抖晃对振动脉冲频响特性估计的影响

Influence of Wow and Flutter on Frequency Characteristic of Measured Impulsive Response

以振动脉冲响应为例,研究抖晃对振动信号分析和估计的影响。应用傅里叶变换和贝塞尔函数,从理论上分析含抖晃振动脉冲频率响应和倒谱的特征;用仿真手段直观展示估计误差的分布、纳奎斯特图形态及抖晃初相的作用。分析和仿真表明:抖晃对振动脉冲频响干扰的数学表达是真实振动频率响应函数与复宗量贝塞尔系数加权旋转脉冲序列卷积的结果。抖晃现象对振动冲击响应的信号处理中的频率响应估计、纳奎斯特图形态和倒谱特征影响极大,所引入的估计误差在信号分析中不可被忽略。

This paper is concerned with the problem of wow and flutter that occurs in the process of storage of analog signal. It is the first time to reveal the error caused by wow and flutter mixed in the frequency characteristic of measured impulse response of a system. Main contributions of this paper are as follows: (a)Give out the Fourier formation of the impulse response mixed with wow and flutter by setting up a complex signal model, which is expressed as a result of convoluting the frequency characteristic of an original signal with a weighting pulse series;(b) Indicate that the wow and flutter have great effect on the frequency characteristic of impulsive response by simulating examples, such as the distortion in the form of side band of its frequency spectrum, the additional circles or bending in its Nyquist plot and the characteristic components in its cepstrum; (c) Confirm the distribution and formation of estimation error closely related to the initial phase of wow and flutter. Through theoretical analysis and simulation, it shows that the effect of wow and flutter on vibration signal processing could not be ignored in engineering applications.