Based On Large-caliber Projectile Impact Point Positioning Method Of Seismic Waves

According to the characteristics of seismic wave generate by the large diameter projectile landed, expends a study of the projectile impact point positioning technologies,laying the foundation for developing the positioning system of the large diameter projectile impacting point.Analysis the impact energy, the propagation distance and action time when155mm caliber projectile hit the ground, probe the effect of the source, sensor coupling with the ground, the sensor’s sensitivity, the impact of surface on the sensor for detection distance.The paper describes the propagation of Rayleigh wave and its dispersion feature, the main factors that influent the sensors detecting in long distance, Theoretical analysis the internal structure of magnetic sensors, electromechanical motion equation, the frequency characteristics.Designing a moving-coil magnetic sensor by adding a negative feedback circuit at the output of the moving coil geophone.Design a hardware and software development for seismic signal acquisition device based on FPGA. Design the signal conditioning circuit with two amplified voltage-controlled voltage source and the second-order Butterworth low-pass filter, using EP2C5Q208C8N with AD7606A/D finish the design of acquisition and the control module. design a clock reset, A/D control, set the trigger level, SDRAM control, FIFO and RS232control module with Verilog. complete the acquisition of seismic wave signal communication, storage, and communication with the host computer.Analysis the distortion of seismic waves propagating along the surface,respectively analysis the source, sensor coupling with the ground, the sensor’s sensitivity, the impact of surface on the sensor for detection distance. Analysis each of detector signals one to one by using correlation method find that with seismic wave propagation distance increases, the correlation with the initial seismic wave signal becomes smaller, obtain the conclusion that seismic wave distortion is the main effective factors on the time difference extraction.Study the SO-TDOA and TDOA positioning principle, carry out experiments with five element array to locate seismic waves, test data analysis compare the different influence of cross-correlation, peak extraction method, the first arrival time difference extraction method on SO-TDOA and TDOA location algorithm. Compare the effects of its stability and positioning accuracy of the two positioning methods. The comparison shows that peak extraction has a high precision and stable positioning performance using in TDOA algorithm. The effect of three kinds of time difference extraction almost have the same accuracy on SO-TDOA location algorithm. In the case of fewer number of sensors,TDOA has high positioning accuracy when increasing sensors number, SO-TDOA positioning has a increasing trend in accuracy and stability significantly; combing SO-TDOA and TDOA positioning principle, advance a hybrid positioning method with SO-TDOA and TDOA that can be further improved positioning accuracy.