Development Of UAV-borne Miniaturized Cesium Optical Pump Magnetometer Recording System

Cesium optical pump magnetometer is a magnetic detection instrument commonly used in geophysics and military fields,it has significant advantages such as high sensitivity,insensitivity to attitude changes,and no zero drift.Compared with manned drones,rotary-wing UAVs have the advantages of flexible take-off and landing,low cost,and suitable for small survey areas.Therefore,the aeromagnetic system based on the integration of rotary-wing UAV platforms and cesium optical pump magnetometers has strong practical value.This paper studies a data acquisition and recording system of CS-3 cesium optical pump magnetometer,which is used to build a miniaturized aeromagnetic measurement system based on a rotary-wing UAV platform.The specific research work is as follows:（1）Development of signal conditioning circuit for cesium optical pump magnetometer.In order to reduce the noise of the output signal of the cesium optical pump magnetometer,this paper adopts the scheme of the output signal of the coaxial cable interface of the cesium optical pump magnetometer,and realizes the input noise level of 10.53n V/√Hz@50k Hz.The original sine wave signal of the instrument is shaped into a TTL square wave signal,which is convenient for subsequent high-precision frequency measurement.（2）Research on high precision frequency measurement method based on FPGA.In this paper,based on the traditional equal-precision frequency measurement method,according to the output frequency signal of the cesium optical pump magnetometer and the characteristics of the operating environment,an improved equal-precision frequency measurement method is proposed.The relative error of the method in the range is less than equal0.19×10^-7.（3）Development of inertial navigation data acquisition module based on FPGA.Attitude and position information is of great significance for the measurement of aviation magnetic field.In this paper,FPGA is used for inertial navigation and GPS data acquisition,which has the advantages of high acquisition accuracy,good synchronization with magnetic field information,fast processing speed,and high cross-clock domain data processing efficiency.（4）Development of ARM-based SD card storage and Bluetooth data transmission module.Based on the advantages of the ARM platform in floating-point operation and control,the Bluetooth data transmission module and the SD card storage module are developed,which realizes the miniaturization and intelligence of the data recording system.At the same time,the host computer software based on Lab VIEW is designed for system ground debugging,which improves the practicability of the data recording system.（5）The system function test was carried out to verify the overall function of the system;the ground static test was carried out,and the average error and standard deviation of the measured data were both less than 0.2n T,achieving high static measurement accuracy;flight experiments were carried out to verify This ensures that the system has reliability and stability under dynamic flight conditions and meets actual exploration needs.