Development Of Multi-channel Fluxgate Data Acquisition Unit

Geomagnetic field data acquisition has become an indispensable key technology in modern industry and national defense.Benefiting from the rapid development of electronic information technology and microelectronics technology in recent years,geomagnetic detection equipment has also been increasingly developed in the direction of multi-channel,higher,low-noise and easy-tooperate.Relying on the national key research and development plan "High-resolution three-axis weak magnetic sensor" project,this paper aims at the shortcomings of the existing magnetic fluxgate sensor-based geomagnetic field data acquisition equipment,such as the small number of channels and the single sensor model,and has carried out high-speed large data volume.Through research on key technologies such as throughput and large dynamic range acquisition,a multichannel data acquisition unit compatible with fluxgate sensors with different power supply and output modes has been developed.The multi-channel fluxgate data acquisition unit adopts a modular design and has developed supporting user operating software.The hardware mainly includes the data acquisition module and the operation logic module,which are packaged in an integrated chassis,and the power supply,USB and fluxgate sensor interfaces are reserved on the chassis panel.The main functions of the data acquisition module include power conversion,signal processing,and A/D conversion.It is composed of two acquisition circuits of the same design.Each acquisition circuit can be connected to 5 three-axis fluxgate sensors to achieve 15 channels of voltage data.Synchronous A/D conversion,and compatible with both single-ended and differential output types of fluxgates,the data accuracy is up to 24 bits,the sampling rate can be adjusted,the fastest can reach 10 k SPS,the data transmission adopts the SPI protocol,and the highest transmission rate is 5.76Mbps;The main function of the running logic module is to describe the bottom-level control and data transmission logic of the acquisition unit.The core controller adopts Cyclone ? series FPGA,and the peripheral USB transceiver chip is configured to communicate with the PC-side host computer software through the USB interface.Configure the parameters such as the signal attenuation coefficient and sampling rate of the data acquisition module,and receive the data after A/D conversion by the data acquisition module,and finally send the acquired data to the PC;the host computer software is designed in C# in the development environment provided by Microsoft Visual Studio.It provides a visual operation interface for users of the acquisition unit,which can run on Windows 7 and above systems,and mainly realizes the functions of acquisition start and stop control,acquisition parameter configuration,real-time data display and storage.It mainly realizes the functions of acquisition start and stop control,acquisition parameter configuration,real-time data display and storage.In an indoor environment,the multi-channel fluxgate data acquisition unit was used to conduct acquisition tests to verify its functions and performance.During the acquisition period,the equipment was running stably,the control and data transmission logic design met the expected requirements,and the data display and storage of the host computer software And other functions are normal.The collected 30-channel data shows that the range of the acquisition unit is singleended ±10V or differential ±3V,with 3k Hz bandwidth,dynamic range better than105 d B@(fs=100Hz),up to 113 d B@(fs=100Hz),and There is good consistency among the channels.The test results show that all functions of the multi-channel fluxgate data acquisition unit have been realized,and the performance indicators have basically reached expectations.At present,the collection unit has been produced and put into use,which has been affirmed by users.