多分量调幅-调频信号的瞬时频率直接计算与畸变消除方法

Direct Computing and Aberration Eliminating Method for Extracting Instantaneous Frequency of Multi-Components AM-FM Signals

针对局部均值分解(LMD)在多分量调幅-调频(AM-FM)信号解调过程中的瞬时频率求解问题,提出了一种瞬时频率快速直接计算与畸变消除方法。首先通过LMD将多分量AM-FM信号分解为一系列单分量AM-FM信号,使用未展开瞬时相位的差分绝对值替代相位展开,有效提高了瞬时频率的计算效率;然后针对直接计算法求得的瞬时频率在极值点附近存在畸变的问题,根据畸变位置分布规律定位畸变位置并剔除畸变点,使用插值法补全被剔除数据,最终得到可用的瞬时频率。将提出的方法成功应用于转子碰磨故障诊断和语音信号基音频率识别,试验结果表明:与传统的基于相位展开的直接计算法相比,提出的快速直接计算法的运行效率更高;同时,求得的瞬时频率中的畸变能够被完整的定位和消除,最终得到正确可用的信号瞬时频率。

For extracting instantaneous frequency from multi-component amplitude modulationfrequency modulation（AM-FM）signals,an improved local mean decomposition（LMD）method with direct computing and aberration eliminating capability in extracting instantaneous frequencies is proposed.Firstly,a multi-component AM-FM signal is decomposed into a series of mono-component AM-FM signals.A difference operation for the absolute value of wrapped phase is utilized to directly compute the instantaneous frequency of mono-component AM-FM signals.Then,the aberration phenomena of instantaneous frequency near the extreme points are analyzed.The aberration points are located by a locating strategy and eliminated with the cubic spline interpolation.As a result,the undistorted instantaneous frequency is obtained.The simulation and experimental results show that the instantaneous frequency is effectively extracted and aberrations are eliminated successfully.