New brazilian Non Ionizing Radiation (NIR) monitoring system

Background:

Non Ionizing Radiation Monitoring systems are employed as a part of management risk information system used by national regulators in order to promote conscious awareness on the subject and attenuate people concerns on this matter.

There are several systems available from different manufactures to perform such measurements, being the different choices based on the local demands and also the economical and social conditions.

In Brazil, NIR exposure limits for Radio Frequency emitters are defined by the National Telecommunications Agency – ANATEL, according to OMC and ICNIRP standards. ANATEL also perform regular measurements following an annual regulatory enforcement plan and in response to specific demands, collect from different sources, such as call center, web services and other standard public relations channels.

Information:

As an effort to increase the information about NIR levels in Brazil, ANATEL, which already operates 12 broadband isotropic probes for electric and magnetic field, and 30 narrowband isotropic probes for electric field, considered in 2007 the implementation of an automated NIR monitoring network, taking into consideration the following principles:

• The measuring system must be able to run measures in all relevant frequency bands including radio and TV broadcasting in the 500 kHz up to 800 MHz range, mobile communications bands and other services up to 2,7 GHz frequency bands.
   

• The measuring system must be able to measure electrical fields from as low as 0,8 V/m, defined at about 3% of the lower general public exposure limit, up to 61 V/m, defined as 100% of the lower occupational exposure limit. Values bellow this range might severely limit the manufactures competition on a bidding process without adding relevant capability for the measurement system, while values above this range will also be non practical for any application, since higher limits would demand immediate action to reduce the emission levels and further analysis of the specific causes, using a narrow band probe to isolate the contribution form different emitters.
   

• The measuring system must be able to work without any human interference for long periods, up to 14 days and keep these data in its memory.
   

• The measuring system must be able to transmit collected data using mobile network.
   

• The system must be equipped with GPS, been able to operate mounted on a vehicle, allowing simple measurements to be performed in movement along a route, in the same fashion as drive tests. Such large area overview are useful to confirm possible “hot spots”, produce large volumes of data with low human cost, provide a “safe” environment to operate the equipment, even when no agreement can be achieved for a fixed installation.
   

• The measuring system must have its own power supply in order to operate at least two hours without any external power supply. And with external power supply system must operate in continuous way.
   

• The measuring system must have an anti-thief module and must be able to operate in open areas without any special environmental protection.
   

• All these specifications for measuring system must be compatible with software system in development inside ANATEL, recording complete statistical data from all measurements, including time stamp, average and standard deviation for the level and geographic coordinate measurements, maximum EF measurement, number of measurements and duration of each record, plus relevant error detected during measurements that might compromise the presented results.

In order to achieve these requirements ANATEL published a tender process at the end of 2007, asking for manufacturers to provide 52 measuring systems. The project winner was SALTECH (www.saltech.com.br), a Brazilian industry in a technological partnership with CPqD Foundation (www.cpqd.com.br), a Brazilian research and development center for telecom. CPqD already have developed a NIR system, CPqD Monitoração RNI (CPqD NIR Monitoring), which was presented in last CITEL meeting at San Salvador.

The measuring system unit is called Unidade Remota de Coleta e Armazenamento – URCA, which means Collect and Storing Remote Unit for electrical field.

This unit is composed by an isotropic electrical field sensor constructed with three axes short dipoles with Schottky diodes with high impedance lines in the frequency band between 300 kHz and 3 GHz.

Micro controlled and with an internal GPS module to provide geographical and time stamp data together with electrical field measurements, the unit, automatically, will provide all registries during its operation. For remote operation, there is a modem connection for use with mobile networks allowing operation in GSM and CDMA technologies. Your battery system provides system operation during at least two hours without external power, AC (110 – 240 V) or DC (12V). There is an adapter for DC power supply for use in cars or vans allowing continuous colleting data during car driving.

The Figure 1 shows URCA with a notebook for programming its collecting functions, like time, space and delay between measurements. In the notebook screen is possible to see actual electrical field intensity value and a graphical with the values collected.

Figure 1 – URCA and a notebook for programming

The Figure 2 and Figure 3 show some kind of URCA mounting for data logging, in a car for mobile measurements and in a fixed point.

Figure 2 – URCA mounting on car

Figure 3 – Fixed URCA mounting

The Table 1 shows probe characteristics and Table 2 shows URCA unit general specification.

National Telecommunications Agency
ANATEL