Hybrid Calibration Method for Three-Axis Gradiometer

The performance of a three-axis gradiometer (TAG) is limited by measurement and misalignment errors of two three-axis magnetometers (TAMs). We describe a simplified calibration method for TAGs. One TAM is calibrated with a scalar method. Self-errors of the other TAM and misalignment errors between the two TAMs are then calibrated as integrated errors based on a vector calibration. The experimental results show that the scalar output errors of the two TAMs and the vector output errors of the TAG are greatly reduced and the performance of the TAG is improved dramatically.