基于IDCT域的加窗全相位数字滤波器

Windowed All Phase Digital Filter Based on IDCT

为了改善直接基于逆离散余弦变换(IDCT)域设计的全相位数字滤波器(APDF)幅频特性,推导了IDCT域加窗APDF的设计公式.IDCT域加窗APDF是一种零相位数字滤波器.滤波器设计实验表明,与加其他窗函数相比,依据此公式设计的基于IDCT域的加凯塞窗APDF能使滤波器达到更好的幅频特性.在相同频率采样点数的情况下,基于IDCT域设计的加凯塞窗APDF和传统频率采样法设计的FIR低通滤波器的幅频特性相比而言,其通带、阻带更平坦,过滤带更窄.

To improve the amplitude-frequency response characteristics of all phase digital fiher（APDF） based on inverse discrete cosine transform（IDCT） ,the design formula of windowed APDF based on IDCT is derived. This kind of filters is zero phase filters. Experiments of filter design show that better amplitude frequency response characteristics of APDF are achieved whe, using Kaiser window compared with other windows. Under the condition of the same number of frequency samples, the amplitude-frequency response characteristics of Kaiser windowed APDF based on IDCT are better than that of FIR digital filter disigned by traditional frequency sampiing method, the pass band and stop band are platter and the transition band is narrower.