A Sensor Data Fusion Procedure for Environmental Monitoring Applications by a Configurable Network of Smart Web-Sensors

The present Chapter describes a methodical approach to the design of a monitoring process for environmental applications. The case study and experimental results concern the remote control of exposure levels to electromagnetic pollution. The main contribution focuses on the design of a configurable network of wireless and smart web-sensors and the development of a two-levels data fusion procedure. The aim of an environmental monitoring process is to provide qualified information on the investigated phenomenon, so to minimize possible errors or hazardous consequences for the exposed population. That objective requires not only an appropriate choice of the measurement system, but care has to be paid about the maintenance of instrumentation in order to assure a suitable metrological state. On the contrary measured data may be inconsistent and meaningless so to provide an erroneous knowledge about the monitored process, often that occurrence is cause of underestimated risks. Therefore the operating state of the measurement system has to be guaranteed with the passing of time, in order to get reliable data. So the matter requires to evaluate the measurement system performances, (Neely et al., 2000). Moreover data processing stage plays a crucial role when decisions have to be taken with reference to warning limits. In fact several laws and regulations have been issued to limit the exposure levels to environmental parameters responsible for pollution, in order to keep under control the status of our habitat and so to guarantee an appropriate quality of life. But such decisions are the result of a comparison between the fixed limits and the measured data, consequently the uncertainty contribution due to measurement process may be reason of wrong decisions if its effect is not taken into consideration. In that context, the considered application field needs methodical monitoring processes being able to characterize and manage in real time warning and risky situations so to reduce possible harms for the exposed population. In the urban centers today it is possible to characterize several electromagnetic pollution sources to different working frequencies, as in example the lines of power supply or the antennas of the radio-television service, (Ahlbom et al., 1998; IEC 50166-2, 1995). Medical studies would seem to point out a relationship between the continual exposure to high electromagnetic field levels and the onset of some typologies of cancer. The World Health Organization suggests prudence and the observance of the quality O pe n A cc es s D at ab as e w w w .in te ch w eb .o rg