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

中文翻译：

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分数延迟滤波器中的失真减少

作为连续时间延迟的数字版本，分数延迟（FD）的概念可用于近似所需的延迟，该延迟不是采样间隔的倍数。但是，在FD滤波器中，延迟信号的开始总是存在严重的失真，称为头部变形 。这封信确定了磁头失真的原因，并提出了解决此问题的解决方案，以减少FD​​滤波器的整体失真。为了进行性能评估，将相对均方根（RMS）误差公式化为量化FD滤波器的频域响应与理想滤波器的频域响应之间总体差异的度量。此外，在带有经典Sinc，Farrow和Lagrange插值的FD滤波器中，所提出的方案的说明性数值结果证实了我们解决方案的有效性和可行性。