基于分段波形的信号瞬时频率计算方法

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基于分段波形的信号瞬时频率计算方法

作者：张亢,程军圣,杨宇,邹宪军

来源：《湖南大学学报·自然科学版》2011年第11期

摘要：针对局部均值分解（Local Mean Decomposition，LMD）中乘积函数（Product Function，PF）分量的瞬时频率计算问题，引入了一种新的信号瞬时频率计算方法.该方法基于分段波形，先将信号分成若干个全波段（full wave），然后以一组递增的反正弦函数定义每个全波段的瞬时相位，进而得到信号的瞬时频率.由该方法得到的瞬时频率理论上是正的、稳定的并且能够确保信号局部特征信息的完整.应用该方法计算了仿真信号和实际齿轮故障振动信号的瞬时频率，并与其他方法求得的瞬时频率进行了对比.结果表明，本文方法非常适合求取信号的瞬时频率.

关键词：故障检测；局部均值分解；乘积函数；纯调频信号；瞬时频率；分段波形

中图分类号：TN911.7 文献标识码：A

A Piece-wise Based Signal Instantaneous

Frequency Computing Method

ZHANG Kang, CHENG Jun-sheng, YANG Yu, ZOU Xian-jun

(State key Laboratory of Advanced Design and Manufacture for Vehicle Body, Hunan Univ, Changsha，Hunan 410082,China)

Abstract:To address the computing instantaneous frequency of the product function (PF) in local mean decomposition (LMD), a new instantaneous frequency of a signal computing method was introduced. This method is piece-wise wave based. Firstly, a signal was separated to a number of full waves. Then, the instantaneous phase of each full wave was defined by a set of monotonic increasing arcsine functions. Therefore, the instantaneous frequency of a signal was obtained. Theoretically, the instantanoues frequency obtained in this method was positive, stable and could guarantee the characteristic information of signal integrity. This method was applied to compute the instantaneous frequency of simulated signals and actual gear fault vibration signals, and the results were compared with those obtained in other methods. It has been shown that this method is quite suitable for extracting the instantaneous frequency of a signal.

Key words: fault detection;local mean decomposition; product function; pure frequency modulated signal; instantaneous frequency; piece-wise wave