基于GNSS-R技术的实时潮位高度变化反演方法

Real-time tidal level change inversion method based on GNSS-R technology

潮位高度变化反演过程中易产生部分数据丢失情况,导致实时潮位高度变化反演精度不高,为了提高对潮位实时监测能力,研究基于全球导航卫星系统反射信号(GNSS-R)技术的实时潮位高度变化反演方法。通过信号采集设备采集GNSS-R原始信噪比(SNR)信号后,采用奇异谱分析(SSA)和经验模态分解(EMD)相结合的去噪方法去除原始SNR信号的噪声,保留有价值SNR信号;通过线性尺度变换得出线性化SNR信号,经多项式去掉直射信号分量,得出多径振荡分量;采用小波变换分析多径振荡分量提取实时潮位,完成实时潮位高度变化反演。试验结果表明,该方法应用效果较好,可实现实时潮位高度变化反演,SSA-EMD针对不同信号的去噪效果均较好,其中GNSS-R信号去噪最佳,在保留原信号趋势同时,可去除信号中多余噪声;该方法的海面高度反演结果和对比区域实际潮位高度基本一致,且可增强实时潮位反演结果时间分辨率。

In the inversion process of tidal level change,some data is likely to be lost,resulting in low inversion accuracy of real-time tidal level changes.In order to improve the ability of real-time tidal level monitoring,a real-time tidal level change inversion method based on global navigation satellite system reflection(GNSS-R)technology was studied.After the original signal-to-noise ratio(SNR)signal of GNSS-R was collected by signal acquisition equipment,the noise removal method combining singular spectrum analysis(SSA)and empirical mode decomposition(EMD)was used to remove the noise in the original SNR signal and retain the valuable SNR signal.The linearized SNR signal was obtained by linear scale transformation,and the multipath oscillation component was derived by removing the direct signal component by polynomial.Wavelet transform was used to analyze the multipath oscillation component to extract real-time tidal levels and complete the inversion of real-time tidal level changes.The experimental results show that this method has a good application effect and can realize inversion of real-time tidal level changes.SSA-EMD has a good denoising effect for different signals,among which the GNSS-R signal shows the best effect as the excess noise in the signal can be removed while retaining the trend of the original signal.The results of sea surface height inversion by this method are basically consistent with the actual tidal level in the comparison area,and the time resolution of real-time tidal level inversion results can be enhanced.