Research Of Digital Environmental Noise Automatic Monitoring Terminal

The city environmental noise monitoring is one of the primary environmental monitoring projects. Currently, the environmental noise is monitored with manual monitoring methods in most cities of China. For its poor real time property and continuity, it is difficult for environmental protection departments to control the city's overall environmental degradation. Therefore, the development of environmental noise automatic monitoring system is an urgent job.The digital environmental noise automatic monitoring system is composed of several noise monitoring terminals, the transmission connection and the noise data administering center, which combines the sensor technique , computer technique and the modern communication technique. This paper proposed a structure and realization scheme of the digital environmental noise automatic monitoring system which can satisfy the requirements of the city environmental noise monitoring. A robust, high accurate, real-time system using floating-point DSP (TMS320C6713) chip as core processor to finish frequency weighting, time weighting and FFT, and the high-performance S3C2440 single chip processor as data collection and port controller is presented.The main jobs of this paper are as follows:Firstly, according to the need of environmental noise automatic monitoring, a novel structure and realization scheme is proposed.The sound signal is processed in TMS320C6713 and the whole system is under the control of S3C2440.Secondly, the design of the DSP circuit is completed. And the frequency weighting, time weighting and FFT are realized in DSP. A method using the multichannel buffered serial port McBSP to emulate software UART is provided.Thirdly, the program design of the S3C2440 is completed. The noise data is transmitted through GPRS with SIM300. The CMOS camera can work well under the control of ARM. Image compression and transportation are completed.Lastly, the experiment proved that the accuracy of frequency weighting and time weighting meets the IEC Standard IEC61672-2002 class I, and the system accuracy is up to 0.1dB. The system has good spectral analysis performance, and can work stably for long time, which meets the requirements of the environmental noise monitoring.