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Information network for continuous electromagnetic fields monitoring.

1 INTRODUCTION

The rapid technological progress of the man-made electricity sources has also multiplied sources of electromagnetic fields (EMFs), diversifying their characteristics. The exposure to EMFs has been increased dramatically due to the increased demand for electric power and wireless communications. As a result, almost all human population is now exposed to the EMFs produced by power lines, radio and TV broadcast facilities, mobile telephones and their base stations, the variety of wireless technologies systems and household electrical appliances. In those systems EMFs frequencies vary between 0 Hz to 300 GHz (1).

Potentially constant exposure has caused an alert in public opinion and governments about the so-called the environmental electromagnetic pollution. At present, the definition of EMFs level's precise limits is still searching, regarding to how the exposure to those fields may increase the risk of some adverse health effects.

The European Council Recommendation on limitation of exposure of general public to EMFs (2), fixes the basic restrictions and reference levels for the exposure of general public to EMFs. These basic restrictions and reference levels are based on the guidelines published by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) (3).

The Government of the Republic of Serbia and Ministry of Environment, Mining and Spatial Planning (4), already adopted and implemented some of the ICNIRP's guidelines and recommendations, trough the national "Law on non-ionizing radiation protection" (5). The law and some other regulations controlling the non-ionizing radiation exposure (6-8), establish the legislation framework for investigation, monitoring and control of the EMFs level in the environment.

According to the law, the systematic testing of the non-ionized radiation levels in the environment will be performed in accordance with the national "Program of systematic testing of non-ionizing radiation in the environment" (9). The Program set up the foundation for systematic and continuous EMFs investigation (10), and our research team proposed an information network (11-13), as a support for automatic monitoring of the overall EMFs level in a non-ionizing radiation range.

The proposed system is able to monitor all EMFs emitting sources, over the territory covered by the sensor network, on a day by day and 24 hours a day base. The system collects the EMFs data and compares them with the legally prescribed limits of exposure (7). Through the Internet network, the results are instantly available, providing information to the relevant institutions in the area of the environmental protection against the electromagnetic pollution (4,14), produced by a number of EMFs sources.

The proposed system is capable to constantly provide investigation and monitoring of the EMFs. Therefore, it is a significant support in efforts to take systematic care about potentially dangerous effects of non-ionizing EMFs on the population health, taking into account their concern about the long-term exposure to non-ionizing radiation.

In this paper, some of the main points of project that develops an information network for continuous monitoring of the EMFs are presented. In Section 2, basic concept of the proposed system is given, while Section 3 describes its benefits. In Section 4, a few cases of possible utilization are presented, while Section 5 presents conclusion of the paper.

2 DESCRIPTION OF INFORMATION NETWORK

The project develops an information network, based on the wireless sensor network, consisting of:

a) autonomous sensors, spatially distributed to monitor the EMFs total level, over supervised territory,

b) central control station (CCS), which coordinates activity of remote sensor elements, collects, processes and stores data obtained by monitoring,

c) communication network, that provide connection and communication between sensors and CCS,

d) software package that manages and supports the information network flow.

The proposed system is designed to continuously, day by day, investigates the EMFs for the low frequency range applications (magnetic field), as well as for high frequency applications (electric field), as it is shown in Fig. 1.

[FIGURE 1 OMITTED]

The proposed network is able to perform investigation for a number of sources, that can be found in power system and system for the power transmission (transmission lines, distribution and substation equipment), through a system of radio and television broadcasting, to the wireless communication networks (like GSM, UMTS or Wi-Fi), as shown in Fig. 2.

[FIGURE 2 OMITTED]

Communication with remote sensors is performed via a communication network (15), which relies on the existing GSM mobile phone networks. Thus, the proposed system and sensor network possess a high degree of mobility, which is required in order to set up this system to cover any area of interest, as shown in Fig. 3.

[FIGURE 3 OMITTED]

The data obtained from the sensors, are collected in a centralized CCS database and will be available through a user-friendly web portal and Internet network. The web portal will present results of investigation for each sensor, showing the overall level of EMF, from all sources surrounding the sensor, as shown in Fig. 4.

[FIGURE 4 OMITTED]

The wideband monitoring systems are sometimes more attractive then the selective ones. On the other hand, the growing number of mobile communication installations triggers the public requirements for discrimination between the fields generated by different services. Thus, the proposed monitoring system implements sensors (16-18), capable to provide multi-band monitoring, as shown in Fig. 1.

Main characteristics of the sensor's field probes are presented in Table 1 and 2.

Sensors are designed to make three-dimensional measurements, providing isotropic response. The measurements along three orthogonal axes are processed internally, in the field probe, to yield the isotropic result, as an output for each frequency band. This paper does not deal with specific sensor elements, but more detail can be found in (16-18).

3 BENEFITS OF THE PROPOSED SYSTEM

The project propose an autonomous wireless system that will systematically perform the EMFs measurements, remotely and on a daily bases, having thus a superior position comparing to the classical measurements, performing by technical personal on measuring equipment.

The proposed system is designed to perform long term EMFs monitoring, as shown in Table 3, and it is capable to constantly provide information about the current total and cumulative EMFs level, produced by all sources around the sensors.

The long term monitoring is not possible with technical personnel and therefore development and research within this project gains in importance. Compared to the conventional approach, where it is necessary that qualified personnel goes to the field and operates with measuring instruments, the proposed system does not require personnel in the field. As a result, system provides faster and more efficient monitoring and performs continuous investigation, 24 hours a day during desired period.

Thanks to the communication via widespread GSM mobile phone network (15), the proposed monitoring system has a high degree of mobility and can be installed in any part of the area of interest, as shown in Fig. 3. Mobility of sensor elements enables their spatial deployment and integration into information network for permanent EMFs monitoring, over large area of interest, including national wide coverage. Such feature is not possible in a conventional approach.

In addition, the system is capable to provide history overview of the EMF levels fluctuation, as shown in Fig. 5.

[FIGURE 5 OMITTED]

This simplifies the process of the first and periodic testing of radiation sources by the municipal authorities (14), as well as licensing the new sources installation and investigation of the present sources, in accordance with the national "Rules for non-ionizing radiation sources of interest, types of sources, the manner and period of their investigation" (8).

By implementing such information network, municipal authorities for environmental protection, will obtain a valuable tools of great benefit for the interested users and the general public, in the field of prevention, timely informing and protection of population from the exposure to EMFs, in accordance with the national "Regulation on the limits exposure of non-ionizing radiation" (7).

4 MONITORING SYSTEM APPLICATION

The proposed monitoring system is developing under the supervision of the Laboratory for electromagnetic compatibility, established in Faculty of Technical sciences, University of Novi Sad, accredited by Serbian Accreditation Body (19), according to standard SRPS ISO/IEC 17025:2006 - "General requirements for competence of testing and calibration laboratories, in area of electromagnetic compatibility".

One of the main contributions of the proposed system, by its accredited activities, is in increasing the trust in institutions for population protection from the EMFs exposure, as well as promoting ecological awareness on environmental protection in the area of electromagnetic pollution.

In following subsections, we will shortly consider possible application of monitoring system. Our intention is only to give some ideas without going into details.

4.1 Low Frequency Application Monitoring

Measurements of the non-ionizing radiation levels in the environment, produced by an overhead electric power transmission or distribution lines, will be highly important according to the Program (9). The possible application of our system is shown in Fig. 6.

[FIGURE 6 OMITTED]

For outdoor measurements it is possible to install sensor on the mast (18), and place it on particular position and at particular height. Allocation of the sensors array close to power lines provides very convenient way for continuous monitoring EMFs in neighboring environment (20).

The sensors array position can be determined according to standard IEC 61786 (21), internal Laboratory system of quality documents and other documents regulating measurements in low frequency range.

4.2 High Frequency Application Monitoring

The Program (9), also considers measurements of the non-ionizing radiation levels in the environment, produced by a system of radio and television broadcasting and base station for GSM/UMTS mobile phone communication. The possible application of the system is shown in Fig. 7.

[FIGURE 7 OMITTED]

Measurements in the vicinity of such systems can be performed according to the standard IEC 61566 (22), the Laboratory documents and the documents for high frequency measurements.

4.3 Monitoring Over Large Territory

Considering the fact that national mobile phone companies have already covered over 95% of the Republic of Serbia's territory, the system has a high mobility degree and sensor network can be set up over any area of interest, allowing GSM connection from nearly every spot, as shown in Fig. 8.

[FIGURE 8 OMITTED]

The developing system can be highly useful in the areas of increased sensitivity (8), where Program (9), predicts systematic testing of the radiation level.

5 CONCLUSION

The proposed system implements a wireless technology that allows automatically and continuous monitoring of EMFs and records the overall electromagnetic pollution level in the environment.

The developing autonomous system does not require personnel in the field. As a result, the system provides more efficient monitoring and performs investigation, 24 hours per day during desired period. None of the previous EMFs investigation methods is able to perform continuous monitoring on a daily basis.

The proposed system is unique at the national level and therefore the research in this project gains in importance. At the international level, similar systems have been applied or are under development, in a several European countries, as Ireland, Portugal, Switzerland, Italy and Greece. For that reason the competitiveness of the project is increased, both regionally and internationally.

With the proposed monitoring system implementation, municipal agencies for environmental protection will obtain the valuable tool for occasionally informing interested users and public, and for carrying out other tasks in prevention and population protection against exposure to the EMFs.

In addition, this system is the most suitable solution for continuous surveillance of EMFs and it can reach the requirements defined in the national "Program of systematic testing of non-ionizing radiation in the environment".

6 ACKNOWLEDGEMENT

This paper has been supported by Ministry of Sciences and Technological Development of the Republic of Serbia, through the grant for the project of technological development TR 32055.

REFERENCES

(1.) International Commission on Non-Ionizing Radiation Protection (ICNIRP) - "Guidelines for limiting exposure to time-varying electric, magnetic, and electro-magnetic fields (up to 300 GHz)", 1998, http://www.icnirp.de/documents/emfgdl.pdf.

(2.) "Council Recommendation 1999/519/EC of 12 July 1999 on the limitation of exposure of the general public to electromagnetic fields (0 Hz to 300 GHz)", http://ec.europa.eu/enterprise/sectors/electrical/files/lv/rec519_en.pdf.

(3.) International Commission on Non-Ionizing Radiation Protection (ICNIRP) - http://www.icnirp.de.

(4.) Ministry of Environment and Spatial Planning of the Republic of Serbia - http://www. ekoplan. gov. rs/src/index.php.

(5.) "Law on non-ionizing radiation protection", the law of Republic of Serbia, no. 36/09.

(6.) Bajovic. V, Djuric. N, Herceg. D, "Serbian laws and regulations as foundation for electromagnetic field monitoring information network", 10th International Conference on Applied Electromagnetics, ITEC 2011, Nis, Serbia, September 25 - 29, 2011, Session O7 O6, ISBN: 978-86-6125-042-2.

(7.) "Regulation on the limits exposure of non-ionizing radiation", the law of Republic of Serbia, no. 104/09.

(8.) "Rules for non-ionizing radiation sources of interest, types of sources, the manner and period of their investigation", the law of Republic of Serbia, No. 104/09.

(9.) Draft version of the "Program of Systematic Testing of Non-ionizing Radiation in the Environment", http://www.ekoplan.gov.rs/src/download-1105/upload-centar/dokumenti/ zakoni-i-nacrti-zakona/predlozi_podzakonski/programa_nejon_201112__2_.pdf.

(10.) Bajovic. V, Djuric. N, Herceg. D, "Serbian Program of Systematic Testing of Non-ionizing Radiation in the Environment", Acta Electrotehnica, Proceedings of the 4th International Conference on modern Power Systems MPS 2011, Cluj-Napoca, Romania, May 17 - 20, 2011, 35-38, ISSN 1841-3323.

(11.) Djuric. N, Prsa. M, Kasas-Lazetic. K, "Serbian System for Remote Monitoring of Electromagnetic Fields", Acta Electrotehnica, Proceedings of the 4th International Conference on modern Power Systems MPS 2011, Cluj-Napoca, Romania, May 17 - 20, 2011, 140-142, ISSN 1841-3323.

(12.) Djuric. N, "Razvoj informacione mreze za kontinualno i daljinsko isptivanje elektromagnetskih Polja", submitted for Serbian journal Telekomunikacije, 2011.

(13.) Djuric. N, Prsa. M, Bajovic. V, Kasas-Lazetic. K, ""Serbian remote monitoring system for electromagnetic environmental pollution," 10th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services, Nis, Serbia, October 5-8, 2011, (2): 701-704, ISBN 978-1-4577-2016-1.

(14.) Municipal Agency for the Environmental Protection - city of Novi Sad - http://www.environovisad.org.rs.

(15.) Vukobratovic. B, Djuric. N, Miskovic. D, Knezevic. D, "Sensor communication in wireless electromagnetic field monitoring system", XLVI International Scientific Conference on Information, Communication and Energy Systems and Technologies - ICEST 2011, Serbia, Nis, June 29 - July 1, 2011, (1): 221-224, ISBN: 978-86-6125-031-6.

(16.) Milutinov. M, Djuric. N, Vukobratovic. B, "Multi-band area monitor sensor in information network for electromagnetic fields monitoring", 10th International Conference on Applied Electromagnetics, TEC 2011, Nis, Serbia, September 25 - 29, 2011. Session O7 O5, ISBN: 978-86-6125-042-2.

(17.) Milutinov. M, Djuric. N, Miskovic. D, Knezevic. D, "Area monitor sensor for broadband electromagnetic environmental pollution monitoring", XLVI International Scientific Conference on Information, Communication and Energy Systems and Technologies--ICEST 2011, Serbia, Nis, June 29-July 1, 2011, (1): 217-220, ISBN: 978-86-6125-031-6.

(18.) Narda Safety Test Solutions GmbH, AMB-8057 User's Manual, Narda, 2007.

(19.) Serbian Accreditation Body--http://www.ats.org.rs.

(20.) Milutinov. M, Djuric. N, Vukobratovic. B, "Sensor network for power lines magnetic field monitoring," 16th International Symposium on Power Electronics--Ee 2011, Novi Sad, Serbia, October 26-28, 2011. T6-1.5, 1-5, ISBN 978-86-7892-355-5.

(21.) Measurement of low-frequency magnetic and electric fields with regard to exposure of human beings--Special requirements for instruments and guidance for measurements, IEC 61786.

(22.) Measurement of exposure to radio-frequency electromagnetic fields--Field strength in the frequency range 100 kHz to 1 GHz, IEC 61566 ed1.0.

Nikola Djuric, Miroslav Prsa, Karolina Kasas-Lazetic

University of Novi Sad, Faculty of Technical Sciences, Trg D. Obradovica 6, 21000 Novi Sad, ndjuric@uns.ac.rs, vrsa@uns.ac.rs, kkasas@uns.ac.rs
Table 1. Electric field probe
characteristics

Frequency range

100 kHz-3 GHz  EGSM 900    EGSM 1800     UMTS 2100

Measuring range (V/m)

0,2 - 200      0,2 - 200   0,03 - 30     0,03 - 30

Measuring resolution (V/m)

0,01           0,01        0,01          0,01

Table 2. Magnetic field probe
characteristics

Frequency      Measuring range        Measuring
range                                 resolution

10 Hz - 5 kHz  50 nT - 200 [micro]T   1 nT

Table 3. Memory capacity of the sensor.

Storing   Memory
time      capacity

30 sec    5 days
1 min     10 days
2 min     20 days
6 min     60 days
15 min    169 days
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Author:Djuric, Nikola; Prsa, Miroslav; Kasas-Lazetic, Karolina
Publication:International Journal of Emerging Sciences
Article Type:Report
Geographic Code:4EXRU
Date:Dec 1, 2011
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