A New Method to Restrain Schuler Periodic Oscillation in Inertial Navigation System Based on Normal Time–Frequency Transform

Zhou, Zhibo; Liang, Xinghui; Shi, Zhimin; Wang, Guocheng; Lang, Junjian; Liu, Lintao

doi:10.1109/tim.2022.3170993

Cited by 3 publications

(2 citation statements)

References 24 publications

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“…It unifies the three classical transforms in the field of time-frequency analysis, namely short-time Fourier transform, wavelet transform, and S-transform, and unifies their inverse transforms. NTFT has been widely applied in many fields such as oceanic tides [9] [10], Earth rotation [11] [12], Global Position System (GPS) [13], Inertial Navigation System (INS) [14] and so on.…”

Section: Normal Time-frequency Transformmentioning

confidence: 99%

Harmonicity Spectrum

Liu,

Wang,

et al. 2023

OJS

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Perceiving harmonic information (especially weak harmonic information) in time series has important scientific and engineering significance. Fourier spectrum and time-frequency spectrum are commonly used tools for perceiving harmonic information, but they are often ineffective in perceiving weak harmonic signals because they are based on energy or amplitude analysis. Based on the theory of Normal time-frequency transform (NTFT) and complex correlation coefficient, a new type of spectrum, the Harmonicity Spectrum (HS), is developed to perceive harmonic information in time series. HS is based on the degree of signal harmony rather than energy or amplitude analysis, and can therefore perceive very weak harmonic information in signals sensitively. Simulation examples show that HS can detect harmonic information that cannot be detected by Fourier spectrum or time-frequency spectrum. Acoustic data analysis shows that HS has better resolution than traditional LOFAR spectrum.

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Section: Normal Time-frequency Transformmentioning

confidence: 99%

Harmonicity Spectrum

Liu,

Wang,

et al. 2023

OJS

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“…The IM is based on the normal time-frequency transform (NTFT) theory proposed by Liu et al (2007Liu et al ( , 2015 and Liu and Hsu (2011), which can directly extract harmonic information from harmonic signals without inverse transformation. It is widely used in the extraction and analysis of periodic signals such as polar motion, diurnal variation, tides and Schuler oscillation (Cai et al, 2018;Duan et al, 2015;Su et al, 2014;Zhou et al, 2022). By combining the IM and HA, this paper adopts an IMHA method (Methods) to achieve the following four scientific objectives.…”

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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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