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Shen, Ziyu, Wenbin Shen, Xinyu Xu, Shuangxi Zhang, Tengxu Zhang, Lin He, Zhan Cai, Si Xiong i Lingxuan Wang. "A Method for Measuring Gravitational Potential of Satellite’s Orbit Using Frequency Signal Transfer Technique between Satellites". Remote Sensing 15, nr 14 (12.07.2023): 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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Wu, Huanqin, Maocai Wang, Zhiming Song, Xiaoyu Chen, Guangming Dai, Wei Zheng i Qingrui Zhou. "Random Error Analysis of Launch and Injection Positions for Distributed Multi Micro-nano Satellite System". Journal of Physics: Conference Series 2640, nr 1 (1.11.2023): 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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Tong, Minglei, Song Li, Xiaoxiang Wang i Peng Wei. "Inter-Satellite Cooperative Offloading Decision and Resource Allocation in Mobile Edge Computing-Enabled Satellite–Terrestrial Networks". Sensors 23, nr 2 (6.01.2023): 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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Utami, Vi Bauty Riska, Imam MPB i Shinta Romadhona. "Analysis the impact of sun outage and satellite orbit at performance of the telkom 3S satellite communication system". JURNAL INFOTEL 13, nr 3 (31.08.2021): 134–42. http://dx.doi.org/10.20895/infotel.v13i3.626.
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Satellites of communication are located at altitude of thousands kilometers above the earth's surface, so the signal is transmitted by satellite to earth station is very susceptible to interference. Every March and September equinox or when the sun crosses the Earth's equator for several days, earth station occurs a naturally interference called by sun outage. At this time, satellite and the sun reach the closest distance because satellite's position is same direction with the sun. This interference makes the signal received by earth station weaken and even disappears due to temperature noise which increases drastically. Loss of signal on the downlink side caused by noise greatly affects to the performance of satellite communication system. This study aims to analyze the effect of sun outage and satellite orbit to determine sun outage period on the performance of Telkom 3S satellite communication system. The results obtained that indicate the signal quality is represented by degradation in the Carrier to Noise Ratio (C/N) from 14,777 dB to 6,0 dB, Energy bits per Noise Ratio (Eb/No) from 11,515 dB to 2,738 dB, and increase the Bit Error Rate (BER) from 8,29×10-7 to 11,08×10-3. In addition, sun outage makes lost of satellite communication traffic and affecting link availability to 99,855324%. Meanwhile, the result from satellite orbit calculation for sun outage period based on ITU-R S.1525 standard and based by satellite’s handbook.
Keywords – Telkom 3S satellite, sun outage, C/N, Eb/No, BER, link availability, sun outage period.
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Shakila Hosseinzadeh Kondori, Mustafa Helvacı. "Satellite Temperature Modeling in Geostationary Orbit Using COMSOL". Tuijin Jishu/Journal of Propulsion Technology 44, nr 5 (29.11.2023): 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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Papiya, Sumaiya Janefar, Dr Bobby Barua i Mehnaz Hossain. "Prospects Challenges of Bangabandhu Satellite-2". International Journal of Advanced Networking and Applications 14, nr 02 (2022): 5342–52. http://dx.doi.org/10.35444/ijana.2022.14204.
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The development of the Bangabandhu Satellite-1 has changed the direction of Bangladesh's satellite communication research. Bangladesh's dream project was the Bangabandhu Satellite 1. This satellite's primary goal is to maintain effective internet and communication services in remote places. First of all, we must concentrate to the depth of satellite communication system and its process to reach any conclusion. Our main goal of the research is to recognize a feasibility review on Bangabandhu satellite-2. So, for the feasibility studies we reviewed the most promising technical parts of Bangabandhu satellite-1. Here, we only focused the certain parts of the satellite such as coding, modulation, battery, purpose of ground station and the benefits of the satellite communication system. Then we moved on the main parts of the Bangabandhu satellite-2. As, Bangabandhu satellite-1 was Geosynchronous equatorial orbit (GEO) communication satellite and Bangabandhu satellite-2 will be Low Earth Orbit (LEO) observation satellite (LEO) so, some of configurations between them might be changed. Furthermore, we largely focused on Facts, efficiency, performance and noticeable difference between two satellites.
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Williamson, M. "Satellites rock! [satellite radio]". IEE Review 49, nr 11 (1.12.2003): 34–37. http://dx.doi.org/10.1049/ir:20031104.
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Wei, Hui, Jiancheng Li, Shoujian Zhang i Xinyu Xu. "Cycle Slip Detection and Repair for Dual-Frequency LEO Satellite GPS Carrier Phase Observations with Orbit Dynamic Model Information". Remote Sensing 11, nr 11 (29.05.2019): 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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Wu, Shiyu, Dongkai Yang, Yunlong Zhu i Feng Wang. "Improved GNSS-Based Bistatic SAR Using Multi-Satellites Fusion: Analysis and Experimental Demonstration". Sensors 20, nr 24 (11.12.2020): 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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Yun, Seok-Teak, i Seung-Hyun Kong. "Forecasting Methods of Battery Charge and Discharge Current Profile for LEO Satellites". Electronics 10, nr 23 (1.12.2021): 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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Nakajima, Ayano, Shigeru Ida i Yota Ishigaki. "Orbital evolution of Saturn’s satellites due to the interaction between the moons and the massive rings". Astronomy & Astrophysics 640 (sierpień 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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Zhao, Xiangyu, Chunjuan Zhao, Jiale Li, Yongliang Guan, Shanbo Chen i Lei Zhang. "Research on Design, Simulation, and Experiment of Separation Mechanism for Micro-Nano Satellites". Applied Sciences 12, nr 12 (13.06.2022): 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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Guo, Jinyun, Guangzhe Wang, Hengyang Guo, Mingsen Lin, Hailong Peng, Xiaotao Chang i Yingming Jiang. "Validating Precise Orbit Determination from Satellite-Borne GPS Data of Haiyang-2D". Remote Sensing 14, nr 10 (21.05.2022): 2477. http://dx.doi.org/10.3390/rs14102477.
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Haiyang-2D (HY-2D) is the fourth satellite in the marine dynamic satellite series established by China. It was successfully launched on 19 May 2021, marking the era of the 3-satellite network in the marine dynamic environment satellite series of China. The satellite’s precision orbit determination (POD) and validations are of great significance for ocean warning and marine altimetry missions. HY-2D is equipped with a laser reflector array (LRA), a satellite-borne Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) receiver, and a satellite-borne dual-frequency GPS receiver named HY2 that was independently developed in China. In this paper, the quality of GPS data collected by the HY2 is analyzed based on indicators such as the multipath effect, cycle slips, and data completeness. The results suggest that the receiver can be used in POD missions involving low-Earth-orbit (LEO) satellites. The precise orbits of HY-2D are determined by the reduced-dynamics (RD) method. Apart from POD, validation of orbit accuracy is another important task for LEO POD. Therefore, two external validation methods are proposed, including carrier differential validation using one GPS satellite and inter-satellite differential validation using two GPS satellites. These are based on space-borne carrier-phase data, and the GPS satellites used for POD validation do not participate in orbit determination. The results of SLR range validation cannot illustrate the orbit accuracy in x, y, and z directions particularly, so to make validation results more intuitive, the SLR three-dimensional (3D) validation is proposed based on SLR range validation, and the RMSs in x, y, and z directions are 2.66, 3.32, and 2.69 cm, respectively. The results of SLR 3D validation are the same as those of SLR range validation, which proves that the new external validation method provided by SLR 3D is reliable. The RMSs of carrier differential validation and inter-satellite differential validation are 0.68 and 1.06 cm, respectively. The proposed validation methods are proved to be reliable.
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Welling, D. T. "The long-term effects of space weather on satellite operations". Annales Geophysicae 28, nr 6 (24.06.2010): 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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Volkov, G. Yu, i D. V. Fadyushin. "DYNAMIC CONDITIONS FOR INCREASING THE STRUCTURAL STABILITY OF THE WORKING MECHANISM OF A PLANETARY-ROTARY HYDRAULIC MACHINE". Spravochnik. Inzhenernyi zhurnal, nr 283 (październik 2020): 33–39. http://dx.doi.org/10.14489/hb.2020.10.pp.033-039.
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A structural feature of planetary-rotor hydraulic machines (PRHM) is the presence of floating satellites. The satellite forms kinematic pairs with the rotor and stator, which, depending on the applied forces, can change their class. In PRHM with “standouts” of satellites intended for gas media, the kinematic satellite-stator pair operates at critically high values of the pressure angle. Under the influence of the pressure force of the working medium, the satellite, taking up the radial clearance in the gearing, is shifted towards the rotor and pressed against it on both sides of the tooth, and the satellite-stator pair becomes a single-moving pair of class 4. The resulting satellite offset further worsens the conditions for transmitting motion in the satellite-stator pair. As a result, there is a probability of jamming of the mechanism, accompanied by unacceptable deformations, and the satellite's exit from engagement with the stator. From the point of view of the theory of mechanisms and machines, this means that the system loses its structural stability and goes into an undesirable structural state. The article studies the conditions under which inertial forces, overcoming the pressure forces of the working medium, press the satellite against the stator. This eliminates the situation when a kinematic pair characterized by a critically high pressure angle is single-moving. As a result of the performed dynamic analysis, calculated dependencies are obtained that allow determining the rotor rotation speed that provides more reliable operation of the PRHM.
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Volkov, G. Yu, i D. V. Fadyushin. "DYNAMIC CONDITIONS FOR INCREASING THE STRUCTURAL STABILITY OF THE WORKING MECHANISM OF A PLANETARY-ROTARY HYDRAULIC MACHINE". Spravochnik. Inzhenernyi zhurnal, nr 283 (październik 2020): 33–39. http://dx.doi.org/10.14489/hb.2020.10.pp.033-039.
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A structural feature of planetary-rotor hydraulic machines (PRHM) is the presence of floating satellites. The satellite forms kinematic pairs with the rotor and stator, which, depending on the applied forces, can change their class. In PRHM with “standouts” of satellites intended for gas media, the kinematic satellite-stator pair operates at critically high values of the pressure angle. Under the influence of the pressure force of the working medium, the satellite, taking up the radial clearance in the gearing, is shifted towards the rotor and pressed against it on both sides of the tooth, and the satellite-stator pair becomes a single-moving pair of class 4. The resulting satellite offset further worsens the conditions for transmitting motion in the satellite-stator pair. As a result, there is a probability of jamming of the mechanism, accompanied by unacceptable deformations, and the satellite's exit from engagement with the stator. From the point of view of the theory of mechanisms and machines, this means that the system loses its structural stability and goes into an undesirable structural state. The article studies the conditions under which inertial forces, overcoming the pressure forces of the working medium, press the satellite against the stator. This eliminates the situation when a kinematic pair characterized by a critically high pressure angle is single-moving. As a result of the performed dynamic analysis, calculated dependencies are obtained that allow determining the rotor rotation speed that provides more reliable operation of the PRHM.
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Bloßfeld, Mathis, Julian Zeitlhöfler, Sergei Rudenko i Denise Dettmering. "Observation-Based Attitude Realization for Accurate Jason Satellite Orbits and Its Impact on Geodetic and Altimetry Results". Remote Sensing 12, nr 4 (19.02.2020): 682. http://dx.doi.org/10.3390/rs12040682.
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For low Earth orbiting satellites, non-gravitational forces cause one of the largest perturbing accelerations. During a precise orbit determination (POD), the accurate modeling of the satellite-body attitude and solar panel orientation is important since the satellite’s effective cross-sectional area is directly related to the perturbing acceleration. Moreover, the position of tracking instruments that are mounted on the satellite body are affected by the satellite attitude. For satellites like Jason-1/-2/-3, attitude information is available in two forms—as a so-called nominal yaw steering model and as observation-based (measured by star tracking cameras) quaternions of the spacecraft body orientation and rotation angles of the solar arrays. In this study, we have developed a preprocessing procedure for publicly available satellite attitude information. We computed orbits based on Satellite Laser Ranging (SLR) observations to the Jason satellites at an overall time interval of approximately 25 years, using each of the two satellite attitude representations. Based on the analysis of the orbits, we investigate the influence of using preprocessed observation-based attitude in contrast to using a nominal yaw steering model for the POD. About 75% of all orbital arcs calculated with the observation-based satellite attitude data result in a smaller root mean square (RMS) of residuals. More precisely, the resulting orbits show an improvement in the overall mission RMS of SLR observation residuals of 5.93% (Jason-1), 8.27% (Jason-2) and 4.51% (Jason-3) compared to the nominal attitude realization. Besides the satellite orbits, also the estimated station coordinates benefit from the refined attitude handling, that is, the station repeatability is clearly improved at the draconitic period. Moreover, altimetry analysis indicates a clear improvement of the single-satellite crossover differences (6%, 15%, and 16% reduction of the mean of absolute differences and 1.2%, 2.7%, and 1.3% of their standard deviations for Jason-1/-2/-3, respectively). On request, the preprocessed attitude data are available.
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Fankhauser, Forrest, J. Anthony Tyson i Jacob Askari. "Satellite Optical Brightness". Astronomical Journal 166, nr 2 (13.07.2023): 59. http://dx.doi.org/10.3847/1538-3881/ace047.
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Abstract The apparent brightness of satellites is calculated as a function of satellite position as seen by a ground-based observer in darkness. Both direct illumination of the satellite by the Sun as well as indirect illumination due to reflection from the Earth are included. The reflecting properties of the satellite components and of the Earth must first be estimated (the Bidirectional Reflectance Distribution Function, or BRDF). The reflecting properties of the satellite components can be found directly using lab measurements or accurately inferred from multiple observations of a satellite at various solar angles. Integrating over all scattering surfaces leads to the angular pattern of flux from the satellite. Finally, the apparent brightness of the satellite as seen by an observer at a given location is calculated as a function of satellite position. We develop an improved model for reflection of light from Earth’s surface using aircraft data. We find that indirectly reflected light from Earth’s surface contributes significant increases in apparent satellite brightness. This effect is particularly strong during civil twilight. We validate our approach by comparing our calculations to multiple observations of selected Starlink satellites and show significant improvement on previous satellite brightness models. Similar methodology for predicting satellite brightness has already informed mitigation strategies for next-generation Starlink satellites. Measurements of satellite brightness over a variety of solar angles widens the effectiveness of our approach to virtually all satellites. We demonstrate that an empirical model in which reflecting functions of the chassis and the solar panels are fit to observed satellite data performs very well. This work finds application in satellite design and operations, and in planning observatory data acquisition and analysis.
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Tong, Minglei, Xiaoxiang Wang, Song Li i Liang Peng. "Joint Offloading Decision and Resource Allocation in Mobile Edge Computing-Enabled Satellite-Terrestrial Network". Symmetry 14, nr 3 (12.03.2022): 564. http://dx.doi.org/10.3390/sym14030564.
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With the development of satellite-terrestrial network (STN), mobile edge computing (MEC) servers are deployed at low orbit earth (LEO) satellites to provide computing services for user devices (UEs) in areas without terrestrial network coverage. There is symmetry between satellite networks and terrestrial networks, but there is asymmetry between their resources. Computing resources of satellites’ MEC servers may not be enough. The satellite-terrestrial cooperation is promising, where a satellite migrates tasks to a base station (BS) in an adjacent area, thus utilizing computing resources of the BS’s MEC server. Although there are some studies on computation offloading in STN, few studies consider a satellite as both a relay and a computing unit to assist UEs in computing tasks. This paper proposes a joint offloading decision and resource allocation scheme in MEC-enabled STN, which minimizes the completion delay of all UEs’ indivisible tasks. Firstly, the optimization problem is formulated and decomposed. Then, the proposed scheme based on potential game and the Lagrange multiplier method makes UEs’ task offloading decisions and allocates the satellite’s and the BS’s computing resources, thus obtaining the optimal solution through continuous iterations. Finally, the simulation results validate that the proposed scheme can obtain better gain than other baseline schemes.
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Woo, Hyung Je, i Bjorn Buckwalter. "Geostationary Satellite Station Keeping Robustness to Loss of Ground Control". Journal of Astronomy and Space Sciences 38, nr 1 (marzec 2021): 65–82. http://dx.doi.org/10.5140/jass.2021.38.1.65.
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For the vast majority of geostationary satellites currently in orbit, station keeping activities including orbit determination and maneuver planning and execution are ground-directed and dependent on the availability of ground-based satellite control personnel and facilities. However, a requirement linked to satellite autonomy and survivability in cases of interrupted ground support is often one of the stipulated provisions on the satellite platform design. It is especially important for a geostationary military-purposed satellite to remain within its designated orbital window, in order to provide reliable uninterrupted telecommunications services, in the absence of ground-based resources due to warfare or other disasters. In this paper we investigate factors affecting the robustness of a geostationary satellite’s orbit in terms of the maximum duration the satellite’s station keeping window can be maintained without ground intervention. By comparing simulations of orbit evolution, given different initial conditions and operations strategies, a variation of parameters study has been performed and we have analyzed which factors the duration is most sensitive to. This also provides valuable insights into which factors may be worth controlling by a military or civilian geostationary satellite operator. Our simulations show that the most beneficial factor for maximizing the time a satellite will remain in the station keeping window is the operational practice of pre-emptively loading East-West station keeping maneuvers for automatic execution on board the satellite should ground control capability be lost. The second most beneficial factor is using short station keeping maneuver cycle durations.
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Mo, Shiming, Xiaojun Jin, Chen Lin, Wei Zhang, Zhaobin Xu i Zhonghe Jin. "Multi-Satellite Relative Navigation Scheme for Microsatellites Using Inter-Satellite Radio Frequency Measurements". Sensors 21, nr 11 (27.05.2021): 3725. http://dx.doi.org/10.3390/s21113725.
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The inter-satellite relative navigation method—based on radio frequency (RF) range and angle measurements—offers good autonomy and high precision, and has been successfully applied to two-satellite formation missions. However, two main challenges occur when this method is applied to multi-microsatellite formations: (i) the implementation difficulty of the inter-satellite RF angle measurement increases significantly as the number of satellites increases; and (ii) there is no high-precision, scalable RF measurement scheme or corresponding multi-satellite relative navigation algorithm that supports multi-satellite formations. Thus, a novel multi-satellite relative navigation scheme based on inter-satellite RF range and angle measurements is proposed. The measurement layer requires only a small number of chief satellites, and a novel distributed multi-satellite range measurement scheme is adopted to meet the scalability requirement. An inter-satellite relative navigation algorithm for multi-satellite formations is also proposed. This algorithm achieves high-precision relative navigation by fusing the algorithm and measurement layers. Simulation results show that the proposed scheme requires only three chief satellites to perform inter-satellite angle measurements. Moreover, with the typical inter-satellite measurement accuracy and an inter-satellite distance of around 1 km, the proposed scheme achieves a multi-satellite relative navigation accuracy of ~30 cm, which is about the same as the relative navigation accuracy of two-satellite formations. Furthermore, decreasing the number of chief satellites only slightly degrades accuracy, thereby significantly reducing the implementation difficulty of multi-satellite RF angle measurements.
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Zhao, Yafei, Jiaen Zhou, Zhenrui Chen i Xinyang Wang. "A DRL-Based Satellite Service Allocation Method in LEO Satellite Networks". Aerospace 11, nr 5 (13.05.2024): 386. http://dx.doi.org/10.3390/aerospace11050386.
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Satellite computing represents a recent computational paradigm in the development of low Earth orbit (LEO) satellites. It aims to augment the capabilities of LEO satellites beyond their current transparent relay functions by enabling real-time processing, thereby providing low-latency computational services to end users. In LEO constellations, a significant deployment of computationally capable satellites is orchestrated to offer enhanced computational resources. Challenges arise in the optimal allocation of terminal services to the most suitable satellite due to overlapping coverage among neighboring satellites, compounded by constraints on satellite energy and computational resources. The satellite service allocation (SSA) problem is recognized as NP-hard, yet assessing allocation methods through results allows for the application of deep reinforcement learning (DRL) to obtain improved solutions, partially addressing the SSA challenge. In this paper, we introduce a satellite computing capability model to quantify satellite computational resources. A DRL model is proposed to address service demands, computational resources, and resolve service allocation conflicts, strategically placing each service on appropriate servers. Through simulation experiments, numerical results demonstrate the superiority of our proposed method over baseline approaches in service allocation and satellite resource utilization, showcasing advancements in this field.
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Batthula, Venkata Jaipal Reddy, Richard S. Segall, Daniel Berleant, Hyacinthe Aboudja i Peng-Hung Tsai. "Future Satellite Lifetime Prediction From the Historical Trend in Satellite Half-Lives". Journal of Systemics, Cybernetics and Informatics 20, nr 3 (czerwiec 2022): 40–45. http://dx.doi.org/10.54808/jsci.20.03.40.
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Satellite lifetime is one of the important characteristics of satellite design and construction. It’s also of practical importance to know when a satellite is about to fail, as reentry and disposal can become operational matters. Satellite lifetime estimation is not necessarily a one-time action, but can be repeated, and it depends on many factors such as orbital parameters, operational requirements, and various others. Many products today are designed with safety, quality, and service life in mind. Based on the historical trend in satellite lifetimes, the approach used here is to predict the lifetimes of satellites using half-life values of their launch year cohorts. Half-life calculations can be made using either launch year or failure year cohorts, making a comparison of these of interest in forecasting the future lifetimes of satellites. This study focuses on analyzing satellite half-lives and using that information to project lifetimes of satellites that are still operational from the satellite launch year. We examine conformance of satellite lifetime data to fitted curves that remove noise from the data and thereby predict lifetimes of satellites from their launch year cohorts.
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Liu, Gaosai, Xinglong Jiang, Huawang Li, Zhenhua Zhang, Siyue Sun i Guang Liang. "Adaptive Access Selection Algorithm for Large-Scale Satellite Networks Based on Dynamic Domain". Sensors 22, nr 16 (11.08.2022): 5995. http://dx.doi.org/10.3390/s22165995.
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The traditional satellite access selection algorithm, which is used in large-scale satellite networks, has some disadvantages, such as frequent link switching, high interrupt probability, and unable to adapt to a dynamic environment. According to the periodicity of the large-scale satellite network and the prior knowledge provided by acknowledgment packages, a dynamic domain-based adaptive access algorithm (DAA) is proposed in this paper. Firstly, this algorithm divides the large-scale satellite network into different domains according to the minimum elevation angle of the Earth station (ES) and the predictable characteristics of the trajectory of the satellite. Then, the ES selects the access satellites according to the relationship between the traffic volume and the satellites’ coverage time. Finally, the ES selects the backup access satellite based on the satellites’ coverage time, the traffic volume of the ES, satellite status provided by prior knowledge, and other information. When the access satellite cannot satisfy the communication demand, the ES adaptively switches the earth-satellite link to the backup access satellite. The ES first choice of access satellite does not require interaction with the satellites, reducing the consumption of communication resources. The selection strategy of backup access satellite and the concept of virtual destination address proposed in this paper can reduce the routing overhead after switching. Through theoretical analysis and simulation results in the StarLink constellation, it is proved that this paper improves the coverage time utilization of accessing satellites and reduces the switching probability compared with the traditional access algorithm, which is more suitable for ES to access large-scale satellite networks.
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Agrusa, Harrison F., Yun Zhang, Derek C. Richardson, Petr Pravec, Matija Ćuk, Patrick Michel, Ronald-Louis Ballouz i in. "Direct N-body Simulations of Satellite Formation around Small Asteroids: Insights from DART’s Encounter with the Didymos System". Planetary Science Journal 5, nr 2 (1.02.2024): 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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Meng, Fan Qin, Xu Hai Yang, Ji Kun Ou i Pei Wei. "Method of Determining Satellite Clock Error by Using Observation Data of Satellite-Ground and Inter-Satellite". Advanced Materials Research 718-720 (lipiec 2013): 474–79. http://dx.doi.org/10.4028/www.scientific.net/amr.718-720.474.
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We have done some simulate analysis on GPS data in this paper. The main research is method of determining satellite clock error by usining observation data of satellite-ground and inter-satellite under the condition of regional station arrangement. The research method is as follows: when the satellite in the visible area of regional observation network, we can get satellite clock error directly by satellite-ground time comparison, and predict the satellite clock error in invisible area. When the satellite in the invisible area of regional observation network, if this satellite can establish inter-satellite links with other satellites in the visible area, then the satellite clock error can be determined by time comparison of satellite-ground and inter-satellite; If there is no inter-satellite link between this satellite and other satellites in the visible area, then we can only predict the satellite clock error by given data. The simulation conditions of this paper are as follows: the system error of satellite-ground is 0.5 ns, the random error is 0.5 ns; the system error of inter-satellite is 1 ns, the random error is 0.5 ns. In this case, we can obtain the satellite clock error of PRN02 in an orbital period by method of this paper, and the accuracy is about 1.3 ns.
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Zheng, Yuzhi, Zhenwei Chen i Guo Zhang. "Application and Evaluation of the Gaofen-3 Satellite on a Terrain Survey with InSAR Technology". Applied Sciences 10, nr 3 (23.01.2020): 806. http://dx.doi.org/10.3390/app10030806.
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The Gaofen-3 satellite is the first SAR satellite independently developed in China that achieves interferometric imaging and measurement, which improves upon Chinese civil SAR satellite data. To verify the ability of the Gaofen-3 satellite’s InSAR technology, we acquired data from Dengfeng, China, to evaluate the application and accuracy of an InSAR terrain survey. To reduce the effects introduced by data processing of Gaofen-3 data, high-accuracy InSAR image pair co-registration and phase filtering methods were adopted. Six GCPs data and 1:2000-scale DEM data were used to evaluate the elevation accuracy. In addition, for comparison with other satellites, we processed the dataset of the same area acquired by the non-civilian Yaogan-29 satellite with the same methods and evaluated the results. The experimental results indicated that the interferometric data of the Gaofen-3 satellite can achieve an accuracy of higher than 4 m of interferometric height measurement. Therefore, it will have broad prospects in the domestic InSAR application. Our research provides a certain value for the reference of the development of InSAR sensors in China.
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Ильченко, Михаил Ефимович, Теодор Николаевич Нарытник, Владимир Ильич Присяжный, Сергей Владимирович Капштык i Сергей Анатольевич Матвиенко. "ПРИМЕНЕНИЕ СТАНДАРТА ШИРОКОПОЛОСНОГО ДОСТУПА IEEE 802.16 ДЛЯ ОПРЕДЕЛЕНИЯ ВЗАИМНОГО ПОЛОЖЕНИЯ КУБСАТОВ В СОСТАВЕ LEGA-SAT". Aerospace technic and technology, nr 4 (14.10.2018): 98–106. http://dx.doi.org/10.32620/aktt.2018.4.12.
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It is considered the possibility of optimizing the use of the power capabilities of the cube-sat platform included in the "distributed satellite" to improve the performance of its payload. To optimize the use of energy capabilities, it was proposed to disconnect the onboard equipment of the command-and-telemetric radio link in the mode of regular operation of cube-sat in the "distributed satellite". To measure the current navigation parameters of cube-satellite in the conditions of group flight in the "distributed satellite" it is proposed to use the coordinates of the cube-satellite in the satellite coordinate system of the "distributed satellite" root satellite and the relative cube-relative velocity vector relative to the root satellite as the initial data. It is proposed to use a technique based on measurements of the distances between satellites in a "distributed satellite" and the projections of the vector of relative velocity for these distances to determine the coordinates of cube-sat in the satellite coordinate system. The features of the WiMAX broadband access protocol IEEE 802.16 protocols are examined to determine whether it is possible to perform mutual position measurements of satellites as part of a "distributed satellite" in one channel with information transmission. It pointed that the use of built-in means of measuring the range and access of mobile stations to the mobile WiMAX network makes it possible to perform measurements of the distance from the root satellite to the final satellite - cube-sat in the "distributed satellite". To perform the operations of measuring distances between the final satellites in the "distributed satellite", it is proposed to use the "competitive access zone" of the uplink sub-frame in the WiMAX network. A procedure for measuring the range between terminal satellites is proposed, based on measuring the propagation time of the distance measurement test signal between the assigned terminal satellites. It proposed a procedure for transmitting a test signal, taking into account the features of multiple access with orthogonal carrier separation (OFDMA). The proposed procedure can be implemented in a variant of the IEEE 802.16 standard network for application in a "distributed satellite"
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Wei, Junyong, Jiarong Han i Suzhi Cao. "Satellite IoT Edge Intelligent Computing: A Research on Architecture". Electronics 8, nr 11 (31.10.2019): 1247. http://dx.doi.org/10.3390/electronics8111247.
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As the number of satellites continues to increase, satellites become an important part of the IoT and 5G/6G communications. How to deal with the data of the satellite Internet of Things is a problem worth considering and paying attention to. Due to the current on-board processing capability and the limitation of the inter-satellite communication rate, the data acquisition from the satellite has a higher delay and the data utilization rate is lower. In order to use the data generated by the satellite IoT more effectively, we propose a satellite IoT edge intelligent computing architecture. In the article, we analyze the current methods of satellite data processing, combined with the development trend of future satellites, and use the characteristics of edge computing and machine learning to describe the satellite IoT edge intelligent computing architecture. Finally, we verify that the architecture can speed up the processing of satellite data. By demonstrating the performance of different neural network models in the satellite edge intelligent computing architecture, we can find that the lightweight of neural networks can promote the development of satellite IoT edge intelligent computing architecture.
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Jie, Geng, Gong Jinggang, Wang Zuowei i Lyu Nan. "Research on the Technological Development of GSO Small Satellite". MATEC Web of Conferences 288 (2019): 02003. http://dx.doi.org/10.1051/matecconf/201928802003.
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The application and technological development of geosynchronous orbit(GSO) small satellite are researched in this paper. Firstly the application field and application value of GSO small satellites are analysed. Secondly, the technology development status of foreign GSO small satellites is overviewed. Then the differences and similarities among GSO small satellite, traditional large satellite and low earth orbit(LEO) small satellite are compared, and characteristic and key technique are systematically studied. Finally, for China’s future military and civilian needs, combined with the development trend of modern small satellite technology, the preliminary proposal for the development of China’s GSO small satellite are given.
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Tayebi Khorrami, Fereshteh, Mohammad Hossein Fallah i Hassn Zareei Mahmood Abadi. "The Effect of Unconscious Influences of Satellite Channels on Attitude of Using Satellite". Journal of Research in Science, Engineering and Technology 8, nr 1 (29.09.2020): 14–21. http://dx.doi.org/10.24200/jrset.vol8iss1pp14-21.
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In recent years, users of satellite networks is increasing, and users of learning hidden and the effects of the unconscious as a result of the use of satellite data to be transferred is limited. The present study aimed to investigate the effect of unconscious influences satellite networks in changing the attitude of the satellite was done. This research is quasi-experimental pretest - post-test with control group. The study population consisted of all parents participating in the Parents Community School District 2 city Safashahr school year was 92%. For this purpose, 30 female users of of 90-minute experimental satellites were trained on the unconscious effects. Subjects in both groups at the beginning and end of the study using a questionnaire approach were tested using satellites. To analyze the data, analysis of covariance was used. The results of analysis of covariance showed the effects of unconscious cause’s negative attitude of the satellite. So we can unconsciously influence the teaching and learning process in the use of satellites may be hidden causing a negative attitude towards the use of satellites.
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Nafieva, E. N., i A. V. Grechishchev. "SPACE RADAR SYSTEMS OF EARTH MONITORING". ECOLOGY ECONOMY INFORMATICS. GEOINFORMATION TECHNOLOGIES AND SPACE MONITORING 2, nr 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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Ding, Huixia, Sicheng Zhu, Sachula Meng, Jinxia Han, Heng Liu, Miao Wang, Jiayan Liu, Peng Qin i Xiongwen Zhao. "Matching-Based Resource Allocation for Satellite–Ground Network". Sensors 22, nr 21 (2.11.2022): 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 i Jing Wu. "A Fast Time Synchronization Method for Large Scale LEO Satellite Networks Based on A Bionic Algorithm". Photonics 11, nr 5 (19.05.2024): 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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Li, Fangchao, Zengke Li, Jingxiang Gao i Yifei Yao. "A Fast Rotating Partition Satellite Selection Algorithm Based on Equal Distribution of Sky". Journal of Navigation 72, nr 04 (21.02.2019): 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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Solíz, J., M. Quiroga i R. Puma-Guzmán. "DESIGN OF A SPACE MISSION FOR THE ACQUISITION OFTERRESTRIAL IMAGES FOR BOLIVIA". Revista Mexicana de Astronomía y Astrofísica Serie de Conferencias 52 (5.10.2020): 21–22. http://dx.doi.org/10.22201/ia.14052059p.2020.52.08.
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The importance of having a terrestrial observation satellite consists of the need of governments and private entities to have recent images of a specific area, for the use of cartography, illicit plantations, mining, petroleum deposits, natural disasters, etc. Therefore, having up-to-date images of the national territory should be a priority. This analysis and design of mission focuses on the design of the orbit of the satellite, studying what type of orbit is appropriate for a future Earth observation satellite. The simulation of the orbit is carried out in this work through the study of the perturbations that most affect low-altitude satellites. The calculation of the satellite's revisit time will be based on areas of potential study interest for both the government and private companies settled in the country.
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Bai, Tian, Lin Kong, Hongrui Ao i Feng Jiang. "Heat Sink Equivalent Thermal Test Method and Its Application in Low-Orbit Satellites". Applied Sciences 14, nr 10 (13.05.2024): 4123. http://dx.doi.org/10.3390/app14104123.
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In order to shorten the length of satellite thermal testing and reduce the cost of satellite development, a new method of satellite thermal testing using a heat sink to simulate space heating flow has been proposed. First, based on the characteristics of low-orbit satellites and the current research of thermal tests, the necessity of studying high-efficiency thermal test methods for satellites is expounded, and the advantages of the heat sink equivalent thermal tests compared to conventional tests are explained. Then, the principle of the heat sink equivalent thermal tests is described, the formula to calculate the heat sink temperature is given, and an error analysis of the formula is conducted. It is found that when the emissivity of the heat sink surface is greater than 0.9 and the ratio of the heat sink’s surface area to the satellite’s is greater than 10, the error of the heat sink equivalent tests should be within 1 °C. Next, the application of the heat sink equivalent thermal test is described using the Jilin−1 GF02F satellite as an example. Finally, the test results and the flight temperature of the GF02F satellite are acquired and analyzed. The results show that the error of the heat sink equivalent thermal test is 0.9 °C, the test time is shortened by one-third compared to traditional thermal tests, and the cost of the thermal test is reduced by more than 70%.
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Meng, Lingdong, Jiexian Wang, Junping Chen, Bin Wang i Yize Zhang. "Extended Geometry and Probability Model for GNSS+ Constellation Performance Evaluation". Remote Sensing 12, nr 16 (9.08.2020): 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 i Shanwei Liu. "Performance Evaluation of China’s First Ocean Dynamic Environment Satellite Constellation". Remote Sensing 15, nr 19 (30.09.2023): 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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Bielicki, Damian M. "Legal Aspects of Satellite Constellations". Air and Space Law 45, Issue 3 (1.06.2020): 245–64. http://dx.doi.org/10.54648/aila2020038.
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In recent years a few entrepreneurs proposed launching into space large fleets of satellites, consisting of hundreds of satellites, often referred to as ‘constellations’. Their role is to provide satellite services to the largest possible number of users on Earth. This article provides a review of key legal issues associated with satellite constellations, including responsibility and liability for potential damages caused by satellites being a part of a constellation, insurance, registration of space objects, allocation of radio frequencies and orbital slots, and space debris. satellite constellations, space law, space insurance, liability, space debris
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Huseynov, Mugabil, i Elshan Hashimov. "Imaginary Intelligence Via Satellites". Modeling Control and Information Technologies, nr 6 (22.11.2023): 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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Hellmann, Jennifer K., Kelly A. Stiver, Susan Marsh-Rollo i Suzanne H. Alonzo. "Defense against outside competition is linked to cooperation in male–male partnerships". Behavioral Ecology 31, nr 2 (14.12.2019): 432–39. http://dx.doi.org/10.1093/beheco/arz206.
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Abstract Male–male competition is a well-known driver of reproductive success and sexually selected traits in many species. However, in some species, males work together to court females or defend territories against male competitors. Dominant (nesting) males sire most offspring, but subordinate (satellite) males are better able to obtain fertilizations relative to unpartnered males. Because satellites only gain reproductive success by sneaking, there has been much interest in identifying the mechanisms enforcing satellite cooperation (defense) and reducing satellite sneaking. One such potential mechanism is outside competition: unpartnered satellites can destabilize established male partnerships and may force partnered satellites to restrain from cheating to prevent the dominant male from replacing them with an unpartnered satellite. Here, we manipulated perceived competition in the Mediterranean fish Symphodus ocellatus by presenting an “intruding” satellite male to established nesting and satellite male pairs. Focal satellite aggression to the intruder was higher when focal satellites were less cooperative, suggesting that satellites increase aggression to outside competitors when their social position is less stable. In contrast, nesting male aggression to the intruder satellite increased as spawning activity increased, suggesting that nesting males increase their defense toward outside competitors when their current relationship is productive. We found no evidence of altered spawning activity or nesting/satellite male interactions before and after the presentation. These results collectively suggest that response to outside competition is directly linked to behavioral dynamics between unrelated male partners and may be linked to conflict and cooperation in ways that are similar to group-living species.
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Stein, Josephine Anne. "Satellites, anti‐satellite weapons and security". RUSI Journal 133, nr 4 (grudzień 1988): 48–54. http://dx.doi.org/10.1080/03071848808445329.
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Wang, Yixiao, Cui Tu, Feng Wei i Xiong Hu. "Design of Novel Reconfigurable Single-Board Satellite for Enhanced Space Environment Detection". Electronics 12, nr 23 (24.11.2023): 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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Khomsin, Ira Mutiara Anjasmara, Danar Guruh Pratomo i Wahyu Ristanto. "Accuracy Analysis of GNSS (GPS, GLONASS and BEIDOU) Obsevation For Positioning". E3S Web of Conferences 94 (2019): 01019. http://dx.doi.org/10.1051/e3sconf/20199401019.
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Global Navigation Satellite System called GNSS is a term used for the entire global navigation that already operate or are in the planning for the future. Some of the satellite that can be used are GPS (Global Positioning System) operated by USA, GLONASS (Global Navigation Satellite System) operated by Rusia and BeiDou/Compass operated by China. Many errors and biases that occur when measuring with GNSS in the field. Theoritically, there are some errors and biases that can be eliminated or subtracted by strength of satellite geometric. One factor to get a good satellite geometric is to increase the number of satellites received by receiver. In general, the more number of satellites received, the better the geometric satellites received by receivers. The development of receiver technology is currently able to capture GPS, GLONASS and BeiDou signals at one time. Thus the receiver can receive many satellites and finally the shape of geometric satellite becomes better. HiTarget V30 is one of the latest GNSS technology on the market today. This receiver is capable of receiving GPS signals, GLONASS and BeiDou at one time of observation. This research will compare the accuracy of positioning using GPS, GLONASS and BeiDou satellite.
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Yuan, Zhimin, Changsheng Cai, Lin Pan i Cuilin Kuang. "An Improved Multi-Satellite Method for Evaluating Real-Time BDS Satellite Clock Offset Products". Remote Sensing 12, nr 21 (5.11.2020): 3638. http://dx.doi.org/10.3390/rs12213638.
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Two methods are widely used for evaluating the precision of satellite clock products, namely the single-satellite method (SSM) and the multi-satellite method (MSM). In the satellite clock product evaluation, an important issue is how to eliminate the timescale difference. The SSM selects a reference satellite to eliminate the timescale difference by between-satellite differencing, but its evaluation results are susceptible to the gross errors in the referenced satellite clock offsets. In the MSM, the timescale difference is first estimated and then removed. Unlike the GPS, the BeiDou Navigation Satellite System (BDS) consists of three types of satellites, namely geosynchronous earth orbit (GEO), inclined geosynchronous orbit (IGSO), and medium earth orbit (MEO) satellites. The three types of satellites have uneven orbital accuracy. In the generation of satellite clock products, the orbital errors are partly assimilated into the clock offsets. If neglecting the orbital accuracy difference of the three types of BeiDou satellites, the MSM will obtain biased estimates of the timescale difference and finally affect the clock product evaluation. In this study, an improved multi-satellite method (IMSM) is proposed for evaluating the real-time BDS clock products by removing the assimilated orbital errors of the three types of BDS satellites when estimating the timescale difference. Three real-time BDS clock products disseminated by three different International GNSS Service (IGS) analysis centers, namely CLK16, CLK20, and CLK93, over a period of two months are used to validate this method. The results indicate that the assimilated orbital errors have a significant impact on the estimation of the timescale difference. Subsequently, the IMSM is compared with the SSM in which the referenced satellite is rigorously chosen, and their RMS difference is only 0.08 ns, which suggests that the evaluation results obtained by the IMSM are accurate. Compared with the traditional MSM, the IMSM improves the RMS by 0.16, 0.11, and 0.07 ns for CLK16, CLK20, and CLK93, respectively. Finally, three real-time BDS clock products are evaluated using the proposed method, and results reveal a significant precision difference among them.
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Ahmad, Syed Farhan, Worapong Singchat, Maryam Jehangir, Aorarat Suntronpong, Thitipong Panthum, Suchinda Malaivijitnond i Kornsorn Srikulnath. "Dark Matter of Primate Genomes: Satellite DNA Repeats and Their Evolutionary Dynamics". Cells 9, nr 12 (18.12.2020): 2714. http://dx.doi.org/10.3390/cells9122714.
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A substantial portion of the primate genome is composed of non-coding regions, so-called “dark matter”, which includes an abundance of tandemly repeated sequences called satellite DNA. Collectively known as the satellitome, this genomic component offers exciting evolutionary insights into aspects of primate genome biology that raise new questions and challenge existing paradigms. A complete human reference genome was recently reported with telomere-to-telomere human X chromosome assembly that resolved hundreds of dark regions, encompassing a 3.1 Mb centromeric satellite array that had not been identified previously. With the recent exponential increase in the availability of primate genomes, and the development of modern genomic and bioinformatics tools, extensive growth in our knowledge concerning the structure, function, and evolution of satellite elements is expected. The current state of knowledge on this topic is summarized, highlighting various types of primate-specific satellite repeats to compare their proportions across diverse lineages. Inter- and intraspecific variation of satellite repeats in the primate genome are reviewed. The functional significance of these sequences is discussed by describing how the transcriptional activity of satellite repeats can affect gene expression during different cellular processes. Sex-linked satellites are outlined, together with their respective genomic organization. Mechanisms are proposed whereby satellite repeats might have emerged as novel sequences during different evolutionary phases. Finally, the main challenges that hinder the detection of satellite DNA are outlined and an overview of the latest methodologies to address technological limitations is presented.
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Zheng, Jun Hua, i Chang Ju Wu. "Design of Moving System for Pico-Satellite Deployer". Applied Mechanics and Materials 325-326 (czerwiec 2013): 1009–13. http://dx.doi.org/10.4028/www.scientific.net/amm.325-326.1009.
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Pico-satellite’s potential use is increasingly gaining nation’s recognition. Because of its small volume and light weight, it is necessary to develop the special deployer. The key technologies of Zhejiang University Pico-Satellite Deployer (ZDPSD) are, cutter unlocking the door, conical spring driving the pico-satellite, oriented rail restricting the direction and locking shaft fixing the door. In September 2010, the two pico-satellites were launched and deployed successfully at the predetermined orbit. The paper includes designing and analyzing of the moving system, mode analyzing of the deployer and the experiments on ground and in-orbit. The key process of the development is summarized, which can be regarded as reference for the further developing.
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Ma, Xiaofeng, Mingsen Lin, Jin Zhao, Yongjun Jia i Chengfei Jiang. "On-Orbit Calibration Method for Correction Microwave Radiometer of the HY-2 Satellite Constellation". Remote Sensing 15, nr 24 (6.12.2023): 5643. http://dx.doi.org/10.3390/rs15245643.
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The HY-2D satellite was successfully launched in 2022, which marks the first phase of the HY-2 satellite constellation. In order to reduce the deviation of wet path delay (WPD) between different satellites in the HY-2 satellite constellation and increase precision in the correction microwave radiometer (CMR) products, on-orbit calibration must be performed to the brightness temperature (BT) of the CMR in this constellation. This study describes the principle and process of on-orbit calibration for CMR in detail. For the three satellites of the HY-2 satellite constellation, after cross-matching with each other within a limited spatio-temporal range, the HY-2B satellite with sounding on the global ocean is selected to the calibration source, calibrating BT from the CMR of the HY-2C and HY-2D satellites to the BT dimension of the HY-2B satellite CMR. To check on-orbit calibration, a retrieval algorithm is built using atmospheric profile data from ECMWF and BT data, obtained from the CMR of the HY-2B satellite; this is used to calculate the atmospheric water vapor (AWV) and WPD from the HY-2 satellite constellation. After on-orbit calibration to the CMRs of the HY-2 satellite constellation, the deviation between the CMR products of different satellites is significantly reduced by over 20%, and the RMS of WPD for the same type of products from the Jason-3 satellite is less than 1 cm. It may be concluded that on-orbit calibration improves the accuracy of AWV and WPD by normalizing the BT dimension for CMRs of the HY-2 satellite constellation, so this calibration method is effective and credible for enhancing the quality of altimeter products in the HY-2 satellite constellation.
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Farhangian, Farzan, i René Landry. "Multi-Constellation Software-Defined Receiver for Doppler Positioning with LEO Satellites". Sensors 20, nr 20 (16.10.2020): 5866. http://dx.doi.org/10.3390/s20205866.
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A Multi-Constellation Software-Defined Receiver (MC-SDR) is designed and implemented to extract the Doppler measurements of Low Earth Orbit (LEO) satellite’s downlink signals, such as Orbcomm, Iridium-Next, Globalstar, Starlink, OneWeb, SpaceX, etc. The Doppler positioning methods, as one of the main localization algorithms, need a highly accurate receiver design to track the Doppler as a measurement for Extended Kalman Filter (EKF)-based positioning. In this paper, the designed receiver has been used to acquire and track the Doppler shifts of two different kinds of LEO constellations. The extracted Doppler shifts of one Iridium-Next satellite as a burst-based simplex downlink signal and two Orbcomm satellites as continuous signals are considered. Also, with having the Two-Line Element (TLE) for each satellite, the position, and orbital elements of each satellite are known. Finally, the accuracy of the designed receiver is validated using an EKF-based stationary positioning algorithm with an adaptive measurement matrix. Satellite detection and Doppler tracking results are analyzed for each satellite. The positioning results for a stationary receiver showed an accuracy of about 132 m, which means 72% accuracy advancements compared to single constellation positioning.