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Journal articles on the topic 'Satellite constellations'
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1
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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Huang, Feijiang, Xiaochun Lu, Guangcan Liu, Liping Sun, Wang Sheng, and Yingde Wang. "Improvement and Simulation of an Autonomous Time Synchronization Algorithm for a Layered Satellite Constellation." Mathematical Problems in Engineering 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/136301.
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Autonomous time synchronization for satellite constellations is a key technology to establish a constellation system time without the use of a ground station. The characteristics of satellite visibility time for layered satellite constellations containing geostationary earth orbit (GEO), inclined geosynchronous orbit (IGSO), and medium earth orbit (MEO) satellites are simulated by establishing a visible satellite model. Based on the satellite visible simulation results for a layered constellation, this study investigates the autonomous time synchronization algorithm that corresponds to the layered constellation structure, analyzes the main error of the time synchronization algorithm, and proposes methods to improve the characteristics of satellite movement in the constellation. This study uses an improved two-way time synchronization algorithm for autonomous time synchronization in the GEO-MEO satellite layer of a layered satellite constellation. The simulation results show that in a condition with simulation errors, the time synchronization precision of this improved algorithm can be controlled within 5 ns and used in high-precision autonomous time synchronization between layered satellite constellations.
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Matricciani, Emilio. "Geocentric Spherical Surfaces Emulating the Geostationary Orbit at Any Latitude with Zenith Links." Future Internet 12, no. 1 (January 18, 2020): 16. http://dx.doi.org/10.3390/fi12010016.
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According to altitude, the orbits of satellites constellations can be divided into geostationary Earth orbit (GEO), medium Earth orbit (MEO), and low Earth orbit (LEO) constellations. We propose to use a Walker star constellation with polar orbits, at any altitude, to emulate the geostationary orbit with zenith paths at any latitude. Any transmitter/receiver will be linked to a satellite as if the site were at the equator and the satellite at the local zenith. This constellation design can have most of the advantages of the current GEO, MEO, and LEO constellations, without having most of their drawbacks. Doppler phenomena are largely minimized because the connected satellite is always seen almost at the local zenith. The extra free-space loss, due to the fixed pointing of all antennas, is at most 6 dBs when the satellite enters or leaves the service area. The connections among satellites are easy because the positions in the orbital plane and in adjacent planes are constant, although with variable distances. No steering antennas are required. The tropospheric propagation fading and scintillations are minimized. Our aim is to put forth the theoretical ideas about this design, to which we refer to as the geostationary surface (GeoSurf) constellation.
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Swaszek, Peter F., Richard J. Hartnett, and Kelly C. Seals. "Lower Bounds on DOP." Journal of Navigation 70, no. 5 (June 22, 2017): 1041–61. http://dx.doi.org/10.1017/s0373463317000248.
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Code phase Global Navigation Satellite System (GNSS) positioning performance is often described by the Geometric or Position Dilution of Precision (GDOP or PDOP), functions of the number of satellites employed in the solution and their geometry. This paper develops lower bounds to both metrics solely as functions of the number of satellites, effectively removing the added complexity caused by their locations in the sky, to allow users to assess how well their receivers are performing with respect to the best possible performance. Such bounds will be useful as receivers sub-select from the plethora of satellites available with multiple GNSS constellations. The bounds are initially developed for one constellation assuming that the satellites are at or above the horizon. Satellite constellations that essentially achieve the bounds are discussed, again with value toward the problem of satellite selection. The bounds are then extended to a non-zero mask angle and to multiple constellations.
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Curzi, Giacomo, Dario Modenini, and Paolo Tortora. "Large Constellations of Small Satellites: A Survey of Near Future Challenges and Missions." Aerospace 7, no. 9 (September 7, 2020): 133. http://dx.doi.org/10.3390/aerospace7090133.
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Constellations of satellites are being proposed in large numbers; most of them are expected to be in orbit within the next decade. They will provide communication to unserved and underserved communities, enable global monitoring of Earth and enhance space observation. Mostly enabled by technology miniaturization, satellite constellations require a coordinated effort to face the technological limits in spacecraft operations and space traffic. At the moment in fact, no cost-effective infrastructure is available to withstand coordinated flight of large fleets of satellites. In order for large constellations to be sustainable, there is the need to efficiently integrate and use them in the current space framework. This review paper provides an overview of the available experience in constellation operations and statistical trends about upcoming constellations at the moment of writing. It highlights also the tools most often proposed in the analyzed works to overcome constellation management issues, such as applications of machine learning/artificial intelligence and resource/infrastructure sharing. As such, it is intended to be a useful resource for both identifying emerging trends in satellite constellations, and enabling technologies still requiring substantial development efforts.
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Guan, Meiqian, Tianhe Xu, Fan Gao, Wenfeng Nie, and Honglei Yang. "Optimal Walker Constellation Design of LEO-Based Global Navigation and Augmentation System." Remote Sensing 12, no. 11 (June 6, 2020): 1845. http://dx.doi.org/10.3390/rs12111845.
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Low Earth orbit (LEO) satellites located at altitudes of 500 km~1500 km can carry much stronger signals and move faster than medium Earth orbit (MEO) satellites at about a 20,000 km altitude. Taking advantage of these features, LEO satellites promise to make contributions to navigation and positioning where global navigation satellite system (GNSS) signals are blocked as well as the rapid convergence of precise point positioning (PPP). In this paper, LEO-based optimal global navigation and augmentation constellations are designed by a non-dominated sorting genetic algorithm III (NSGA-III) and genetic algorithm (GA), respectively. Additionally, a LEO augmentation constellation with GNSS satellites included is designed using the NSGA-III. For global navigation constellations, the results demonstrate that the optimal constellations with a near-polar Walker configuration need 264, 240, 210, 210, 200, 190 and 180 satellites with altitudes of 900, 1000, 1100, 1200, 1300, 1400 and 1500 km, respectively. For global augmentation constellations at an altitude of 900 km, for instance, 72, 91, and 108 satellites are required in order to achieve a global average of four, five and six visible satellites for an elevation angle above 7 degrees with one Walker constellation. To achieve a more even coverage, a hybrid constellation with two Walker constellations is also presented. On this basis, the GDOPs (geometric dilution of precision) of the GNSS with and without an LEO constellation are compared. In addition, we prove that the computation efficiency of the constellation design can be considerably improved by using master–slave parallel computing.
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Cui, Haomeng, and Shoujian Zhang. "Satellite Availability and Service Performance Evaluation for Next-Generation GNSS, RNSS and LEO Augmentation Constellation." Remote Sensing 13, no. 18 (September 16, 2021): 3698. http://dx.doi.org/10.3390/rs13183698.
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Positioning accuracy is affected by the combined effect of user range errors and the geometric distribution of satellites. Dilution of precision (DOP) is defined as the geometric strength of visible satellites. DOP is calculated based on the satellite broadcast or precise ephemerides. However, because the modernization program of next-generation navigation satellite systems is still under construction, there is a lack of real ephemerides to assess the performance of next-generation constellations. Without requiring real ephemerides, we describe a method to estimate satellite visibility and DOP. The improvement of four next-generation Global Navigation Satellite Systems (four-GNSS-NG), compared to the navigation constellations that are currently in operation (four-GNSS), is statistically analyzed. The augmentation of the full constellation the Quasi-Zenith Satellite System (7-QZSS) and the Navigation with Indian Constellation (11-NavIC) for regional users and the low Earth orbit (LEO) constellation enhancing four-GNSS performance are also analyzed based on this method. The results indicate that the average number visible satellites of the four-GNSS-NG will reach 44.86, and the average geometry DOP (GDOP) will be 1.19, which is an improvement of 17.3% and 7.8%, respectively. With the augmentation of the 120-satellite mixed-orbit LEO constellation, the multi-GNSS visible satellites will increase by 5 to 8 at all latitudes, while the GDOP will be reduced by 6.2% on average. Adding 7-QZSS and 11-NavIC to the four-GNSS-NG, 37.51 to 71.58 satellites are available on global scales. The average position DOP (PDOP), horizontal DOP (HDOP), vertical DOP (VDOP), and time DOP (TDOP) are reduced to 0.82, 0.46, 0.67 and 0.44, respectively.
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Kitajima, Natsumi, Rie Seto, Dai Yamazaki, Xudong Zhou, Wenchao Ma, and Shinjiro Kanae. "Potential of a SAR Small-Satellite Constellation for Rapid Monitoring of Flood Extent." Remote Sensing 13, no. 10 (May 18, 2021): 1959. http://dx.doi.org/10.3390/rs13101959.
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Constellations of small satellites equipped with synthetic aperture radar (SAR) payloads can realize observations in short time intervals independently from daylight and weather conditions and this technology is now in the early stages of development. This tool would greatly contribute to rapid flood monitoring, which is usually one of the main missions in upcoming plans, but few studies have focused on this potential application and a required observation performance for flood disaster monitoring has been unclear. In this study, we propose an unprecedented method for investigating how flood extents would be temporally and spatially observed with a SAR small-satellite constellation and for evaluating that observation performance via an original index. The virtual experiments of flood monitoring with designed constellations were conducted using two case studies of flood events in Japan. Experimental results showed that a SAR small-satellite constellation with sun-synchronous orbit at 570 km altitude, 30-km swath, 15–30° incidence angle, and 20 satellites can achieve 87% acquisition of cumulative flood extent in total observations. There is a difference between the results of observation performance in two cases because of each flood’s characteristics and a SAR satellite’s observation system, which implies the necessity of individual assessments for various types of rivers.
9
Zhang, Lei, and Bo Xu. "A Universe Light House — Candidate Architectures of the Libration Point Satellite Navigation System." Journal of Navigation 67, no. 5 (March 12, 2014): 737–52. http://dx.doi.org/10.1017/s0373463314000137.
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In view of the shortcomings of existing satellite navigation systems in deep-space performance, candidate architectures which utilise libration point orbits in the Earth-Moon system are proposed to create an autonomous satellite navigation system for lunar missions. Three candidate constellations are systematically studied in order to achieve continuous global coverage for lunar orbits: the Earth-Moon L1,2 two-satellite constellation, the Earth-Moon L2,4,5 three-satellite constellation and the Earth-Moon L1,2,4,5 four-satellite constellation. After a thorough search for possible configurations, the latter two constellations are found to be the simplest feasible architectures for lunar navigation. Finally, an autonomous orbit determination simulation is performed to verify the autonomy of the system and two optimal configurations are obtained in a comprehensive consideration of coverage and autonomous orbit determination performance.
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Paek, Sung Wook, Sivagaminathan Balasubramanian, Sangtae Kim, and Olivier de Weck. "Small-Satellite Synthetic Aperture Radar for Continuous Global Biospheric Monitoring: A Review." Remote Sensing 12, no. 16 (August 7, 2020): 2546. http://dx.doi.org/10.3390/rs12162546.
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Space-based radar sensors have transformed Earth observation since their first use by Seasat in 1978. Radar instruments are less affected by daylight or weather conditions than optical counterparts, suitable for continually monitoring the global biosphere. The current trends in synthetic aperture radar (SAR) platform design are distinct from traditional approaches in that miniaturized satellites carrying SAR are launched in multiples to form a SAR constellation. A systems engineering perspective is presented in this paper to track the transitioning of space-based SAR platforms from large satellites to small satellites. Technological advances therein are analyzed in terms of subsystem components, standalone satellites, and satellite constellations. The availability of commercial satellite constellations, ground stations, and launch services together enable real-time SAR observations with unprecedented details, which will help reveal the global biomass and their changes owing to anthropogenic drivers. The possible roles of small satellites in global biospheric monitoring and the subsequent research areas are also discussed.
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Li, Jiang, Ma, Lv, Yuan, and Li. "LEO Precise Orbit Determination with Inter-Satellite Links." Remote Sensing 11, no. 18 (September 11, 2019): 2117. http://dx.doi.org/10.3390/rs11182117.
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Traditional precise orbit determination (POD) for low Earth orbit (LEO) satellites relies on observations from ground stations and onboard receivers. Although the accuracy can reach centimeter level, there are still problems such as insufficient autonomous operation capability. The inter-satellite link (ISL) is a link used for communication between satellites and has a function of dual-way ranging. Numerous studies have shown that observational data using ISLs can be adopted for POD of navigation satellites. In this contribution, we mainly focus on LEO satellites POD with ISLs. First, we design LEO constellations with different numbers of satellites and ISL measurements, based on which the constellations are simulated. Then rough tests of POD using different link topologies are carried out. The results show that in the 60-LEO constellation the average 3-dimensional (3D) orbital errors are 0.112 m using “4-connected” link topology with constant 4 links per satellite and 0.069 m using “all-connected” link topology with theoretically maximum numbers of links. After that, we carry out refined POD experiments with several sets of satellite numbers and different observation accuracy. The results show the higher link ranging accuracy and the more numbers of links bring higher POD precision. POD with ISLs gets bad performance in the case of center of gravity reference when link ranging accuracy is poor and numbers of links are small. When the link accuracy is 40 cm, average 3D orbital errors of 60-LEO constellation are 0.358 m, which can only meet the demand of autonomous navigation. With the constraint of the right ascension of the ascending node (RAAN), POD using ISLs reaches an extremely high precision when adopting a spatial reference provided by navigation satellites. For 120-LEO constellation, the average 3D orbital errors are 0.010 m; for 192-LEO constellation, the errors are 0.006 m.
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Li, Xingxing, Hongbo Lv, Fujian Ma, Xin Li, Jinghui Liu, and Zihao Jiang. "GNSS RTK Positioning Augmented with Large LEO Constellation." Remote Sensing 11, no. 3 (January 22, 2019): 228. http://dx.doi.org/10.3390/rs11030228.
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It is widely known that in real-time kinematic (RTK) solution, the convergence and ambiguity-fixed speeds are critical requirements to achieve centimeter-level positioning, especially in medium-to-long baselines. Recently, the current status of the global navigation satellite systems (GNSS) can be improved by employing low earth orbit (LEO) satellites. In this study, an initial assessment is applied for LEO constellations augmented GNSS RTK positioning, where four designed LEO constellations with different satellite numbers, as well as the nominal GPS constellation, are simulated and adopted for analysis. In terms of aforementioned constellations solutions, the statistical results of a 68.7-km baseline show that when introducing 60, 96, 192, and 288 polar-orbiting LEO constellations, the RTK convergence time can be shortened from 4.94 to 2.73, 1.47, 0.92, and 0.73 min, respectively. In addition, the average time to first fix (TTFF) can be decreased from 7.28 to 3.33, 2.38, 1.22, and 0.87 min, respectively. Meanwhile, further improvements could be satisfied in several elements such as corresponding fixing ratio, number of visible satellites, position dilution of precision (PDOP) and baseline solution precision. Furthermore, the performance of the combined GPS/LEO RTK is evaluated over various-length baselines, based on convergence time and TTFF. The research findings show that the medium-to-long baseline schemes confirm that LEO satellites do helpfully obtain faster convergence and fixing, especially in the case of long baselines, using large LEO constellations, subsequently, the average TTFF for long baselines has a substantial shortened about 90%, in other words from 12 to 2 min approximately by combining with the larger LEO constellation of 192 or 288 satellites. It is interesting to denote that similar improvements can be observed from the convergence time.
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Han, Yi, Jia Luo, and Xiaohua Xu. "On the Constellation Design of Multi-GNSS Reflectometry Mission Using the Particle Swarm Optimization Algorithm." Atmosphere 10, no. 12 (December 13, 2019): 807. http://dx.doi.org/10.3390/atmos10120807.
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Due to the great success of the CYclone Global Navigation Satellite System (CYGNSS) mission, the follow-on GNSS Reflectometry (GNSS-R) missions are being planned. In the perceivable future, signal sources for GNSS-R missions can originate from multiple global navigation satellite systems (GNSSs) including Global Positioning System (GPS), Galileo, GLONASS, and BeiDou. On the other hand, to facilitate the operational capability for sensing ocean, land, and ice features globally, multi-satellite low Earth orbit (LEO) constellations with global coverage and high spatio-temporal resolutions should be considered in the design of the follow-on GNSS-R constellation. In the present study, the particle swarm optimization (PSO) algorithm was applied to seek the optimal configuration parameters of 2D-lattice flower constellations (2D-LFCs) composed of 8, 24, 60, and 120 satellites, respectively, for global GNSS-R observations, and the fitness function was defined as the length of the time for the percentage coverage of the reflection observations reaches 90% of the globe. The configuration parameters for the optimal constellations are presented, and the performances of the optimal constellations for GNSS-R observations including the visited and the revisited coverages, and the spatial and temporal distributions of the reflections were further compared. Although the results showed that all four optimized constellations could observe GNSS reflections with proper temporal and spatial distributions, we recommend the optimal 24- and 60-satellite 2D-LFCs for future GNSS-R missions, taking into account both the performance and efficiency for the deployment of the GNSS-R missions.
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Ren, Jing, Dan Sun, Deng Pan, Mingtao Li, and Jianhua Zheng. "Cost-Efficient LEO Navigation Augmentation Constellation Design under a Constrained Deployment Approach." International Journal of Aerospace Engineering 2021 (September 4, 2021): 1–18. http://dx.doi.org/10.1155/2021/5042650.
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The advantages of the Low Earth Orbit (LEO) satellite include low-latency communications, shorter positioning time, higher positioning accuracy, and lower launching, building, and maintenance costs. Thus, the introduction of LEO satellite constellation as a regional navigation augmentation system for the current navigation constellations is studied in this paper. To achieve the navigation performance requirement with the least system cost, a synthetic approach is presented to design and deploy a cost-efficient LEO navigation augmentation constellation over 108 key cities. To achieve lower construction costs, the constellation is designed to be deployed by constrained piggyback launches, which brings additional complexity to the constellation design. Two optimization models with discrete and continuous performance indices are established. They are solved by the genetic algorithm and differential evolution algorithm, and both Walker and Flower constellations are adopted. Results for 77 and 70 satellites are obtained. During the construction phase, a synthesis procedure containing five impulses is proposed by utilizing natural drift under J 2 perturbation. This work presents a method for designing the optimal LEO navigation constellation under a constraint deployment approach with the lowest construction cost and a strategy to deploy the constellation economically.
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Januszewski, Jacek. "Visibility And Geometry Of Galileo Satellites Constellation During Initial Operation Capability." Annual of Navigation 19, no. 1 (November 1, 2012): 79–90. http://dx.doi.org/10.2478/v10367-012-0007-7.
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Abstract The European Space Agency (ESA) confirmed that it plans to declare an Initial Operational Capability (IOC) once a constellation of 18 satellites is achieved in 2014 and after few Soyuz and Ariane launches Full Operational Capability (FOC) once a constellation of 26 satellites next year or later. In the paper are presented the distribution of the number of satellites visible by the observer and the distribution of GDOP coefficient values both for different masking elevation angles (Hmin) at different observer’s latitudes for three constellations, with 18, 22 and 26 satellites, the distribution of satellite azimuths in open area and the percentage of satellites visible above given angle. Additionally for latitude of Poland (zone 50-60°) No Fix (in per cent) and the detailed distribution of GDOP values for six angles Hmin for all these constellations and the results of other calculations are showed. Finally the results concern the possibility of the positioning and its accuracy for different numbers of Galileo satellites at different observer’s latitudes
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Li, Xin, Xingxing Li, Fujian Ma, Yongqiang Yuan, Keke Zhang, Feng Zhou, and Xiaohong Zhang. "Improved PPP Ambiguity Resolution with the Assistance of Multiple LEO Constellations and Signals." Remote Sensing 11, no. 4 (February 17, 2019): 408. http://dx.doi.org/10.3390/rs11040408.
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The fusion of low earth orbit (LEO) constellation and Global Navigation Satellite Systems (GNSS) can increase the number of visible satellites and optimize spatial geometry, which is expected to improve the performance of precise point positioning (PPP) ambiguity resolution (AR). In addition, the multi-frequency signals of LEO satellites can bring a variety of observation combinations, which is potential to further improve the efficiency of PPP AR. In this contribution, multi-frequency PPP AR was achieved with the augmentation of different LEO constellations. Three types of LEO constellations were designed with 60, 192, and 288 satellites. Moreover, the corresponding observation data were simulated with the GNSS observations over the ground stations. The LEO constellations were designed to transmit navigation signals on three frequencies: L1, L2, and L5 at 1575.42, 1227.6, and 1176.45 MHz, respectively, which are consistent with the GPS signals. For PPP AR, the uncalibrated phase delay (UPD) products of GNSS and LEO were estimated first. Furthermore, the quality of UPD products was also analyzed. The research findings show that the performance of estimated LEO UPD is comparable to that of GNSS UPD. Based on the UPD products, LEO-augmented multi-GNSS PPP AR can be achieved. Numerous results show that the performance of single-system and multi-GNSS PPP AR can be significantly improved by introducing the LEO constellations. The augmentation performance is more remarkable in the case of increasing LEO satellites. The time to first fix (TTFF) of the GREC fixed solution can be shortened from 7.1 to 4.8, 1.1, and 0.7 min, by introducing observations of 60-, 192-, and 288-LEO constellations, respectively. The positioning accuracy of multi-GNSS fixed solutions is also improved by about 60%, 80%, and 90% with the augmentation of 60-, 192-, and 288-LEO constellations, respectively. Compared to the dual-frequency solutions, the triple-frequency LEO-augmented PPP fixed solution presents a better performance. The TTFF of GREC fixed solutions is shortened to 33 s with the augmentation of 288-LEO constellation under the triple-frequency environment. It is worth indicating that the 288-satellite LEO-only PPP AR was conducted in dual-frequency and triple-frequency modes, respectively. The averaged TTFFs of both modes are 71.8 s and 55.2 s, respectively. It indicates that LEO constellation with 288 satellites is capable of achieving high-precision positioning independently and shows an even better performance than GNSS-only solutions.
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Liu, Li, Wei Zheng, and Guojian Tang. "Autonomous Positioning of Satellite Constellations via X-ray Pulsar Measurements." Journal of Navigation 66, no. 5 (June 21, 2013): 671–82. http://dx.doi.org/10.1017/s0373463313000325.
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A novel autonomous positioning approach based on X-ray pulsars is proposed in this paper. First, the principles of the pulsar–based measurement model and the inter-satellite range model in the autonomous positioning of satellite constellations are presented. The observability of the pulsar-based measurement model is then shown. Second, the autonomous positioning algorithms, including measurement models and orbital dynamics models, are formulated using an unscented Kalman filter to estimate the position vectors of satellites. Finally, the feasibility of the proposed measurement scheme compared with an inter-satellite range scheme is illustrated by numerical simulation. The results show that the proposed approach can keep the satellite state convergent, and achieve position accuracies of 2 m. The proposed scheme provides a promising approach for autonomous absolute positioning of constellation systems by using X-ray pulsars.
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Farhangian, Farzan, and René Landry. "Multi-Constellation Software-Defined Receiver for Doppler Positioning with LEO Satellites." Sensors 20, no. 20 (October 16, 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.
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Zong, Peng, and Saeid Kohani. "Optimal Satellite LEO Constellation Design Based on Global Coverage in One Revisit Time." International Journal of Aerospace Engineering 2019 (December 6, 2019): 1–12. http://dx.doi.org/10.1155/2019/4373749.
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This paper presents a globe coverage of constellation satellite in one revisit and the regional coverage at defined latitude. This constellation seems to be very close to optimal under the maximum revisit time comparing to the results in other papers. They are produced easily by using tables and data achievements. These satellites are fully connected by crosslinks sweeping the Earth. This model is more optimal comparing to the conventional constellations that distribute satellites evenly in the space. Since satellites on the LEO orbit are side by side, in most cases, they can maintain communication continuously. This special feature allows all satellites in the constellation connecting ground at any time when a satellite is available to the stations. Length of the crosslink is allowed to reject location connection or real-time data transmission. For example, six satellites in the constellation cover the whole Earth within one revisit time and all the data are collected by two Earth stations for keeping continuous coverage. Thus, the adjacent satellites may be more efficient and provide more coverage.
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Paek, Sung, Sangtae Kim, and Olivier de Weck. "Optimization of Reconfigurable Satellite Constellations Using Simulated Annealing and Genetic Algorithm." Sensors 19, no. 4 (February 13, 2019): 765. http://dx.doi.org/10.3390/s19040765.
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Agile Earth observation can be achieved with responsiveness in satellite launches, sensor pointing, or orbit reconfiguration. This study presents a framework for designing reconfigurable satellite constellations capable of both regular Earth observation and disaster monitoring. These observation modes are termed global observation mode and regional observation mode, constituting a reconfigurable satellite constellation (ReCon). Systems engineering approaches are employed to formulate this multidisciplinary problem of co-optimizing satellite design and orbits. Two heuristic methods, simulated annealing (SA) and genetic algorithm (GA), are widely used for discrete combinatorial problems and therefore used in this study to benchmark against a gradient-based method. Point-based SA performed similar or slightly better than the gradient-based method, whereas population-based GA outperformed the other two. The resultant ReCon satellite design is physically feasible and offers performance-to-cost(mass) superior to static constellations. Ongoing research on observation scheduling and constellation management will extend the ReCon applications to radar imaging and radio occultation beyond visible wavelengths and nearby spectrums.
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Zhang, Lei, and Bo Xu. "Simplified Constellation Architecture for the Libration Point Satellite Navigation System." Journal of Navigation 69, no. 5 (April 5, 2016): 1082–96. http://dx.doi.org/10.1017/s0373463316000114.
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In this paper, a simplified constellation architecture consisting of only two navigation satellites located around the Earth-Moon L1,2 libration points is obtained for the Universe Lighthouse. In order to determine the feasible constellations that can achieve continuous global coverage for lunar orbits, an exhaustive search over all possible combinations of libration point orbits is performed first. With the use of a fitting procedure, amplitude relations between the feasible L1 and L2 libration point orbits are derived by polynomial interpolation. After that, a cislunar navigation simulation is conducted to verify the navigation performance of the candidate two-satellite constellations. The final Monte Carlo simulation results indicate that the simplified system is available for cislunar navigation and the best accuracy of a few tens of metres can be achieved for both the trans-lunar cruise phase and lunar orbit phase.
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Xu, Xiaohua, Yi Han, Jia Luo, Jens Wickert, and Milad Asgarimehr. "Seeking Optimal GNSS Radio Occultation Constellations Using Evolutionary Algorithms." Remote Sensing 11, no. 5 (March 8, 2019): 571. http://dx.doi.org/10.3390/rs11050571.
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Given the great achievements of the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission in providing huge amount of GPS radio occultation (RO) data for weather forecasting, climate research, and ionosphere monitoring, further Global Navigation Satellite System (GNSS) RO missions are being followingly planned. Higher spatial and also temporal sampling rates of RO observations, achievable with higher number of GNSS/receiver satellites or optimization of the Low Earth Orbit (LEO) constellation, are being studied by high number of researches. The objective of this study is to design GNSS RO missions which provide multi-GNSS RO events (ROEs) with the optimal performance over the globe. The navigation signals from GPS, GLONASS, BDS, Galileo, and QZSS are exploited and two constellation patterns, the 2D-lattice flower constellation (2D-LFC) and the 3D-lattice flower constellation (3D-LFC), are used to develop the LEO constellations. To be more specific, two evolutionary algorithms, including the genetic algorithm (GA) and the particle swarm optimization (PSO) algorithm, are used for searching the optimal constellation parameters. The fitness function of the evolutionary algorithms takes into account the spatio-temporal sampling rate. The optimal RO constellations are obtained for which consisting of 6–12 LEO satellites. The optimality of the LEO constellations is evaluated in terms of the number of global ROEs observed during 24 h and the coefficient value of variation (COV) representing the uniformity of the point-to-point distributions of ROEs. It is found that for a certain number of LEO satellites, the PSO algorithm generally performs better than the GA, and the optimal 2D-LFC generally outperforms the optimal 3D-LFC with respect to the uniformity of the spatial and temporal distributions of ROEs.
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Jordanova, L., L. Laskov, and D. Dobrev. "Constellation and Mapping Optimization of APSK Modulations used in DVB-S2." Engineering, Technology & Applied Science Research 4, no. 5 (October 11, 2014): 690–95. http://dx.doi.org/10.48084/etasr.496.
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This article represents the algorithms of APSK constellation and mapping optimization. The dependencies of the symbol error probability Ps on the parameters of the 16APSK and 32APSK constellations are examined and several options that satisfy the requirements to the minimum value of Ps are selected. Mapping optimization is carried out for the selected APSK constellations. BER characteristics of the satellite DVB-S2 channels are represented when using optimized and standard 16APSK and 32APSK constellations and a comparative analysis of the results achieved is made.
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Williamson, M. "Satellite constellations in the ascendant." IEE Review 44, no. 5 (September 1, 1998): 209–13. http://dx.doi.org/10.1049/ir:19980506.
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Guerman, Anna, Erick Lansard, and Alfred Ng. "Satellite constellations and formation flying." Acta Astronautica 102 (September 2014): 295. http://dx.doi.org/10.1016/j.actaastro.2014.06.013.
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Karsaev, Oleg. "Analysis of Information Interaction Efficiency in Low-Orbit Satellite Constellations." SPIIRAS Proceedings 18, no. 4 (July 18, 2019): 858–86. http://dx.doi.org/10.15622/sp.2019.18.4.858-886.
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The objects of the research are networks and information interactions in low-orbit satellite constellations performing tasks of remote sensing of the Earth. Research of network creation questions in this case is a necessary condition as opportunities and efficiency of information interaction directly depend on opportunities of a network. DTN (Delay-and-Disruption Tolerant Networking) technology is a basis of the network creation and CGR (Contact Graph Routing) approach is a basis of message routing. DTN technology and CGR approach are originally developed and used to provide communication with spacecraft located in a deep space. Therefore, the article discusses issues and problems arising in the context of their use in relation to low-orbit satellite constellations. The purpose of the information interaction study is development of effective interaction schemes (protocols). In the paper, the schemes of information interaction that can be used by a group of satellites in case of autonomous planning are considered. Along with autonomous planning, the paper also considers information interaction that can be used to implement network control of a satellite constellation in the case of ground planning. The effectiveness of the information interaction schemes are assessed by efficiency of orders’ execution. Measurement of efficiency is estimated via simulation of the communication network and the corresponding scheme of information interaction.
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Wang, Jue-yao, and Bin Liang. "4-GNSS radio occultation satellite constellation design based on Dual-gate uniformity evaluation index." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 1 (November 13, 2016): 3–16. http://dx.doi.org/10.1177/0954410016674746.
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A brand-new area of low earth orbit satellite constellation research has been expanded by global navigation satellite system (GNSS) radio occultation (RO) atmosphere sounding technology in the last decade. The possibility of reducing the sounding satellites while keeping the amount of atmosphere soundings increasing to produce low-cost meteorological data product is investigated, and a constellation capable of receiving the RO signals from all the 4-GNSS, such as GPS, GLONASS, Galileo, and Compass, is proposed in this paper. This paper focuses on the mathematical problems on the design of 4-GNSS RO satellite constellation. A forward GNSS RO sounding simulation algorithm based on ideal atmosphere model and two-dimensional radial tracing algorithm is presented for a rapidly and accurately sounding performance prediction of 4-GNSS RO satellite constellations. Then, an improved uniformity evaluation factor named Dual-gate is established for 4-GNSS RO satellite constellation optimization design, which is a combination of the uniformity evaluation factors for the latitudinal distribution of RO soundings and those for the gridding uniformity. On the basis of low earth orbit satellite orbit dynamics and spherical geometry, the impacts of partial constellation parameters on the amount and coverage performance accorded with Dual-gate uniformity evaluation index are derived, and a series of design criteria of 4-GNSS RO satellite constellation are summarized. A simplified 4-GNSS RO satellite constellation model is built on the basis of the design criteria, and an improved ant colony algorithm is used to optimize the parameters of a 4-GNSS RO constellation including as many satellites as COSMIC-2. The simulation result shows that this 4-GNSS RO constellation is capable of obtaining near 3000 atmosphere soundings per 3 h. It obtains 13% more soundings than COSMIC-2 with the same 4-GNSS RO sounding devices, and the uniformity of soundings is increased by 9%.
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Butash, Tom, Peter Garland, and Barry Evans. "Non‐geostationary satellite orbit communications satellite constellations history." International Journal of Satellite Communications and Networking 39, no. 1 (August 27, 2020): 1–5. http://dx.doi.org/10.1002/sat.1375.
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Usui, Tomonori, Tsutomu Kawabata, Yoshikuni Onozato, and Ikuo Oka. "Satellite constellations for a multiple LEO satellite network." Electronics and Communications in Japan (Part III: Fundamental Electronic Science) 76, no. 4 (1993): 24–34. http://dx.doi.org/10.1002/ecjc.4430760404.
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Chen, Weigang, Yu Peng, Changcai Han, and Jinsheng Yang. "Design of Nonequiprobable High-Order Constellations over Non-Linear Satellite Channels." Electronics 9, no. 1 (January 8, 2020): 123. http://dx.doi.org/10.3390/electronics9010123.
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High-order modulations are essential to improve the bandwidth efficiency of communication systems. However, such modulated signals with large envelopes are typically sensitive to the non-linear distortion caused by high power amplifiers (HPAs) in the transponder of satellite channels. In this paper, a new nonequiprobable constellation is designed to combat the non-linear effects of HPAs. We use non-uniformly distributed symbols to construct the appropriate high-order constellation for non-linear satellite channels. The nonequiprobable symbols are generated using the non-linear mapping method, which specifically consists of expansion mapping, symbol decomposition, permutation, and combination. Moreover, the demapping method adapting to the designed nonequiprobable constellation is also discussed. The simulation results show that the proposed scheme has considerable performance improvements compared with the traditional equiprobable constellations over the non-linear satellite channel.
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Itkin, M., and A. Loew. "Multi-satellite rainfall sampling error estimates – a comparative study." Hydrology and Earth System Sciences Discussions 9, no. 10 (October 12, 2012): 11677–706. http://dx.doi.org/10.5194/hessd-9-11677-2012.
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Abstract. This study focus is set on quantifying sampling related uncertainty in the satellite rainfall estimates. We conduct observing system simulation experiment to estimate sampling error for various constellations of Low-Earth orbiting and geostationary satellites. There are two types of microwave instruments currently available: cross track sounders and conical scanners. We evaluate the differences in sampling uncertainty for various satellite constellations that carry instruments of the common type as well as in combination with geostationary observations. A precise orbital model is used to simulate realistic satellite overpasses with orbital shifts taken into account. With this model we resampled rain gauge timeseries to simulate satellites rainfall estimates free of retrieval and calibration errors. We concentrate on two regions, Germany and Benin, areas with different precipitation regimes. Our results show that sampling uncertainty for all satellite constellations does not differ greatly depending on the area despite the differences in local precipitation patterns. Addition of 3 hourly geostationary observations provides equal performance improvement in Germany and Benin, reducing rainfall undersampling by 20–25% of the total rainfall amount. Authors do not find a significant difference in rainfall sampling between conical imager and cross-track sounders.
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Zhodzishskiy, A. I., S. K. Zhidkova, and D. N. Nagornykh. "Construction of a Unified Ground-based Control Complex for a Multi-satellite ERS Constellation." Rocket-Space Device Engineering and Information Systems 7, no. 4 (2020): 14–21. http://dx.doi.org/10.30894/issn2409-0239.2020.7.4.14.21.
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Taking into account the increasing number of spacecraft the further development of the Russian ground-based control systems (GCS) for Earth remote sensing spacecraft requires new approaches to solving the problems of increasing the efficiency and global control of these spacecraft. The paper considers the possibility of creating a unified ERS GCS (ERS UGCS), including the existing ERS GCS and providing control capabilities for promising, newly created ERS SC. As part of the ERS UGCS, a single control center should be created that provides modeling, planning, analysis and control of future and existing spacecraft constellations and ground-based facilities. Using international experience in managing multi-satellite constellations and implementing our own experience in creating special software for the control centers, for new spacecraft constellations, it is proposed to automate the tasks of a typical regular control cycle, automate periodic maintenance operations of the spacecraft and localize emergency situations. With the aim of automating control processes, the creation of a digital mathematical model of the orbital constellation and ground-based facilities is also proposed for Russian remote sensing constellations. A model that takes into account and describes the spatio-temporal position of the spacecraft constellations, the location of the GCS, ground based data receiving processing and distribution complexes, multifunctional relay stations (MFRS), their technical condition, composition and performance should form the basis for the implementation of end-to-end planning of the main control operations and the targeted use of multi-satellite constellations.
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ILIESCU, Alexandru Iulian, Tiberiu RUS, Valentin DANCIU, Constantin MOLDOVEANU, and Andrei ILIE. "Current Situation of GNSS Networks in Romania." Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Horticulture 76, no. 2 (November 19, 2019): 202. http://dx.doi.org/10.15835/buasvmcn-hort:2019.0040.
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Nowadays, the need for a more precise positioning is a very high, therefore very demanding one, and this is one of the reasons why very large research funding is allocated in satellite technology, the second reason being global geopolitics situation. New satellite constellations are being developed existing satellites that have completed their mission are being replaced with satellites that incorporate technology far superior to their predecessors. Currently we have four constellations with global coverage, NAVSTAR-GPS and Glonass, Galileo and Compass. With the development of these global satellite systems, it is also necessary to develop the user segment, so this requires terrestrial reference stations to be updated to recognize the new signals from them. The article presents the situation of the global satellite systems and the situation of the permanent reference networks in Romania, which are developed by state or private companies.
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Gao, Zhao-Yang, and Xi-Yun Hou. "Coverage Analysis of Lunar Communication/Navigation Constellations Based on Halo Orbits and Distant Retrograde Orbits." Journal of Navigation 73, no. 4 (March 24, 2020): 932–52. http://dx.doi.org/10.1017/s0373463320000065.
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AbstractWith more and more missions around the Moon, a communication/navigation constellation around the Moon is necessary. Halo orbits, due to their unique geometry, are extensively studied by researchers for this purpose. A dedicated survey is carried out in this work to analyse the coverage ability of halo orbits. It is found that a two-satellite constellation is enough for continuous one-fold coverage of the north or the south polar regions but never both. A three-satellite constellation is enough for continuous one-fold coverage of both north and south polar regions. A four-satellite constellation can cover nearly 100% of the whole lunar surface. In addition, the coverage ability of another special orbit – distant retrograde orbit (DRO) – is analysed for the first time in this study. It is found that three satellites on DROs can cover 99·8% of the lunar surface, with coverage gaps at polar caps. A four-satellite constellation moving on spatial DROs can cover nearly the whole lunar surface. By combining halo orbits and DROs, we design a five-satellite constellation composed of three halo orbit satellites and two DRO satellites. This constellation can provide 100% continuous one-fold coverage of the whole lunar surface.
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Trishchenko, Alexander P., Louis Garand, and Larisa D. Trichtchenko. "Observing Polar Regions from Space: Comparison between Highly Elliptical Orbit and Medium Earth Orbit Constellations." Journal of Atmospheric and Oceanic Technology 36, no. 8 (August 2019): 1605–21. http://dx.doi.org/10.1175/jtech-d-19-0030.1.
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AbstractContinuous observation of polar regions from space remains an important unsolved technical challenge of great interest for the international meteorological community. This capacity would allow achieving global continuous coverage once combined with the geostationary (GEO) satellite network. From a practical point of view, continuous coverage of polar regions with a small number of spacecraft can be obtained from a constellation of satellites either in highly elliptical orbits (HEO) or in medium Earth orbits (MEO). The study compares HEO and MEO satellite constellations for their capacity to provide continuous imaging of polar regions as function of the viewing zenith angle (VZA) and evaluates the corresponding latitude limits that ensure sufficient overlap with GEO imagery. Earlier studies assumed the latitude boundary of 60° and the VZA range 70°–85° depending on the space mission focus: meteorological purposes or communications. From the detailed analysis of meteorological retrieval requirements, this study suggests that the overlap of the GEO and polar observing systems (HEO or MEO) should occur down to the latitude band 45°–50° with a maximum VZA ranging between 60° and 64°. This coverage requirement can be met with two sets of three-satellite HEO constellations (one for each polar area) or a six-satellite MEO constellation. The 12-h Molniya and 14-, 15-, and 16-h HEO systems have been analyzed and determined to meet these revised requirements. The study demonstrates that the six-satellite 24-h MEO system can provide a suitable solution, which is also beneficial from the point of view of ionizing radiation and image acquisition geometry. Among the HEO systems, the 16-h HEO has some advantages relative to other HEO systems from the point of view of spatial coverage and space radiation.
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Wang, Zi Lu, and Bin Wu. "GNSS RAIM Performance Analysis for World Wide Area." Applied Mechanics and Materials 565 (June 2014): 217–22. http://dx.doi.org/10.4028/www.scientific.net/amm.565.217.
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Multi-constellations provide much better satellite geometrics, thus RAIM algorithms areexpected to achieve greater reliability and integrity performance. This paper mainly discusses different RAIM algorithms and gives simulations of RAIM availability and reliability of standalone GPS and integrated GPS/GLONASS, GPS/BEIDOU and GPS/GLONASS/BEIDOU constellations.The results show that multi-constellation improve RAIM availability and reliability greatly. It is no less than 99.7%for APV I. Also MDB values indicate thatinternal and external reliability of satellite navigation system can be enhanced by multi-constellation.
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Gwynne, Peter. "Observations under threat from satellite constellations." Physics World 33, no. 10 (November 2020): 13ii. http://dx.doi.org/10.1088/2058-7058/33/10/17.
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Potyupkin, A. Yu, I. N. Panteleymonov, Yu A. Timofeev, and S. A. Volkov. "Control of Multi-Satellite Orbital Constellations." Rocket-space device engineering and information systems 7, no. 3 (2020): 61–70. http://dx.doi.org/10.30894/issn2409-0239.2020.7.3.61.70.
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Vasile, Massimiliano. "Preface: Satellite constellations and formation flying." Advances in Space Research 67, no. 11 (June 2021): 3379–80. http://dx.doi.org/10.1016/j.asr.2021.03.001.
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Li, Shuang, Kaihua Hou, Chengqi Cheng, Shizhong Li, and Bo Chen. "A Space-Interconnection Algorithm for Satellite Constellation Based on Spatial Grid Model." Remote Sensing 12, no. 13 (July 2, 2020): 2131. http://dx.doi.org/10.3390/rs12132131.
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With the rapid development of large-scale satellite constellations and the increasing demand for rapid communication and emergency rescue using global satellite-based Internet, there have been new requirements for efficient algorithms for inter-communication between satellites. As the constellations of low-orbit satellites become larger, the complexities of real-time inter-satellite calculation and path planning are becoming more complicated and are increasing geometrically. To address the bottlenecks in large-scale node space computing, we introduced a global space grid. Based on this grid, an efficient calculation method of spatial inter-connection between satellite constellations is proposed, according to the concept of “storage for computing” and the high computational efficiency of the spatial grid model. This strategy includes the following parts: (1) the introduction of the GeoSOT-3D global grid model into aerospace and the construction of the aerospace grid indexing BigTable; (2) a set of algorithms for satellite visibility analysis according to the visible grid look-up table and the secondary grid index; and (3) planning inter-satellite routing by querying the grid’s inherent visibility. The idea at the basis of this method is to employ the “space for time” concept to convert the high-dimensional floating operations into one-dimensional matching operations by querying the inherent “visible” attribute of the grid. In our study, we simulated thousands of satellites, discretized their trajectories into grids, and pre-calculated the visibility between grid cells to plan the routing path for the ground data transmission. The theoretical analysis and experimental verification show that the algorithm is feasible and efficient, and it can significantly improve the computational efficiency of inter-satellite connection. We hope that the method can be used in emergency communications, disaster warning, and maritime rescue, and can contribute to the next generation of satellite internet and “satellite-ground” integrated networks.
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Li, Min, Tianhe Xu, Haibo Ge, Meiqian Guan, Honglei Yang, Zhenlong Fang, and Fan Gao. "LEO-Constellation-Augmented BDS Precise Orbit Determination Considering Spaceborne Observational Errors." Remote Sensing 13, no. 16 (August 12, 2021): 3189. http://dx.doi.org/10.3390/rs13163189.
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The precise orbit determination (POD) accuracy of the Chinese BeiDou Navigation Satellite System (BDS) is still not comparable to that of the Global Positioning System because of the unfavorable geometry of the BDS and the uneven distribution of BDS ground monitoring stations. Fortunately, low Earth orbit (LEO) satellites, serving as fast moving stations, can efficiently improve BDS geometry. Nearly all studies on Global Navigation Satellite System POD enhancement using large LEO constellations are based on simulations and their results are usually overly optimistic. The receivers mounted on a spacecraft or an LEO satellite are usually different from geodetic receivers and the observation conditions in space are more challenging than those on the ground. The noise level of spaceborne observations needs to be carefully calibrated. Moreover, spaceborne observational errors caused by space weather events, i.e., solar geomagnetic storms, are usually ignored. Accordingly, in this study, the actual spaceborne observation noises are first analyzed and then used in subsequent observation simulations. Then, the observation residuals from the actual-processed LEO POD during a solar storm on 8 September 2017 are extracted and added to the simulated spaceborne observations. The effect of the observational errors on the BDS POD augmented with different LEO constellation configurations is analyzed. The results indicate that the noise levels from the Swarm-A, GRACE-A, and Sentinel-3A satellites are different and that the carrier-phase measurement noise ranges from 2 mm to 6 mm. Such different noise levels for LEO spaceborne observations cause considerable differences in the BDS POD solutions. Experiments calculating the augmented BDS POD for different LEO constellations considering spaceborne observational errors extracted from the solar storm indicate that these errors have a significant influence on the accuracy of the BDS POD. The 3D root mean squares of the BDS GEO, IGSO, and MEO satellite orbits are 1.30 m, 1.16 m, and 1.02 m, respectively, with a Walker 2/1/0 LEO constellation, and increase to 1.57 m, 1.72 m, and 1.32 m, respectively, with a Walker 12/3/1 constellation. When the number of LEO satellites increases to 60, the precision of the BDS POD improves significantly to 0.89 m, 0.77 m, and 0.69 m for the GEO, IGSO, and MEO satellites, respectively. While 12 satellites are sufficient to enhance the BDS POD to the sub-decimeter level, up to 60 satellites can effectively reduce the influence of large spaceborne observational errors, i.e., from solar storms.
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Baburov, V. I., N. V. Vasileva, and N. V. Ivantsevich. "NAVIGATION SHARING PROSPECTS GLONASS AND PSEUDOLITES FIELDS FOR NAVIGATION AND LANDING OF AIRCRAFT IN ARCTIC." Issues of radio electronics, no. 7 (July 20, 2018): 13–17. http://dx.doi.org/10.21778/2218-5453-2018-7-13-17.
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In view of the development of the Arctic Region the problem of aircraft (AC) navigation support under arctic conditions throughout the flight, including the landing stage, acquires special momentum. Given that land-based navigation systems have a limited range which does not cover the Arctic Region and are significantly inferior to satellite radio navigation systems (SRNS), SRNS user navigation equipment (UNE) becomes extremely important for AC navigation and landing. The functioning of SRNS UNE in the polar regions is determined by the characteristics of the satellite signal propagation path under arctic conditions and considerable radio signal reflection from the underlying surface. Multipath errors are of special significance for low satellite elevations. If low satellites are excluded from processing by UNE while maintaining acceptable positioning accuracy, both the integral accuracy rates and accessibility may be improved. The paper analyses the composition and information characteristics of working satellite constellations in integrated GLONASS and pseudolites positioning in the Arctic region of Russia. Our study performed by simulation modelling has established considerable redundancy of working constellations at the nominal value of admissible satellite elevation. This factor has been studied for forming controllable working constellations in aircraft on board navigation and landing complex.
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Januszewski, Jacek. "Visibility and Geometry of Global Satellite Navigation Systems Constellations." Artificial Satellites 50, no. 4 (December 1, 2015): 169–80. http://dx.doi.org/10.1515/arsa-2015-0014.
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Abstract Nowadays (November 2015) there are two global fully operational satellite navigation systems, American GPS and Russian GLONASS. Two next are under construction, Galileo in Europe and BeiDou in China. As the error of observer’s position obtained from these systems depends on geometry factor DOP (Dilution Of Precision) among other things the knowledge of the number of satellites visible by this observer above given masking elevation angle Hmin and the distributions of DOP coefficient values, GDOP in particular, is very important. The lowest and the greatest number of satellites visible in open area by the observer at different latitudes for different Hmin, the percentage of satellites visible above angle H (9 intervals, each 10O wide), distributions (in per cent) of satellites azimuths (8 intervals, each 45O wide) and GDOP coefficient values (8 intervals) for Hmin = 5O for all these four systems at different observer’s latitudes (9 intervals, each wide 10O wide) are presented in the paper. Additionally the lowest elevation for which the number of satellites visible at different latitudes by the observer in open area above this angle is equal 4 or 3 and the distributions (in per cent) of GDOP coefficient values for different Hmin at observer’s latitudes 50-60O for the same four systems are showed. All calculations were made for constellation of GPS 27 satellites, GLONASS 24, Galileo 30 and BeiDou 27 MEO satellites.
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Sreesawet, Suwat, Seksan Jaturat, and Sittiporn Channamsin. "Orbit Design for Thai Space Consortium Satellite." Proceedings 39, no. 1 (December 27, 2019): 1. http://dx.doi.org/10.3390/proceedings2019039001.
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Currently, Geo-Informatics and Space Technology Development Agency (GISTDA), National Astronomical Research Institute of Thailand (NARIT) and Synchrotron Light Research Institute (SLRI) have a co-operation on a project of developing a satellite for scientific research called Thai Space Consortium (TSC). The project is aiming at Earth remote sensing mission by a small satellite about 100 kg. The main payload of the satellite is an optical instrument with the secondary payload of energetic particle detector for space weather. The satellite is designed to be in a Sun Synchronous orbit due to requirement of same light condition throughout the operational lifetime. In the meantime, there is another project by GISTDA named THEOS-2. This project consists of two remote-sensing satellites, THEOS-2 MainSAT and THEOS-2 SmallSAT, under the development in Europe. The SmallSAT does not have the propulsion subsystem. So it cannot perform station-keeping maneuvers or maintain constellation with others. Therefore, in this paper, we analyze two scenarios that the TSC satellite flies as constellations with the MainSAT of THEOS2 project. The constellation is in the sense that the TSC satellite flies on the same ground track path with the MainSAT satellite with slightly differences in local solar time. The ground track sequencing is presented with a methodology for obtaining orbital parameters with a discussion on accuracy relating to Keplerian assumption.
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Huo, Xiang, Xue Wang, Sen Wang, Xiaofei Chen, Ganghua Zhou, and Xiaochun Lu. "Receiving and Assessing L1C Signal for In-Orbit GPS III and QZSS Transmissions Using a Software-Defined Receiver." Electronics 9, no. 1 (December 21, 2019): 11. http://dx.doi.org/10.3390/electronics9010011.
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To avoid signal interference in L1 frequency and provide various services, GPS has updated a modern signal, called L1C, which has been tested with three QZSS satellites launched in 2017. In December 2018, the first GPS III satellite was launched, which implies improved joint positioning using GPS and QZSS L1C signal. The L1C signal offers a series of advanced designs in signal modulation, message structure and coding. We present complete methodologies for joint L1C signal receiving and processing. For the transmitted signals, we present a methodology and results from collecting and assessing Binary Offset Carrier (BOC) modulation and time-multiplexed BOC (TMBOC) modulation used in the L1C signal. Using the same omnidirectional antenna and test equipment, we collected the L1C signal in Xi’an and Sanya, China, respectively. The experiments in Xi’an verify the joint positioning method to complement the GPS III and QZSS satellite constellations. Our methodology evaluates the ranging difference and positioning error of BOC and TMBOC modulation under the same environment and satellite constellation configuration in Sanya. It is also verified that the joint positioning error is less than the QZSS-only positioning due to the optimization of the satellite constellation.
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Li, Xingxing, Yiting Zhu, Kai Zheng, Yongqiang Yuan, Gege Liu, and Yun Xiong. "Precise Orbit and Clock Products of Galileo, BDS and QZSS from MGEX Since 2018: Comparison and PPP Validation." Remote Sensing 12, no. 9 (April 30, 2020): 1415. http://dx.doi.org/10.3390/rs12091415.
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In recent years, the development of new constellations including Galileo, BeiDou Navigation Satellite System (BDS) and Quasi-Zenith Satellite System (QZSS) have undergone dramatic changes. Since January 2018, about 30 satellites of the new constellations have been launched and most of the new satellites have been included in the precise orbit and clock products provided by the Multi Global Navigation Satellite System (Multi-GNSS) Experiment (MGEX). Meanwhile, critical issues including antenna parameters, yaw-attitude models and solar radiation pressure models have been continuously refined for these new constellations and updated into precise MGEX orbit determination and precise clock estimation solutions. In this context, MGEX products since 2018 are herein assessed by orbit and clock comparisons among individual analysis centers (ACs), satellite laser ranging (SLR) validation and precise point positioning (PPP) solutions. Orbit comparisons showed 3D agreements of 3–5 cm for Galileo, 8–9 cm for BDS-2 inclined geosynchronous orbit (IGSO), 12–18 cm for BDS-2 medium earth orbit (MEO) satellites, 24 cm for BDS-3 MEO and 11–16 cm for QZSS IGSO satellites. SLR validations demonstrated an orbit accuracy of about 3–4 cm for Galileo and BDS-2 MEO, 5–6 cm for BDS-2 IGSO, 4–6 cm for BDS-3 MEO and 5–10 cm for QZSS IGSO satellites. Clock products from different ACs generally had a consistency of 0.1–0.3 ns for Galileo, 0.2–0.5 ns for BDS IGSO/MEO and 0.2–0.4 ns for QZSS satellites. The positioning errors of kinematic PPP in Galileo-only mode were about 17–19 mm in the north, 13–16 mm in the east and 74–81 mm in the up direction, respectively. As for BDS-only PPP, positioning accuracies of about 14, 14 and 49 mm could be achieved in kinematic mode with products from Wuhan University applied.
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Zhang, Lei, and Bo Xu. "Navigation Performance of the Libration Point Satellite Navigation System for Future Mars Exploration." Journal of Navigation 69, no. 1 (June 22, 2015): 41–56. http://dx.doi.org/10.1017/s0373463315000478.
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Based on the candidate architectures of the libration point satellite navigation system, a Mars navigation performance analysis is conducted in this paper to further verify the feasibility of the Universe Lighthouse. Firstly, a high-fidelity Mars exploration mission is developed as the reference scenario. Then, with the use of a novel adaptive unscented Kalman filter, navigation performance of the candidate Earth-MoonL1,2,4,5four-satellite constellations is evaluated by Monte-Carlo simulations. The final results indicate that the libration point satellite navigation system is available for Mars navigation and the effects of different constellation configurations and measurement types are also compared and analysed.
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Schetter, Thomas, Mark Campbell, and Derek Surka. "Multiple agent-based autonomy for satellite constellations." Artificial Intelligence 145, no. 1-2 (April 2003): 147–80. http://dx.doi.org/10.1016/s0004-3702(02)00382-x.
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Liu, Lin, Hai-hong Wang, and Jian-bo Ma. "On the formation flying of satellite constellations." Chinese Astronomy and Astrophysics 28, no. 2 (April 2004): 188–99. http://dx.doi.org/10.1016/s0275-1062(04)90023-9.
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Kim, Richard. "Stochastic Inventory Control Modeling for Satellite Constellations." Journal of Spacecraft and Rockets 57, no. 3 (May 2020): 612–20. http://dx.doi.org/10.2514/1.a34614.
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