Conversion And Processing Method Of Aeromagnetic Data In Frequency Domain

With the rapid development of China's aeronautical technology,the interpretation and processing of the total field,three-component and tensor gradient data of aeromagnetic has became one of the hot spots in China's aero-geophysical research.Compared with scalar measurement,three component and tensor gradient' components can refer to each other and contain more geological information.However,different types of magnetic anomalies reflect different geological information.Therefore,it is of great significance and application value to study the relationship among the total magnetic field,three components and tensor gradient data,and how to use different types of magnetic data for processing and interpretation.Based on the potential field theory,this paper analyzes the calculation principle of the total magnetic field,the three components and the tensor gradient.Taking the dipole field as an example,it introduces the forward calculation process of the total magnetic field,the three components,the tensor gradient and the total field gradient in the space domain.Introduce the calculation principle of magnetic anomaly data,and the conversion between different anomalies by the frequency domain factor.The conversion from the total field to the three components and the conversion from the three components to the tensor gradient are realized by the derivative operator in frequency domain.In the study of the different influencing factors of the magnetic anomalies obtained from the frequency domain conversion,the following conclusions are obtained:(1)The trend of the abnormal signal-to-noise ratio and the noise energy is the same,and the noise in the converted three components will not be amplified.(2)In the same measurement area,increasing the distance between measurement points can improve the signal-to-noise ratio.(3)When the magnetic properties of the target are weak,the analytical signal value can be calculated by integrating the components of the tensor gradient,which is helpful to highlight the position of the field source.(4)When determining the deep abnormal position,using band-pass filter to deal with the vertical component not only effectively suppresses the noise,but also highlights the abnormal position.The theoretical analysis of normalized source strength(NSS)calculated by tensor gradient is carried out.It is proved by the model data that the NSS calculated by tensor gradient is independent of the magnetization direction and its amplitude is only affected by the magnitude of magnetization.It can effectively reduce the interference of surrounding sources and remanence.By using NSS combined with Euler deconvolution method to estimate the model and measurement location of field source,which is more accurate to estimate target position.