小波域内瞬时频率提取方法研究

Extraction of Instantaneous Frequency in Wavelet Domain

根据振动信号本身的特征 ,由小波系数模极大值与小波函数的关系 ,提出了一种在小波域内提取瞬时频率的方法 ,这种方法比较适合于频率随时间变化的振动信号 .把该方法用于由碰摩转子模型生成的振动信号 ,可得到一条锯齿状的瞬时频率曲线 ,而用短时Fourier变换对该信号进行分析 ,则不能检测出这样的特征 .这证明了该方法在瞬时频率的提取中是很有效的 .对实测碰摩信号获得的瞬时频率也显示了这种方法的有效性 。

A new method is presented to extract the instantaneous frequency of vibration signal in wavelet domain. Use is made of the relationship between the maximum of wavelet modulus and the wavelet function. This method is suitable for the signal with time-variant spectrum. A jagged curve of instantaneous frequency is obtained when the method is applied to a simulated signal for the rub-impact model. This jagged feature can not be detected by the short-time Fourier-transform. It is proved that the method is very effective for extracting instantaneous frequency. Application of a measured rub-impact signal also shows that the method has a wide range of application for fault diagnosis and determination of feature of signals.