Variable Fractional Delay FIR Filters with Sparse Coefficients

Implementing a variable fractional delay (VFD) filter in Farrow model is costly as each coefficient of a VFD filter is a polynomial rather than a numerical scalar as in a conventional digital filter. This paper presents a method for the design of VFD filters with sparse coefficients which admits efficient implementation. The design is accomplished in two phases with the first phase identifying locations in polynomial impulse response that are suitable to be set to zero and the second phase optimizing the remaining nonzero coefficients so as for the VFD filter to best approximate a desired frequency response. Performance evaluation and comparison of the proposed algorithm relative to an equivalent nonsparse counterpart are also presented.