Addressing drawbacks of analog components and questions of multi-channel fluxgate signal operation, a FPGA (Field Programmable Gate Array) based signal processing system is designed. Three copies of sub modules compose the whole system, each of which exclusively processes one of three outputs of the fluxgate sensor. A "Phase-Sensitive-Rectification & Low-Pass-Filtering" circuit structure is employed in the processing module, through which the fluxgate signal harmonics are extracted and converted into direct quantities according to detected magnetic intensities. Firstly designed in HDL (Hardware Description Language), afterward configurated in a FPGA chip, finally tested by processing outputs of a fluxgate sensor probe in real-time, the functionality of the designed system is verified. With inherent advantages, this FPGA based design is much reliable over temperature; by processing signals not time-sharingly but synchronously, its working speed is excellently high.
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