Closed-form design of fractional delay FIR filter using discrete hartley transform

In this paper, the design of fractional delay FIR filter is investigated. First, the interpolation formula of discrete-time sequence is derived by using discrete Hartley transform (DHT). Then, the DHT-based interpolation formula is applied to design fractional delay FIR filter by using suitable index mapping. The filter coefficients are easily computed because closed-form design is obtained. Finally, design examples are demonstrated to show the proposed method has smaller design error than the conventional Lagrange fractional delay FIR filter using the same design parameters