全相位FIR滤波器及其在频谱分析中的应用

All Phase FIR Filter and Its Application in Spectrum Analysis

为了减小谱分析中的各种误差 ,更好地反映原始信号的实际谱分布。本文首先给出了一种加双窗重叠频域滤波器 ,并经理论推导得到相应的全相位 FIR滤波器模型 ;进而将加权重叠滤波思想 (W-O)引入频谱分析中 ,给出了在无窗、单窗和双窗条件下由 W-O得到的谱和由传统方法得到的谱之间的关系。结果表明 ,W-O方法得到的信号频谱比传统加窗具有更少的旁瓣干扰和更高的主瓣 -第一旁瓣能量比。实验中通过对低信噪比信号的对比分析 ,验证了结论的正确性和 W-O方法的可行性。

In order to decrease various errors in analyzing signal spectrum and to obtain its factual spectrum distribution, a novel overlapping filer with double windows in frequency domain is proposed. Through theoretically analyzing the structure, its corresponding all phase FIR module is also presented. Then the idea of overlapping and windowed filtering is introduced in spectrum analysis. The relations between the spectrum deduced out in W-O way and the conventional way are respectively given under the conditions of no window,single window and double windows. Result indicates that the spectrum gained from using W-O way comprises much fewer side lobes and achieves higher energy ratio of main lobes to the first side lobe. Experimental result verifies the validity of the feasibility of the W-O way by the analysis of signal with low SNR.