Simplest magnetometer configuration scheme to measure magnetic field gradient tensor

Due to geomagnetic anomaly strength can´t be separated from magnetic field data, underwater vehicle localization based on geomagnetic anomaly needs vehicle draft depth information. For this localization method, we conclude that the simplest configuration be seven single-axis vector magnetometers to measure magnetic dipole gradients. The essential conditions and optimal measurement matrix of magnetic gradient tensor are analyzed, and a kind of configuration about seven single-axis magnetometers is put forward, which installed respectively seven vertexes of a cubic supporter. The relationships that the relative errors of magnetic gradients and localization to the side-length are simulated numerically and the results show that these errors increase rapidly with the length of baseline. To measure magnetic gradient tensor precisely, ten single-axis magnetometers configuration should be adopted.