Home Encyclopedia Dictionaries Read more

Electromagnetic compatibility of radio-electronic means (EMC RES)

The ability of the radio electronic agent (RES) to function in real operating conditions with the required quality when exposed to unintentional interference, without creating radio interference to other RES of the group of troops. The EMC problem is primarily with the features of the operation of the RES, which, as a rule, includes three main elements - a radio transmission, radio and antenna-feeder device. In this case, a radio transmitting device is intended for generating, modulation and amplification of high frequency currents, a radio reception device - for selection, conversion, amplification and detection of electrical signals, and an antenna feeder device - for radium and selection of electromagnetic oscillations of the radio band, as well as their conversion to electric currents .

Each of the named elements of the RES influences EMC in its own way. The radio transmitting device, which is the source of radio emission, is characterized by the following parameters: frequency, spectrum width, power, modulation type. In the radiation structure of the radio transmission device, the following types of radiation are distinguished: the main, out-of-band and side.

Taking into account the selected types of radiation, the main parameters of radio transmitting devices that affect the EMC are: the main radiation power, the width of the main radiation spectrum, carrier frequency (central frequency of the main radiation spectrum), operating frequency range, transmitter stability, frequency (bandwidth) and levels Overseas and side emissions, etc.

The contribution of the radio receiver in the RES EMC problem is determined by the presence of various reception channels, both signals and interference.

Maintain the main reception channel (the minimum frequency band in which it is possible to provide high-quality (reliable) reception of the message with the required speed) and non-core receiving channels, which in turn are divided into adjacent (frequency bands equal to the main channel and directly adjacent to its lower and top borders) and side (frequency band outside the main reception channel, being in which the signal or interference pass on the output of the radio receiver). The presence of non-core receiving channels is determined not only by the parameters of the element base of the receiving path, but also the principles of constructing a radio receiver.

From side channels of reception, the so-called mirror canal is most famous. This reception channel is the mandatory affiliation of super-metrogenous receivers. A distinctive feature of the mirror channel of reception is the same sensitivity with the main channel.

The main parameters of the radio receiving device that affect the EMC are: sensitivity, operating frequency range, bandwidth, the value of the intermediate frequency, selectivity, the value of weakening over the mirror channel, etc.

Considering the antenna-feeder from the point of view of their effect on the EMC, we note that it solves the problem of spatial, polarization and to a certain extent frequency selection of radio waves. In this case, spatial selection is carried out by the directional properties of most types of antennas, which are characterized by the dependence of the level of radiated or received radiation from the direction. This dependence is called a radiation chart. As a rule, the directional diagram has the main and lateral petals of radiation (reception).

The capabilities of the antenna systems on polarization selection are determined by its type, for example, a pin antenna forms (accepts) electromagnetic oscillation with vertical polarization, spiral - with circular.

The frequency selection of the antennas is determined by the dependence of its parameters from the frequency of emitted or converted radio emission. The parameters of the antenna-feeder devices that affect the EMC are: the width of the radiation diagram, the level of lateral petals, the working range, etc. It should be noted that many of the above parameters constitute the tactical and technical characteristics of the radio transmission, radio and antenna-feeder devices.

Thus, even one RES has a large number of parameters and characteristics defining its EMC, and to ensure the normal joint functioning of dozens of different RES on one object or hundreds and thousands of RES in the grouping of the troops is a major task.

In general, the task of determining the degree of achievement of EMC in a specific situation is reduced to solving two private problems: external and internal (in relation to this RES) .

External task lies in evaluation of the electromagnetic situation (emo) at the point of the receptor receiverdefined as a set of parameters of useful and interfering signals at the receptor input. At the same time compiled statistical model Emo., which, along with constant parameters (PS and MS frequency disorders, their average power values, etc.) includes all probabilistic parameters of useful and interfering radio signals, taking into account the statistical nature of their formation and distribution: the random of the parameters of the modulating signals at this formulation, Fast and slow fading useful and interfering radio signals, possible nonlinear effects in the receiver at elevated levels of radio signals at the receiver input). Internal task is to quantify the degree of impact of unintended interference on the quality of the functioning of the RES . The solution of the internal problem is usually done using the methods of statistical radio engineering and the statistical theory of optimal reception of signals developed in relation to cases of exposure to unintended interference, taking into account the need to provide EMC RES.

The decision on whether the EMC has been achieved by the Sobuity of the RES, must be taken on the basis of admissibility or inadmissibility. calculated percentage of place-passable reduction in the quality of the functioning of radio receivers of all RES in this emo due to the effects of interfering signals. It follows the three-stage scheme for solving the EMC Evaluation Task:

Stage 1.. The task is solved evaluation Emo. . As noted above, its source data are geographical and energy characteristics and parameters of sources of useful and interfering signals. The result of solving this problem is the quantitative deterministic and probabilistic characteristics of useful and interfering signals that affect the receiving device of each RES. At the same time, the combination of interfering signals potentially dangerous in relation to the impairment of EMC and requiring a quantitative analysis, called noise atmosphere.

Stage 2.. The task is solved estimates of the deterioration of the quality of reception of the useful signal due to the influence of unintentional interference. The source data for its solution are the results of solving the task of the first stage. The result of solving the task of the second stage characterizes the degree.

Stage 3. According to the results of solving the task of the second stage produced evaluation EMC RES. Based on the exceeding or unacceptable values calculated on the selected EMC criterion percentages of the time-step reduction of quality operation of radio receivers all RES.in this emo, due to the impact of interfering signals.

Evaluation EMC RES.can be made by various methods:

1 / settlement;

2 / experimental - based on measurements of a number of parameters of interacting RES;

3 / mixed (combination of settlement and experimental methods).

Estimated EMC Evaluation Methods Used when solving the following tasks:

Predicting the electromagnetic situation;

Promising planning and efficient use of radio frequency spectrum;

Preparation of materials for conclusions (solutions) on the right to use certain frequency bands;

Determining the degree of provision of EMC RES;

Assessment of the degree of influence of unintentional interference on the quality of the functioning of the RES;

Evaluation of the effectiveness of measures to provide EMC RES;

Development of the norms of the frequency-territorial separation between the RES.

Given the importance of solving the EMC tasks, in many countries, including in Russia, there is a whole system of regulatory documents (state standards, norms on transmitter emission parameters, etc.), which regulate the main characteristics and parameters of the RES affecting their EMC . The most important regulatory documents of this kind include the following:

GOST 30372- 95. Compatibility of technical means electromagnetic. Terms and Definitions;

GOST 23882-710. Electromagnetic electron electronics compatibility. Nomenclature of parameters and classification of technical characteristics;

GOST R50842-95. Devices Radio Protection of National Equipment. Requirements for side radio emission. Measurement and control methods;

GOST R 51319-910. Compatibility of technical means electromagnetic. Instruments for measuring industrial radio interference. Technical requirements and test methods.

GOST R 51320-910. Compatibility of technical means electromagnetic. Industrial radioometers. Methods of testing technical means - sources of industrial interference;

Norms 19-02. Norms on the width of the radio frequency band and out-of-band radiation of civilian radio transmitters.

1.5 General ECC Methods

Ensuring EMC in practice is achieved by the implementation of a complex of mandatory for users of the radio spectra of organizational and technical measures established and controlled by the relevant government agencies:

a) centralized distribution and allocation of frequency bands to various radio services;

b) scientifically based on the use of radio spectra;

c) strict control of the implementation of regulatory indicators of EMC (in particular, the restriction of the power of radio emission in certain directions).

One of the most important technical ways to achieve EMC RES is to ensure the frequency-territorial separation (CT) of these RES. CTR is a combination of frequency separation (CR - the difference in operating frequencies of PS and MS transmitters) and the minimally necessary territorial separation (TR) of each of the transmitters of interfering signals relative to the receptor. The tr for each interfering transmitter depends, in particular, and on the set of parameters RM, and the so-called "situational plan" (Fig. 1.8).

Figure 1.8 adopted the following notation: PRS - radio station of the main (useful) radio system (SRS) exposed to MS from another RES; MRC is a radio station of a preserving SRS, which is the source of MS for the PRS considered; RC - the length of the distribution route of the PS; RM - the length of the distribution route of the MS; F PD with a piece of PS; Bottom - antenna directional diagram; MS - a moving radio signal; j. M is the Angle of MS; F PD M - frequency MS ;; a. M - Outcome angle MS.

In addition to general organizational and technical measures, various

special technical means reducing the impact of MS on the quality of the PS reception by reducing the level of MS at the receptor input or weakening the effect of MS on the quality of reception through the use of interference compensators. Consideration of such funds was conducted in chapter 10.

Fig.1.8 Watching the obstruction plan when exposed to one interfering signal

The general methodology for analyzing the EMC RES, which includes a general analysis algorithm for an EMC analysis, preparation and primary analysis of the initial data for an arbitrary complex case of EMO, an algorithm for verifying the implementation of the EMC for each of the interaction in this emo, examples of the calculations of the EMCD, various options and a list of references containing a large number of necessary For calculations of ITU-R recommendations, given in.

A constant increase in the density of the placement of radio-electronic means with a limited frequency resource leads to an increase in the level of mutual interference that violates the normal operation of these funds. The dense placement of the RES and their antennas leads to the fact that the electromagnetic fields emitted by radio transmitter antennas can create high-frequency emfs in the antennas, which can create an overloading of input cascades and a violation of the normal functioning of radio receivers (RPM) or even failure.

When analyzing the intra-scale electromagnetic compatibility, the following types of estimates are used:

1) Pair.When pairwise estimates, EMC consists of the effects of a radio transmitter (RPD) of one RES on the RPM of another object.

2) Group. In group estimates - the accounting of the interference effect of all RPDs per RPM object

3) Comprehensive. With a comprehensive assessment of the EMC, the compatibility of each of the RES of the object with all other RES of this object is analyzed.

EMC RES object is calculated in the following order:

1) determination of potentially incompatible steam RES,

2) the calculation of the energy characteristics of unintentional radio interference,

3) Determining the degree of provision of EMC.

Based on the frequency analysis, sources and receptors of radio interference are determined. The calculation of the energy characteristics of radio domain provides for the determination of the power of the total radio interference given to the entrance of the RPM, taking into account the penetration of radio interference through the antenna-feeder path.

The degree of provision of EMC RES of the object is based on a pair or group assessment of EMC.

Order of conduct pair assessment EMC RES:

1) determine the power p ij of an unintended radio interference given to the input of the i-th RPM, from the jth interfering RPD;

2) analytically determine the permissible power P I is an extra-impaired radio interference at the input of the i-th RPM from the JT RPD;

3) compare the power level of the radio interference, in dB, at the input of RPM with permissible and determine the degree of EMC provision, which is determined by the indicator

(1)

Group Evaluation EMC RES is carried out according to the following algorithm:

1) the total power P Iς of the radio domain given to the input of the i-th RPM, from the RPD of the object;

2) analytically determined the permissible power of P i additional radioometers at the input of the i-th RPM of the estimated RES;

3) compare the level of the total radio cell power with a permissible level and determine the degree of provision of the EMC of the receiver of the estimated RES with the RPD of the remaining RES of the object.

The indicator of the EMC of the RES of the object, in dB, with a group estimate is determined by the formula

(2)

The values \u200b\u200band in decibels are characterized by the degree of stock of the EMC (if it is positive) or the degree of failure of the EMC provision (if it is negative).

A comprehensive assessment of the EMC RES is the most difficult and in practice is rare.

Technical parameters of RES affecting their EMC

The main normalized technical parameters defining the EMC RES are:

1) For radio devices:

· Power carrier RPD;

· Strip width of the main radiation frequencies of the RPD;

· Deviation of the carrier frequency of the RPD of the transmitter from the nominal value;

· The level of out-of-band radiation (V) of the RPD;

· The level of spike radiation (PI), including the intermodulation radiation (s) of the RPD;

2) For radio receivers:

· RPM sensitivity, which characterizes the ability of the receiver to take weak signals, i.e. The level of the received signal in which the transmitted information can be reproduced with satisfactory quality;

· The selectivity of the RPM along the neighboring channel (SC), on the side channel of the reception (PCP), intermodulation;

· The radiation level of RPM heterodynes, which characterizes the possibility of radiation of the receiver's interference at the frequencies of heterodynes and their harmonics.

In addition to the normalized parameters of transmitters and receivers, the EMC RES affect:

· Focusing diagram (DN) when radiation and reception at working frequencies;

· DN at the frequencies of uncomplicated and side radiation of the RAP;

· DN at the frequencies of neighboring and side channels of the RPM receiver;

· Temporary mode of operation of the RES to radiation and reception.

Due to the technological imperfection of the RPD, their radiation spectrum, in addition to the basic radiation (OI), contains unwanted out-of-band and side radiation, outside the required frequency band.

TO side radiation relate:

· Radio emission on harmonic;

· Radio emission on the subharmonic;

· Radio radio emission;

· Intermodulating radio emission.

Due to the non-idealness of the RPM parameters, in addition to the main reception channel, have a large number of non-core channels - adjacent and side, which are not intended to receive a useful signal. The side channels of the reception include channels that include intermediate, mirror, combination frequency and harmonics of the RPM settings.

Due to the insufficient selectivity of the RPM, a hindrance is possible on the neighboring channel of reception, the interference caused by the blocker effect and the effects of heterodyne noise transfer to the intermediate frequency path of the receiver. The blocking effect is manifested as a change in the C / W ratio at the output of the RPM under the action of a radio interference at its input, the frequency of which is in the frequency band, ranging from the frequency of the adjacent channel to the frequency, on which the level of weakening interference with adjacent RPM contours is -80db. The effect of heteroodine noise transfer is to convert part of the energy spectrum of the noise of heterodyne RPM with a width equal to the transmission band of the PC RPM path, in the intermediate frequency and the noise in the HDM path in the form of noise energy.

When exposed to nonlinear elements of two or more radiopomes, an intermodulation interference may occur in it, causing the appearance of a response at the RPM output, as well as cross-distortion - a change in the spectrum of the useful radio signal at the RPM output when there is a modulated radio interference.

Signs of passing radio interference through an antenna for the observed effect at the exit of the RPM are:

· Complete disappearance of noise at the exit when disconnecting an antenna from RPM and connection instead of an antenna equivalent;

· Changing the level of interference synchronously with a change in the direction of the interference receptor antenna at a fixed antenna of the source of interference;

· The essential dependence of the level of interference from the type of antenna used or its location on the facility;

· Significant reduction in the level of interference with full or partial shielding of an antenna reveal.

Signs of interference through the RPM screen are a significant increase in noise at the RPM output with an artificial deterioration in the quality of its shielding and on the contrary - a decrease in interference when improving the scheduling quality. These effects can be achieved by the following techniques:

· Partial or complete removal of the chassis from the casing when connecting RPM through extension cables;

· Road with RPM in an additional screen.

To determine the type of interference, the following provisions should be guided by the nature of their interfering effect:

· Interference caused by uncommon radiation of the RPD are perceived as an increase in the level of noise at the RPM output;

· Interference caused by side radiation of RPD and caused by the presence of side channels of receiving RPM are perceived as inadvertent (complicated) MODULATION OF RPD - source of unintentional radio interference;

· The effect of the RPM blocking is manifested in simultaneously decreasing the level of the useful signal and noise (industrial radio interference) under the influence of interference. Hindrance as it suppresses (blocks) a useful signal, and the modulation of the radiocher-source of the source of the RPM output is not auditioned;

· Intermodulation intermodulation is usually listened to the yield of RPM parsing as the modulation of one of the RPD source operating at the same time.

The radio frequency spectrum is a valuable state and international resource. The tasks of rational use of this resource are reduced to providing electromagnetic compatibility (EMC) and are becoming increasingly important in the increase in the number of radio-electronic means used (RES).

The work of the RES grouping on a common territory can lead to a violation of the EMC conditions, which will lead to mutual interference. An interference may occur as a result of side radiation, intermodulation effects, non-ideal parameters of transceiver equipment and antennas.

A comprehensive study by specialists of OJSC "Hypospanity" will allow pre-identify potentially interference situations and provide possible paths to solve them. Studies are conducted within the framework of theoretical and practical studies.

To solve the EMC problem in OJSC "Hypospide", specialized software, digital market cards and measuring equipment are applied.

EMC RES located on one object

When placed on one object, a plurality of receiving and transmitting antennas of radio-electronic means (RES) becomes an urgent problem of studying the conditions of electromagnetic compatibility.

An example of a dense placement of antennas is the masts, roofs of high-rise buildings and other high-rise objects, which are simultaneously installed RES antennas for various purposes and operating in various Radio frequency spectrum bands: Cellular Moving Radiocommunication Systems, UMTS, CDMA2000 and LTE, WiMax Broadband Systems (WiMax 802.16 D / E), Wi-Fi and Canopy, broadcast transmitters (analog and digital), radio relay stations, special purpose RES and other RES.

Causes of interference:

• insufficient weakening of the uncomplicated and side radiation of RES transmitters;
• insufficient selectivity of RES receivers;
• insufficient linearity of the amplitude characteristics of transmitting and receiving paths of the RES;
• the formation of intermodulation products in nonlinear sites of amplitude characteristics of transmitting and receiving tacks in the interaction of many different signals;
• the occurrence of electromagnetic communication between the elements of the RES antennas in the working bands of the radio frequency due to the characteristics of their designs and materials;
• blocking the receiving path of the RES when performing the above conditions and presence of a powerful transmitter.

The emerging mutual interference may worsen the parameters of the quality of the RES function or even block the receiving paths.

By customers, we offer comprehensive studies of the conditions for the implementation of the EMC RES located on one object, including theoretical calculations and torture measurements.

Theoretical studies are based on the computational methods of electrodynamics, the theory of the antennas and the propagation of radio waves, the theory of digital radio communications, the theory of radio transmission and radio receptions.

Using information on the type and design of the antennas, the architecture of the mast (roofs) and the nearest metal structures based on the computational methods of electrodynamics, we perform modeling electrodynamic parameters characterizing the electromagnetic bond between the elements of the antennas of various RES, their radiation chart and gain coefficients. Next, using this data, we perform the calculation of the total power from all transmitting RES, which are within the object, at the input of each receiver.

If necessary, theoretical studies can be supplemented with practical measurements using modern vector generators and spectrum analyzers. Based on the results of theoretical and practical studies, the Customer transfers the conclusion on the implementation / violation of the criteria for noise immunity of receiving RES tractors and recommendations to eliminate interference situations.

We apply to the methods of studying the conditions of the EMC RES, located on one object in close proximity, allow you to identify potentially dangerous interference situations and determine the possible ways to eliminate them.

EMC Grouping RES.

Due to the continuous increase in the number of new RES of civil and special purpose, ensuring the conditions of the EMC RES becomes a relevant and important practical task.

At the construction stage of new fixed and mobile radio networks, as well as the introduction of new RES, in addition to the already available grouping, specialists of OJSC "Hypospide" perform project work to ensure electromagnetic compatibility conditions.

Considering that the radio frequency spectrum is a valuable state and international resource, to determine the directions of state policy in the field of communications industry, specialists of OJSC Hypospide are carried out by research work on the analysis of the revolution of the radio frequency spectrum, as well as the conditions for the implementation of new radio communications technologies.

To solve the EMC tasks, specialized software, digital terrain cards and measuring equipment are applied to JSC Hypospide. Software allows you to calculate EMC based on the main technical parameters of the RES using digital location maps based on the developed methods and recommendations of ITU-R:

• service and interference zones for RES Grouping;
• group noise effect on RES;
• duel noise situations in all possible interference penetration channels.

An example of an EMC analysis in a duel situation

Example of calculating the interference zone from the RES grouping

According to the calculations, a list of measures to eliminate interference has been developed.

When working with outdated radio-electronic specials, special purposes often have been encountered with the lack of information on the technical specifications of the RES required for EMC calculations.

In cases where the criteria for noise immunity, it is not possible to determine theoretically, a specialized hardware and software complex (AIC) is used. The apk allows you to generate and measure radio communication radio signals: GSM, UMTS, LTE, CDMA 2000, Wi-Fi, WiMAX, APCO, DECT, ZIGBee, Bluetooth, to interfere with the PES-receptor inlet and get experimental through the criterion of noise immunity. In addition, our APC also allows you to generate special purpose RES signals: radar, delayer, altimeters. The key feature of the APC is the ability to simultaneously generate a set of signals of various technologies.

Customers we carry out the following types of work:

• solving the problems of electromagnetic compatibility of radio-electronic means of various purposes;
• frequency-territorial planning of fixed and mobile radio networks;
• solving the problems of electromagnetic compatibility of the RES in one object;
• electromagnetic compatibility of communication satellite networks;
• analytical work on the use of the frequency resource in the world and the Republic of Belarus.

EMC Satellite Communication Networks

Currently, a project is currently developing a project for the implementation of national satellite communications networks and broadcasting on a geostationary orbit, which will allow the Republic of Belarus to submit telecommunication services at the new level. This will provide the population with information independence, modern communication both on the territory of the Republic of Belarus, and beyond, providing physical and legal entities to a wide range of services (digital satellite broadcasting, data transfer, etc.), as well as obtaining economic benefits from passing Rent a satellite resource.

In early 2011, the question of attracting investments to create a national satellite communications system and broadcasting was initiated. One of the most important issues of creating a national satellite communications system and broadcasting is the issue of the workability and use of the orbital resource (witness), its protection at the international level.

OJSC Hyprosvyaz, specialists conducted a study of the possibility of using witness in national interests.

Creation studies were conducted in positions 37.8 ° V.D., 51.5 ° V.D. and 64.4 ° V.D. As the most relevant to implement the national system of satellite communications and broadcasting. The perspective directions for expanding sediments in these positions are considered, work on the coordination of the stated witness.

To ensure international legal protection of the Republic of Belarus, OJSC Hipposzemage is being drawn by the formation of international Circulars Br IFIC for the need to coordinate new geostationary satellite networks with the already declared networks of the administration of the Republic of Belarus.

Electromagnetic compatibility - This is a set of conditions under which radio-electronic means (systems) can perform their functions without experiencing an invalid deterioration in the basic characteristics when exposed to other radio-electronic means and radiation, in turn, without causing an invalid deterioration in other RES.

If you get interfering signals to the receiver, they are processed in the same way as useful signals reflected from the target would be treated. The images created by the interference on the screen of the indicator may have a regular form if they appear from a single source, and may seem fixed or moving depending on the ratio of the recurrence frequencies of two or more radar.

No electromagnetic compatibility can lead to a decrease in the detection range and deterioration of the image on the RLS indicator.

Events used to improve electromagnetic compatibility and interference suppression:

1. Filtration:

- filters are used to suppress the harmonic signal;

- Reconflated strip filters (preselectors) that have a bandwidth so close to the bandwidth of the receiver, as far as the accuracy of the pairing and manufacturing methods allows. The premistor is designed to attenuate all unwanted energy outside the bandwidth of the receiver;

- Locking filters with fixed settings are used to reduce the effect of strong interfering signals expected on both sides of the receiver setting range.

2. Corner selection, i.e. turn off the receiver or transmitter for a while until the antenna is focused in the specified sector of space. Although such devices can eliminate interference from radar or radio-electronic tools in a given zone, all information about the objectives in this zone is also lost.

3. Blancation device lock the receiver at the time of waiting for the coming of the interfering pulse. The effect of these devices is based on a priori knowledge of the appearance of interfering impulses, such information usually comes on special chains of filing the locking pulses.

4. Discriminators of the pulse repetition frequency, i.e. Devices eliminate pulses of a repeat period of which are differ from the period of repetition of radar pulses.

5. Duration discriminators pulses ie. Devices eliminate pulses of the duration of which differs very different from the duration of radar pulses.

6. Perestroika RLS frequency in range. This is the most effective means of achieving compatibility under conditions of high loading density of the operating frequency range.

7. Reducing lateral petals, to eliminate interference penetrating into the receiver through side petals of the antenna.

8. Compensation of non-directional compensation antenna with small efficiency, working together with the main antenna. Signals from both antennas are fed to individual receivers, and the output signals from these receivers are compared. If, when compared, the signal in the channel of the compensation antenna was higher than in the channel of the main antenna, then it is suppressed. The presence of adjustment of the amplification in the channel of the non-directional antenna allows you to adjust the degree of suppression of the sides of lateral petals.

9. Joint RLC synchronization to prevent damage to the input chains of receivers, in this case all RLS operating in the zone with a high density of the RLC placement will radiate pulses simultaneously.

10. Formation of radiated pulses i.e. Application in various radar pulses of various modulations.

Output:Analysis of radio-electronic means, the use of which is expected to be treated with the new radar, as well as the accounting of the possible mutual influence between the new radar and existing systems is an important aspect of the systemic approach in the development of radio-electronic systems.