Passive-active monitoring system of acoustic contamination of the local urban area
The article deals with passive - active monitoring system of acoustic contamination of the local urban area, ensuring control of pollutions and forecasting the character of their distribution in the given local zone. The diagram of the considered system including the channel for obtaining information on the acoustic noise (the passive channel), the channel for obtaining meteorological data (active channel), position control system and computing device is justified. The meteorological data includes the data about temperature, moisture and pressure in the air environment, as well as speed and wind direction. Receiving/transmitting unit ensuring communication with the central server is used for organization of the distributed network of monitoring. The central signal processor performs signal processing from the microphone sensor in the passive channel circuit. It performs the control function of automotive gain control. Observing noise implies spectral analysis made on the basis of the fast Fourier transform algorithm. Thus, narrow-band amplitude bursts at different frequencies are fixed instead of the mean amplitude values in the given frequency band. The passive channel is implemented with the use of a condenser measuring microphone MRA-216 and the portable ZET017-U2 spectrum analyzer. The active channel implemented on the principle of the active acoustic location is used for obtaining data on the wind parameters. Ultrasonic weather station WXT520 Vaisala is used for implementation of the channel. A power amplifier implemented on LDMOS technology. is developed for the receiving/transmitting unit. The system management program is developed with the help of software package of ZETView which belongs to SCADA systems. The result of the system operation is the prediction of propagation distance of an acoustic noise.