二阶循环相关解调法对调频信号的解调研究

为克服传统解调方法对多载波调频信号解调分析时所产生的混频现象,推导了二阶循环相关解调法对调频信号的解调公式,并对多载波调频仿真信号进行了解调分析。提出利用循环谱切片图识别多载波调频信号的调制频率、载波频率和混频信息的规律,并将该方法用于空分机齿轮箱碰磨故障诊断,结果表明,该方法能够有效地识别各载波频率信息和混频信息,提取故障特征频率。

Study on Demodulating Frequency Modulated Signal by the Second-Order Cyclic Correlation-Envelope Technique

In order to effectively overcome the shortcoming of mixing frequency phenomenon occurred by using conventional demodulation method to demodulate the multi-carrier frequency modulation signal, this paper deduces the formula of the second-order cyclic correlation-envelope for demodulating the frequency modulated signal and has a demodulation analysis on a multi-carrier frequency modulation simulation signal. The paper also presents a method for identifing the modulation frequency, carrier frequency and frequency mixing information of a multi-carrier frequency modulated signal by using the slices of a cyclic spectrum. The method has been used for diagnoing the rub impact fault of an air separation unit's gearbox. The result showes that the cyclic correlation-envelope method can successfully recognize each carrier frequency and frequency mixing information and extract fault characteristic frequency correctly.