Method and device for filtering a digital signal with fractional delay

摘要

Method and device for filtering a digital signal with the aid of an Mth order finite impulse response filtering with a fractional delay d which is a fraction of the sampling period associated with the digital signal, in order to obtain an interpolated value. This involves predetermining (M+1)/2 window weights wk of a window function which is applied to the infinite impulse response of the ideal interpolator, the window function being a symmetric stepped window function. Then simplified filter coefficients (hj)w0 are determined as a function of the fractional delay d, and the finite impulse response filtering is applied to the digital signal. Finally, the weighted result of the finite impulse response filtering is multiplied by a common normalisation factor (F(d))w0. Each filter coefficient determination requires just three operations.