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.