Development of a high-stability FHD (total-field <i>F</i>, horizontal component <i>H</i>, and declination <i>D</i>) geomagnetic vector magnetometer based on bias and compensation fields

Geomagnetic vector measurement can obtain more geomagnetic information, which is one of the main development directions of geomagnetic measurement. To date, the magnetic flux gate magnetometer is the main tool for geomagnetic vector measurement; however, its drift issue cannot be ignored. To address this issue, we propose a geomagnetic vector measurement method based on bias and compensation fields and then develop a high-stability FHD (total-field F, horizontal component H, and declination D) vector magnetometer based on a proton sensor and a magnetic field generator. In addition, a dedicated experimental platform is constructed to verify the performance of the developed magnetometer in a geomagnetic station. Compared to the flux gate magnetometer, the experimental results indicate that the fourth-order differential noise of the declination D, horizontal component H, and vertical component Z are 1″, 0.27, and 0.15 nT, respectively, which are all lower than those of the flux gate magnetometer. In addition, the horizontal component H and vertical component Z of the flux gate magnetometer indicate more than 30 and 60 nT startup drift, respectively; in contrast, the proposed FHD magnetometer shows an excellent stability during a 16 h observation time.