On the capabilities of the inaction method for extracting the periodic components from GPS clock data

Wang, Guocheng; Liu, Lintao; Xu, Aigong; Pan, Feng; Cai, Zhiwu; Xiao, Shenghong; Tu, Yi; Li, Zhonghua

doi:10.1007/s10291-018-0757-3

Cited by 10 publications

(9 citation statements)

References 22 publications

(31 reference statements)

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“…Here, defining the scale factor a > 0, there are two useful properties of NMWT in recovering the target signals as following (the proof can be seen in ref. 12 The above properties of the NMWT method is also called as the inaction method 46,47 . BEPME strategy.…”

Section: Methodsmentioning

confidence: 99%

“…As the previous works (e.g., refs. 47,48 ) indicated, the frequency-resolution of SSA is related to the window length parameter (L), choosing an appropriate L value is important for SSA method to analyze the actual data series (see Supplementary Note 2), which shows that the SSA method is not an ideal approach to distinguish and accurately isolate the target intradecadal components existing in the LOD variations (see Supplementary Figs. 5-7).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Intradecadal variations in length of day and their correspondence with geomagnetic jerks

Duan

Huang

2020

Nat Commun

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Earth's core oscillations and magnetic field inside the liquid outer core cannot be observed directly from the surface, we can infer these information from the intradecadal variations in Earth's rotation rate defined by length of day. However, the fine time-varying characteristics as well as relevant mechanisms of the intradecadal variations are still unclear. Here we report that the intradecadal variations present a significant 8.6-year harmonic component with an unexpected increasing phenomenon, besides a 6-year decreasing oscillation. More importantly, we find that there is a very good correspondence between the extremes of the 8.6year oscillation with geomagnetic jerks. The fast equatorial waves with subdecadal periods propagating at Earth's core surface may explain the origin of this 8.6-year oscillation.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Intradecadal variations in length of day and their correspondence with geomagnetic jerks

Duan

Huang

2020

Nat Commun

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“…Studies show that the BDS periodic terms have some distinction between the GPS and Galileo, but similar variations of the periodic variations have been found in the BDS satellite clock offsets [31]. Considering that the FFT cannot characterize the periodic variations of the clock offsets in time domain [32], the periodic terms obtained by FFT may have certain deviations. In this case, the accuracy of the SAM will be affected, and it is necessary to quantify the periodic terms more accurately.…”

Section: Introductionmentioning

confidence: 77%

BDS Satellite Clock Prediction Considering Periodic Variations

Zhao

et al. 2021

Remote Sensing

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The periodic noise exists in BeiDou navigation satellite system (BDS) clock offsets. As a commonly used satellite clock prediction model, the spectral analysis model (SAM) typically detects and identifies the periodic terms by the Fast Fourier transform (FFT) according to long-term clock offset series. The FFT makes an aggregate assessment in frequency domain but cannot characterize the periodic noise in a time domain. Due to space environment changes, temperature variations, and various disturbances, the periodic noise is time-varying, and the spectral peaks vary over time, which will affect the prediction accuracy of the SAM. In this paper, we investigate the periodic noise and its variations present in BDS clock offsets, and improve the clock prediction model by considering the periodic variations. The periodic noise and its variations over time are analyzed and quantified by short time Fourier transform (STFT). The results show that both the amplitude and frequency of the main periodic term in BDS clock offsets vary with time. To minimize the impact of periodic variations on clock prediction, a time frequency analysis model (TFAM) based on STFT is constructed, in which the periodic term can be quantified and compensated accurately. The experiment results show that both the fitting and prediction accuracy of TFAM are better than SAM. Compared with SAM, the average improvement of the prediction accuracy using TFAM of the 6 h, 12 h, 18 h and 24 h is in the range of 6.4% to 10% for the GNSS Research Center of Wuhan University (WHU) clock offsets, and 11.1% to 14.4% for the Geo Forschungs Zentrum (GFZ) clock offsets. For the satellites C06, C14, and C32 with marked periodic variations, the prediction accuracy is improved by 26.7%, 16.2%, and 16.3% for WHU clock offsets, and 29.8%, 16.0%, 21.0%, and 9.0% of C06, C14, C28, and C32 for GFZ clock offsets.

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“…Its core principle is that after a harmonic signal passes through NTFT, the ridge information at the harmonic frequency corresponding to the harmonic frequency in the NTFT spectrum is equal to the harmonic signal itself. The IM extracts the ridge information from the NTFT spectrum using the inaction principle and by filtering the signal (Figure S1 in Supporting Information S2), which is essentially a "line-pass filtering" method (Cai et al, 2018;Wang et al, 2018). In general, a harmonic signal can be written as:…”

Section: Im and Nmwt Structurementioning

confidence: 99%

Tidal Evolution and Predictable Tide‐Only Inundation Along the East Coast of the United States

Gao

Liu

et al. 2023

JGR Oceans

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Sea level rise (SLR) increases the frequency of floods caused by forces such as spring tides or storm surges. However, with the continuous evolution of global ocean tides, future flooding may be driven only by astronomical tides. Therefore, we introduce an inaction method (IM) that can accurately extract the harmonic constant of tidal components from the time‐frequency spectrum of the tide, and obtain the precise long‐term trend and spatial evolution characteristics of the tides at 18 sites along the East Coast of the United States (ECUS). Except for some sites in the middle of the East Coast, M2 shows an average upward trend of more than 51 mm/century, which is most obvious at three sites in North Carolina, with an average upward trend of more than 80 mm/century. We simultaneously combine the IM with harmonic analysis into an IMHA method to estimate the historical and future “Tide‐only” inundation (TOI) frequency and quantify the effect of tidal evolution on the future TOI frequency. The results show that four stations in the Gulf of Maine have experienced relatively frequent TOI events in the past, with the highest frequency at the Eastport station. The most significant increasing and decreasing effects of tidal evolution on the future TOI frequency under the SLR scenario are at the Wilmington and Lewes stations, respectively. At the spatial scale, there are increases in the northeast and southeast and a decrease in the middle of the ECUS, which is consistent with the spatial characteristics of the long‐term tidal trend.

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On the capabilities of the inaction method for extracting the periodic components from GPS clock data

Cited by 10 publications

References 22 publications

Intradecadal variations in length of day and their correspondence with geomagnetic jerks

Intradecadal variations in length of day and their correspondence with geomagnetic jerks

BDS Satellite Clock Prediction Considering Periodic Variations

Tidal Evolution and Predictable Tide‐Only Inundation Along the East Coast of the United States

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