Development Of Mine Electrical Monitoring System Based On 2~n Pseudorandom Sequence

With the continuous increase of coal mining depth in china,water hazard has became further aggravated.In order to study the mechanism of water inrush lucubrately and prevent water bursting disaster effectively,this thesis presented a coal electrical monitoring system based on 2n pseudorandom sequence used as the artificial geoelectric field.For the purpose of monitoring the dynamic change processes of water-bearing and conducting structures in roof and floor of working face under the influence of mining,the monitoring systm adopted fiber optic and coal mine industrial Ethernet Ring Net,realized remote communication on surface and transmits the monitoring data to the surface for analysis.This thesis introduced the research in aspect of technical scheme,operating principles,reliability design,anti-noise design of the system.The artificial geoelectric field of the monitoring system adopted 2n pseudo random sequence.The characteristics of 2n pseudo random sequence both in time-domin and frequency-domin make the monitoring system aquire multiple frequency points data form single measurement,that’s provide a technical means to dynamically detecting different depth resistivity information and greatly increase the effiency of monitoring.The monitoring system used various measures in order to improve the effiency of data acquisition and capacity of weak signals detection.The data acquisition system adopted completely isolated 8-way parallel data acquire module and the electrode control system used STM32 industrial control module to switch receiving electrodes and emitting electodes,so multiple electrodes of the system could receive signals simultaneously during single squence emission.This design shortened detecting time and improved data consistency.The signal acquisition circuit adopted 24 bit high precision A/D converter controlled by FPGA to improve the system development flexibility and signal resolution capability.The signal conditioning circuit designed two-stage programmable gain instrumentation amplifier that has high input impedance and CMRR and designed 50Hz trap filter circuit to reduce the effect form common-mode interference and power-line interference.The power system took linear,low noise,flameproof and intrinsically safe power as power to reduce the internal noise of the system.In aspect of data processing,power spectrum correlation identification technology based on 2n pseudo random sequence was adopted for noise suppression.The results of performance test and field test showed that the monitoring system operates stably,has outstanding weak signals recogniziton ability and data acquisition reliability and proved that the monitoring system achives the design targets.