极低频信号的一种离散频谱校正新方法

对于振动工程中常见的极低频、极短时、极高频(接近奈奎斯特频率)等极端频率信号,常用的离散频谱分析与校正方法存在较大误差.对极端频率信号的典型情形进行了分析,针对极端频率信号中的极低频信号,提出了一种计及负频率成分干涉影响的离散频谱校正新方法.该方法基于Blackman窗,利用局部谱峰附近的三条谱线,建立包含正负频率贡献的离散频谱校正模型,通过对模型的求解获得频率、幅值和相位校正公式.采用频段内扫描的方式对频谱校正公式进行了仿真验证,结果表明所提方法有效降低了负频率成分的干涉影响,对极低频信号的频率、幅值和相位校正有较高的精度.

A discrete spectrum correction method for ultra low frequency signals

For the extreme frequency signals such as ultra low frequency signals, ultra short frequency signals,ultra high frequency(adjacent Nyquist frequency) signals that existe in vibration engineering domain,the existing discrete spectrum analysis and correction methods aren’t to be adapted to them exactly.The typical extreme frequency signals were firstly expatiated.In order to reduce the influence of negative frequency component,a discrete spectrum correction model with both positive and negative frequency component contribution was established for ultra low frequency signals by three frequency lines closing to the peak value.The frequency,amplitude and phase correction formula was deduced based on the Blackman window.Simulated gradually increasing real sine signals are adapted to assessment the formulas.Simulation results show that the proposed method that reduces the interference caused by the negative frequency components effectively can achieve higher accuracy correction results of spectrum parameters for ultra low frequency.