振动调幅调频信号的调制边频带分析及其解调方法

MODULATION PRINCIPLE OF AMPLITUDE & FREQUENCY MODULATED SIGNAL AND ITS DEMODULATION PROCEDURE

机械设备(如齿轮系统)中的振动信号,调幅现象和调频现象总是同时存在的,测得振动信号的频谱中通常包括有很多调制边频成分。而且不同于单一调幅或者单一调频情况下的对称调制边频带,当调幅和调频共同作用时,调制边频带一般都是不对称的。理论上分析调幅和调频共同作用时频谱中调制边频带不对称的原因,并采用广义检波滤波解调方法和循环自相关分析方法对其进行解调。仿真验证理论结果正确,并对滚动轴承实验信号和齿轮箱实测信号进行了分析。

Phenomenon of both amplitude-modulation and frequency-modulation always exists simultaneousty in mechanical vibration system. The spectrum of this kind of signal contains many modulation sidebands. These sidebands are generally asymmetrical, which are different from the single amplitude-modulation signals or single frequency-modulation signals Theoretically, the reason of existence of asymmetric modulation sidebands is analyzed. Based on the theoretical results, generalized detection-filtering demodulation analysis and cyclic autocorrelation function analysis are used to demodulate the amplitude & frequency modulated signal. Digital simulating results verify the correctness of the theory. These methods are validated using test data from a rolling-bearing test rig and a real gear-box.