Research On Intelligent Terminal For Environmental Noise Detection

Environmental noise monitoring system consists of noise monitoring terminals, transmission network and data management center. The terminal collects and sends the data of current environmental noise to the noise data management center through the transmission network, integrated MEMS, sensor and modern communication technology. User can check the noise data in real time through the Internet. At present, we have successfully designed the terminal with DSP and ARM. The micphone converts noise signals into electrical signals, and then has a series of algorithm processing in the DSP and ultimately count out the value of environmental noise. The terminal can work stably with the high accuracy which can reach 0.1dB. However, the terminal with a single founction can not have a real-time spectrum analysis and it’s very difficult for the environmental protection departments to identify the noise sources. In addition, as the public awareness of environmental protection is growing, the noise mapping begins to be widely used. In order to meet the diverse needs of our users and consider the trend of the environmental noise monitoring terminal, we prepare to develop an intelligent and multi-functional noise monitoring terminal on the basis of the prevous system.The main jobs of this paper are as follows:Firstly, we have designed the front-end amplifier with AD8021. Zhouligong Company’s front-end power converter provides power for the probe and amplifier, complete PCB design, making and debugging; the testing of the amplifier shows that it has a high dynamic range and reliable power supply, meets the system actual needs.Secondly, 1/3 octave spectrum analysis is completed on DSP. Respectively, the band-pass filter, anti-aliasing low-pass filter, analysis algorithms based on multi- sampling techniques are designed; we use EDMA technology and ping-pong operation to ensure that signal processing is in real time.Thirdly, complete the application program based on S3C2440. Build cross-compiler environment with embedded Linux operating system; GPS positioning, audio and image module are designd to achieve the noise terminal location, noise collection and image capture function; use Framebuffer device to operate the display buffer directly for the display of the noise data, images and spectrum in real-time.Finally, the function of the system is verified. 1 / 3 octave spectrum analysis meet the requirements of 0 filters on the national standard GB/T3241; the terminal location information extraction and on-site image capture meets the requirements of the terminal. The system can achieve a real-time spectral analysis and provide more information on noise pollution field, stably and reliably.