The Design And Implementation Of New Cross Hole Resistivity CT Detector

China is a large coal country,it is very important to accurately detect the geological structure of the coal seaming to be excavated before the coal seam mining,which can not only know the general distribution of coal,but also to predict whether the mine has a risk of water and other geological disasters.the conventional cross hole resistivity CT detector in the mine has a large amount of collected data,poor anti-interference ability to weak signal,low dynamic range of data acquisition and low resolution,poor stability and other characteristics,resulting in inversion results are not accurate.A new type of cross hole resistivity CT detector is designed for the shortcomings of conventional cross hole resistivity CT detector.The instrument can be a large dynamic range of data collection and adapt to the signal processing,through the launch of pseudo-random signal and the design of the power frequency limiting circuit effectively limit the power frequency interference,automatically switching the electrode,parallel data collection,high efficiency,and the collection of large amounts of data,high precision,making the inversion results more accurate.The results show that the instrument has the characteristics of simple operation,stable performance and high resolution.The resistivity profile can reflect the actual geological structure.The paper mainly completed the following work:1.The basic principle and positive inversion algorithm of resistivity detection are introduced.For the non-linearity of resistivity inversion,the Gauss-Newton method is used to explain the resistivity data.2.In this paper,the design method of the hardware system is put forward,and the transmission circuit,the power supply circuit,the data acquisition circuit,the electrode conversion circuit and the core control circuit are designed by comparing the data acquisition method of the traditional instrument and the data acquisition mode of the instrument.3.The system software is divided into two parts of data acquisition and data processing.Data acquisition software and the host computer communicate through the Ethernet port.The master and slave communicate through the SPI bus to ensure the reliability of data transmission.Custom communication protocol ensure the flexibility of control.Encapsulation API interface facilitate the subsequent changes and maintenance.4.The performance of the test equipment verify the reliability of the instrument.The geological structure can be more realistic reflection according to the actual data measured by the coal mine resistivity profile.