基于LMD的信号瞬时频率求取方法及实验  

Instantaneous frequency extraction method and experiment based LMD

作　　者：任达千[1] 杨世锡[1] 吴昭同[1] 严拱标[1] 

机构地区：[1]浙江大学机械与能源工程学院,浙江杭州310027

出　　处：《浙江大学学报（工学版）》2009年第3期523-528,共6页Journal of Zhejiang University：Engineering Science

基　　金：国家自然科学基金资助项目(50675194);宁波市自然科学基金资助项目(2007A610014)

摘　　要：研究了调频信号瞬时频率的直接求取法,提出了纯调频信号的瞬时频率直接求取法的适用条件,并用数学方法证明了该适用条件.针对极值点附近瞬时频率的畸变情况引进平滑处理改进了瞬时频率求取法.应用局域均值分解(LMD)和经验模态分解(EMD)求取仿真信号和汽轮机转子振动信号的瞬时频率.结果表明,由LMD方法求取信号瞬时频率时,不会出现难以解释物理意义的负频率现象.A new time-frequency analysis method called local mean decomposition （LMD） was introduced. The results of LMD are a serial of AM-FM signals, and the instantaneous frequency can be calculated by arc cosine function. The direct method of instantaneous frequency extraction was studied. An applicable condition was given and proved by mathematical methods. Considering the aberration near the extreme points, the moving smooth was applied to develop the instantaneous frequency extraction process. LMD and empirical mode decomposition （EMD） were applied to extract the instantaneous frequency of the simulation signal and vibration signal of a turbine rotor. The results showed that the LMD instantaneous frequency was always positive

关 键 词：时频分析 局域均值分解 瞬时频率 适用条件 

分 类 号：TP206[自动化与计算机技术—检测技术与自动化装置] TH113[自动化与计算机技术—控制科学与工程]