一种新的估计瞬时频率的方法—经验包络法

常用的求取瞬时频率的方法，希尔伯特变换，会出现无法解释的负频率和明显的端点效应。标准希尔伯特变换克服了希尔伯特变换出现负频率的缺点，但仍然有端点效应。为了避免希尔伯特变换，基于信号的经验调幅调频分解，论文提出了一种新的求取瞬时频率的方法—经验包络法(empirical envelope method，简称EE）。经验包络法本质上是先通过经验调幅调频分解获取纯调频信号，然后对其求导，再对求导的结果进行经验调幅调频分解，提取出包络信号，便可获得原信号的瞬时频率。论文首先给出了经验调幅调频分解的详细过程，然后给出了经验包络法的原理和具体步骤，最后采用仿真信号将经验包络法与希尔伯特变换、标准希尔伯特变换和反余弦法进行了对比，分析结果表明了经验包络法的优越性

A new instantaneous frequency estimation approach-empirical envelope method

The common method of estimating instantaneous frequency,Hilbert transformation produced negative frequency and boundary effect.Normalized Hilbert transformation overcame the shortcoming of negative frequency of Hilbert transformation,but the boundary effect still existed.In order to avoid using Hilbert transformation,based on the empirical amplitude-modulation frequency-modulation(AM-FM) decomposition,a new method of calculating instantaneous frequency,the empirical envelope method(EE) was proposed.The nature of the empirical envelope method was as follows: getting the FM signal firstly by using the empirical AM-FM decomposition,obtaining the derivative of the FM signal,and then using the empirical AM-FM decomposition again to extract the envelope signal of the derivative of the FM signal.Here,the detailed process of the empirical AM-FM decomposition and the specific steps of the empirical envelope method were presented.Finally,the EE method was compared with Hilbert transformation method,normalized Hilbert transformation method and Arccosine method by analyzing the simulated signals.The analysis results showed that the empirical envelope method is superior to the other methods.