| Debris flow is a global, widely distributed in all over the world in some regions with special landform condition of natural disasters. It has characteristics of outbreak of violent, huge destructiveness and far-reaching, and produces in the process of formation and movement of less than 20 hz infrasound signal. Our country is a mountainous country, influenced by rock fracture structure, many mountain steep,rock structure is not stable, easily outbreak of debris flow in the rainy season, causing a great loss to the people. So the monitoring of landslide has important significance.The world within the scope of monitoring of landslide, ZhangShuCheng teacher and Chinese academy of sciences, chengdu institute of mountain hazards and environment is the main part in the domestic. The instrument their development has been several generations. Overseas have like in the late 80 s, the system of lanslide monitoring presented by American Malo PARK of Wilsion, namely, by the method of meteorological satellite, infrasound signal acquisition, real-time observation rainfall factors such as soil moisture content and pore water pressure and basin and comprehensive to give an alarm. But no matter domestic or foreign debris flow monitoring device, there are some problems more or less lead to poor generalization,such as high rate of false positives, the high price of sensor devices, high maintenance costs. Therefore, this paper proposes a scheme, use cheap but excellent performance of electret condenser microphone combined with low frequency compensation, the hardware threshold circuit and the peripheral circuit, signal processing, it has advantages like low cost, stable performance, strong practicability, easy popularization, etc.The mudslides infrasound monitoring system is introduced in detail of the system scheme design, hardware and software design and system test in this paper.Firstly, the system collect less than 20 hz infrasound signal by electret condenser microphone, low frequency compensation circuit, second-order low-pass filter circuit of 21 hz cut-off frequency and AD chip and stored in the SD card. Then each extraction of signal to process by uCOS operating system, and combined with hardware threshold circuit and setting of signal duration. If the processing result conforms to the characteristics of debris flow infrasound signal, then give an alarm by local alarm circuit of the system, at the same time through the system SIM900 A module implements remote alarm and data of acoustic signal transmission, and implementation of debris flow disaster monitoring. And other peripheral circuit of the system design such as hardware watchdog circuit can guarantee the stability of the system work.Verified by actual test, the software and hardware system of the debris flow infrasound monitoring reaches the design requirements and has a certain practical value and popularization. |
