Spatiotemporal Evaluation of GNSS-R Based on Future Fully Operational Global Multi-GNSS and Eight-LEO Constellations
TLDR
To evaluate the future capacity for repetitive GNSS-R observations, a GNSS satellite selection method is proposed and a simulation of the orbit of eight-satellite LEO and partial multi-GNSS constellations shows that the multi- GNSS -R system has major advantages in terms of available satellite numbers and revisit times over the GPS-R system.Abstract:
Spaceborne GNSS-R (global navigation satellite system reflectometry) is an innovative and powerful bistatic radar remote sensing technique that uses specialized GNSS-R instruments on LEO (low Earth orbit) satellites to receive GNSS L-band signals reflected by the Earth’s surface. Unlike monostatic radar, the illuminated areas are elliptical regions centered on specular reflection points. Evaluation of the spatiotemporal resolution of the reflections is necessary at the GNSS-R mission design stage for various applications. However, not all specular reflection signals can be received because the size and location of the GNSS-R antenna’s available reflecting ground coverage depends on parameters including the on-board receiver antenna gain, the signal frequency and power, the antenna face direction, and the LEO’s altitude. Additionally, the number of available reflections is strongly related to the number of GNSS-R LEO and GNSS satellites. By 2020, the Galileo and BeiDou Navigation Satellite System (BDS) constellations are scheduled to be fully operational at global scale and nearly 120 multi-GNSS satellites, including Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS) satellites, will be available for use as illuminators. In this paper, to evaluate the future capacity for repetitive GNSS-R observations, we propose a GNSS satellite selection method and simulate the orbit of eight-satellite LEO and partial multi-GNSS constellations. We then analyze the spatiotemporal distribution characteristics of the reflections in two cases: (1) When only GPS satellites are available; (2) when multi-GNSS satellites are available separately. Simulation and analysis results show that the multi-GNSS-R system has major advantages in terms of available satellite numbers and revisit times over the GPS-R system. Additionally, the spatial density of the specular reflections on the Earth’s surface is related to the LEO inclination and constellation construction.read more
Citations
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Evaluation of Precipitable Water Vapor from Five Reanalysis Products with Ground-Based GNSS Observations
Shuaimin Wang,Tianhe Xu,Wenfeng Nie,Chunhua Jiang,Yuguo Yang,Zhenlong Fang,Mowen Li,Zhen Zhang +7 more
TL;DR: Evaluation of PWV values derived by 268 Global Navigation Satellite Systems stations around the world covering the period from 2016 to 2018 indicates that the absolute accuracies of five reanalysis products are highest in the polar regions and lowest in the tropics.
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Relationship Between Temporal and Spatial Resolution for a Constellation of GNSS-R Satellites
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A shipborne experiment using a dual-antenna reflectometry system for GPS/BDS code delay measurements
TL;DR: In this paper, a shipborne dual-antenna GNSS-R reflector height retrieval system was developed and performed on a research vessel, where direct and reflected GPS/BDS signals were collected using the same setup, and processed to estimate the reflector heights on the basis of path-delay measurements.
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Helmert Variance Component Estimation for Multi-GNSS Relative Positioning.
TL;DR: It was found that the quality of a phase observation is almost equivalent in each baseline and GNSS constellation, whereas that of a code observation is different, which indicates that the weight proportions of both code and phase observations are stable over a long period of time.
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Improving the GNSS-R Specular Reflection Point Positioning Accuracy Using the Gravity Field Normal Projection Reflection Reference Surface Combination Correction Method
TL;DR: Research on improving the positioning accuracy of the specular reflection point is carried out based on the correction of the GNSS-R reflection reference surface to reduce the positioning error caused by the elevation difference between the reflection references and the sea surface.
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