Fan Gao

TL;DR: This paper designs a LEO-based optimal global navigation and augmentation constellations designed by a non-dominated sorting genetic algorithm III (NSGA-III) and genetic algorithm (GA) and proves that the computation efficiency of the constellation design can be considerably improved by using master–slave parallel computing.

TL;DR: Sea level altimetry determinations are presented for the first time based on geometry-free linear combinations of the carrier phase at low elevation angles from a fixed global positioning system (GPS) station and the results show that sea level changes determined from GPS SNR and carrier phase combinations for the five strategies show good agreement.

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.

TL;DR: 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: High temporal and spatial resolutions are the key advantages of the global navigation satellites system-reflectometry (GNSS-R) technique, while low precision and instabilities constrain its development Compared with conventional Ku/C band nadir-looking radar altimetry, the precision of GNSS-R code-level altimetry is restricted by the smaller bandwidth and the lower transmitted power of the signals Fortunately, modernized GNSS broadcast new open-available ranging codes with wider bandwidth The Chinese BDS-3 system was built on 31 July 2020; its inclined geostationary orbit and medium circular orbit satellites provide B1C and B2a public navigation service signals in the two frequency bands of B1 and B2 In order to investigate their performance on GNSS-R code-level altimetry, a coastal experiment was conducted on 5 November 2020 at a trestle of Weihai in the Shandong province of China The raw intermediate frequency data with a 62 MHz sampling rate were collected and post-processed to solve the sea surface height every second continuously for over eight hours The precisions were evaluated using the measurements from a 26 GHz radar altimeter mounted on the same trestle near our GNSS-R setup The results show that a centimeter-level accuracy of GNSS-R altimetry—based on B1C code after the application of the moving average—can be achieved, while for B2a code, the accuracy is about 10 to 20 cm