Study of Loran-C One-Hop Sky-Wave Fields at Different Altitudes Above the Ground

Zhou, Lili; Jiang, Yuhong; Mu, Zhonglin; Hu, Xiaodong; He, Lifeng

doi:10.1109/lawp.2021.3111690

Cited by 6 publications

(2 citation statements)

References 9 publications

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“…Currently, there are three main methods, the waveguide method, wave-hop method, and Finite Difference Time Domain (FDTD) method, developed to predict the propagation of LF waves [2][3][4][5][6][7][8]. The prediction of Loran-C sky-wave time delays and the analysis of the impact of the propagation channel parameters are mainly based on these three methods [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Measurement and Analysis of Loran-C Sky Waves throughout the Day

Zhao,

Liu,

Zhao

et al. 2024

Electronics

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In this study, Loran-C signals were collected throughout the day, and the characteristics of the received signals at different propagation distances were analyzed. Because the signal amplitude is small and difficult to recognize at a long distance and there is mutual interference between stations, a linear average method is used to process the received signal. At locations closer to the receiver, clear observations of the time delay and amplitude variation in the one-hop sky wave can be made by using the ground wave as a reference, which can be applied to studying the characteristics and parameter inversion of the lower ionosphere. When the distance is further, the significant enhancement of the sky-wave signal during the night may lead to decreased accuracy in timing and positioning. When the distance is much larger than the propagation range of the ground wave, only the sky-wave signal can be received, and the signal is more stable than when the distance is closer. During the night, multiple amplitude-comparable multi-path signals may appear in the sky wave, making the identification of the one-hop sky wave more difficult.

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Section: Introductionmentioning

confidence: 99%

Measurement and Analysis of Loran-C Sky Waves throughout the Day

Zhao,

Liu,

Zhao

et al. 2024

Electronics

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“…Since 2011, we have studied the propagation characteristics of different mode waves in complex Earth-ionosphere waveguide based on the 2-D cylindrical-coordinate FDTD and parabolic equation methods. However, our study did not take into account the effects of the anisotropic ionosphere influenced by the natural magnetic field, and it was limited to the nearillumination region of one-hop sky waves [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Long-distance Propagation Characteristics of LF Multi-hop Sky Waves

Zhou,

Zhu,

et al. 2023

PIER Letters

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This paper focuses on the decomposition of different modes of Loran-C resultant waves, including ground waves and onehop/two-hop sky waves, propagating in the Earth-ionosphere waveguide obtained from direct finite-difference time-domain (FDTD) modeling in the presence of the natural magnetic field. After providing the FDTD iterative formulas for the ionosphere affected by the natural magnetic field, the Loran-C resultant waves propagating in the anisotropic Earth-ionosphere waveguide are estimated using the FDTD algorithm. In both the daytime and nighttime ionosphere models, different orientations of the natural magnetic field are taken into account. The arrival times of the different propagation modes for the resultant waves were then determined using a multipath time-delay estimation method. With the above delays, the amplitudes of the different modes are acquired by solving overdetermined equations. Finally, the decomposition results are compared with those obtained in the absence of the natural magnetic field. The numerical experimental results indicate that, with a radiation power of 1 kW and a natural magnetic field of 0.5 Gs, the influence of the direction of the natural magnetic field on the field strength of one-hop sky waves is significant when the propagation distance of LF radio waves is less than 1000 km. Radio waves have multipath effects such as convergence, divergence, and diffraction due to the curvature of the Earth and the ionosphere. This results in significant interference phenomena when the propagation distance of two-hop sky waves is greater than 500 km.

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