三种GNSS高程时序降噪方法的效果对比分析

Comparison of three noise reduction methods for GNSS elevation time series

  • 摘要: 为了探究经验模态分解(EMD)、整体经验模态分解(EEMD)和小波降噪三种方法的降噪性能,以中国区6个国际GNSS服务(IGS)站高程分量的5 a、10 a和20 a时序数据为例,对它们的降噪结果进行比较分析. 首先利用线性拟合分离趋势项,并采用3σ准则剔除异常值,得到满足符合降噪要求的样本序列;然后分别用这三种方法分离样本序列中的噪声,得到降噪后的序列;最后以信噪比(SNR)、相关系数、均方根误差(RMSE)为评价指标比较分析它们的降噪性能. 实验结果表明:1)当坐标时间序列质量较差时,EEMD和小波降噪可以很好的分离噪声;2)对于5 a和10 a时序数据,小波降噪的效果最好;对于20 a时序数据,EEMD和小波降噪效果接近,优于EMD;3)小波降噪抑制有色噪声的能力最佳.

     

    Abstract: In order to explore the noise reduction performance of the empirical mode decomposition (EMD), ensemble empirical mode decomposition (EEMD) and wavelet analysis, elevation time series data of different lengths from sin IGS stations are taken as examples. Firstly, the outliers and the trend items in the original data are removed to get the sample sequence meeting the experimental requirements. Then, the sample sequence is denoised by three methods and gets the real signal without noise. Finally, calculating the indexes of signal-noise ratio, correlation coefficient and root mean square error of data to compare the three noise reduction methods. The experimental results indicate that: 1) EEMD and wavelet analysis can well denoise when the quality of coordinate time series is poor. 2) Wavelet analysis has the best denoising performance on the Global Navigation Satellite System (GNSS) coordinate time series with time span of 5 a or 10 a; For 20 a time series samples, EEMD and wavelet analysis have similar denoising effects and are better than EMD. 3) The force of wavelet analysis to eliminate colored noise is better.

     

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