Design Of Earthquake Early Warning System Based On Electromagnetic Wave Anomaly

When the devastating earthquake happened, Not only brings the enormous materialloss for people, but also cause spiritual damage. In order to reduce the loss caused byearthquake and win precious time for the escape, this paper introduces an earthquake earlywarning system based on electromagnetic wave anomalies. During the earthquakepreparation and occurrence, the earth would radiate electromagnetic wave, to judge whetheror not the earthquake would happen by receiving the abnormal seismic wave.We choose to receive ultra-low-band seismic electromagnetic waves between20and120Hz which has good anti-interference performance and low attenuation. The system usecoil antenna receive seismic electromagnetic signals, and then conditioning the signal withamplification, filtering, A/D conversion, at last, the signals sent to the master controllerprocessing to judge whether had an earthquake.The design of system mainly includes hardware circuit design and software design.The hardware circuits comprise coil magnetic antennas, signal conditioning circuit, CPUmaster control module, power supply circuit. Coil magnetic antenna is the spiral coilantenna with magnetic core having directivity and limitations, using two magnetic antennaform omni-directional antenna by crossing; using the instrumentation amplifier chipAD8221to amplify the signal, while taking advantage of the90-degree phase shift mergecircuit merged the two signals into one signal; A50Hz double T notch device is designed torestrain50Hz power frequency interference; Using2filter chip MAX267constitute8orderChebyshev band-pass filter, the filter center frequency is70Hz and bandwidth is20Hz~120Hz; this article selected16high-precision, low power A/D converter chip MAX1302which could convert an analog signal into a digital signal; selected ARM7controllerS3C44B0X chip as the main controller that is used to process data; nRF905module-basedwireless communication circuit exchanging monitoring results with other earthquake earlywarning system node, comprehensive judgment in order to reduce the false alarm rate,System software part mainly realize the function of the system and the data processingjudgment, modular programming ideas simplified design and made the system effective andstable.The design of the earthquake early warning system with lower cost, high portabilityand good integration which are suitable for the family and the public places.