Research On Key Technologies Of Magnetic Anomaly Detection And Location Based On The Optically Pumped Atomic Magnetometer

Magnetic anomaly means that the uniform geomagnetic field changes irregularly under the interference of magnetic objects,which makes the geomagnetic field uneven.Based on the phenomenon of magnetic anomaly,many countries have developed magnetic detection devices for detecting magnetic targets.The optically pumped atomic magnetometer occupies an irreplaceable position in magnetic anomaly detection,particularly in the exploration of subtle magnetic anomalies.It is highly valued for its exceptional sensitivity,precise measurements,compact size,and low power consumption.Magnetic anomaly detection and location also play an important role in military,aerospace and other fields.Based on the optically pumped atomic magnetometer,the main research content can be divided into the following parts:Study on the theory of geomagnetic survey.The paper uses the optically pumped atomic magnetometers to measure the geomagnetic field,conducts a variety of characteristics research on the geomagnetic field signal,fully knows the characteristics of the geomagnetic field,and lays a foundation for the research of key technologies for magnetic anomaly detection.The establishment of magnetic target model.Theoretical analysis was performed on the cube model and the magnetic dipole model,examining their respective magnetic field characteristics at varying distances in three directions.Subsequently,simulations were conducted to compare and contrast the relationship between the magnetic field of these models and the distance.finally,it can be concluded that when the measuring distance is more than three times the length of the magnetic target,the influence of the magnetic target’s shape on the alteration of the magnetic field can be disregarded.That is,the magnetic target can be equivalent to a magnetic dipole model.The establishment of magnetic dipole model greatly simplifies the research of magnetic anomaly detection and magnetic location inversion algorithm.Suppression of environmental magnetic field noise.Because the noise of the environmental magnetic field is too strong,it is difficult to detect the weak magnetic anomaly signal,in-depth analysis of magnetic anomaly target signals is conducted.Based on the variation rules of magnetic anomaly fields caused by the movement of magnetic targets,the frequency variation range of magnetic anomaly signals for magnetic targets is determined,and fast Fourier transform filtering technology is used to accurately filter according the frequency variation range,thereby achieving the effect of effective suppression of ambient magnetic field noise.Simulation experiments are conducted to demonstrate the efficacy and precision of the method.Extraction and detection of magnetic anomaly signals.Based on the above research,a new magnetic anomaly signal detection method which is called adaptive filtered entropy detection method is proposed.This method makes up for the deficiency of the information entropy detection method through adaptive filtering technology and kernel density estimation method,and greatly improves the magnetic anomaly detection performance.Compared with the information entropy detection algorithm,the method yields an approximately 48% increase in the average detection probability,furthermore,a comparison is made between the proposed method and the standard orthogonal basis function algorithm,the average detection probability is increased by about 26%.It shows that this method has remarkable superiority in detection performance.Location and inversion of magnetic targets.A magnetic detection array system based on the optically pumped atomic magnetometers was built,the measurement model and positioning principle of magnetic field distributed in the whole space are given and optimized.The optimization problem based on error function is constructed by using the difference of multiple magnetic anomaly measurements obtained from different azimuth measurements.Subsequently,the intelligent optimization algorithm,specifically the particle swarm optimization algorithm,is employed to accurately determine the position,magnetic moment,and other relevant information of magnetic objects,effectively solving the optimization problem.The experimental results show that the positioning accuracy is almost more than 90%,which proves the correctness and effectiveness of the method.