AN OPTIMIZED DIGITAL FILTER FOR THE FOURIER TRANSFORM*

Abstract

A bstract Short filters for calculating Hankel‐transformations, with special attention to the d.c.‐sounding problem, have been published in recent years. These filters, with a typical length of less than 25 coefficients, have made it possible to implement, e.g., VES‐interpretation programs on microcomputers and 3‐D electric and electromagnetic modeling programs on minicomputers. Initially the performance of the short filters was rather poor, but with the introduction of short optimized filters there has been a considerable improvement in the accuracy. An optimization procedure is applied to design a 20‐point filter for the Fourier sine‐transformation. This filter may be useful in electromagnetic prospecting theory, e.g., in the calculation of the electric and magnetic field from a line source.