Alternating Magnetic Dipole Tracking From Search Coil Data Using a Multiplicative Cost Function Approach

This article presents a novel inversion method for tracking a moving alternating magnetic dipole in terms of search coil data. We derive the analytical formula of the search coil response for an arbitrary initial phase alternating magnetic dipole. To extract characteristic data from the time series of the search coil for target tracking, the transform of trigonometrical functions, low-pass filter processing, and coherent demodulation are used to extract the target phase, motion characteristic response, and direct current (dc) characteristic response of the alternating magnetic field. The joint inversion method of multiple characteristic data using a multiplicative cost function is used to estimate the moving target’s trajectory, velocity, and magnetic moment. We design three synthetic examples, with and without random noise, to validate the proposed method. Numerical simulations show that the proposed method can locate the magnetic dipole accurately for noisy data. The proposed method has also been applied to a field test and the result shows that the location of the magnetic source can be estimated well.