加窗全相位DFT数字滤波器

Windowed All Phase DFT Digital Filter

基于全相位离散傅里叶变换(DFT)数字滤波器的直接频域实现网络结构,对输入或输出数据加窗,导出了一种新型的加窗全相位DFT数字滤波器.其频率特性比不加窗的又有较大提高,幅频响应等于或逼近频率采样值,通带纹波极小,阻带衰减极大,过渡带陡峭,零相位,滤波性能和实现的简捷性超过其他传统方法.它除了可以采用通常的卷积结构外,也可采用直接频域网络实现,此文给出了它的直接频域网络组成及其简化算法.这种网络具有实时自设计功能,可构成时变系统,用于滤波器传递函数实时可变的场合,便于集成为频响和长度均可编程的通用零相位数字滤波器.它是数字滤波器的一种新的设计理念和实现结构.

Based on the architecture of the all phase discrete Fourier transform (APDFT) digital filter, a new type of zero-phase digital filter called the windowed all phase DFT (WAPDFT) digital filter is brought out by windowing the input and/or output data of the DFT/IDFT blocks in the APDFT filter network. The frequency characteristics are improved greatly while the frequency response of the filters still passes or approaches the desired frequency samples. It has much less pass-band and stop-band ripple, and sharp transition. The WAPDFT filter can be implemented with common convolution structure and the frequency domain direct network like the APDFT filter, it can also be realized with a simplified structure. This paper gives the network of the new structure and the associate algorithm. Compared with the traditional frequency sampling structure, this network is not sensitive to finite word length effect. It has real-time self-design function and may constitute a time-variant system. It can be easily integrated into a universal zero-phase digital filter with frequency response and length programmable.