HERMES: Human Exposure and Radiation Monitoring of Electromagnetic Sources.

Transcription

1 HERMES Program: The Greek Experience of an Electromagnetic Radiation Monitoring System A. Manassas, A. Boursianis, T. Samaras and J. N. Sahalos

2 HERMES: Human Exposure and Radiation Monitoring of Electromagnetic Sources

3 Objectives To continuously monitor the electromagnetic (EM) environment To create a database of measurements which can characterize the evolution of the EM environment To inform the public on the measurement results

4 Structure and function of the Monitoring Network

5 Structure and function of the Monitoring Network Measurements from broadband monitors are 6-minute averaged Every monitor transmits via GSM network a total of 240 measurements per day, once a day Measurements (both narrowband and broadband) are saved in a specially designed database (more than 3 million entries until now)

6 Size of the Monitoring Network

7 Mode of Operation: Broadband measurements Monitoring Stations Model: Manufacturer: EE4070S EIT srl. Type of sensor: electrical field (E) Directivity: isotropic triaxial Measuring range: 0.5 V/m V/m Resolution: 0.1 V/m Frequency response: 100 khz to 3 GHz; 930 to 960 MHz; 1850 to 1880 MHz; 2110 to 2180 MHz Temp. sensitivity: 0.04 db / C Total error: 1.2 db Operating temp: -10 C to +50 C Dimensions: 530 x 160 x 250 mm Weight: about 5kg

8 Mode of Operation: Broadband measurements Monitoring Stations Model: Manufacturer: MCE410 EIT srl. Type of sensor: electrical field (E) Directivity: isotropic triaxial Measuring range: 0.5 V/m V/m Resolution: 0.1 V/m Frequency response: 100 khz to 3 GHz; 900 MHz to 3 GHz Temp. sensitivity: 0.04 db / C Total error: 2.5 db Operating temp: -10 C to +50 C Dimensions: 565 x 90 x 80 mm Weight: about 1.3kg

9 Mode of Operation: Broadband measurements Acceptance Tests Accuracy Frequency response Isotropicity (Open Area Test Site OATS). Continuous operation (indoors and outdoors)

10 Mode of Operation: Narrowband measurements Equipment Laptop (with in-house made software) + Spectrum Analyzer + Anntena set (portable) (3 antennas serving the freq. range MHz)

11 Measurement results Broadband Whole frequency range (100kHz 3GHz) There seems to be a periodic daily variation of the power density

12 Measurement results Broadband Periodogram with autocorrelation (for the same monitoring station) Sample Autocorrelation Function (ACF) 0.8 Sample Autocorrelation measurements correspond to 24 hours (= 24 hours x 10 points/hour) Lag

13 Measurement results Narrowband Contribution from different frequency bands (for the same monitoring station)

14 Measurement results Narrowband Contribution from different frequency bands (for the same monitoring station)

15 Measurement results Broadband Whole frequency range (100kHz 3GHz) Sample Autocorrelation Function (ACF) 0.8 Sample Autocorrelation Although no periodic variation appears in the left, the processing of the measurements gives a period of 24 hours for this monitoring station as well Lag

16 Measurement results Statistical analysis Median value of electric field at a station (mean from all stations): 1.3 V/m ( 4.5 mw/m 2 ) range of median values: V/m ( 26.5 µw/m mw/m 2 ) Max value of electric field at a station (mean from all stations): 3.5V/m ( 32.5 mw/m 2 ) range of maximum values: V/m ( 2.1 mw/m W/m 2 ) The daily variation for a monitoring station is expressed as mean value of daily variation (from all stations): 47% range of values: 13% - 84% E max E E min min % Remaining questions: peak hours of traffic, other periods, prediction possibilities

17 Advanced services: sms HERMES Information of EM environment on your mobile phone Free service of 4-digit number (in cooperation with mobile operator) Three-step process (first time user), one-step process for frequent user Addressed to people of older age and/or less familiar with the internet 1325

18 Advanced services: mobile HERMES Information of EM environment along routes in a city Many people spend a lot of their time in streets (mainly shopping center of the city) A moving measuring station can allow for a larger geographical coverage

19 Advanced services: mobile HERMES Technical description

20 Advanced services: mobile HERMES Outlook: Attempt to correlate instantaneous measurements with 6-minute averaged values broadband monitors of HERMES (stationary) measuring 6-minute average instantaneous values from mobile HERMES

21 Conclusions Monitoring networks can provide a clear picture of the EM environment at the installation sites of measurement stations It is difficult to characterize comprehensively all temporal and spatial variations of the EM environment There are several ways to present the picture of the EM environment; communicating the measurement results is a big challenge