利用零极点设计数字带陷滤波器

摘要

在数字信号处理的研究中,为解决工频干扰,可以采用数字带陷滤波器方法,传统的零极点配对方法存在频率响应不均匀和增益不对称的特点.提出了一种新的设计带陷数字滤波器方法,能克服传统设计方法的缺陷.方法是从零极点配置法演绎而来的,主要思想是零点设置在带陷频率处,极点不在极径方向,偏移数字滤波器的极点,用最小二乘方法估计出滤波器的参数进行仿真.仿真结果表明方法可以改善传统方法设计带陷数字滤波器的缺陷,使数字滤波器的频谱均匀对称,即直流增益等于Nyquist频率增益,通带增益成对称性.通带特性得到更好改善.证明新方法优于传统的零极点配置法设置带陷数字滤波器.%To solve the frequency interference, we can adopt notch digital filter, but the traditional placement of poles and zeros is of characteristics of unsymmetry. This paper presents an improved design to implement notch digital filter by placement of poles and zeros and overcome the shortcoming of traditional method. This method is derived from the old algorithm by changing the position of the poles, which overcomes the deficiencies of the filter by traditional design. The main idea is to place the zero in the notch frequency, and the pole off the direction of polar radius by moving the pole of the digital filter. Then the coefficients to control the performance of passband are estimated.The result shows that this method not ouly controls passband gain of notch filter but also solves the pessband symmetry of the filter according to the expected specification. The simulation shows that this method is superior to the traditional zero-pole placement method to design the notch digital filter.