Enhanced spectral resolution FFT for step-like signals

A method is presented for obtaining a sampled Fourier transform of a steplike signal with a spectral resolution greater than previously reported. The method is related to zero padding, which is used for enhancing the spectral resolution of an FFT of a limited duration signal. The new method involves final value padding when the extension function outside the observation window is a step, or it involves padding with a sampled exponential function when the extension function is a decaying exponential