FIR带通数字滤波器的有效实现

本文介绍了不对称和对称带通 FIR 滤波器。在单支路的实现中,滤波器由一个 RRS 滤波器和一个幅度均衡器级连组成;在两支路的实现中,每个支路由两个 FIR 节级连而成。在每一个支路中,第一个 FIR 节是成形滤波器,它有很稀疏的脉冲响应(这大大地减少了运算次数);第二个 FIR节是插入器,它把成形滤波器中不需要的通带频谱分量衰减到预给的阻带指标以下。用两个不同字长的 RRS 滤波器级连,可以使一个滤波器节的零点抵消另一个滤波器节的旁瓣峰值,并能减少计算的复杂性。这些结构能方便地调整带通滤波器的中心频率,并且具有良好的合入噪声和系数量化灵敏度特性。

An Efficient FIR Bandpass Digital Filter Implementation

In this paper, the nonsymmetrical and symmetrical bandpass FIR filters are presented. In one-branch realization, it consists of a cascade of RRS filter and an amplitude equalizer. In two-branches realization, each branch consists of a cascade of two FIR sections. In each branch, the first FIR section is the shap- ing filter which has a very sparse impulse response resulting in a greatly redu- ced number of arithmetic operations, the second FIR section is the interpolator which attenuates the undesired spectral images of the passband of the shaping filter below the prescribed stopband level. By cascading two RRS filters with different word lengths, in such a way that the nulls of one cancel the sidelobc peaks of the other, computational complexity can be considerably reduced. These structures allow simple tuning of the center frequency of the bandpass filter and have good roundoff noise and coefficient-quantization sensitivity properties.