Digital filtering of sirotem data

Abstract

Two dimensional Fourier Transforms and tailored filters can be applied to spatially collected electromagnetic data to provide better definition of anomalous responses. These can be applied quickly and easily to large data sets converted to a regular grid. The residual or regional data can then be selected depending on the requirement and studied directly or further enhanced on an image processor. Anomalous responses revealed in the filtered data can be processed and modelled directly or allocated for further definition in the field using more appropriate survey parameters. Three methods described in this paper were applied to a Sirotem survey data set consisting of some 5000 data points. Anomalies that were known were better defined. Anomalies that were not previously identified were modelled and the results therefrom used to design detailed surveys to better define their source in the field.