GNSS Coordinate Time Series Denoising Method Based on Parameter-Optimized Variational Mode Decomposition
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摘要:
针对全球导航卫星系统(global navigation satellite system,GNSS)坐标时间序列中噪声成分难以有效滤除的问题,构建一种基于参数优化变分模态分解(variational mode decomposition,VMD)的降噪方法。该方法首先以排列熵结合互信息为适应度函数,利用灰狼优化(grey wolf optimization,GWO)算法自适应获取VMD的模态分解个数
和二次惩罚因子 的最优参数组合;然后将GNSS坐标时间序列分解为 个本征模态函数分量,并利用样本熵确定有效模态分量,将其重构为有效信号,从而实现信号与噪声的有效分离;最后,利用仿真信号和中国地壳运动观测网络的20个基准站的实测数据进行实验,将GWO-VMD方法与经验模态分解、小波降噪和基于VMD的降噪方法进行对比分析。结果表明,GWO-VMD方法能够更为有效地去除GNSS坐标时间序列中的噪声,且能较好地保留信号的原始特征,为后续的分析处理提供可靠数据。 Abstract:ObjectivesIn order to effectively filter out complex noise components in GNSS coordinate time series and extract effective signals, we construct a denoising method based on parameter-optimized variational modal decomposition (VMD).
MethodsFirst, the combination of permutation entropy and mutual information is used as fitness function, and the optimal parameter combination of the mode decomposition number
and the quadratic penalty factor of VMD is obtained by using grey wolf optimization algorithm(GWO). Then the GNSS coordinate time series is decomposed into eigen mode function components by VMD. Finally, the sample entropy is used to determine the effective modal component, which is reconstructed as an effective signal, so as to realize the effective separation of signal and noise.The GWO-VMD method is compared and analyzed with the empirical mode decomposition (EMD), wavelet denoising (WD) and IVMD methods by using the simulated signal and the measured data from 20 reference stations of the crustal movement observation network of China for experiments. ResultsThe simulated signal experiments show that the three denoising evaluation indexes of root mean square error,correlation coefficient and signal-to-noise ratio of GWO-VMD denoising signal are better than EMD, WD and IVMD methods. The experiments on the measured data show that the GWO-VMD method can reduce the amplitude of noise significantly. In terms of the velocity uncertainty of the reference station, the overall GWO-VMD method reduces the velocity uncertainty better than the EMD, WD and IVMD methods.
ConclusionsThe GWO-VMD method can more effectively remove the noise from GNSS coordinate time series and better preserve the original characteristics of the signal, which can provide reliable data for subsequent analysis and processing.
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Keywords:
- GNSS coordinate time series /
- VMD /
- GWO /
- permutation entropy /
- mutual information /
- sample entropy /
- signal denoising
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http://ch.whu.edu.cn/cn/article/doi/10.13203/j.whugis20220363
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表 1 GWO-VMD分解后各IMF的样本熵
Table 1 Sample Entropy of Each IMF After GMO-VMD Decomposition
信号分量 IMF1 IMF2 IMF3 IMF4 IMF5 IMF6 IMF7 IMF8 IMF9 IMF10 样本熵 0.105 9 0.320 2 0.470 5 0.610 8 0.601 3 0.562 2 0.656 8 0.579 9 0.640 2 0.637 2 表 2 仿真信号Ⅰ 4种方法的降噪评价指标
Table 2 Denoising Evaluation Indexes of the Four Methods for Simulated Signal Ⅰ
降噪方法 RMSE/mm SNR/dB 原始信号 1.40 0.953 3 9.87 EMD 0.91 0.979 3 13.86 WD 0.73 0.986 6 15.73 IVMD 0.48 0.994 2 19.27 GWO-VMD 0.46 0.994 8 19.74 表 3 仿真信号Ⅱ 4种方法的降噪评价指标
Table 3 Denoising Evaluation Indexes of the Four Methods for Simulated Signal Ⅱ
降噪方法 RMSE/mm 相关系数 SNR/dB 原始信号 2.06 0.895 1 12.78 EMD 1.31 0.953 8 16.80 WD 0.48 0.993 6 25.39 IVMD 0.50 0.992 5 24.99 GWO-VMD 0.42 0.994 8 26.53 表 4 20个基准站E、N、U分量的最优噪声模型
Table 4 The Optimal Noise Model for E, N, U Components of 20 Reference Stations
测站 最优噪声模型 测站 最优噪声模型 E N U E N U BJFS WN+FN+RWN WN+FN+RWN WN+FN SUIY WN+FN+RWN WN+FN+RWN WN+FN BJSH WN+FN+RWN WN+FN WN+PL TAIN WN+FN WN+FN WN+PL CHUN WN+FN+RWN WN+FN WN+FN URUM WN+FN+RWN WN+FN+RWN WN+FN DLHA WN+FN+RWN WN+FN+RWN WN+FN WUHN WN+FN+RWN WN+FN WN+FN+RWN GUAN WN+FN+RWN WN+FN WN+FN WUSH WN+FN WN+FN WN+FN HRBN WN+FN+RWN WN+FN WN+FN XIAG WN+PL WN+PL WN+FN JIXN WN+FN+RWN WN+FN+RWN WN+FN XIAM WN+FN+RWN WN+FN+RWN WN+FN KMIN WN+FN+RWN WN+FN+RWN WN+FN XNIN WN+FN+RWN WN+FN+RWN WN+FN LUZH WN+FN+RWN WN+FN WN+FN YANC WN+FN WN+FN WN+FN QION WN+FN WN+FN WN+FN ZHNZ WN+FN+RWN WN+FN WN+FN 表 5 E、N、U方向主要噪声模型下的噪声振幅均值
Table 5 The Mean Value of Noise Amplitude Under the Main Noise Models in E, N and U Directions
方向 噪声模型 原始数据 噪声振幅均值 EMD WD IVMD GWO-VMD E WN+FN+RWN 0.76+3.46+2.72 0.00+0.00+2.78 0.00+0.00+1.78 0.00 +0.00+1.40 0.00+0.00+0.82 N WN+FN 0.72+3.70 0.00+1.23 0.00+1.01 0.00+0.93 0.00+0.68 WN+FN+RWN 0.67+3.04+3.08 0.00+0.00+3.91 0.00+0.00+2.18 0.00+0.00+1.53 0.00+0.00+1.20 U WN+FN 2.62+14.10 0.00+4.11 0.00+2.88 0.00+2.98 0.00+2.21 注: WN、FN和RWN的单位分别为、 和 。 表 6 20个基准站的速度不确定度的平均改正率/%
Table 6 Average Correction Rate of Velocity Uncertainty of 20 Reference Stations/%
方向 平均改正率 EMD WD IVMD GWO-VMD E 15.6 50.3 55.8 71.4 N 29.0 58.0 66.4 72.8 U 68.4 79.2 76.8 83.3 -
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