On designing a wideband fractional delay filter using the farrow approach

In this paper the problem of designing a wideband FIR fractional delay filter using the Farrow approach is considered. A two-stage design with a half-band linear-phase prefilter optimal in the Chebyshev sense and a short maximally flat Lagrangian fractional delay filter in the Farrow structure is proposed. It offers an economic implementation with the number of multiplications smaller than for one-stage approach used hitherto, provided that the prefilter is a Nyquist filter. A novel, accurate method of computing the coefficients of Farrow subfilters is introduced based on symbolic designing of k-th degree differentiators. The proposed filter is intended for applications with variable fractional delay value.