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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(7):1781-1788
The multipath signals of GNSS can act as a tide gauge via a technology called Global Navigation Satellite Systems multipath reflectometry (GNSS-MR), which is based on the relationship between multipath frequency and height to sea surface. In addition to the traditional frequency extraction method of Lomb–Scargle periodogram (LSP), wavelet analysis can be applied to extract instantaneous multipath frequencies of GPS L1, thus improving data utilization. However, because of the sensitivity of instantaneous frequency to noise and the introduction of more signals, multi-constellation retrievals exhibit many outliers and errors. The aim of this study is to apply wavelet analysis to multi-constellation multi-frequency signals and most importantly to find a method to avoid noise. We used coherent superposition to overlap the intra-track inter-signal instantaneous frequency spectrograms to enhance effective information and to weaken noise. This coherent superposition method can achieve intra-track inter-signal combination. The multi-GNSS data from two Multi-GNSS Experiment (MGEX) stations were used. The results showed that the coherent superposition spectrogram has a clear energy concentration, and the frequencies calculated from it depict sea-level changes. To compare the method with the LSP method and to combine inter-track retrievals, a robust regression method was used to combine retrievals and to produce equally spaced retrieval series. The results show that the combined retrievals from the coherent superposition method have a slightly higher accuracy than those from the classical LSP method. Because this method can be used to retrieve sea-level data from instantaneous frequency, it increases data utilization and provides a way to obtain details of SNR arcs, which is a potential method to benefit GNSS-MR, especially for sites with narrow reflecting sensing zones in a small sea azimuth range. 相似文献
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小波变换在动力学系统识别中的应用 总被引:3,自引:0,他引:3
试图用小波变换来讨论动力学系统识别中的几个问题,并用以研究在系统分析中利用小波变换这个工具的可能性。只涉及线性时不变结构的动力学系统,它应该适用于非线性或线性时变系统的分析和识别。做为一个具体应用,给出了使用小波变换识别模态阻尼系数的模拟实侧,可用于颤振数据分析。 相似文献
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V.M. Velasco B. Mendoza 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
The nature of the climatic response to solar variability is assessed over a long-time scale. The wavelet analysis applied to paleoclimatic proxy data of large scale atmospheric phenomena (North Atlantic Oscillation, Atlantic Multidecadal Oscillation, Pacific Decadal Oscillation and Southern Oscillation Index) has revealed coherence between the climatic oscillations and the solar phenomena (the cosmogenic isotope 10Be and the Total Solar Irradiance) preferentially with periods of Schwabe, Hale and Yoshimura–Gleissberg cycles that may reflect a modulation of solar activity. 相似文献
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D.I. González-Gómez X. Blanco-Cano A.C. Raga 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
The principal objective of this study is to analyze structures of Coronal Mass Ejections (CMEs) using a wavelet technique. We use data measured with the SOHO/LASCO coronographs C2–C3, EIT and STEREO COR1A–B, COR2A–B. We have found that different structures show up in a CME at different spatial scales of wavelets. We also study the orientation of the most intense flux and find the orientation of the structures in the CME. 相似文献
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由于遥测参数的时变性和各种干扰的影响,传统的Fourier分析往往不能给出令人满意的处理结果。小波变换是一种同时在时间(或空间)域和频率域内进行局部化分析的新方法;利用小波变换及其自适应性,可以在不同的分辨率下分析和处理数据,尤其是处理非平稳信号。本文介绍小波分析的基本原理,说明利用小波变换将遥测信号在时频平面上表示的方法。在此基础上,将小波变换应用于实测遥测数据的分析和处理,从被噪声淹没的数据中成功地恢复出冲击信号,提高了箭遥数据的信噪比。 相似文献