Application of the Wiener Filter to Total-Field Magnetic Data for Uxo Detection

The detection of UXO in magnetic environments continues to be a difficult task. In these environments identified geophysical anomalies may either be metallic objects (UXO) or of a geologicorigin. Current techniques such as bandpass filtering are sometimes inadequate by themselves in highly magnetic environments where the spatial wavelengths associated with the background geology are comparable to, or overlaps with, those of UXO anomalies. The Wiener filter assumes that the collected field data is a summation of the desired signal and the background response and the two components are not correlated. We develop a procedure based on the Wiener filter to separate geologic responses from UXO signals. Application of the Wiener filter involves the estimation of a transfer function defined by the ratio of signal and data power spectra. We have developed an iterative approach to estimate the transfer function using the power spectra of signal and geologic noise from the measured field data set and limited forward modeling of UXO anomalies. This approach is demonstrated by applying it to synthetic data examples and field data from Helena, Montana.