一种阶跃函数在矩形时间窗口频域特性的分析方法

Method for analyzing frequency-domain characteristics of step function in rectangular time window

傅里叶变换算法受时间窗口因素的影响,容易引起频谱泄漏问题,使非周期信号的频域分析结果出现误差。运用一种算法较为简单的LCR点频滤波器方法分析了影响非周期信号频域分析特性的矩形时间窗口因素,得出了阶跃信号在矩形时间窗口截断时仅对较窄的低频信号分析结果产生影响的结论。且随时间窗口的长度的增加,受影响的信号越少。利用所提分析方法对某惯性环节的幅频特性进行了仿真分析,与理论幅频特性的分析结果非常接近。所提方法还成功辨识出了某锅炉二级过热汽温控制对象的频域特性。

The time window factor may easily influence Fourier transform algorithm in the frequency-domain analysis of nonperiodic signal,resulting in spectrum leakage.A method based on LCR point frequency filter with simpler algorithm is applied to analyze the rectangular time window factor and the conclusion is that,only a narrow low-frequency part of step signal is affected and the affected part decreases along with the increase of time window length.The amplitude-frequency characteristic of an inertial section is analyzed with the proposed method and its result is very close to that of theoretic amplitude-frequency characteristic analysis.The frequency-domain characteristics of an object in the second-stage superheated steam temperature control of boiler are identified by the proposed method.