch”. Outdoor (Outdoor; Fig. 2) and indoor (Indoor; Fig. 3) systems allow the use of the same transmission medium and different carrier frequencies. To transmit data through feeders feeding the building, they use low frequencies, and inside buildings - tall.

For outdoor applications, Ascom offers three carriers with a midrange of 2.4; 4.8 and 8.4 MHz. Depending on the transmission distance, each carrier transmits data at a rate of 0.75 to 1.5 Mbps. With a small distance between an intermediate transceiver point (for example, a transformer substation) and the building, all three carriers are used. This achieves a transmission speed of up to 4.5 Mbit / s. At the minimum baud rate without repeaters, a distance of 200-300 m can be covered. For the highest baud rates, the distance is approximately halved.

The repeater concept allows the PLC to double the coverage of outdoor and internal applications... The repeater receives data traffic from the master and forwards it to endpoints that it cannot directly reach.

Every week Ascom produces about 6 thousand PLC adapters and 2 thousand network devices.

As an example of the implementation of Ascom Powerline projects, one can cite the project of one of the leading electricity suppliers in Germany - RWE, which provides access via the RWE PowerNet network at a lower cost than TV and cable companies. Currently, on the basis of Ascom Powerline Communications AG equipment, a number of projects have already been implemented in Eastern Europe, and pilot projects for the introduction of PLCs in Ukraine and Russia are being prepared.

PLC technologies for home networks

The ability to transmit information over the power grid solves the problem of not only the last mile, but also the "last inch". The fact is that the number of wires that are used to connect home PCs and other home electronics items has already increased exorbitantly: up to 3 km of various cables are laid in a 150-meter apartment. And the electrical network is just the ideal environment for the transmission of control signals between household appliances operating in the 110/220 V network. PLC technologies for home networks make it possible to effectively implement the concept of an intelligent home by providing a range of services for remote monitoring, home protection, and control. modes, resources, etc.

In particular, the well-known company LG offers the connection of its consumer electronics through a power network (Fig. 5):

The Internet refrigerator carries out the functions of control and monitoring of digital electronics connected to the network, and provides access to the Internet;

Internet-based washing machine is network-controlled, allows you to download washing programs from the Internet;

An Internet microwave oven allows you to download a recipe from the Internet, carry out remote Internet monitoring;

The internet air conditioner is controlled via the internet.

It is expected that PLC technology will be able to give a new impetus to the development of data transmission over power lines and will make it possible to directly access the global network from almost anywhere in the world at a minimal cost. The technology has not yet become widespread, but in the near future it can be expected that it will seriously push back alternative technologies and lead to significant changes in the provider services market: to lower prices for access to the Network, including prices for dial-up and leased line connections. ...

If PLC becomes widespread, it can significantly change the balance of power in the Internet access service market and will help to develop new principles for the design of power grids - taking into account both energy and communication requirements.

Smart Power Grids are the smart grids of tomorrow that have become the backbone of Smart Grid technology in industry. The concept is based on intelligent control of power supply systems and data exchange between enterprise equipment, which requires the development of new principles for the administration of energy networks. The idea of ​​the HARTING company: each device becomes a subscriber of the network, regardless of whether it is connected to a data cable or only a power cable.

CJSC "HARTING", Moscow

As part of enterprise management, a general concept for the development of commercial and industrial buildings is being developed, which allows to achieve a constant reduction in production and operating costs and ensure the availability of equipment for maintenance. The main goal is to achieve "green" production, as well as increase productivity and thus profitability of the entire plant by reducing energy costs, increasing energy distribution efficiency, optimizing peak loads or optimizing energy consumption using software tools, as well as by using a modern energy distribution concept in as part of the energy management system of the enterprise in accordance with DIN EN 16001. To achieve this goal, a single and universal communication system is required, combining power and data networks. An energy monitoring system will be created for large consumers of electricity, which will combine the functions of managing the processes of supplying electricity, managing energy consumption and providing users with complete information. Quality communication is the basis of efficiency. The exchange of data between industrial devices is still considered just an auxiliary function. However, if industrial devices operate in isolation, outside the data exchange system, further development and improvement of the efficiency of industrial processes is impossible. The lack of diagnostics negatively affects the equipment readiness for maintenance, and improving energy efficiency during equipment operation is impossible without an effective system for identifying electricity consumers. Both tasks can be solved only when using a data transmission network, which allows you to "see" each working device and control it.

Industrial power supply and communication signal types

The operation of industrial devices is connected with three vital "arteries" - these are power lines, data lines and control lines. Devices that consume more power are permanently connected to the 400 V power line, but less than 50% of them are capable of transmitting and receiving information. For effective administration of such devices, each of them must be integrated into the power network as a terminal device.

Hence the requirements for power supply networks. When the device is connected to the power supply network, the device itself and the value of the power consumed by it must be immediately recognized, and it must also be possible to disconnect the load in accordance with the selected algorithm. To implement the listed functions, a channel with a sufficiently narrow bandwidth is required.

Automation, by contrast, requires communication lines capable of transmitting data at high speed in real time. For example, optical lines of automatic diagnostics operate in a fairly wide frequency range.

Organization of data transmission lines in the power supply network

To reduce installation costs as well as to provide basic power management functions, HARTING has chosen power cable data technology. However, even though the networks are interconnected, they must work as networks organized with separate cables would work. Therefore, the Ethernet standard was chosen as the basis for the power network, allowing new functions to be added to the network depending on user requirements. When intelligent control is integrated into the traditional power supply network, it becomes smartPowerNet. In this case, networked devices begin to play a key role, as they determine the network topology required by the industry. Consequently, the elements of the smartPowerNet network form the basis of the network structure: HARTING drew the same conclusions and was the first company to develop devices for power networks with data transfer function.

Using a standard Ethernet network

The Ethernet network is managed through the managed network components.

It is quite logical that the functions of the managed switches can be taken over by the devices of the smartPowerNet network. One of the main functions of network management is the visualization of the topology and endpoints connected to the network. If the Ethernet standard is selected for a power supply with data transmission, the topology of the data network follows the topology of the power supply, since the same cable is used for data transmission and power supply. Consequently, standard Ethernet functions can be used to administer such a complex network, with a wide variety of choices. Based on this concept, it is possible to create a universal solution. The system is open and scalable, since connecting additional communication lines expands the frequency range of the system without imposing any restrictions on compatibility.

Integrated network management functions

V currently solutions are in demand that support topologies that provide for the use of data and power lines in various combinations and allow the transmission of energy consumption data, for example, to the control room, without laying additional data cables, as well as to continuously monitor the state of the system without installation and configuration additional devices... In such a network, the function of automatic recognition of the network topology at the moment of first power-up and during network operation, as well as displaying data about the power distribution system, is very important. Devices that distribute and consume electricity are recognized when the network is switched on and shown on the display of an industrial PC or the main work control station together with the current energy consumption. The integration of the load management system avoids overloads, the system is triggered when the peak values ​​preset for the load are exceeded. Therefore, it is advisable to determine in advance the consumers who can be safely disconnected in the event of a general network overload.

System status monitoring

The function of monitoring the status of the load in the power distribution system, as well as the load connected to the machine or other equipment, is based on the regular reading and subsequent analysis of the relevant data. It serves to ensure the safety and efficiency of the system. In addition to measuring the signal at the outputs of the T-bends, the status of the entire distribution network and each individual smartPowerNet element is continuously monitored.

Any change in network parameters and performance indicators is recorded and analyzed. For example, faults such as voltage drops, cable breaks, or incorrect connections can be instantly identified before the entire system fails.

Rice. Application of Smart Grid technology in industry will significantly increase efficiency

Energy consumption

To reduce energy costs, you need data on all consumers. For this purpose, a metering integrated circuit is integrated in every smartPowerNet element, in every switchgear or electrical cabinet, which reads and writes the data used to calculate the energy consumption. The simplest way to reduce energy consumption is to turn off consumers. The standard I / O of the administered switchgear allows the disconnection of extra devices using a PLC without using additional network protocols.

Displaying data

All measurement results are processed on an industrial PC. The smartPowerNet data is read out via standard communication interfaces, then processed and archived.

Significant deviations of the measured values ​​from the normal values ​​are registered, analyzed, recorded and displayed on the industrial PC or in the control room according to the degree of importance. It calculates, for example, the energy consumed by the entire system or by each output circuit. The value of the consumed electricity is displayed in relation to the nominal value and an overload warning is issued. It is also possible to graphically analyze electricity consumption and graph energy consumption for a sufficiently long period.

Power Grid Communication Technologies (Power Line Communication, PLC) are actively developing and becoming more and more in demand all over the world. And Russia is no exception. They are used in the automation of technological processes, the organization of video surveillance systems and even to control a "smart" home.

Research in the field of data transmission using the power grid has been going on for a long time. Once upon a time, the use of PLC was hampered by low data transfer rates and insufficient immunity from interference. The development of microelectronics and the creation of modern, and most importantly, more efficient processors (chipsets) made it possible to use complex modulation methods for signal processing, which made it possible to significantly advance in the implementation of PLC. However, only a few specialists still know about the real possibilities of communication technology over the power grid.

PLC technology uses electrical networks for high-speed data transmission and is based on the same principles as ADSL, which is used to transfer data to telephone network... The principle of operation is as follows: a high frequency signal (from 1 to 30 MHz) is superimposed on a conventional electrical signal (50 Hz) using various modulations, and the signal is transmitted through electrical wires. The equipment can receive and process such a signal at a considerable distance - up to 200 m. Data transfer can be carried out both over broadband (BPL) and narrowband (NPL) power lines. Only in the first case, data transmission will go at a speed of up to 1000 Mbit / s, and in the second, it will be much slower - only up to 1 Mbit / s.

At the speed limit?

Today, third generation PLC technologies are available to users. If in 2005, with the advent of the HomePlug AV standard, the data transfer rate increased from 14 to 200 Mbps (this is enough to provide the so-called "Triple Play" services, when users are simultaneously provided with high-speed Internet access, cable TV and telephone communications), the latest generation of PLCs already uses a dual physical layer of data transmission - Dual Physical Layer. Together with FFT OFDM, Wavelet OFDM modulation is used, that is, orthogonal frequency-division multiplexing, but using wavelets. This makes it possible to increase the data transfer rate several times - up to 1000 Mbps.

However, it is important to understand that we are talking about physical speed. The actual data transfer rate depends on many factors and may be several times lower. The quality of the wiring in the house, twists in the line, its heterogeneity (for example, in aluminum wiring the signal attenuation is stronger than in copper, which reduces the communication range by about half) - all this destructively affects the physical speed and quality of data transmission. Also PLC - all adapters must be on the same phase in the electrical network, in the electrical network between the adapters there should be no galvanic isolation (transformers, UPS), pilots, filters and RCDs reduce the data transfer rate. The exception is QPLA-200 v.2 and QPLA-200 v.2P, because a feature of these adapters is the unique Clear Path technology. Using Clear Path technology, it is possible to create a network even when the PLC devices are connected to different phases, i.e. this technology dynamically selects less noisy channels for transmission of information, thereby increasing the data transfer rate. One PLC network can contain up to 8 devices.

Speaking of PLC technology, it is customary to take half-duplex or unidirectional speed as the speed. That is, if the specified speed is 200 Mbit / s, then the real one will be 70-80 Mbit / s. V real life physical speed with great confidence can be divided in half, and proportionally reduced by 10% when each powerful home device is connected - an iron, a kettle, an air conditioner, a refrigerator, etc.

In ordinary household conditions, a signal can be transmitted over a distance of about 200 m by wires using a PLC. For example, a house with an area of ​​200 sq. M. m can be covered without problems. In this case, the quality of communication will depend on the quality of the electrical network. An ordinary surge protector, which is often built into an extension cord, an uninterruptible power supply or a transformer, can become an obstacle to the signal passage. It should also be remembered that the distribution of the network through the wiring is limited by an electrical panel with fuses. So creating a network, for example, with a flatmate will not work. Wi-Fi is better for this.

Pros and cons of PLC

PLC technologies certainly deserve attention, but along with their advantages, they also have obvious disadvantages. But first things first. PLC helps to establish high-quality provision of Triple Play services, does not require wiring for data transmission, and, therefore, additional costs. Fast installation and the ability to connect to existing networks is also a point in favor of the PLC. In addition, the PLC network can be easily disassembled and configured, for example, when moving an office to another building. Such a network is easily scalable - you can organize almost any of its topologies with minimal costs (depending on the number of additional PLC adapters). In difficult conditions (reinforced concrete structures, high level electromagnetic interference) as opposed to wireless Wi-Fi technologies, WiMAX and LTE PLC network will work smoothly. At the same time, due to the use of the most modern encryption algorithms, secure data transmission over the network is also ensured.

PLC has fewer drawbacks, but it's worth knowing about them. First, the wiring capacity of the network is divided among all its participants. For example, if two pairs of adapters are actively exchanging information in one PLC network, then the exchange rate for each pair will be approximately 50% of the total throughput. Secondly, the quality of the wiring (for example, copper and aluminum conductors) affects the stability and speed of the PLC. And thirdly, the PLC does not work through network filters and uninterruptible power supplies not equipped with dedicated PLC Ready outlets.

PLC application in practice

Today PLC finds wide practical application. Due to the fact that the technology uses the existing power grid, it can be used in the automation of technological processes for linking automation units via electrical wires (for example, city electricity meters).

Often, PLCs are used to create video surveillance systems or local area networks in small offices (SOHO), where the main requirements for the network are ease of implementation, device mobility and easy scalability. Moreover, both the entire office network and its individual segments can be built using PLC adapters. It is often necessary to include in an already existing office network remote computer or a network printer located in another room or even on the other side of the building - using PLC adapters, this problem can be solved in a few minutes.

In addition, PLC technology opens up new possibilities for implementing the idea of ​​a "smart" home, in which all consumer electronics must be tied into a single information network with an opportunity centralized management.

Oddly enough, but there are still those who are not indifferent to the idea of ​​transmitting data over electrical wiring. Yes, there are a lot of people in the world who have come across this phenomenon face to face, someone, perhaps, is just going to get acquainted with technologies that open up such opportunities, for someone it is already a successful or unsuccessful experience, and for someone - yesterday day.

So PLC. Unfortunately, there is not so much information on the network as about Ethernet or Wi-Fi. With this article I will try to answer the most popular questions that once interested me myself. PLC (Power Line Communication) is a communication network, the transport of which is the usual electrical wiring of an apartment, office or enterprise. Networks of this kind can be used to transmit data and voice. The electrical cable literally surrounds modern man... It is found in homes, offices and businesses, public places. And this is not surprising, because wires are the only means of delivering electric current to the consumer. Often, not one, but several supply cables are suitable for electrified objects. This is due to the use of several electrical phases or additional power lines.

It goes without saying that the use of an electric cable as a means of communication has been thought for a long time. When this venture was realized, connecting to the network would be reduced to connecting the adapter plug to an outlet. As a result, a new specification was developed, based on the development of PLC and DPL (Digital PowerLine), which were carried out earlier. It was created by the efforts of a group of companies such as Siemens, Nortel, Motorola and others, which formed the HomePlug Powerline Alliance. With the advent of HomePlug 1.0, and then HomePlug AV PLC standards, devices in BPL (Broadband over Power Lines) mode became capable of exchanging data at speeds up to 200Mb / s.

Where can you use Power Line Communication technology? When applied correctly, almost anywhere, but mainly, this technology is used to organize a local area network at home and office, as well as as an access technology at the provider level. The advantages of this technology include easy scalability of the network, the ability to implement the system " smart House"(like Z-Wave technology :)), no additional holes in the wall and no cables in the apartment / house.

Story

At the dawn of the development of electrical networks, the question arose of organizing the exchange of dispatch information between power nodes. The most rational was the use of existing power lines, rather than the construction of separate telegraph lines. Already at the beginning of the 20th century, direct current power lines were used in the United States for the exchange of telegraph information. With the development of radio communications, it became possible to use networks for the same purposes. alternating current.

At present, the exchange of dispatcher information over power lines is widely used as one of the main types of communication. The transceiver is connected to the power transmission line through a connection filter formed from a small capacitor (2200 - 6800 picofarads) and a high-frequency transformer (autotransformer). Such a system allows transmitting both voice information and telemetry and telecontrol data. The idea behind PLC technology is to use power lines for high-speed data exchange.

As it turned out during the development and subsequent operation, the bottleneck of the technology was weak noise immunity and low data transfer rate. In March 2000, the HomePlug Powerline Alliance became the result of the merger of several of the largest telecommunications companies, organized for the purpose of joint research, development and testing, in addition, it was decided to adopt a single standard for data transmission over power supply systems. By the way, at the moment, the HomePlug Powerline Alliance includes more than a hundred organizations.

The prototype of PowerLine is Intellon's PowerPacket technology, which formed the basis for the single HomePlug1.0 standard (adopted by the HomePlug alliance on June 26, 2001), in which the data transfer rate was determined up to 14 Mb / s. However on this moment the HomePlug AV standard has raised the data transfer rate to 200 Mbps. And the new G.hn standard will expand the bandwidth to 1 Gbps in the coming year.

It is worth noting that HomePlug is not the only package of existing specifications. In addition to HomePlug there are others - this is a broadband technology supported by an international association UPA(Universal Powerline Association), as well as the technology of the same name, which was developed by a number of influential Japanese companies that have united in an alliance HD-PLC(High-Definition Powerline Communications). In Europe, the alliance contributed to the development of PLC technology OPERA(Open PLC European Research Alliance). I will briefly tell you about them.

OPERA

OPERA was founded by European manufacturing companies and universities in 2004. The alliance has over 40 members. The aim was research and development in the field of integrated PLC networks for organizing broadband access.

In 2006, the first project of the alliance was completed. The result of the completion was the release of the first version of the standard, which was rushed to use by many manufacturers of PLC equipment. The second phase of the project began in January 2007 and ended in December 2008. The goal of the project was to develop specifications to enable broadband systems to operate using existing wiring as the physical medium. Hence the other name - BPL (Broadband over Power Line).

BPL-technology provides high-speed data transmission (streaming video, IP-telephony, etc.), as well as the organization of home local networks. The participants in the second stage of the project included the leading European universities Swiss Federal Institute of Technology (Switzerland), University of Dresden and University of Karlsruhe (Germany) and others, large technology development companies DS2 (Spain) and CTI (Switzerland), as well as European PLC operators EDEV-CPL (France), ONI (Portugal), PPC (Germany), utilities and OEMs - 26 members in total. The specifications proposed by the alliance are based on the technology developed by the Spanish company DS2, which was the first to introduce commercial PLC-modem microcircuits, providing a communication channel at the physical layer of up to 200 Mbps. It provides for data transmission in the 10, 20 or 30 MHz frequency band. The modulation method is OFDM, the number of subcarriers is 1536. To modulate the subcarriers, modulation of the ADPSK type (Amplitude Differential Phase Shift Keying) is used, which ensures the transmission of up to 10 bits per subcarrier. The theoretically achievable data rate is 205 Mbps.

UPA

UPA was founded in 2004. It includes leading manufacturers of electronic equipment and research centers: Analog Devices, Ambient, Buffalo, Comtrend, Corinex, D-Link, NETGEAR, Korea Electrotechnology Research Institute, Toshiba, etc. The purpose of the association was to develop standards and regulatory documents defining various aspects of the data transmission process to accelerate the development of the PLC market and promote data transmission systems over the power grids at the government and corporate levels. One of the aspects of the UPA certification is the interoperability of equipment of different standards using the same physical data transmission medium, i.e., for example, the simultaneous use of the same power grid for the transmission of data streams in accordance with the HomePlug and OPERA standards. UPA supports the basic specifications proposed by the OPERA alliance.

HD-PLC

HD-PLC was founded by the Japanese corporation Panasonic Corporation, which includes such companies as AOpen, Advanced Communications Networks, Icron Technologies Corporation, IO DATA DEVICE, Analog Devices, APTEL, Audiovox Accessories Corporation, Buffalo, OKI, Kawasaki Microelectronics, OMURON NOHGATA, Murata and others. The HD-PLC broadband technology proposed by Panasonic Corporation is designed to organize high-speed data transmission and reception over the power grid and is supported by the CEPCA (Consumer Electronics Powerline Communication Alliance).

This alliance was formed in 2005 by the influential Japanese corporations Panasonic, Sony, Toshiba, Mitsubishi, Sanyo and Yamaha. One of the activities of CEPCA is to combine efforts to develop technology that is compatible with different standards, which will potentially allow the interconnection of multimedia data networks within an apartment or building. Competitors to HD-PLC technology are technologies promoted by the HomePlug and UPA associations. A distinctive feature of HD-PLC technology is the proposed method for synthesizing an OFDM signal. In contrast to the method of forming an OFDM signal using the inverse fast Fourier transform (FFT) adopted, for example, in HomePlug AV technology, the authors proposed using Wavelet transforms in HD-PLC technology. Wavelet OFDM is a broadband power grid technology with high spectral efficiency. This technology uses Wavelet transforms to synthesize the OFDM signal. In this case, the theoretically achievable data transfer rate is 210 Mbit / s.

Participants

You need to understand that all the listed alliances and associations are a kind of "interest clubs", the core of which is made up of several large manufacturers integrated circuits pursuing commercial benefits. On the periphery, there are manufacturers of modems and other equipment. This is how "non-profit" organizations were formed, developing and promoting the "manufacturer-independent" standard.

The core of the Homeplug Powerline Alliance is comprised of Cisco, Intel, LG, Motorola, Texas Instruments. They are the allies of Intellon, which reflects the American direction of the development of this technology. The European direction is determined by the DS2 company supported by the European Union within the framework of the OPERA project. More than two dozen DS2 partner companies have joined the UPA association, which includes Buffalo, Corinex, D-Link, Intersil, Netgear, Toshiba and other companies. Panasonic Corporation adheres to the specifications of the industrial alliance CEPCA in its developments. Companies such as Hitachi, Mitsubishi, Philips, Pioneer, Sanyo, Sony and others are guided by this standard. The Institute of Electrical and Electronic Engineers (IEEE) and the International Telecommunication and Standardization Union (ITU ). These organizations include representatives of leading companies from around the world.

In December 2008, the ITU-T Institute for Standardization adopted an international standard for high-speed data transmission over power lines, telephone and coaxial cables. The new standard ITU-T (G.9960), also referred to as G.hn, is a data link and physical layer specification package that unifies the concept of wired home networking. At the end of 2008, an international standard appeared for the first time, allowing full use of the potential of wired networks, in which power lines, coaxial or telephone cables are used as the physical medium of data transmission. The Home Grid Forum, a non-profit organization co-founded by DS2, is overseeing the interoperability of all G.hn-based networks.

In late 2008, DS2 announced its intention to develop a PLC modem chip that is compliant with G.hn, UPA and OPERA specifications. In July 2005, the IEEE announced the creation of working group, which will prepare the Broadband PowerLine standard. Competing and incompatible specifications for the use of power grids for high-speed data transmission were adopted as the object of study. The specifications were presented by the HomePlug Powerline Alliance, Panasonic Corporation and DS2.

As a result, the first draft of the standard was approved: IEEE P1901 Draft Standard for Broadband over Power Line Networks: Medium Access Control and Physical Layer Specifications. The draft standard provides for the possibility of using two incompatible modulation methods at the physical layer (FFT OFDM and Wavelet OFDM). Moreover, the possibility of using two incompatible methods of forward error correction was admitted.

One of them is based on convolutional turbo codes, the second uses LDPC codes - codes with low density of parity checks. Currently, turbo codes are used in satellite and mobile communication systems, wireless broadband access and digital television... In the draft standard there are no references to the use of technology proposed by DS2, and the two PHY options taken as a basis differ significantly from each other. As a result, equipment with different kinds modulation cannot interoperate on the same network, although it will meet the requirements of the IEEE P1901 standard. In writing, the material from this site was used.

In theory

The basis of the PowerLine technology is the use of frequency division of the signal, in which a high-speed data stream is parsed into several relatively low-speed streams, each of which is transmitted on a separate subcarrier frequency and then combined into one signal.

Frequency-Division Multiplexing (FDM) uses the available spectrum inefficiently. This is due to the presence of guard intervals (Guard Band) between subcarriers. The presence of guard intervals is necessary to prevent the mutual influence of signals.

Therefore, orthogonal frequency division multiplexing (OFDM) is used. The idea is to place the centers of the subcarriers so that the peak of each subsequent signal coincides with the zero value of the previous one. As you can see, the available bandwidth is spent more efficiently when using OFDM.

Before being combined into a single signal, the individual subcarriers are phase modulated, each with its own bit sequence.

Then comes the turn of the PowerPacket engine, in which the subcarriers are collected into a single information packet (OFDM-symbol). The PowerLine technology uses 1536 subcarriers with 84 best allocated in the 2-32 MHz range. Any data transmission technology needs to adapt to the physical environment, which means it needs a means of detecting and eliminating errors and conflicts. The PLC is no exception. When transmitting signals over a household network, large attenuation can occur at certain frequencies, which will lead to loss of data. Powerline technology provides special method The solution to this problem is dynamically turning off and on data-carrying signals. The essence of the method consists in constant monitoring of the channel in order to identify the part of the spectrum with exceeding the maximum attenuation threshold. If such a section is found, data transmission in the problem frequency range is terminated until an acceptable attenuation value is restored.

The strength of PowerLine technology in its wide spectrum of frequencies is at the same time its weak point. In various countries, the spectrum of prohibited frequencies is strictly regulated. While operating, the PLC device is able to "jam" the radio reception in the used spectrum. This problem is well known to radio amateurs. Therefore, the use of OFDM and a wide frequency range makes PowerLine technology flexible for use in various environments. Technically, this is implemented through the settings, the so-called Signal Mode and Power Mask on devices (in which the corresponding option is provided). Signal Mode is a software method for determining the operating frequency range. Power Mask is a software method for limiting the spectrum of the frequencies used. Due to this, PowerLine devices can easily coexist in the same physical environment and not noise the frequency ranges used by radio amateurs.

Another significant problem, now for the PLC devices themselves, is impulse noise, the sources of which can be various chargers, halogen lamps, turning on or off various electrical appliances.

The complexity of the situation lies in the fact that, using the above method, the PLC device does not have time to adapt to rapidly changing conditions, because their duration can be equal to one microsecond or less. To solve this problem, concatenated coding of bit streams is used before modulating them and then transferring them to the network. The essence of error-correcting coding is to add redundant bits to the original information stream, which are used by the decoder at the receiving end to detect and correct errors. Cascading a block Reed-Solomon code and a simple convolutional code decoded by the Viterbi algorithm allows you to correct not only single errors, but also bursts of errors, which significantly increases the integrity of the transmitted data.

In addition, error-correcting coding increases the security of transmitted information in a common transmission medium. Since the household power supply network has been selected as the data transmission medium, several devices can start transmission at the same time. To resolve collisions, the CSMA / CA method is used. By adding prioritization fields to PowerLine data frames, it has become possible to transmit voice and video over IP.

On practice

HomePlug 1.0

The first "electrical" specification of the HomePlug standard was developed and adopted after a year of the alliance's work - in mid-2001. This specification describes the following rules for the functioning of a local network:

• a "bus" is used as a network topology;
• the maximum data transfer rate is 14 Mbps;
• the maximum network diameter is 100 m (in practice, the distance can be more than 1000 m, but with a lower data transfer rate);
• the use of repeaters is allowed, which allows to increase the distance of data transmission up to 10,000 m;
• adaptive mechanisms are used to change the frequency or turn off certain channels when strong interference is detected;
• QoS (Quality of Service) service is used with four levels of delivery quality;
• data is encrypted using DES with a 56-bit encryption key.

After a short period of time, an unofficial version of HomePlug 1.0 appeared, marked Turbo, the technical characteristics of which repeated the characteristics of HomePlug 1.0 with the only but significant difference: the data transfer rate was increased to 85 Mbps.

HomePlug AV

The adoption of the HomePlug AV specification in 2005 was a landmark event as it allowed the standard to be used for high-volume data streams such as HDTV (HDTV) streaming. If you analyze this specification in detail, you will notice that during its development, many approaches were revised that were used in the development of the HomePlug 1.0 and HomePlug 1.0 Turbo specifications. The HomePlug AV specification has the following capabilities:

• the maximum data transfer rate is 200 Mbps;
• data transmission is carried out in the frequency ranges 2-28 MHz and 4-32 MHz;
• the method of access to the transmission medium CSMA / CA is used;
• QoS (Quality of Service) service is applied;
• AES technology with 128-bit encryption key is used for data encryption.

Nowadays, the vast majority of end connections are made through cable laying from a high-speed line to a user's apartment or office. This is the cheapest and most reliable solution, but if cable laying is not possible, then you can use the power electrical communications system available in each building. In this case, any electrical outlet in the building can become a point of access to the Internet. The user is only required to have a PowerLine-modem for communication with a similar device installed, as a rule, in the electrical control room of the building and connected to a high-speed channel.

Also, PLC perfect solution the last mile in cottage settlements and in low-rise buildings, due to the fact that the organization of alternative communication channels is 4 or more times more expensive than ready-made wiring.

PowerLine technology can be used to create a local area network in small offices (up to 10 computers), where the main requirements for the network are ease of implementation, device mobility and easy extensibility. Moreover, both the entire office network and its individual segments can be built using PowerLine adapters. There is often a situation when it is necessary to include in an already existing network a remote computer or network printer located in another room or on the other side of the building. This problem is easily solved with PowerLine adapters.

PowerLine technology can be used to implement the idea of ​​a "smart home", where all consumer electronics are connected into a single information network with the possibility of centralized control. Due to the fact that the PLC uses ready-made communications, PowerLine-technology can be used in the automation of technological processes, connecting automation units via electrical wires or other types of wires. Due to the fact that the PLC can operate on various wires (not necessarily electrical), it becomes possible to use the technology in security fire systems, as well as for organizing video surveillance systems.

There are also disadvantages: for example, the need to connect all LAN adapters to the same phase. They also include the disadvantage of the "bus" topology - the speed is shared among all devices on the network.

I will give an example of the implementation of the technology in the Internet provider's network. There are various options for implementing the technology.

I will tell you about one, perhaps the simplest. Connecting to Ethernet switches is not unusual. The PLC controller is installed in the box together with the switch on the house. They are connected to each other with a standard patch cord in 100Mb / s FastEthernet ports. The box, depending on the model of the PLC controller or Head End "a (hereinafter HE), may look different.

The PLC signal is transmitted over a coaxial cable, which, on the one hand, is connected to the NOT, and on the other, to the splitter. A splitter is a kind of adapter used to connect multiple NOTs in a house. Such a need may arise with a large number of connections or with high requirements for the bandwidth of the communication channel.

In the case of using several, DO NOT produce Power settings Mask with Signal Mode selection. The adoption of this measure is necessary to unambiguously determine the actual NOT for a specific CPE client. Otherwise, there will be a situation with CPE switching between HE, and hence re-authorization after each switch.

The number of switches is determined by the stability of the connection between HE and CPE. With the Signal Mode setting, it will not work out too much, there are only a few options, but the Power Mask can be configured quite flexibly. The engineer has a 256-bit data field at his disposal, within which it is possible to enable or disable work in a particular frequency spectrum. At this stage, we have two independent networks: the electrical and the data network. How do you get a network capable of transmitting data through the coveted environment? Here you cannot do without a device for "pouring" the PLC signal into the electrical wires. Such a device is an injector or, as it is also called, a coupler, and the "infusion" process is injection.

Special connectors are used to connect coaxial cables.

Ferrite beads can also be injected. Yes, they can be not only filters protecting from noise. It should be said here that not every ferrite is suitable, and installation is not as easy as we would like. As a result of mounting a ferrite ring, a signal is injected, but the result will be definitely worse than using a coupler.

After that, the end user can already access the network through the electrical outlet. But the key word here is "can." There are many factors affecting the signal strength and the ability to transmit data over the electrical network. They need to be identified by measuring the signal level at different parts of the network and eliminated in the most appropriate way. Usually this is a high level of noise on the lower floors, for example, a nine-story building, or strong noise in the section of the electrical circuit after the RCD (towards the consumer). In these situations, it is effective to use a shunt, which is a kind of "workaround" for the PLC signal transmitted in the mains. With a weak signal, additional injection can be made using the same ferrite ring or coupler. Ultimately, the connection diagram looks something like this:

In the dry residue

In conclusion, I will say that PowerLine technology is fraught with many pitfalls and is not as easy to implement and use as the manufacturer writes about it. This technology is quite well suited for use at enterprises to control automated lines. Building a local network at home using this technology is probably economically unprofitable, because one of the cheapest PLC adapters costs about 1,200 rubles. It should be noted that at least two devices are needed, which means that the amount of the solution already increases to two and a half thousand rubles, while there is no guarantee that such a network will work stably 24x7. But here, as they say, everyone decides for himself what is acceptable for him.

As for the use of Power Line in the provider's network, then, most likely, the PLC time has already passed. First of all, because 1-15 users can comfortably work in the network, then problems with the speed and stability of the connection may begin. Currently, the situation is NOT overloaded rarity, because most of the houses included in the network coverage area are connected via Ethernet technologies... PLC has one serious advantage: the service is ready to be provided to any potential client. What does it mean?

If we compare it with the same Ethernet, then the client must first leave a request, conclude an agreement for the provision of services, after which the installers will come, drill, stretch, crimp and it’s ready - the service can be used. The PLC is different. The client makes an application by phone, on the website, or through ICQ, after all, he can simply come to the sales office to conclude a contract and receive equipment. The installation of the equipment is extremely simple: you just need to plug the modem into a power outlet. After 10 minutes, the connection will already work (unless, of course, there are problems with the signal in the apartment). At the same time, the user does not even suspect that the modem establishes a connection with NOT, is authorized for RADIUS, is entered into the database, configuration parameters are assigned to it, formed in the form of a separate configuration file, which the modem downloads and uses. And only after that, the client equipment receives an ip address with which it can work in the network. From this point on, the equipment is considered to be installed. Subsequent connections behind the same HE are made in less than a minute.

If you use CPE behind a different HE (different address or different entrance), you will have to re-install the equipment. The process goes so smoothly that some users do not even know how many hundreds of meters of cables and various kinds of devices, from NOT to BGW, are behind their modem.

One day a client turned in and was annoyed at how it was, his internet connection did not work in his dacha. At home and with friends, everything works with his modem! And this is not an isolated case, there have been clients who even move to another city with equipment issued to them for temporary use. The request to hand over the equipment was answered, they say, there is no time, in addition, the client was going to continue using this equipment. The operator tried to convince the client to give the equipment back to the company, arguing that it was useless for him anyway, and it would not be possible to connect to the Internet there, in another city. The answer was filled with sarcasm: "There are sockets there too." Well what can I say ...

The advantages of PLC technology include the fact that the transmitter power is 75 mW, and this avoids the registration of equipment as radio frequency. Why is it important? We, mere mortals, should not forget about radio amateurs, whose interests are protected by law, and in case of infringement of the rights or noise of the selected radio frequency range, Rospotrebnadzor will stand up to protect them. You can write a separate large article about the existing battles and engineering solutions. I can only say that the ax of war is buried, the shaky peace is supported by the prompt response of engineers to requests from radio amateurs.

Now it is the turn of the disadvantages of the technology. In addition to the cost of the equipment, it is also the dependence on the number of CPEs working for one HE. This circumstance is determined by the bus topology of the network. Do not forget about high-frequency noises that appear in the network due to the inclusion of electrical appliances or when using switching power supplies, energy-saving lamps, etc. In some cases, you have to literally choose: either connecting to the network in the dark or without the Internet, but in a lighted room. Irony irony, but it all seems ridiculous until you have to face the problem face to face. In addition, the quality and speed of communication is negatively affected by the quality of the wiring, the presence of twists (reduction in speed until it completely disappears), the type, power of household electrical appliances and devices.

Hopefully, the material presented in this article will answer some questions, perhaps sparking a healthy interest in the technology.

Transmission of information over power supply networks using the IS of the Semtech company (2015)

The Semtech Corporation product line includes a variety of ICs physical layer, allowing to organize the transmission of information both by wire and by radio (optical transceivers, line drivers, radio transceivers, etc.). The acquisition in early 2015 of EnVerv, a leader in the development of PLC (Power Line Communications) modems, allowed Semtech to expand its communications product line with devices that exchange data over standard power lines. Within the framework of this article, we will focus on the principles of operation and construction of networks based on single-chip PLC microcircuits from Semtech, consider the features of individual representatives of the new family and give examples of practical implementation of devices based on them.

INTRODUCTION
The transmission of information and the organization of power supply over the same wires is used quite effectively in various applications. For example, you can recall standard telephone lines or Ethernet networks that connect remote nodes using a technology in which power is supplied through individual cores of a communication cable. However, most of these solutions have an obvious drawback: they all generally require installation work, the costs of which often make up a large part of the cost of setting up a network. Moreover, there are a number of situations in which the laying of new cables is extremely undesirable or even impossible - an example of such situations is a recently completed repair, after which it suddenly turns out that it is necessary to lay additional wires for computer networks or a rented office with an unintended Internet connection. In these cases, it is almost always possible to confine oneself to the existing infrastructure, namely, to use the electrical wiring already available in almost every room to organize a relatively fast and reliable communication channel branched out throughout the building.

PLC telecommunication technology, based on the use of power grids for data exchange by superimposing a useful signal over a standard alternating current with a frequency of 50 or 60 Hz, is distinguished by its ease of implementation and prompt installation of devices based on it. The first data transmission systems over electric grids appeared in the 1930s, they were mainly used for signaling in power systems and on railways, characterized by a very low throughput... At the end of the 1990s, a number of companies implemented the first large projects in this area, however, during operation, serious problems were identified, the main one of which was poor noise immunity. The operation of energy-saving lamps, switching power supplies, chargers, thyristor dimmers and household electrical appliances, as well as electric motors and welding equipment, especially those switched on in the immediate vicinity of the PLC modem, caused impulse noise in the wires unprotected from high-frequency radiation, which led to a sharp decrease in reliability data transmission. Also, the stability and speed of signal transmission was negatively influenced by the heterogeneity of communication lines, in particular, the quality and deterioration of electrical networks, the presence of joints made of materials with different electrical conductivity (for example, copper and aluminum), the presence of twists, etc. As a result, the overall reduction in the nominal data rate ranged from 5% to 50%. In addition, in the rooms where the PLC devices were operating, in some cases there was a violation of radio reception at a distance of about 3-5 meters from the modem, especially at medium and short waves. This was due to the fact that the wires of the power grid began to act as antennas for radio repeaters, emitting, in fact, all the traffic on the air.
The technology of data transmission over power grids received due commercial application only at the beginning of this century, and its introduction and widespread use is due to the appearance of an appropriate element base, incl. high-performance microcontrollers and fast DSP processors (digital signal processors), allowing to implement complex signal modulation methods and modern data encryption algorithms. This provided not only a high level of reliability in the transmission of information, but also its protection from unauthorized access. Also of great importance was the solution of the problem of standardization of various aspects of technology. Currently, IEEE, ETSI, CENELEC, OPERA, UPA and HomePlug Powerline Alliance are the main organizations and communities that regulate the requirements for PLC devices. The latter is an international alliance uniting about 80 well-known companies in the telecommunications market, including Siemens, Motorola, Samsung and Philips. The alliance, founded in 2000, aims to conduct research and practical testing of the compatibility of devices from various manufacturers using this technology, as well as support and promote a single standard called HomePlug.
All existing PLC systems are usually divided into broadband (BPL - Broadband over Power Lines) and narrowband (NPL - Narrowband over Power Lines). The range of tasks solved with their help is very wide, and the choice of the required method is based on the characteristics and volume of the transmitted information. Broadband devices (with speeds from 1 to 200 Mbit / s) are focused on Internet access systems, on the creation of home computer networks, as well as on applications requiring high-speed data exchange: streaming video, video conferencing systems, digital telephony, etc. Of greatest interest to hardware developers are narrowband PLC modems due to their relative cheapness and improved characteristics, which make it possible to operate not only in conventional networks, but also in networks with an increased level of interference. Microcircuits and modules for narrowband modems (with channel bandwidth from 0.1 to 100 Kbps) are widely used as part of various household and industrial products, when creating distributed automated control and management systems in workshops and building life support systems (elevators, devices air conditioning and ventilation), metering devices for the consumption of electricity, water, gas, heat, security and fire alarm devices.

FEATURES OF PLC TECHNOLOGY
The basis of PLC technology is the use of frequency division of the signal, in which a high-speed data stream is divided into several relatively low-speed ones, each of which is transmitted at a separate subcarrier frequency and then combined into the resulting signal (Fig. 1).

With conventional frequency division modulation (FDM), the available spectrum is wasted inefficiently. This is due to the presence of guard intervals between individual subcarriers, necessary to prevent the mutual influence of signals (Fig. 2a). Therefore, PLC devices use Orthogonal Frequency Division Multiplexing (OFDM), in which the centers of the subcarriers are located so that the peak of each subsequent signal coincides with the zero value of the previous one. As seen in Fig. 2b, the available frequency band in this case is spent more rationally.

Before being combined into a single signal, all subcarriers are subjected to phase modulation, each with its own sequence of bits. After that, they pass through the shaping unit, where they are assembled into a single information packet, also called an OFDM symbol. Figure 3 shows an example of Differential Quadrature Phase Shift Keying (DQPSK) for each of the four subcarriers in the 4.5-5.1 MHz range. In reality, in PLC technology, transmission is carried out using 1536 subcarriers with the choice of 84 best ones in the range from 2 to 32 MHz, depending on the current state of the line and the presence of interference. This method gives PLC technology flexibility for use in various conditions. For example, as mentioned above, a working PLC device is capable of jamming radio reception at certain frequencies, this problem is well known to radio amateurs. Another example is when an application is already using part of a range. Technically, the elimination of unwanted mutual influence is implemented by using settings, the so-called Signal Mode and Power Mask, on devices that provide the corresponding option. Signal Mode is a software method for determining the operating frequency range, and Power Mask is a software method for limiting the spectrum of the frequencies used. Due to this, PLC devices can easily coexist in the same physical environment and not noise the frequency ranges used for radio communication.

When transmitting signals over a household power supply, significant attenuation of the transmitted signal at certain frequencies can occur, which can lead to loss and distortion of data. To solve the problem of adaptation to the physical transmission medium, a method is provided for dynamically turning on and off signal transmission, which makes it possible to detect and eliminate errors and conflicts. The essence of this method lies in the constant monitoring of the transmission channel in order to identify the part of the spectrum in excess of a certain attenuation threshold value. If this fact is detected, the use of the problem band is temporarily stopped until an acceptable attenuation value is restored, and data is transmitted at other frequencies (Fig. 4).

Another significant difficulty in transmitting data over a household electrical network, now for the PLC devices themselves, is impulse noise, the sources of which can be various chargers, halogen lamps, turning on or off various electrical appliances (Fig. 5). The complexity of the situation lies in the fact that, using the above method, the PLC-modem does not have time to adapt to rapidly changing conditions, because their duration may not exceed one microsecond, as a result, some of the bits may be lost. To solve this problem, a two-stage (cascade) error-correcting coding of bit streams is used before they are modulated and enter the data transmission channel. Its essence consists in adding redundant ("guard") bits to the original information stream according to certain algorithms, which are used by the decoder on the receiving side to detect and correct errors. Cascading a block Reed-Solomon code and a simple convolutional code decoded by the Viterbi algorithm allows you to correct not only single errors, but also bursts of errors, which significantly increases the integrity of the transmitted data. In addition, anti-jamming coding increases the security of transmitted information from the point of view of protection against unauthorized access.

Since an extensive network of household power supply has been selected as the data transmission medium, several connected devices can start transmission at the same time. In such a situation, a regulatory mechanism is used to resolve traffic collision conflicts - the CSMA / CA Media Access Protocol. Collision resolution is based on one or another priority, which is set in special fields for prioritizing data packets.

SEMTECH IC FOR PLC TECHNOLOGY IMPLEMENTATION
Semtech PLC products are designed for use on typical low or medium voltage power lines. Any modem that works with an analog physical line must have the functional units necessary for processing analog data, converting it to digital form, and, of course, for processing digital data. On the transmission side, the modem must also encode digital data in accordance with the specified algorithm, convert it to analog and send it to the line.
All these actions are performed by the EV8xxx series microcircuits. System-on-a-chip narrowband ICs are highly integrated and contain all the necessary building blocks to implement the physical, MAC, and other protocol layers (6LoWPAN and IEC). They support several types of modulation; in practice, OFDM is most often used to organize a stable and noise-free communication channel. The SICs that have passed interoperability testing in the HomePlug Alliance Netricity are versatile and can be used as the basis for both endpoint and network coordinator designs. The Netricity specification is designed for network communications over long-haul power lines and is intended for off-building infrastructure, smart power distribution and industrial process control. The technology can be used in both dense urban and rural power grids using frequencies below 500 kHz. It also includes an IEEE 802.15.4 (MAC) -based access layer, which is key to the development of hybrid wired / wireless networks. The main technical characteristics of Semtech PLC microcircuits are presented in Table 1.

The EV8xxx series ICs have programmable frequency ranges from 10 to 490 kHz, covering CENELEC A (10 - 95 kHz), CENELEC B (95 - 120 kHz), CENELEC C (120 - 140 kHz), FCC (10 - 490 kHz) and ARIB (10 - 490 kHz) bands without changes in the design of the device. They can be configured to operate in ITU-T G.9903 (G3-PLC), ITU G.9902, ITU-T G.9904 (PRIME), IEEE P1901.2 and IEC-61334 (S-FSK). In addition, they support the proprietary high-performance 4GPLC mode. Structurally, the microcircuits of the family are manufactured in low-profile surface-mount cases designed for operation in the operating temperature range from -40 to + 85 ° C. Simplified structure depicting the main functional units is shown in Fig. 6, the following blocks can be distinguished here:
The AFE (Analog Front-End) block is a set of analog components that provide isolation using a transformer with a decoupling capacitor, filtering and amplifying the input signal, and shaping the specified levels of the output transmitted signal using the line driver on the op-amp;
PHY is a block designed to interface the digital part of the microcircuit with an analog line;
32-bit RISC microcontroller provides in-circuit implementation of the MAC-level, performs data processing, packet formation, data encoding according to the symmetric AES block cipher algorithm, etc., and also solves applied problems;
Peripheral blocks that interface the built-in microprocessor with external microcircuits - EEPROM memory, ADC with high resolution and a host controller. For communication, the hardware implementation of the widespread SPI, I2C and UART interfaces is used;
Integrated RAM and flash memory. The size of the built-in program memory varies from 1 to 2 MB, the operative memory - from 256 KB for the EV8100 to 384 KB for the rest, other options are possible upon request to the manufacturer;
Clock control unit;
A power subsystem that provides all the voltages required for individual nodes. Typically, a source is used that operates on the same AC mains as used for data transmission.
Separately, it is worth noting the EV8100 IC, which, in addition to typical units, contains an integrated controller for a 6x33 segment LCD display and a touch keyboard driver.

APPLICATIONS FOR EV8XXX FAMILY ICs
Semtech PLC microcircuits are focused primarily on use in automation systems, remote control and control of remote objects, the most popular areas of their application:
Building Automation Networks (AMI);
Landing light control systems at airports;
;
Home local area networks;
Intelligent equipment (“smart things”), incl. consumer electronics;
Control and management systems for solar power plants;
Street lighting networks;
Communication equipment with substations;
Traffic management systems.
Among the above, the main focus is AMI (Smart Metering Infrastructure) networks that integrate smart meters, data concentrators, energy management tools, displays and other components of building automation systems (Figure 7).

Power line communication is the main element automated systems control and accounting of energy carriers used by utilities. The main advantages of this technology: the ability to automatically receive information from residential and industrial premises located in remote areas with low population density and low quality infrastructure, long service life, scalability and low costs. The principle of the system is quite simple. Electricity from the power plant is transmitted through a high-voltage cable to the substation. Here, the voltage is reduced and distributed to a large number of low-voltage transformer substations, which reduce the voltage to the household one. Typically 500 to 1000 end users are connected to one transformer. Thus, the following option for constructing PLC systems for these purposes can be proposed: a concentrator acting as a central unit is based on low-voltage substations and regularly (for example, once an hour) collects measurement results from meters (these can be not only electricity meters, but also water, heat, gas). Then the information is sent to the server for further processing, for example, via the GSM channel. This type of system is not limited only to receiving information from meters and can perform other functions.
For the practical implementation of this system, Semtech offers a developer starter kit that includes both ready-made solutions based on the EV8000, EV8100 and EV8200 microcircuits for the fastest organization of data transmission over the PLC network, as well as debugging tools for assessing the system's capabilities (Table 2).

The latter are modules for end nodes (meters) and hubs, the delivery set of which includes everything you need, including recommendations for use, as well as software for configuring the parameters of individual nodes and monitoring the quality of communication in the projected network. The accompanying graphical user interface allows you to program the operating frequency range, modulation type, transmission rate, output power level, etc., as well as visually track the PER and BER error rates in the received data packets.
Debug kits EVM8K-01, EVM8K-02 and EVM8K-03 can act both as remote measurement nodes and as data collection hubs. The modules are designed for operation in single- and three-phase networks; they are powered from a built-in 80-280 V AC source (EVM8K-01 and EVM8K-02) or from a 12 V DC supply (EVM8K-01 and EVM8K-03). Communication with the host controller is carried out via RS-232 or USB interfaces. The EVM8K-13 kit is a network hub that combines an EV8000-based PLC modem with a 32-bit RISC microcontroller on a single PLC card to run a custom application. The set is capable of servicing up to 500 end nodes (up to 2000 optional), among the distinctive features we can note the presence of a “onboard” 3G / EDGE / GPRS modem, GPS module and 8 GB SD card. In addition to wireless data transmission to the server, you can also use the RS-232, USB or Ethernet interfaces. Appearance development kits are shown in fig. eight.

CONCLUSION
The widespread use of low-voltage electrical networks 0.22-0.38 kV and the absence of the need for costly installation work for laying cables stimulate an increased interest in electrical networks as a data transmission medium. The current development of PLC technology is largely associated with the emergence of generally accepted regulatory standards and the improvement of the corresponding element base. Semtech's PLC modems, featuring a high degree of integration, provide a stable and interference-free communication channel with a sufficiently high bandwidth.

BIBLIOGRAPHY
1. Okhrimenko V. PLC-technology. // Electronic components. 2009. No. 10. With. 58-62.
2. Official website of the Semtech company. www.semtech.com
3. Product brochure. EV8000: Single-chip multimode PLC modem.
4. Product brochure. EV8010: Single-chip standards-based PLC modem.
5. Product brochure. EV8020: Single-chip standards-based PLC modem.
6. Product brochure. EV8100: Split-meter display SoC with integrated PLC.
7. Product brief. Power line communication products.