Design Of Synchronous Acquisition Circuit For Full Tensor Magnetic Gradient Signal

With the progress and development of science and technology,magnetic prospecting and exploration technology has been widely used in the field of mineral exploration,military exploration and non explosive detection.Compared with the traditional magnetic prospecting,the magnetic gradient tensor measurement has the advantages of its unique prominent anomaly field weakening background field and so on.The three component of full tensor magnetic gradient measurement technology mainly measuring magnetic vector in the three directions of the geographical coordinates of space on the rate of change,but because the two pickup magnetic gradient sensor ring in the process of measuring ability to suppress common mode of magnetic field is limited,resulting in the target(gradient)into common mode noise signal.Usually,a three axis SQUID magnetometer is needed to eliminate the common mode noise by modifying the unbalance of the 6 plane gradiometer.In order to solve this problem,this paper designs a eight channel synchronous acquisition circuit based on FPGA,and realizes the synchronous acquisition of the nine signals by the way of parallel connection.The validity and reliability of the proposed scheme are verified by the experiment of nine signal synchronization and the full tensor signal acquisition.In this paper,the specific research content:(1)The principle of full tensor magnetic gradient measurement is studied systematically.On the basis of this,the whole scheme of the signal acquisition circuit is designed.According to the overall design,developed a synchronous full tensor magnetic gradient signal acquisition circuit,including power module,amplifier module,A/D conversion module,FPGA control module,data module and the module of communication with computer storage,the realization of nine channel analog signal acquisition,synchronization in amplification,conversion,transmission and other functions.(2)Based on the full tensor magnetic gradient signal synchronous acquisition circuit,the upper computer control program is programmed.Set the transmission mode,the host computer and the communication module of the data storage format and the output in the form of written digital filter,voltage conversion and signal output voltage and magnetic field gradient conversion program,realize data transmission,storage,analysis,display and other functions.(3)The indoor experiment is carried out,and the performance parameters of the full tensor magnetic gradient signal acquisition circuit are tested and verified.The squelch circuit level,through the verification proof acquisition circuit can realize the full tensor 9 SQUID measurement channel synchronous acquisition.