Development Of A Six-sensor Vehicle Magnetic Field Measurement System

Overhauser magnetometer is a scalar magnetometer that measures the total magnetic field based on the dynamic nuclear polarization effect(DNP).It is widely used in the fields of magnetic exploration,petroleum and mineral exploration,aviation and marine magnetic survey,natural disaster prediction,and archaeological and environmental investigations.The multi-sensor measurement under the vehicle platform can obtain magnetic anomaly information more quickly and comprehensively,which has important application value.After years of experimental accumulation,our research group has successfully developed the JOM-4SF Overhauser magnetometer,and on the basis of this instrument,combined multiple sensors to realize the six-sensor vehicle magnetic field measurement system to carry out relevant research.Under the premise of understanding the research background at home and abroad,the measurement principle of the sensor and instrument system of Overhauser magnetometer is expounded,and the function of the instrument is analyzed and perfected.Based on the STM32 + CPLD architecture on the hardware,a software system has been created and improved.The high-precision time synchronization function between two instruments is designed and implemented.The time synchronization accuracy between instruments is controlled within 1 ms.And the driver of GPS module is designed and completed.At the same time,a dedicated file system supporting multifile management is designed.The non-blocking design of the display driver and the Larmor signal envelope detection based on DMA are implemented,which greatly improves the CPU efficiency.A signal quality evaluation system is implemented which improved the gradient tolerance of the instrument,so that the instrument could obtain more accurate data in a gradient field of 0 to 12000 nT.These have laid the foundation for the construction of the vehicle system.Finally,based on the gradient measurement unit formed by the improved instrument,this paper explores the effect of the target body on the Lamor signal at close distance.Then the forward analysis of the magnetic anomaly of the target body is performed,and the measurement and interpretation of the line response of the magnetic anomaly are performed on several different target bodies.Based on this,a vehicle measurement system is built,and actual site measurements of target detection are carried out multiple times.The results show that the developed vehicle measurement device can accurately detect the position of the target and effectively remove the interference of environmental noise.