基于全通滤波器的IIR陷波器抑制信号中的周期性干扰

Eliminating Periodic Interference in Signal UsingIIR Notch Filter Based on All-Pass Filter

从滤波器的系数敏感度角度 ,提出一种基于全通滤波器的 IIR陷波器来抑制信号中的周期性干扰。该滤波器是由全通滤波器的级联构成的 ,因为全通滤波器传递函数的分子和分母多项式之间的镜像对称关系 ,该滤波器可以用高效的格型运算结构来实现 ,并且具有很低的系数敏感度 ,使得系数量化后的陷波频点偏移量最小。本文详细论述了该陷波器的设计方法 ,并深入分析了其在低频段的系数敏感度问题。通过实际数据验证了这种滤波器能够有效的抑制电力线通信信号中的谐波干扰。

From the point of the coefficient sensitivity of filter, a method for eliminating periodic interference in signal using IIR notch filter based on all-pass filter is proposed. A cascade of all-pass filter constitutes the notch filter. Due to the mirror-image symmetry relation between the numerator and denominator polynomials of transfer function of all-pass, the notch filter can be realized by a computationally efficient lattice structure. The filter has very low sensitivity and the notch frequency shift after coefficient quantization is the least. The design method of the filter is discussed, and coefficient sensitivity in low frequency band is analyzed. Practical experiments prove that the filter eliminates harmonic interference effectively in the signal of power line communication.