Distortion Reduction in Fractional Delay Filters

As the digital version of a continuous-time delay, concept fractional delay (FD) is exploited to approximate desired that not multiple sampling interval. However, in FD filters, there always severe distortion at beginning delayed signals, referred as head distortion. This letter identifies cause and proposes solution this problem for reducing overall filters. For purpose performance evaluation, relative root-mean-square (RMS) error formulated metric quantify difference between frequency-domain response an filter ideal one. Moreover, illustrative numerical results on proposed scheme applied filters with classical sinc, Farrow Lagrange interpolation substantiate validity feasibility our solution.