Magnetic moment direction estimation based on magnetic anomaly signature analysis

In this paper, we proposed a measurement procedure to estimate the magnetic moment orientation (MMO) of an object. As vector magnetic field B
i
(i=x, y, z) in each orthogonal direction can be regarded as the superposition of the three basic elements along certain direction. We propose an orthogonal energy ratio (OER) algorithm to infer the MMO by calculating the signal energy distribution along each axis. The first step is to develop a theoretical model and obtain the dipole signature waveforms decomposed of 9 basic elements. The second step is to develop a standard OER database which provides a metric reference to compare with the measured OER. In this standard database, the one having the smallest variance is determined as the estimated MMO. Owing to symmetric property in space, it generally introduces 8 possible solutions. In the last step, an octant determination procedure is applied to select the unique MMO. In particular, the algorithm is independent of changes in CPA (closest path approach) and velocity. Through the complete processing of this algorithm, the target MMO can be estimated precisely with limited errors.