The Design And Implementation Of Geomagnetic Signal Acquisition System Based On SOPC

Geomagnetic navigation technology behaves some good characteristics such as passiveness, no radiation, all-time, all-weather, all terrain, low power, reliablity, anti-interference. Magnetic anomaly location is a new research field of geomagnetic navigation. Because magnetic anomaly signal is relatively smaller than magnetic background field, it is easily to be submerged. So, Magnetic anomaly location system requie geomagnetic signal acquisition instrument with high-precision and high-resolution.In this paper,system adopt high precision fluxgate sensor andΣ-ΔADC,a highly integrated geomagnetic signal acquisition system is designed based on SOPC(System on a Programmable Chip), which include signal acquisition, algorithm processing and real-time communication modules.An embedded system based on SOPC is constructed by memory, peripheral controller and user-defined logic module, and NiosⅡis the core of system.The traditional acquisition system composed of discrete components is unreliable, difficult to debug and upgrade,and the problem can be solved by the embedded system based on SOPCAccording to module function, the system can be divided into four parts:signal conditioning modules, data acquisition module, data processing module, communication and display module. The original signal is to be amended to meet the requirement of AD range in signal conditioning modules.In order to take full use of the resolution of ADC and improve the accuracy of data acquisition circuit.Take some actions,such as attenuation,filtering and single-ended to differential. At the same time,noise can be filtered outside the sampling bandwidth. In data acquistion module, the command is sent to be read or write the ADC (AD) on-chip registers to complete the various operations by SPI master, and the geomagnetic signal is converted into digital signal through SPI interface. To achieve graphical algorithm easily, DSP Builder is used to construct FIR filter in DSP module and a design scheme based on Avalon bus slave peripheral by customer is put forward, And constitute a user-defined module into to the SOPC system,improve the efficiency of the system.it achieve optimal performance that traditional processor can not. In the communication module,The geomagnetic data is uploaded to the VISA-based Serial Commnication Interface. In order to analysis data by other software,Using the TDMS format to store data at real time.In the end, debugging hardware and software of the system is,and the experimental data is tested and analysised by using histogram method.Experimental results show that the design of hardware and softeware about system can meet the primary requirements of data acquisition, which can lay foundation for the follow-up studies of magnetic navigation system. And so, it is a certain valuable instrument.