Research On Key Technologies Of Semi-aeronautical Frequency Domain Electromagnetic Embedded Recording System

With increasing energy demand,the semi-aviation frequency domain electromagnetic method is widely used in resource exploration and geological structure exploration.A common working method is to use a UAV equipped with an electromagnetic receiving system and magnetic sensors to collect magnetic field signals in a specified area in the air.By identifying anomalies at different frequencies,information such as the position,depth,and size of the anomaly can be determined.However,this method uses the method of receiving the vertical magnetic field signal in the air to obtain the secondary field information.The signal is relatively weak,and it needs to be amplified after collection,which will introduce circuit noise to affect the detection accuracy;and the drone flight will be subject to the the overall size,weight impact receiving system,the internet IPC(Industrial Personal Computer)discarded,selection of embedded systems to receive collection work,and for the high speed internet embedded portable storage requirements made higher.This article has done the following work to address the above issues.1)Theoretical research is made on the design of low-noise sensors and high-speed storage methods in frequency-domain electromagnetic receiver systems.Analysis of semi-aviation frequency-domain electromagnetic detection principle,the basic principle of the magnetic field signal measurement by the inductive hollow coil sensor is studied,and the storage technology applicable to the semi-aviation frequency domain electromagnetic receiver is discussed.2)The optimal design method of the hollow coil sensor is studied.Established mathematical models of internal resistance,capacitance,inductance and matching resistance and a pre-differential amplifier circuit is designed according to the characteristics of the hollow coil source impedance.Two equivalent noise models of resistance matching and capacitance matching for hollow coil sensors are established,and the proportion of voltage noise,current noise,and resistance noise in the total noise in each sensor model is analyzed in depth,and the capacitance matching sensor models at different resonance frequencies are analyzed.Noise conditions.Aiming at the problem of large noise generated by the matching resistor,an equivalent model of the sensor based on capacitance tuning is established,and simulation results in two matching modes are given.3)Aiming at the data storage requirements of the semi-aeronautical frequency domain electromagnetic receiver,a portable Micro SD card is used as a storage medium,a high-speed storage module based on an embedded platform is designed,and a stable circular storage mechanism is established to realize continuous storage.In order to strengthen the storage stability,a soft reset module is written to cope with the unexpected situation that the system may encounter in the field detection.In-depth understanding of the file system storage mechanism and sector indexing methods,Finally,research on high-speed storage method based on memory card life.4)To verify the performance of the sensor,performance tests and field applications were performed.The sensor short-circuit noise test and various noise tests were conducted in a shielded room,and the short-circuit noise level reached about 2nV??Hz in a wide frequency band.The experimental results were in line with the theoretical analysis.Two types of matching sensors are used to conduct a comparative test of the signal to be measured in addition.The test results show that the capacitance-matched sensor acquires an equivalent effective magnetic field signal at the nV level at the effective frequency point.Accuracy and excellent low-noise performance to meet the needs of large depth detection.Finally,a field flight test was carried out,which verified that the system has engineering application value.