EMD用于GPS时间序列降噪分析

摘要

针对GPS位置时间序列噪声成分复杂、建模困难、噪声与信号难以有效分离等特点,用自适应信号分析方法经验模态分解(EMD)对中国区域9个IGS站时间序列的N、E、U方向作降噪处理.首先对各方向分量作EMD分解,获取各方向噪声强度依次降低的一系列本征模态分量及其趋势项;其次利用相关系数辨别出噪声与信号的分界本征模态分量,并按重构方法重构各本征模态分量;最后用相关系数、信噪比、能量百分比等参数评价EMD方法降噪的有效性.结果表明,EMD方法能合理地分离序列中的信号与噪声,有效削弱噪声对GPS位置时间序列的影响,进一步提高GPS位置时间序列的精度.%The noise of GPS site time series is difficult to model and separate from signal.In this paper,the noise of GPS time series for 9 IGS stations is reduced by empirical mode decomposition (EMD),an adaptive signal analysis method.First,we decompose the GPS time series by EMD and get a series of intrinsic mode components and its trends.Then we use the correlation coefficient to distinguish the intrinsic mode function (IMF) between noise with signal and restructure the intrinsic mode function.Finally,we use the correlation coefficient,signal-to-noise ratio,and percentage of energy,to evaluate the effectiveness of the EMD method for noise reduction.The results show that the EMD method could separate signal and noise in sequence reasonably and it effectively weakens the impact of noise in GPS time series.Furthermore,it could further improve the accuracy of the GPS site time series.