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Journal articles on the topic 'Satellites'
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1
Shen, Ziyu, Wenbin Shen, Xinyu Xu, Shuangxi Zhang, Tengxu Zhang, Lin He, Zhan Cai, Si Xiong, and Lingxuan Wang. "A Method for Measuring Gravitational Potential of Satellite’s Orbit Using Frequency Signal Transfer Technique between Satellites." Remote Sensing 15, no. 14 (July 12, 2023): 3514. http://dx.doi.org/10.3390/rs15143514.
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We introduce an approach for the direct measurement of the gravitational potential (GP) along the trajectory of a satellite, with a specific focus on Low-Earth Orbit (LEO) satellites. A LEO satellite communicates with several Geosynchronous Equatorial Orbit (GEO) satellites via frequency signal links. The GP difference can be measured in real-time using the gravitational frequency shift approach by equipping both LEO and GEO satellites with precise atomic clocks. Since the GP at the high orbits of the GEO satellites can be precisely determined by the present gravitational field model EGM2008, the GP along the LEO satellite’s trajectory can be determined. In this study, simulation experiments were conducted, featuring a GRACE-type satellite as the LEO satellite in communication with three equidistant GEO satellites. The results indicated that the accuracy of the GP measurements along the LEO satellite’s trajectory primarily depends on the precision of the onboard atomic clocks. Supposing optical atomic clocks attain an instability level of 1×10−17τ−1/2 (τ in seconds), we determined the GP distribution covered by the LEO satellite’s trajectories with 30-day observations. Then, we determined a gravitational field at the centimeter level based on the GP distribution. The GP data derived from the trajectory of a LEO satellite can be utilized to establish temporal gravitational fields, which have broad applications in different disciplines.
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Agrusa, Harrison F., Yun Zhang, Derek C. Richardson, Petr Pravec, Matija Ćuk, Patrick Michel, Ronald-Louis Ballouz, et al. "Direct N-body Simulations of Satellite Formation around Small Asteroids: Insights from DART’s Encounter with the Didymos System." Planetary Science Journal 5, no. 2 (February 1, 2024): 54. http://dx.doi.org/10.3847/psj/ad206b.
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Abstract We explore binary asteroid formation by spin-up and rotational disruption considering the NASA DART mission's encounter with the Didymos–Dimorphos binary, which was the first small binary visited by a spacecraft. Using a suite of N-body simulations, we follow the gravitational accumulation of a satellite from meter-sized particles following a mass-shedding event from a rapidly rotating primary. The satellite’s formation is chaotic, as it undergoes a series of collisions, mergers, and close gravitational encounters with other moonlets, leading to a wide range of outcomes in terms of the satellite's mass, shape, orbit, and rotation state. We find that a Dimorphos-like satellite can form rapidly, in a matter of days, following a realistic mass-shedding event in which only ∼2%–3% of the primary's mass is shed. Satellites can form in synchronous rotation due to their formation near the Roche limit. There is a strong preference for forming prolate (elongated) satellites, although some simulations result in oblate spheroids like Dimorphos. The distribution of simulated secondary shapes is broadly consistent with other binary systems measured through radar or lightcurves. Unless Dimorphos's shape is an outlier, and considering the observational bias against lightcurve-based determination of secondary elongations for oblate bodies, we suggest there could be a significant population of oblate secondaries. If these satellites initially form with elongated shapes, a yet-unidentified pathway is needed to explain how they become oblate. Finally, we show that this chaotic formation pathway occasionally forms asteroid pairs and stable triples, including coorbital satellites and satellites in mean-motion resonances.
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Wu, Huanqin, Maocai Wang, Zhiming Song, Xiaoyu Chen, Guangming Dai, Wei Zheng, and Qingrui Zhou. "Random Error Analysis of Launch and Injection Positions for Distributed Multi Micro-nano Satellite System." Journal of Physics: Conference Series 2640, no. 1 (November 1, 2023): 012014. http://dx.doi.org/10.1088/1742-6596/2640/1/012014.
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Abstract Accurate satellite orbit calculation has always been a focus in the aerospace field. Especially, the error distribution of the orbit involving various internal and external factors in the satellite launch process has an important influence on the effectiveness of the satellite cluster. To qualitatively and quantitatively analyze the cooperative efficiency of multi-satellite clusters involving various random errors, this paper analyzes the random error sources in the launch process of micro-nano satellites and studies the distribution law of these satellite orbit position errors. Based on the parameter estimation and the central limit theorem of probability theory, the expression of the error function for the satellite’s orbit position is also constructed. In addition, the probability distribution model of the satellites in a certain range is designed, and the relationship between the number of satellites and the overall errors is proposed. Finally, the result is verified by the simulation experiment, which provides the rationale behind the position and altitude adjustment and constellation optimization of micro-nano satellites.
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Shakila Hosseinzadeh Kondori, Mustafa Helvacı. "Satellite Temperature Modeling in Geostationary Orbit Using COMSOL." Tuijin Jishu/Journal of Propulsion Technology 44, no. 5 (November 29, 2023): 127–39. http://dx.doi.org/10.52783/tjjpt.v44.i5.2440.
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In our world, communication satellites are becoming more and more significant. They are costly to create, launch, operate, and maintain, thus these costs are crucial. Due to the fact that electronic and satellite components can only operate within a limited temperature range, it is crucial to understand and manage the satellite's temperature in order to maximize efficiency both before and during the mission. This study considers GEO and comparable satellites with the goal of showing satellite temperature. We ignored the entire satellite's internal structure and focused only on the external heat generated by its surface (main body and solar panels). COMSOL is used in this project that is a simulation platform. Finally, the results have been displayed for the model at different times.
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Welling, D. T. "The long-term effects of space weather on satellite operations." Annales Geophysicae 28, no. 6 (June 24, 2010): 1361–67. http://dx.doi.org/10.5194/angeo-28-1361-2010.
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Abstract. Integrated lifetime radiation damage may cause spacecraft to become more susceptible to operational anomalies by changing material characteristics of electronic components. This study demonstrates and quantifies the impact of these effects by examining the National Oceanic and Atmospheric Administration (NOAA) National Geophysical Data Center (NGDC) satellite anomaly database. Energetic particle data from the Geostationary Operational Environmental Satellites (GOES) is used to construct the total lifetime particle exposure a satellite has received at the epoch of an anomaly. These values are compared to the satellite's chronological age and the average exposure per year (calculated over two solar cycles.) The results show that many anomalies occur on satellites that have received a total lifetime high-energy particle exposure that is disproportionate to their age. In particular, 10.8% of all events occurred on satellites that received over two times more 20 to 40 MeV proton lifetime particle exposure than predicted using an average annual mean. This number inflates to 35.2% for 40 to 80 MeV protons and 33.7% for ≥2 MeV electrons. Overall, 73.5% of all anomalies occurred on a spacecraft that had experienced greater than two times the expected particle exposure for one of the eight particle populations used in this study. Simplistically, this means that the long term radiation background exposure matters, and that if the background radiation is elevated during the satellite's lifetime, the satellite is likely to experience more anomalies than satellites that have not been exposed to the elevated environment.
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Zhao, Xiangyu, Chunjuan Zhao, Jiale Li, Yongliang Guan, Shanbo Chen, and Lei Zhang. "Research on Design, Simulation, and Experiment of Separation Mechanism for Micro-Nano Satellites." Applied Sciences 12, no. 12 (June 13, 2022): 5997. http://dx.doi.org/10.3390/app12125997.
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The separation mechanism is a critical device that transports and releases satellites during launch and on-orbit. However, as satellites become smaller and more compact, the traditional belt-locking device or pyrotechnic release and separation device cannot meet the micro-nano satellite’s separation requirements. A novel separation mechanism kinematic system was designed, analyzed, and experimentally verified to achieve non-interference and non-pyrotechnic separation of the satellites from the launch vehicle while maintaining the initial separation attitude. First, an overall structural strategy for the kinematics system was proposed based on the MF (product code of the satellite) satellite’s structural properties. The structural characteristics of the separation mechanism were also confirmed by the principle of energy conservation. Then, a finite element model and a dynamic model of the kinematic coupling system between the MF satellite and the separation mechanism during launch and deployment were constructed, along with an analysis of the mechanical characteristics and a kinematic simulation. Finally, the mechanical characteristics and dependability of the separation mechanism were verified using a ground vibration test and a separation test. The prototype test results demonstrate that the separation process is essentially identical to the numerical simulation results and that the MF satellite can be deployed successfully without interference, with the MF satellite’s initial separation attitude fully satisfying the designed technical indexes.
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Williamson, M. "Satellites rock! [satellite radio]." IEE Review 49, no. 11 (December 1, 2003): 34–37. http://dx.doi.org/10.1049/ir:20031104.
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Tong, Minglei, Song Li, Xiaoxiang Wang, and Peng Wei. "Inter-Satellite Cooperative Offloading Decision and Resource Allocation in Mobile Edge Computing-Enabled Satellite–Terrestrial Networks." Sensors 23, no. 2 (January 6, 2023): 668. http://dx.doi.org/10.3390/s23020668.
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Mobile edge computing (MEC)-enabled satellite–terrestrial networks (STNs) can provide task computing services for Internet of Things (IoT) devices. However, since some applications’ tasks require huge amounts of computing resources, sometimes the computing resources of a local satellite’s MEC server are insufficient, but the computing resources of neighboring satellites’ MEC servers are redundant. Therefore, we investigated inter-satellite cooperation in MEC-enabled STNs. First, we designed a system model of the MEC-enabled STN architecture, where the local satellite and the neighboring satellites assist IoT devices in computing tasks through inter-satellite cooperation. The local satellite migrates some tasks to the neighboring satellites to utilize their idle resources. Next, the task completion delay minimization problem for all IoT devices is formulated and decomposed. Then, we propose an inter-satellite cooperative joint offloading decision and resource allocation optimization scheme, which consists of a task offloading decision algorithm based on the Grey Wolf Optimizer (GWO) algorithm and a computing resource allocation algorithm based on the Lagrange multiplier method. The optimal solution is obtained by continuous iterations. Finally, simulation results demonstrate that the proposed scheme achieves relatively better performance than other baseline schemes.
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Ye, Xin, Zheng Hong Dong, Qing Pan, and Li Hao Liu. "Application of the IOCP in Multi-Domain Modeling and Simulation Based on Multiple Interfaces of Satellite." Advanced Materials Research 1049-1050 (October 2014): 1923–28. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.1923.
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Aiming at modeling and simulation, the study of improving the performance of the method of multi-domain based on multiple interfaces of satellites by the IOCP technology were focused on. The satellite's attitude and orbit controlling simulation platform was build, with the server based on the IOCP technology build, and the designation problem of interfaces between different software solved, while the model of the satellite build, by using software , such as MATLAB / Simulink, ADAMS, Pro/E, STK and VS. Finally, the model of satellite's attitude maneuver was simulated, and the result proved the efficiency of the method of multi-domain based on multiple interfaces of satellites improved by the IOCP technology.
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Parks, Lisa. "Signals and oil." European Journal of Cultural Studies 12, no. 2 (May 2009): 137–56. http://dx.doi.org/10.1177/1367549409102421.
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This article examines the strategies of two satellite operators working across post-communist territories of Central Asia: Eutelsat and Kazsat. To do so it develops a critical approach called footprint analysis, which involves investigating the variety of practices that occur within range of a given satellite's service. Satellites have been used in post-communist territories to circulate broadcast and telecommunication signals, facilitate flows of capital and reshape geographic imaginaries. In addition, satellites have become orbital platforms for the Caspian's booming oil industry. Satellites are used to support everything from surveying oil fields to monitoring drilling operations, from construction of oil rigs to the maintenance of pipelines. The article sets out to develop a model of analysis which can account for the more 'cultural' uses of satellites (i.e. for broadcasting) in relation to their more 'extractive' uses (i.e. for natural resource development).
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Nafieva, E. N., and A. V. Grechishchev. "SPACE RADAR SYSTEMS OF EARTH MONITORING." ECOLOGY ECONOMY INFORMATICS. GEOINFORMATION TECHNOLOGIES AND SPACE MONITORING 2, no. 5 (2020): 89–95. http://dx.doi.org/10.23885/2500-123x-2020-2-5-89-95.
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This article explores the relevance of radar sensing methods. The principles of its operation and the advantages of use are considered: the independence of obtaining images from weather conditions and the time of day, the possibility of wide viewing at long ranges with high resolution and the flexibility of controlling and changing radar parameters, which allows you to vary the position and size of the viewing area, resolution and forms of information. In addition, the main satellite radar systems were considered: satellites of the European Space Agency ERS-1,2 and ENVISAT; Canadian satellites of MDA Radarsat-1,2; satellites launched by the German Aerospace Center (DLR) and the leading European space company Airbus DS-TerraSAR-X, TanDEM-X; Spanish satellite PAZ; Japanese satellites ALOS and ALOS-2; Italian constellation of Cosmo-SkyMed satellites; Indian satellite RISAT-1; English satellite NovaSAR-1; Finnish ICEYE satellites; Korean satellite KOMPSAT-5, Chinese satellite Huan Jing 1C, European satellites Sentinel-1 (A, B) and Russian satellites Condor. Also in this article are considered radar spacecraft planned to launch, namely: the second generation of Italian satellites COSMO-SkyMed – CSG – 2; 2 spacecraft ICEYE (Finland); 4 X-band radar satellites SuperView (China); 2 radar satellites Zhuhai (China); ALOS-4 JAXA (Japan); KOMPSAT-6 (Korea), 3 radar spacecraft of the IRS constellation (India), SAOCOM (Argentina), Russian-made satellites Obzor-P1 and Kondor-FKA, in addition, ROSKOSMOS plans to create a space complex that includes an orbital constellation of 6 small-sized spacecraft for radar observation
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Santos-Santos, Isabel M., Rosa Domínguez-Tenreiro, and Marcel S. Pawlowski. "An updated detailed characterization of planes of satellites in the MW and M31." Monthly Notices of the Royal Astronomical Society 499, no. 3 (October 13, 2020): 3755–74. http://dx.doi.org/10.1093/mnras/staa3130.
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ABSTRACT We present a detailed characterization of planes of satellite galaxies in the Milky Way (MW) and M31. For a positional analysis, we introduce an extension to the ‘4-galaxy-normal density plot’ method from Pawlowski, Kroupa & Jerjen. It finds the normal directions to the predominant planar configurations of satellites of a system, yielding for each a collection of planes of increasing member satellites. This allows to quantify the quality of planes in terms of population (Nsat) and spatial flattening (c/a). We apply this method to the latest data for confirmed MW and M31 satellite samples, with 46 and 34 satellites, respectively. New MW satellites form part of planes previously identified from a smaller sample of Nsat= 27: we identify a new plane with Nsat = 39 as thin as the VPOS-3 (c/a ∼ 0.2), and with roughly the same normal direction; so far the most populated plane that thin reported in the Local Group. We introduce a new method to determine, using kinematic data, the axis of maximum co-orbitation of MW satellites. Interestingly, this axis approximately coincides with the normal to the former plane: $\ge 45\pm 5{{\ \rm per\ cent}}$ of satellites co-orbit. In M31 we discover a plane with Nsat = 18 and c/a ∼ 0.15, i.e. quality comparable to the GPoA, and perpendicular to it. This structure is viewed face-on from the Sun making it susceptible to M31 satellite distance uncertainties. An estimation of the perpendicular velocity dispersion suggests that it is dynamically unstable. Finally we find that mass is not a property determining a satellite’s membership to good quality planes.
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Georges, Martine. "Les satellites." Revue française d'administration publique 52, no. 1 (1989): 65–76. http://dx.doi.org/10.3406/rfap.1989.2285.
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Satellites Martine Georges The distinction between the operational and regulatory functions in the satellite telecommunications sector is far more clearcut at the international level. A detailed analysis nevertheless reveals that in reality the regulations sometimes favour the notion of content, as in the case of broadcasting satellites, and at others that of support, as in the case of telecommunication satellites. The regulations governing the latter are insufficiently adapted to the growing diversity of services offered by satellite at a time when the effectiveness of the operational framework for satellite Systems as a whole is being called into question.
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Pratiwi, N., D. Herdiwijaya, T. Hidayat, and M. I. Ikhsan. "Comparison of the SRP spherical model between LEO and GEO satellites." Journal of Physics: Conference Series 2734, no. 1 (March 1, 2024): 012012. http://dx.doi.org/10.1088/1742-6596/2734/1/012012.
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Abstract Solar Radiation Pressure (SRP) is a phenomenon caused by the pressure exerted by solar photons on a satellite’s surface when it is exposed to sunlight. It is a form of radiation force and can significantly impact the motion and behaviour of satellites in space. SRP influences a satellite’s orbit by causing changes in its semimajor axis, eccentricity, inclination, argument of perigee, right ascension of the ascending node, and mean anomaly. SRP models are used to simulate the effects of solar radiation pressure on satellites. These models are essential for accurately predicting satellite trajectories and orbital behaviour. There are several types of SRP models, such as spherical model, flat model, box-wing model, faceted model, and analytical SRP models. This research focuses on Telkom 1 and LAPAN A1 satellites, both belonging to Indonesia and positioned in Geostationary Earth Orbit (GEO) and Low Earth Orbit (LEO) orbits, respectively. The study aims to find a comparison of the effects of SRP spherical model on LEO and GEO satellites. Our modelling shows that the semimajor axis and eccentricity are sensitive to SRP, while the inclination and right ascension of the ascending node are not significantly affected. Comparing the effects of SRP on LEO and GEO satellites, we concluded that both LEO and GEO orbit experience the most significant fluctuations in January (perihelion), likely due to the influence of solar radiation pressure.
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Yun, Seok-Teak, and Seung-Hyun Kong. "Forecasting Methods of Battery Charge and Discharge Current Profile for LEO Satellites." Electronics 10, no. 23 (December 1, 2021): 2999. http://dx.doi.org/10.3390/electronics10232999.
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The orbital characteristics of low Earth orbit (LEO) satellite systems prevent continuous monitoring because ground access time is limited. For this reason, the development of simulators for predicting satellite states for the entire orbit is required. Power-related prediction is one of the important LEO satellite simulations because it is directly related to the lifespan and mission of the satellite. Accurate predictions of the charge and discharge current of a power system’s battery are essential for fault management design, mission design, and expansion of LEO satellites. However, it is difficult to accurately predict the battery power demand and charging of LEO satellites because they have nonlinear characteristics that depend on the satellite’s attitude, season, orbit, mission, and operating period. Therefore, this paper proposes a novel battery charge and discharge current prediction technique using the bidirectional long short-term memory (Bi-LSTM) model for the development of a LEO satellite power simulator. The prediction performance is demonstrated by applying the proposed technique to the KOM-SAT-3A and KOMSAT-5 satellites operating in real orbits. As a result, the prediction accuracy of the proposed Bi-LSTM shows root mean square error (RMSE) within 2.3 A, and the prediction error well outperforms the most recent the probability-based SARIMA model.
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Velgas, Lev Borisovich, and Liia Lvovna Iavolinskaia. "Seven main discoveries, rigorously proven." Interactive science, no. 6 (40) (June 21, 2019): 103–5. http://dx.doi.org/10.21661/r-496981.
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We are striving to prove that all planets rotate around their axis due to their satellites. Rotation of the collateral gravitation is analogous for all the planets, for the Sun as well. The Sun, as well as every single planet, can have multiple satellites. Satellite and planet’s collateral gravitation, if it moves because of satellite’s movement around the orbit, rotates the planet or the Sun. The article proves that collateral gravitation of the Moon and the Earth, that moves around the Earth due to Moon’s movement around the Earth, rotates the Earth around it’s axis.
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Granados-Cruz, L. G., R. G. Chávez-Moreno, J. A. Ferrer-Perez, C. Romo-Fuentes, and J. A. Ramírez-Aguilar. "Historical review of simulators for satellite position and orientation control." Journal of Physics: Conference Series 2804, no. 1 (July 1, 2024): 012013. http://dx.doi.org/10.1088/1742-6596/2804/1/012013.
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Abstract In the design of satellite systems, it is essential to control the satellite’s position for various reasons, either to have correct communication with a ground station or to make connections with other satellites. In the same way, the positioning of a satellite poses a significant challenge since its behavior is non-linear; due to these issues, several test benches have been developed for the satellite’s position problem. In this review, there will be a journey from the rise of the space age to the latest advances in technology for emulating the satellite’s dynamics.
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Wei, Hui, Jiancheng Li, Shoujian Zhang, and Xinyu Xu. "Cycle Slip Detection and Repair for Dual-Frequency LEO Satellite GPS Carrier Phase Observations with Orbit Dynamic Model Information." Remote Sensing 11, no. 11 (May 29, 2019): 1273. http://dx.doi.org/10.3390/rs11111273.
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Cycle slip detection and repair are crucial for precise GPS-derived orbit determination of the low-Earth orbit (LEO) satellites. We present a new approach to detect and repair cycle slips for dual-frequency LEO satellite GPS observations. According to Newton’s equation of motion, the second-order time difference of the LEO satellite’s position (STP) is only related to the sampling interval and the satellite’s acceleration, which can be precisely obtained from the known orbit dynamic models. Then, several kinds of second-order time-difference geometry-free (STG) phase combinations, taking full advantage of the correlation between the satellite orbit variations and the dynamic model, with different level of ionospheric residuals, are proposed and adopted together to detect and fix cycle slips. The STG approach is tested with some LEO satellite GPS datasets. Results show that it is an effective cycle slip detection and repair method for LEO satellite GPS observations. This method also has some important features. Firstly, the STG combination is almost independent of the pseudorange. Secondly, this method is effective for LEO satellites, even in real-time application. Thirdly, this method is suitable for ground-based GPS receivers if we know the acceleration of the receivers.
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Li, Zhipeng, Meng Li, and Qian Wang. "Predator–Prey Model Based Asymmetry Resource Allocation in Satellite–Terrestrial Network." Symmetry 13, no. 11 (November 7, 2021): 2113. http://dx.doi.org/10.3390/sym13112113.
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In the traditional satellite networks, network resources are mainly allocated among all the satellites based on the same allocation algorithm. This kind of symmetry model limits the increase of throughput. In this paper, we study an asymmetry resource allocation method in a satellite–terrestrial network and propose a Lotka–Volterra based predator–prey model to achieve optimal resource allocation among different satellites. In the proposed satellite–terrestrial network, we divide all the satellites into two groups, and we try to achieve load stability between these two satellites groups. Using the predator–prey model, one group is the prey–satellites, which can obtain service requirements from mobile users. The other group is considered as predator–satellites, which can only obtain the loads from the group of the prey–satellites. Once the satellites are divided into two groups using the Lotka–Volterra model, the resource allocation problem among these satellites in two groups would be asymmetry resource. We prove the existence of solutions to the proposed model. Numerical simulation results are given to show the correctness and effectiveness of the proposed model.
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Huseynov, Mugabil, and Elshan Hashimov. "Imaginary Intelligence Via Satellites." Modeling Control and Information Technologies, no. 6 (November 22, 2023): 57–60. http://dx.doi.org/10.31713/mcit.2023.014.
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This article gives basic information about all types of satellites. The types of satellites reveal the functions, purposes and applications. Information is provided on the sections required to use a satellite. The features of reconnaissance satellites are characterized. Analytical factors of satellite imagery, their pros and cons were compared. The role and functions of satellite imagery in current and probable future wars are declared.
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Wang, Yixiao, Cui Tu, Feng Wei, and Xiong Hu. "Design of Novel Reconfigurable Single-Board Satellite for Enhanced Space Environment Detection." Electronics 12, no. 23 (November 24, 2023): 4761. http://dx.doi.org/10.3390/electronics12234761.
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In response to the growing need for enhanced space environment detection in ultra-low Earth orbits, this study introduces a pioneering design for a reconfigurable single-board satellite. Beyond the conventional attributes of compactness and a lightweight design, the single-board satellite also has unique features that are reconfigurable for the space detection mission it undertakes, as well as autonomous Earth communication capabilities that are not available in other very small satellites. Such advancements address the limitations of traditional very small satellites such as CubeSats and ChipSats. This paper delves deeply into the satellite’s design feasibility, including its functional requirements, power equilibrium, and communication links. Supplementing our design, a proof-of-concept prototype was crafted, and rigorous laboratory tests were performed to corroborate its key specifications and functionalities.
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Saiko, Volodymyr, Teodor Narytnyk, Valeriy Gladkykh, and Natalia Sivkova. "INNOVATIVE SOLUTION FOR LEO-SYSTEM WITH DISTRIBUTED SATELLITE ARCHITECTURE." Information systems and technologies security, no. 1 (2) (2020): 77–83. http://dx.doi.org/10.17721/ists.2020.1.77-83.
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An innovative solution for practical implementation in a LEO system with a "distributed satellite" architecture that can be used to provide low-orbital spacecraft communications with ground stations and users of 5G / IoT satellite services is proposed. The essence of the proposed development in the system of low-orbital satellite communication with FC-architecture is that to reduce the delay in signaling to consumers and the probability of overloading the network into a prospective system of low-orbital satellite communication, which contains artificial Earth satellites, each of which functions in Earth orbit and equipped with onboard repeaters, inter-satellite communications, a network of ground-based communication and control systems for artificial satellites of the Earth, a grouping of low-orbiting space their devices (LEO-system), which includes the grouping of root (leading) satellites and satellites-repeaters (slave), around each root satellite is formed micro-grouping of satellites-repeaters, and functions of the root satellite in the selected orbital phase of the orbital -or micro-satellites that are connected to the annular network by communication lines between satellites, and - functions of satellites-repeaters - kubsat, new is the introduction of a multilevel boundary cloud system, which is a heterogeneity distributed computing cloud structure. At the same time, the boundary clouds of the multilevel system are connected by ultra-high-speed wireless terahertz radio lines and wireless optical communication systems. The technique of estimation of access time in the proposed structure of "fog computing" on the basis of the model of access in "fog computing" with the resolution of collisions of data sources implementing the survey mode is presented.
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Xu, Baopeng, Xing Su, Zhimin Liu, Mudan Su, Jianhui Cui, Qiang Li, Yan Xu, Zeyu Ma, and Tao Geng. "Analysis on BDS-3 Autonomous Navigation Performance Based on the LEO Constellation and Regional Stations." Remote Sensing 15, no. 12 (June 13, 2023): 3081. http://dx.doi.org/10.3390/rs15123081.
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The global navigation satellite system (GNSS) is developing rapidly, and the related market applications and scientific research are increasing. Studies based on large low Earth orbit (LEO) satellite constellations have become research hotspots. The global coverage of the LEO constellation can reduce the dependence of navigation satellites on ground-monitoring stations and improve the precise orbit determination (POD) accuracy of navigation satellites. In this paper, we simulate various LEO satellite constellations (with 12, 30, and 60 satellites), along with ground stations’ observation data, to examine the impact of LEO satellites on the precision of the BeiDou-3 Global Navigation Satellite System (BDS-3) in terms of its POD accuracy. Using the simulated observation data of both LEO satellites and ground-monitoring stations, we analyze the integrated orbit determination for the LEO and BDS-3 satellites. The findings reveal that the 3D orbital accuracy of BDS-3 is 9.51 dm by using only seven ground-monitoring stations, and it is improved to a centimeter level after adding the LEO constellations. As the number of LEO constellation satellites increases, the impact on improving accuracy gradually diminishes. In terms of time synchronization accuracy in the BDS-3, compared to the results of clock offset using only ground stations, the addition of 12 LEO satellites resulted in an improvement of 49% for RMS1(root mean square) and 52% for RMS2 (standard deviation), the addition of 30 LEO satellites resulted in an improvement of 66% for RMS1 and 70% for RMS2, and the addition of 60 LEO satellites resulted in an improvement of 87% for RMS1 and 90% for RMS2. The integrated orbit determination of the LEO and BDS-3 satellites constellation greatly improves the accuracy of time synchronization. In addition, we also use simulated inter-satellite link (ISL) data to perform enhanced BDS-3 satellites POD and time synchronization experiments. The experiments showed that the orbit determination accuracy of the seven sta (seven stations) and ISL scheme is comparable to that of the seven sta and LEO12 scheme, and that the time synchronization accuracy of the seven sta and ISL scheme is slightly worse. The preliminary experiments showed that the LEO satellite could enhance the orbit determination accuracy of BDS-3 and obtain a higher time synchronization accuracy.
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AA, Periola, and Ohize H. "Enhanced dynamic data storage for enabling low cost space astronomy observations for capital constrained astronomy organizations." Physics & Astronomy International Journal 1, no. 4 (November 17, 2017): 139–44. http://dx.doi.org/10.15406/paij.2017.01.00025.
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Mechanisms that reduce the capital and operational costs are important for increased participation in astronomy. It is important that capital constrained organizations can engage in astronomy in cost effective manner. Approaches such as telescope conversion and using small satellites reduce the cost of astronomy observations. However, astronomy data observed by converted and small satellite telescopes require storage and processing by high performance computing infrastructure. High performance computing infrastructure acquisition is expensive for capital constrained astronomy organizations. The reduction in costs obtained by using converted and small satellite telescopes is not matched by a corresponding reduction in high performance computing. This paper addresses this challenge and proposes using a software defined space data storage system. The software defined space data storage system considers space telescopes as primary satellites and telecommunication and earth observation satellites as secondary satellites. The primary and secondary satellites are grouped in logical clusters. Secondary satellites are temporal data centers that store the astronomy data that cannot be held on primary satellites. The discussion in this paper presents algorithms that enable the identification of suitable secondary satellites and also influence the entry and exit of secondary satellite into dynamic clusters.
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Mok, Esmond, and Paul A. Cross. "A Fast Satellite Selection Algorithm for Combined GPS and GLONASS Receivers." Journal of Navigation 47, no. 3 (September 1994): 383–89. http://dx.doi.org/10.1017/s0373463300012327.
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This paper derives a fast satellite selection algorithm; that is, an algorithm to select the best subset of satellites to use for positioning in circumstances whereby a satellite navigation receiver is not capable of using all satellites in view. The algorithm adopts the weighting factor concept to determine the contribution of each satellite to the overall positioning accuracy. Selection by this algorithm is shown to be especially efficient when the number of available satellites is large, so it is likely to be particularly useful for receivers capable of making combined measurements to GPS and GLONASS satellites.
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Ye, Shirong, Yongwei Yan, and Dezhong Chen. "Performance Analysis of Velocity Estimation with BDS." Journal of Navigation 70, no. 3 (February 1, 2017): 580–94. http://dx.doi.org/10.1017/s0373463316000813.
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The regional part of the current BeiDou navigation satellite system (BDS) consists of five Geostationary Earth Orbit (GEO) satellites, five Inclined Geosynchronous Satellite Orbit (IGSO) satellites and four Medium Earth Orbit (MEO) satellites. We examined three algorithms for BDS velocity estimation. In addition, the performance of velocity estimation using different BDS satellite combinations was analysed. Static tests demonstrated that velocity precision using Raw Doppler (RD) measurements was of the order of centimetres per second, whereas the carrier-phase-Derived Doppler (DD) measurements and Time-Differenced Carrier Phase (TDCP) method provided accuracies of the order of millimetres per second. Because of the irregularity of the satellites' distribution, three peaks exist on the north component in the 24-hour velocity series. Besides, the GEO satellites contribute significantly in velocity estimation and the satellites' geometry condition seriously declined when excluding GEO satellites. In kinematic tests, the root mean square of the velocity error derived by DD and TDCP both attained the centimetre per second level. Moreover, the precision of velocity determination with these three methods was degraded by the sudden acceleration of the vehicle.
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Nashimoto, Masashi, Masayuki Tanaka, Masashi Chiba, Kohei Hayashi, Yutaka Komiyama, and Takashi Okamoto. "The Missing Satellite Problem outside of the Local Group. II. Statistical Properties of Satellites of Milky Way–like Galaxies." Astrophysical Journal 936, no. 1 (August 29, 2022): 38. http://dx.doi.org/10.3847/1538-4357/ac83a4.
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Abstract We present a new observation of satellite galaxies around seven Milky Way (MW)–like galaxies located outside of the Local Group (LG) using Subaru/Hyper Suprime-Cam imaging data to statistically address the missing satellite problem. We select satellite galaxy candidates using magnitude, surface brightness, Sérsic index, axial ratio, FWHM, and surface brightness fluctuation cuts, followed by visual screening of false positives such as optical ghosts of bright stars. We identify 51 secure dwarf satellite galaxies within the virial radius of nine host galaxies, two of which are drawn from the pilot observation presented in Paper I. We find that the average luminosity function of the satellite galaxies is consistent with that of the MW satellites, although the luminosity function of each host galaxy varies significantly. We observe an indication that more massive hosts tend to have a larger number of satellites. Physical properties of the satellites such as the size–luminosity relation are also consistent with the MW satellites. However, the spatial distribution is different; we find that the satellite galaxies outside of the LG show no sign of concentration or alignment, while that of the MW satellites is more concentrated around the host and exhibits a significant alignment. As we focus on relatively massive satellites with M V < −10, we do not expect that the observational incompleteness can be responsible here. This trend might represent a peculiarity of the MW satellites, and further work is needed to understand its origin.
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Korol, V., S. Toonen, A. Klein, V. Belokurov, F. Vincenzo, R. Buscicchio, D. Gerosa, et al. "Populations of double white dwarfs in Milky Way satellites and their detectability with LISA." Astronomy & Astrophysics 638 (June 2020): A153. http://dx.doi.org/10.1051/0004-6361/202037764.
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Context. Milky Way dwarf satellites are unique objects that encode the early structure formation and therefore represent a window into the high redshift Universe. So far, their study has been conducted using electromagnetic waves only. The future Laser Interferometer Space Antenna (LISA) has the potential to reveal Milky Way satellites through gravitational waves emitted by double white dwarf (DWD) binaries. Aims. We investigate gravitational wave signals that will be detectable by LISA as a possible tool for the identification and characterisation of the Milky Way satellites. Methods. We used the binary population synthesis technique to model the population of DWDs in dwarf satellites and we assessed the impact on the number of LISA detections when making changes to the total stellar mass, distance, star formation history, and metallicity of satellites. We calibrated predictions for the known Milky Way satellites on their observed properties. Results. We find that DWDs emitting at frequencies ≳3 mHz can be detected in Milky Way satellites at large galactocentric distances. The number of these high frequency DWDs per satellite primarily depends on its mass, distance, age, and star formation history, and only mildly depends on the other assumptions regarding their evolution such as metallicity. We find that dwarf galaxies with M⋆ > 106 M⊙ can host detectable LISA sources; the number of detections scales linearly with the satellite’s mass. We forecast that out of the known satellites, Sagittarius, Fornax, Sculptor, and the Magellanic Clouds can be detected with LISA. Conclusions. As an all-sky survey that does not suffer from contamination and dust extinction, LISA will provide observations of the Milky Way and dwarf satellites galaxies, which will be valuable for Galactic archaeology and near-field cosmology.
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Hong, Ju, Rui Tu, Rui Zhang, Lihong Fan, Pengfei Zhang, Junqiang Han, and Xiaochun Lu. "Analyzing the Satellite-Induced Code Bias Variation Characteristics for the BDS-3 Via a 40 m Dish Antenna." Sensors 20, no. 5 (February 29, 2020): 1339. http://dx.doi.org/10.3390/s20051339.
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The satellite-induced code bias variation of geostationary satellite orbit satellites and medium earth orbit satellites of the second-generation BeiDou Navigation Satellite System (BDS-2) exceeds 1 m, which severely affects the accuracy and stability of the ambiguity resolution and high-precision positioning. With the development of the third-generation BDS (BDS-3) with a new system design and new technology, analysis of the satellite-induced code variation characteristics of BDS-3 has become increasingly important. At present, many scholars have explored the satellite-induced code bias of BDS-3, but most of them focus on BDS-3 experimental satellites via normal geodetic antenna. Compared to normal geodetic antenna, the 40-m dish antenna from the National Time Service Center can accurately detect satellite-induced code variations with low noise and high gain. Thus, observational data from fifteen BDS-3 medium earth orbit satellites are collected with the B1I/B2b/B3I/B1C/B2a frequency bands on the day of year (DOY) 199–206 in 2019, the PRN numbers of which are C19/C20/C21/C22/C23/C24/C25/C26/C27/C28/C30/C32/C33 /C35/C37, via the 40 m dish antenna to analyze the code bias variation characteristics. The results show that the obvious satellite-induced elevation‑dependent code bias variations exist in the B1I/B2b/B3I/B1C/B2a frequency bands of C28, compared with other satellites. Similarly, the multipath (MP) combination of B3I has an obvious elevation‑dependent variation within a range of 0.1 m for C21/C24/C27/C28/C37 and elevation‑dependent variation of the B2a and B2b frequency bands also exists in most satellites with a range of 0.1 m. However, the MP combination values of some satellites are asymmetric with respect to elevation, which is different from BDS-2 satellites and especially obvious for BDS-3 satellites B1I and BIC frequency bands with elevation‑dependent variations of 0.2 m, indicating that the code bias variation is not uniquely related to elevation, especially for the B1I/BIC frequency bands. What’s more, the satellite-induced code bias variation of the BDS-3 satellites is greatly reduced compared with that of the BDS-2 satellites. In addition, the similar code bias variation appears at the Xia1 station with a normal geodetic antenna of B1I/B1C/B3I/B2a/B2b of C21, B3I/B2a/B2b of C24 and B2b of C28 among B1I/B1C/B3I/B2a/B2b of C21/C24/C27/C28/C37. The influence of the BDS-3 satellite-induced elevation‑dependent code bias on precision positioning and ambiguity fixing is worth further study using different antennas or receivers.
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Li, Fangchao, Zengke Li, Jingxiang Gao, and Yifei Yao. "A Fast Rotating Partition Satellite Selection Algorithm Based on Equal Distribution of Sky." Journal of Navigation 72, no. 04 (February 21, 2019): 1053–69. http://dx.doi.org/10.1017/s0373463318001145.
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To achieve fast satellite selection for a multi-Global Navigation Satellite System (GNSS), thereby reducing the burden on a receiver's processing element and the cost of hardware, and improving the utilisation ratio of receiver signal channels, the relationship between the number of satellites and Geometric Dilution Of Precision (GDOP), the number of satellites selected and the computation time is analysed. A fast rotating partition algorithm for satellite selection based on equal distribution of the sky is proposed. The algorithm divides the satellite selection process into two parts: rough selection and detailed selection. Unhealthy satellites, according to a health identifier, and low elevation angle satellites with a large troposphere delay are eliminated during the rough selection process. During the detailed satellite selection process, the satellite sky is divided and rotated to match satellites based on the average angle distance between the satellite and central partition line. Static data from the International GNSS Service (IGS) station and dynamic data collected at China University of Mining and Technology were used to verify the algorithm, and the results demonstrated that an inverse matrix could be avoided to reduce computation complexity. Additionally, the new satellite selection algorithm has the merit that there is little effect on the computation when the selected satellites and number of satellites in the field increased. A single system of the Global Positioning System (GPS) and double system of GPS/Globalnaya Navigazionnaya Sputnikovaya Sistema (GLONASS) both passed the hypothesis test for each epoch. By including BeiDou Navigation Satellite System (BDS) data, data utilisation increased to more than 95% using the rotating partition algorithm. Also, the GDOP and positioning performance of a rotating partition algorithm and an optimal Dilution Of Precision (DOP) algorithm are compared in this paper, and the analysis result shows that both of the algorithms have only a small difference of GDOP and have comparable positioning performance.
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Zhou, Li. "Optical System in Laser Inter-Satellites Communication." Advanced Materials Research 945-949 (June 2014): 2213–16. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.2213.
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We know that Inter-satellites communica-tion is a very important to us.However, real global coverage can only be achieved by satellite systems. Satellites communication is the most important mean of the communication network. The traditional satellites communication and inter-satellites links are built by microwave. Recent years, laser links for inter-satellites communication are becoming more and more important.
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Tai, Chang-Kou. "On the Aliasing and Resolving Power of Sea Level Low-Pass Filtered onto a Regular Grid from Along-Track Altimeter Data of Uncoordinated Satellites: The Smoothing Strategy." Journal of Atmospheric and Oceanic Technology 25, no. 4 (April 1, 2008): 617–24. http://dx.doi.org/10.1175/2007jtecho514.1.
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Abstract It is shown that smoothing (low-pass filtering) along-track altimeter data of uncoordinated satellites onto a regular space–time grid helps reduce the overall energy level of the aliasing from the aliasing levels of the individual satellites. The rough rule of thumb is that combining N satellites reduces the energy of the overall aliasing to 1/N of the average aliasing level of the N satellites. Assuming the aliasing levels of these satellites are roughly of the same order of magnitude (i.e., assuming that no special signal spectral content significantly favors one satellite over others at certain locations), combining data from uncoordinated satellites is clearly the right strategy. Moreover, contrary to the case of coordinated satellites, this reduction of aliasing is not achieved by the enhancement of the overall resolving power. In fact (by the strict definition of the resolving power as the largest bandwidths within which a band-limited signal remains free of aliasing), the resolving power is reduced to its smallest possible extent. If one characterizes the resolving power of each satellite as a spectral space within which all band-limited signals are resolved by the satellite, then the combined resolving power of the N satellite is characterized by the spectral space that is the intersection of all N spectral spaces (i.e., the spectral space that is common to all the resolved spectral spaces of the N satellites, hence the smallest). It is also shown that the least squares approach is superior to the smoothing approach in reducing the aliasing and upholding the resolving power of the raw data. To remedy one of the shortcomings of the smoothing approach, the author recommends a multismoother smoothing strategy that tailors the smoother to the sampling characteristics of each satellite. Last, a strategy based on the least squares approach is also described for combining data from uncoordinated satellites.
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Gao, Youtao, Tanran Zhao, Bingyu Jin, Junkang Chen, and Bo Xu. "Autonomous Orbit Determination for Lagrangian Navigation Satellite Based on Neural Network Based State Observer." International Journal of Aerospace Engineering 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/9734164.
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In order to improve the accuracy of the dynamical model used in the orbit determination of the Lagrangian navigation satellites, the nonlinear perturbations acting on Lagrangian navigation satellites are estimated by a neural network. A neural network based state observer is applied to autonomously determine the orbits of Lagrangian navigation satellites using only satellite-to-satellite range. This autonomous orbit determination method does not require linearizing the dynamical mode. There is no need to calculate the transition matrix. It is proved that three satellite-to-satellite ranges are needed using this method; therefore, the navigation constellation should include four Lagrangian navigation satellites at least. Four satellites orbiting on the collinear libration orbits are chosen to construct a constellation which is used to demonstrate the utility of this method. Simulation results illustrate that the stable error of autonomous orbit determination is about 10 m. The perturbation can be estimated by the neural network.
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Teng, Yunlong, and Jinling Wang. "New Characteristics of Geometric Dilution of Precision (GDOP) for Multi-GNSS Constellations." Journal of Navigation 67, no. 6 (July 15, 2014): 1018–28. http://dx.doi.org/10.1017/s037346331400040x.
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For multi-Global Navigation Satellite System (GNSS) constellations, the Geometric Dilution of Precision (GDOP) is an important parameter utilised for the selection of satellites. This paper has derived new formulae to describe the change of GDOP. The result shows that, for GNSS single point positioning solutions, if one more satellite belonging to the existing tracked multi-GNSS constellation used in the single point positioning solution is added, the GDOP always decreases with the number of the added satellites. On the other hand, when the constellation of the added satellite is not from the tracked existing constellations, the different numbers of the added satellites have different influences on the change of GDOP. Generally, adding one satellite from another constellation into the existing multi-GNSS constellations will increase the GDOP, but adding two satellites will decrease the GDOP compared with adding one from another constellation. Additionally, the GDOP also increases in the cases of adding two satellites from two different constellations into the tracked existing constellations.
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Nakajima, Ayano, Shigeru Ida, and Yota Ishigaki. "Orbital evolution of Saturn’s satellites due to the interaction between the moons and the massive rings." Astronomy & Astrophysics 640 (August 2020): L15. http://dx.doi.org/10.1051/0004-6361/202038743.
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Context. Saturn’s mid-sized moons (satellites) have a puzzling orbital configuration with trapping in mean-motion resonances with every-other pairs (Mimas-Tethys 4:2 and Enceladus-Dione 2:1). To reproduce their current orbital configuration on the basis of a recent model of satellite formation from a hypothetical ancient massive ring, adjacent pairs must pass first-order mean-motion resonances without being trapped. Aims. The trapping could be avoided by fast orbital migration and/or excitation of the satellite’s eccentricity caused by gravitational interactions between the satellites and the rings (the disk), which are still unknown. In our research we investigate the satellite orbital evolution due to interactions with the disk through full N-body simulations. Methods. We performed global high-resolution N-body simulations of a self-gravitating particle disk interacting with a single satellite. We used N ∼ 105 particles for the disk. Gravitational forces of all the particles and their inelastic collisions are taken into account. Results. Dense short-wavelength wake structure is created by the disk self-gravity and a few global spiral arms are induced by the satellite. The self-gravity wakes regulate the orbital evolution of the satellite, which has been considered as a disk spreading mechanism, but not as a driver for the orbital evolution. Conclusions. The self-gravity wake torque to the satellite is so effective that the satellite migration is much faster than was predicted with the spiral arm torque. It provides a possible model to avoid the resonance capture of adjacent satellite pairs and establish the current orbital configuration of Saturn’s mid-sized satellites.
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Shao, Shi, Marius Cautun, and Carlos S. Frenk. "Evolution of galactic planes of satellites in the eagle simulation." Monthly Notices of the Royal Astronomical Society 488, no. 1 (June 26, 2019): 1166–79. http://dx.doi.org/10.1093/mnras/stz1741.
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ABSTRACT We study the formation of planes of dwarf galaxies around Milky Way (MW)-mass haloes in the eagle galaxy formation simulation. We focus on satellite systems similar to the one in the MW: spatially thin or with a large fraction of members orbiting in the same plane. To characterize the latter, we introduce a robust method to identify the subsets of satellites that have the most coplanar orbits. Out of the 11 MW classical dwarf satellites, 8 have highly clustered orbital planes whose poles are contained within a 22° opening angle centred around (l, b) = (182°, −2°). This configuration stands out when compared to both isotropic and typical ΛCDM satellite distributions. Purely flattened satellite systems are short-lived chance associations and persist for less than $1\, \rm {Gyr}$. In contrast, satellite subsets that share roughly the same orbital plane are longer lived, with half of the MW-like systems being at least $4\, \rm {Gyr}$ old. On average, satellite systems were flatter in the past, with a minimum in their minor-to-major axes ratio about $9\, \rm {Gyr}$ ago, which is the typical infall time of the classical satellites. MW-like satellite distributions have on average always been flatter than the overall population of satellites in MW-mass haloes and, in particular, they correspond to systems with a high degree of anisotropic accretion of satellites. We also show that torques induced by the aspherical mass distribution of the host halo channel some satellite orbits into the host’s equatorial plane, enhancing the fraction of satellites with coplanar orbits. In fact, the orbital poles of coplanar satellites are tightly aligned with the minor axis of the host halo.
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Park, Jeong-Eon. "A Control Algorithm for Tapering Charging of Li-Ion Battery in Geostationary Satellites." Energies 16, no. 15 (July 26, 2023): 5636. http://dx.doi.org/10.3390/en16155636.
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Recently, as the satellite data service market has grown significantly, satellite demand has been rapidly increasing. Demand for geostationary satellites with weather observation, communication broadcasting, and GPS missions is also increasing. Completing the charging process of the Li-ion battery during the sun period is one of the main tasks of the electrical power system in geostationary satellites. In the case of the electrical power system of low Earth orbit satellites, the Li-ion battery is connected to the DC/DC converter output, and the charging process is completed through CV control. However, in the case of the regulated bus of the DET type, which is mainly used in the electrical power system of geostationary satellites, a Li-ion battery is connected to the input of the DC/DC converter. Therefore, a method other than the CV control of the DC/DC converter is required. This paper proposes a control algorithm for tapering charging of the Li-ion battery in the regulated bus of the DET type for Li-ion battery charge completion operation required by space-level design standards. In addition, the proposed control algorithm is verified through an experiment on a geostationary satellite’s ground electrical test platform. The experiment verified that it has a power conversion efficiency of 99.5% from the solar array to the battery. It has 21 tapering steps at the equinox and 17 tapering steps at the solstice.
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Zhang, Jiao Yan, Jun Yan Wang, Wei He, Hong Lan Bu, and Yan Zhang. "The Analysis of Abnormal Phenomena of GEO Satellites Solar Array." Advanced Materials Research 823 (October 2013): 559–62. http://dx.doi.org/10.4028/www.scientific.net/amr.823.559.
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Satellites solar array provides sustainable and reliable energy for satellite by changing the solar energy into electrical energy in order to ensure the normal working of the satellite. The working status of solar array is directly related to the satellites normal running in orbit. The thesis summarized the normal trend of the GEO satellites solar array output power, through comparing the real output power of a certain satellites solar array with the normal trend, and detected four abnormal phenomena of solar array output power. Then the thesis analyzed the reasons, and made related suggestions.
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Ren, Ping, and Jie Ming Zhou. "The Evaluation and Application Study of Remote Sensing Data Quality of Environment and Disaster Monitoring." Advanced Materials Research 573-574 (October 2012): 271–76. http://dx.doi.org/10.4028/www.scientific.net/amr.573-574.271.
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The existing Fengyun (FY) satellites, resource satellites and ocean satellites all can observe the earth muti-funtionally and work well in monitoring environment and disasters. However, all these satellites are insufficient for space resolution, time resolution, spectral resolution and all-weather requirements when facing complicated environmental problems and natural disasters. This paper evaluates the multi-spectral remote sensing data quality of the Environment and Disasters Monitoring Micro-satellite Constellation (HJ-1A/B)A/B satellite and extracts data characteristics to offer references for promotion and application this data.
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Mohamed Sanad and Noha Hassan. "A review: Performance of multibeam dual parabolic cylindrical reflector antennas in LEO satellites." ITU Journal on Future and Evolving Technologies 5, no. 2 (June 3, 2024): 221–29. http://dx.doi.org/10.52953/tsum9295.
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The characteristics of multibeam dual parabolic cylindrical reflector antennas are summarized in this article. They can generate an arbitrary number of beams with arbitrary tilt angles for each beam. They can be remotely controlled to cover any arbitrary area, of any shape and size, even if the antenna was mounted on a quasi-stationary platform. Their performance in Low-Earth Orbit (LEO) satellites and ground stations (terminals) have been presented. A simple beam tracking technique was developed. For any specific satellite orbit, the orientation of the ground-station antenna could be adjusted such that its beams are parallel to the satellite's beams and directed toward them. The ground-station antenna can simultaneously communicate with multiple satellites in different orbits. A single antenna can cover the whole mm-band (17.8-30 GHz), which is one of the most widely used bands in LEO satellites. The overall size of a mm-wave antenna, generating 20-24 dB gain, is 14.8x10.4x3.7 cm3 and its weight is 0.37 kg.
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Yin, Yabo, Chuanhe Huang, Dong-Fang Wu, Shidong Huang, M. Wasim Abbas Ashraf, Qianqian Guo, and Lin Zhang. "Deep Reinforcement Learning-Based Joint Satellite Scheduling and Resource Allocation in Satellite-Terrestrial Integrated Networks." Wireless Communications and Mobile Computing 2022 (February 24, 2022): 1–18. http://dx.doi.org/10.1155/2022/1177544.
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Satellite-terrestrial integrated networks (STINs) are considered to be a new paradigm for the next generation of global communication because of its distinctive merits, such as wide coverage, high reliability, and flexibility. When the satellite associates with different base stations (BSs) and adopts different channels for communication, the utility of offloading data to BSs is different. In our work, we study how to jointly associate satellites with appropriate BSs and allocate channels to satellites. Our purpose is to maximize the utility of the data offloaded from satellites to BSs while considering the load balance of BSs. However, some satellites are often unable to connect to BSs because of their periodic flight characteristic, which makes the joint satellite-BS association and channel allocation more challenging. To solve the problem that satellites sometimes cannot connect to BSs, we abstract the communication model between satellites and BSs into a bipartite graph and add a virtual BS to ensure that all satellites can connect to at least one BS. Then, in the constructed joint optimization problem, we solve the assignment of satellites and channels simultaneously. Considering that the joint optimization problem is nonconvex, we use double deep Q-Network (DDQN) for achieving the optimal strategy of satellite association and channel allocation. Furthermore, the reward value in most state transition information generated by satellites is 0, which leads to the low learning efficiency of DDQN. Aiming at enhancing the learning efficiency of DDQN, the priority sampling-based DDQN (PSDDQN) algorithm is proposed. Experimental results demonstrate that PSDDQN gets better utility and achieves the load balance of BSs compared with other algorithms.
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Ding, Huixia, Sicheng Zhu, Sachula Meng, Jinxia Han, Heng Liu, Miao Wang, Jiayan Liu, Peng Qin, and Xiongwen Zhao. "Matching-Based Resource Allocation for Satellite–Ground Network." Sensors 22, no. 21 (November 2, 2022): 8436. http://dx.doi.org/10.3390/s22218436.
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With the vigorous development of information and communication technology, mobile internet has undergone tremendous changes. How to achieve global coverage of the network has become the primary problem to be solved. GEO satellites and LEO satellites, as important components of the satellite–ground network, can offer service for hotspots or distant regions where ground-based base stations’ coverage is limited. Therefore, we build a satellite–ground network model, which transforms the satellite–ground network resource allocation problem into a matching issue between GEO satellites, LEO satellites, and users. A GEO satellite provides data backhaul for users, and a LEO satellite provides data transmission services according to users’ requests. It is important to consider the relationships between all entities and establish a distributed scheme, so we propose a three-sided cyclic matching algorithm. It is confirmed by a large number of simulation experiments that the method suggested in this research is better than the conventional algorithm in terms of average delay, satellite revenue, and number of users served.
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Xu, Yue, Tao Dong, Jie Yin, Ziyong Zhang, Zhihui Liu, Hao Jiang, and Jing Wu. "A Fast Time Synchronization Method for Large Scale LEO Satellite Networks Based on A Bionic Algorithm." Photonics 11, no. 5 (May 19, 2024): 475. http://dx.doi.org/10.3390/photonics11050475.
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A fast time synchronization method for large-scale LEO satellite networks based on a bionic algorithm is proposed. Because the inter-satellite links are continuously established and interrupted due to the relative motion of the satellites, the topology of the LEO satellite networks is time varying. Firstly, according to the ephemeris information in navigation messages, a connection table which records the connections between satellites is generated. Then, based on the connection table, the current satellite network topology is calculated and generated. Furthermore, a bionic algorithm is used to select some satellites as time source nodes and calculate the hierarchy of the clock transmission tree. By taking the minimum level of the time transmission tree as the optimization objective, the time source nodes and the clock stratums of the whole satellite networks are obtained. Finally, the onboard computational center broadcasts the time layer table to all the satellites in the LEO satellite networks and the time synchronization links can be established or recovered fast.
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Jacobsen, K. "WHICH SATELLITE IMAGE SHOULD BE USED FOR MAPPING." ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences X-1/W1-2023 (December 5, 2023): 827–34. http://dx.doi.org/10.5194/isprs-annals-x-1-w1-2023-827-2023.
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Abstract. Today, topographical mapping based on satellite images is a standard method. With the large number of very high-resolution optical satellites, it only a question of the Ground Sampling Distance (GSD) and the map scale to be generated. But the classical large-format satellite images are expensive. With the today’s variety of the classical small satellites (601kg to 1200kg) to Nano-satellites (1.1kg to 10kg) of 3U (10cm × 10cm × 30cm), various options are available that influence the economic solutions. An overview of the accessible optical satellites is given, with some specific information on the mini-satellites that offer new economical solutions for topographic mapping. Significantly more optical satellites are currently in operation, but their images are used only for military purposes or they are restricted for national use due to lack of image storage and limited download possibilities.
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Wu, Shiyu, Dongkai Yang, Yunlong Zhu, and Feng Wang. "Improved GNSS-Based Bistatic SAR Using Multi-Satellites Fusion: Analysis and Experimental Demonstration." Sensors 20, no. 24 (December 11, 2020): 7119. http://dx.doi.org/10.3390/s20247119.
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The Global Navigation Satellite System (GNSS)-based Bistatic Synthetic Aperture Radar (SAR) is getting more and more attention in remote sensing for its all-weather and real-time global observation capability. Its low range resolution results from the narrow signal bandwidth limits in its development. The configuration difference caused by the illumination angle and movement direction of the different satellites makes it possible to improve resolution by multi-satellite fusion. However, this also introduces new problems with the resolution-enhancing efficiency and increased computation brought about by the fusion. In this paper, we aim at effectively improving the resolution of the multi-satellite fusion system. To this purpose, firstly, the Point Spread Function (PSF) of the multi-satellite fusion system is analyzed, and focusing on the relationship between the fusion resolution and the geometric configuration and the number of satellites. Numerical simulation results show that, compared with multi-satellite fusion, dual-satellite fusion is a combination with higher resolution enhancement efficiency. Secondly, a method for dual-satellite fusion imaging based on optimized satellite selection is proposed. With the greedy algorithm, the selection is divided into two steps: in the first step, according to geometry configuration, the single-satellite with the optimal 2-D resolution is selected as the reference satellite; in the second step, the angles between the azimuthal vector of the reference satellite and the azimuthal vector of the other satellites were calculated by the traversal method, the satellite corresponding to the intersection angle which is closest to 90° is selected as the auxiliary satellite. The fused image was obtained by non-coherent addition of the images generated by the reference satellite and the auxiliary satellite, respectively. Finally, the GPS L1 real orbit multi-target simulation and experimental validation were conducted, respectively. The simulation results show that the 2-D resolution of the images produced by our proposed method is globally optimal 15 times and suboptimal 8 times out of 24 data sets. The experimental results show that the 2-D resolution of our proposed method is optimal in the scene, and the area of the resolution unit is reduced by 70.1% compared to the single-satellite’s images. In the experiment, there are three navigation satellites for imaging, the time taken to the proposed method was 66.6% that of the traversal method. Simulations and experiments fully demonstrate the feasibility of the method.
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Meng, Lingdong, Jiexian Wang, Junping Chen, Bin Wang, and Yize Zhang. "Extended Geometry and Probability Model for GNSS+ Constellation Performance Evaluation." Remote Sensing 12, no. 16 (August 9, 2020): 2560. http://dx.doi.org/10.3390/rs12162560.
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We proposed an extended geometry and probability model (EGAPM) to analyze the performance of various kinds of (Global Navigation Satellite System) GNSS+ constellation design scenarios in terms of satellite visibility and dilution of precision (DOP) et al. on global and regional scales. Different from conventional methods, requiring real or simulated satellite ephemerides, this new model only uses some basic parameters of one satellite constellation. Verified by the reference values derived from precise satellite ephemerides, the accuracy of visible satellite visibility estimation using EGAPM gets an accuracy better than 0.11 on average. Applying the EGAPM to evaluate the geometry distribution quality of the hybrid GNSS+ constellation, where highly eccentric orbits (HEO), quasi-zenith orbit (QZO), inclined geosynchronous orbit (IGSO), geostationary earth orbit (GEO), medium earth orbit (MEO), and also low earth orbit (LEO) satellites included, we analyze the overall performance quantities of different constellation configurations. Results show that QZO satellites perform slightly better in the Northern Hemisphere than IGSO satellites. HEO satellites can significantly improve constellation geometry distribution quality in the high latitude regions. With 5 HEO satellites included in the third-generation BeiDou navigation satellite system (BDS-3), the average VDOP (vertical DOP) of the 30° N–90° N region can be decreased by 16.65%, meanwhile satellite visibility can be increased by 38.76%. What is more, the inclusion of the polar LEO constellation can significantly improve GNSS service performance. When including with 288 LEO satellites, the overall DOPs (GDOP (geometric DOP), HDOP (horizontal DOP), PDOP (position DOP), TDOP (time DOP), and VDOP) are decreased by about 40%, and the satellite visibility can be increased by 183.99% relative to the Global Positioning System (GPS) constellation.
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Qin, Dan, Yongjun Jia, Mingsen Lin, and Shanwei Liu. "Performance Evaluation of China’s First Ocean Dynamic Environment Satellite Constellation." Remote Sensing 15, no. 19 (September 30, 2023): 4780. http://dx.doi.org/10.3390/rs15194780.
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China’s first dynamic environment satellite constellation includes the HY-2B, HY-2C, and HY-2D satellites. In this study, the along track SLA, SWH, and SSWS of this satellite constellation were evaluated. SLA parameters are evaluated using self-crossing and dual-crossing methods. The SSWS and SWH data were evaluated by comparing with NDBC buoy and other available satellites’ data. The evaluation revealed that the standard deviation of the SLA from the HY-2B/C/D satellites’ single mission crossovers was 3.29 cm, 3.51 cm, and 3.72 cm, respectively. In addition, at the dual-crossovers of the Jason-3 satellite and the HY-2B satellite, the HY-2B satellite, and the HY-2C/D satellites, the standard deviation was determined to be 3.40 cm, 3.48 cm, and 4.25 cm, respectively. The accuracy of the SWH products of the HY-2B/C/D satellite radar altimeters was observed to be 0.23 m, 0.25 m, and 0.26 m, respectively. The accuracy of the SSWS data of the HY-2B/C/D satellite radar altimeters was observed to be 1.48 m/s, 1.59 m/s, and 1.35 m/s, respectively. In addition, this study also analyzed and compared the observation efficiency of the dynamic environment satellite constellation with the following six satellites: Sentinel-3(A, B), Jason-3, Sentinel-6A, Saral, and Cryosat-2. Observation efficiency refers to selection of any point on the globe to find a minimum radius of at least one observation point within a circle in a 14-day period. The analysis results demonstrated that observation efficiency of China’s first dynamic environment satellite constellation was comparable to that of the six satellites.
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Najder, Joanna, and Krzysztof Sośnica. "Quality of Orbit Predictions for Satellites Tracked by SLR Stations." Remote Sensing 13, no. 7 (April 3, 2021): 1377. http://dx.doi.org/10.3390/rs13071377.
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This study aims to evaluate and analyze the orbit predictions of selected satellites: geodetic, Global Navigational Satellite Systems (GNSS), and scientific low-orbiting, which are tracked by laser stations. The possibility of conducting satellite laser ranging (SLR) to artificial satellites depends on the access to high-quality predictions of satellite orbits. The predictions provide information to laser stations where to aim the telescope in search of a satellite to get the returns from the retroreflectors installed onboard. If the orbit predictions are very imprecise, SLR stations must spend more time to correct the telescope pointing, and thus the number of collected observations is small or, in an extreme case, there are none of them at all. Currently, there are about 120 satellites equipped with laser retroreflectors orbiting the Earth. Therefore, the necessity to determine the quality of predictions provided by various analysis centers is important in the context of the increasing number of satellites tracked by SLR stations. We compare the orbit predictions to final GNSS orbits, precise orbits of geodetic satellites based on SLR measurements determined in postprocessing, and kinematic orbits of low-orbiting satellites based on GPS data. We assess the quality degradation of the orbit predictions over time depending on the type of orbit and the satellite being analyzed. We estimate the time of usefulness of prediction files, and indicate those centers which publish most accurate predictions of the satellites’ trajectories. The best-quality predictions for geodetic satellites and Galileo reach the mean error of 0.5–1 m for the whole 5-day prediction file (for all three components), while the worst ones can reach values of up to several thousand meters during the first day of the prediction.
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Stein, Josephine Anne. "Satellites, anti‐satellite weapons and security." RUSI Journal 133, no. 4 (December 1988): 48–54. http://dx.doi.org/10.1080/03071848808445329.
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Shen, Fei, Mingming Sui, Yifan Zhu, Xinyun Cao, Yulong Ge, and Haohan Wei. "Using BDS MEO and IGSO Satellite SNR Observations to Measure Soil Moisture Fluctuations Based on the Satellite Repeat Period." Remote Sensing 13, no. 19 (October 3, 2021): 3967. http://dx.doi.org/10.3390/rs13193967.
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Soil moisture is an important geophysical parameter for studying terrestrial water and energy cycles. It has been proven that Global Navigation Satellite System Interferometry Reflectometry (GNSS-IR) can be applied to monitor soil moisture. Unlike the Global Positioning System (GPS) that has only medium earth orbit (MEO) satellites, the Beidou Navigation Satellite System (BDS) also has geosynchronous earth orbit (GEO) satellites and inclined geosynchronous satellite orbit (IGSO) satellites. Benefiting from the distribution of three different orbits, the BDS has better coverage in Asia than other satellite systems. Previous retrieval methods that have been confirmed on GPS cannot be directly applied to BDS MEO satellites due to different satellite orbits. The contribution of this study is a proposed multi-satellite soil moisture retrieval method for BDS MEO and IGSO satellites based on signal-to-noise ratio (SNR) observations. The method weakened the influence of environmental differences in different directions by considering satellite repeat period. A 30-day observation experiment was conducted in Fengqiu County, China and was used for verification. The satellite data collected were divided according to the satellite repeat period, and ensured the response data moved in the same direction. The experimental results showed that the BDS IGSO and MEO soil moisture estimation results had good correlations with the in situ soil moisture fluctuations. The BDS MEO B1I estimation results had the best performance; the estimation accuracy in terms of correlation coefficient was 0.9824, root mean square error (RMSE) was 0.0056 cm3cm−3, and mean absolute error (MAE) was 0.0040 cm3cm−3. The estimations of the BDS MEO B1I, MEO B2I, and IGSO B2I performed better than the GPS L1 and L2 estimations. For the BDS IGSO satellites, the B1I signal was more suitable for soil moisture retrieval than the B2I signal; the correlation coefficient was increased by 19.84%, RMSE was decreased by 42.64%, and MAE was decreased by 43.93%. In addition, the BDS MEO satellites could effectively capture sudden rainfall events.