The Development Of Semi-airborne Transient Electromagnetic Receiver

With the rapid development of national economy,mineral resources are very important to human production and life,and the demand for mineral resources is increasing.Semi-airborne transient electromagnetic which is a new exploration method proposed in recent years is an effective means of the survey,it adopts the mode of ground transition and air receiving and combines large transmission power of ground transient electromagnetic with the advantages of airborne electromagnetic,that are large scale reception and flexible.Developing a practical semi-airborne transient electromagnetic receiver with independent intellectual property rights is of great significance to research on detection method of semi-airborne transient electromagnetic,improve the ability of mineral resources exploration in China and popularize and apply in production practice.This paper is based on the national ministry of land and resources public welfare project,"the research on the technology of semi-airborne transient electromagnetic exploration based on unmanned aerial vehicles(UAV)"(project number:201311037),in this paper,the principle and signal characteristics of semi airborne transient electromagnetic method are analyzed,and the key technology of the semi-airborne transient electromagnetic receiver based on UAV is researched.This paper firstly introduces the research background and the research status of semi-airborne transient electromagnetic receiver,then analyses the characteristics and data processing methods of semi-airborne transient electromagnetic signals;analyses the instrument function of semi-airborne transient electromagnetic or transient electromagnetic of the domestic and international,comprehensively analysis the functional requirements and technical specifications of the semi-airborne transient electromagnetic receiver,and research on the GPS synchronization technology and storage technology;then according to the characteristics of the semi-airborne transient electromagnetic signals,the design scheme of the semi-airborne transient electromagnetic receiver based on FPGA and ARM which are logic and control center is proposed;on the basis of GPS synchronization technology and the characteristics of constant temperature crystal oscillator(TCXO),the high precision second pulse synchronization system is designed based on FPGA and constant temperature crystal oscillator;in the semi-airborne transient electromagnetic signal acquisition,this design uses low noise pre differential amplifier to amplify the weak analog signal acquired by coil sensor,and uses a sigmadelta type structure high precision A/D converter of 24 bits for data acquisition;on the data storage,the SD card is used to store the data controlled by ARM,in addition to the storage of transient electromagnetic signal data,according to the requirements of the inversion,the GPS time and position,coil attitude and relative altitude data are stored after being processed and packaged.The semi-airborne transient electromagnetic receiver usually adopt continuous acquisition mode to acquire data and use local mode to store data.Finally,In order to verify the performance of the semi-airborne transient electromagnetic receiver,the performance of the receiver is tested and analyzed and carry out field experiments;by analyzing the test results,The receiver GPS synchronization accuracy of 100 ns,the minimum resolution of the signal 50?V,the receiver can meet the design requirements of the system,but the overall performance of the receiver needs to be further improved.