Synthetic aperture array dipole moment detector and localizer

Abstract

A synthetic array comprising a moving magnetic sensor that provides a signal representative of an array of magnetic sensors is coupled to a digital signal processor is used to break a magnetic dipole field into its components, and a magnetic signature of the present magnetic field is created. Predicted dipole 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 moving synthetic array are processed and each magnetic value is predicted to process against background noise. A long term time average consistent with the relative motion of the dipole is computed using bandpass filtering of the signals from the synthetic array. The bandpass filtered data is used to update the predicted data so that anomalies and other non-dipole data is removed from the signals that are processed. The data are then expressed in terms of Anderson functions. The data are matched faltered, wherein it is correlated with the stored precomputed predicted dipole signatures. The correlation yields a set of values that is then thresholded. If a dipole is present at any of the locations, then the correlated normalized value computed as stated above will be higher than the chosen threshold. The dipole locations that are above the threshold are then displayed on a monitor showing the relative location and dipole orientation.