Dipole moment detection and localization

Abstract

An array of magnetic sensors and a digital signal processor are used to break a target magnetic dipole field into its components, and a magnetic signature of the present magnetic field is created. Predicted target signatures are precomputed for multiple magnetic orientations of the dipole at each of a plurality of range locations, expressed in terms of Anderson functions, which are a set of equations that decompose the magnetic field in each of the magnetic response locations, and are stored in a lookup table for reference. Input data measured by the sensors are processed and each sensor's magnetic value is predicted to process against background noise using the other sensors of the array. A long term time average consistent with the relative motion of the target is computed using bandpass filtering of the signals from the sensor array. The bandpass filtered data is used to update the predicted data so that anomalies and other non-target data is removed from the signals that are processed. The data are then expressed in terms of Anderson functions. The data are matched filtered, wherein it is correlated with the stored precomputed predicted target signatures. The correlation yields a set of values that is then thresholded. If a target is present at any of the locations, then the correlated normalized value computed as stated above will be higher than the chosen threshold. The target locations that are above the threshold are then displayed on a monitor showing the relative location and dipole of orientation.