Robert E. Bracken 2004 This report describes an unwinnowing algorithm that utilizes a discrete Fourier transform, and a resulting Fortran subroutine that winnows or unwinnows a 1-dimensional stream of discrete data; the source code is included. The unwinnowing algorithm effectively increases (by integral factors) the number of available data points while maintaining the original frequency spectrum of a data stream. This has utility when an increased data density is required together with an availability of higher order derivatives that honor the original data. application/pdf 10.3133/ofr03229 en The inverse of winnowing: a FORTRAN subroutine and discussion of unwinnowing discrete data reports