Accession Number : AD0774163

Title :   A Method for Fitting EMP Waveforms that Facilitates Calculation of the Time Derivative and Fourier Transform.

Descriptive Note : Topical rept.,


Personal Author(s) : Higgins,Daniel F.

Report Date : 29 NOV 1973

Pagination or Media Count : 37

Abstract : A method is developed for finding a smooth fit to an EMP waveform over several decades in time with a minimal number of input data points. The fitting function between data points is a polynomial chosen so that first and second derivatives of the function are everywhere continuous. The beginning and end of the waveform are fitted with exponentials to insure that the function goes to zero at both ends. With this curve fit, a relatively smooth time derivative is easily calculated. An expression for the Fourier transform written in terms of a summation of the discontinuities in the third and fourth derivatives is then derived. Difficulties in evaluating this expression due to round-off error at low frequencies are discussed and sample results are included. (Author)

Descriptors :   *Electromagnetic pulses, *Waveforms, *Curve fitting, Fourier transformation, Graphics, Analytic functions

Subject Categories : Electromagnetic Pulses

Distribution Statement : APPROVED FOR PUBLIC RELEASE