Benefits of BDS-3 B1C/B1I/B2a triple-frequency signals on precise positioning and ambiguity resolution
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ORIGINAL ARTICLE
Benefits of BDS‑3 B1C/B1I/B2a triple‑frequency signals on precise positioning and ambiguity resolution Jinlong Li1 · Yuanxi Yang2 · Haibo He1 · Hairong Guo1 Received: 9 April 2020 / Accepted: 24 July 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract BDS-3 currently has 28 operational satellites in orbit, of which 27 IGSO/MEO satellites provide open services on five frequencies simultaneously. In particular, the linear combinations of the BDS-3 B1C/B1I/B2a signals have significant benefits in reducing the influence of ionospheric delay error as well as improving ambiguity estimation and positioning accuracy. The presented optimal ionosphere-free combination (242, 218, − 345) and ionosphere-reduced combination (2, 2, − 3) can improve the measurement accuracy by about 20% compared to the BDS-3 B1C/B2a or GPS L1/L5 dual-frequency combination. The ionosphere-reduced combination (2, 2, − 3) with a wavelength of 10.9 cm is almost immune to the ionospheric delay error and has a smaller noise amplification factor compared to the existing dual-frequency combinations. Therefore, its combined ambiguities can be fixed directly even in the case of a long baseline, which can simplify the traditional precise positioning process based on the ionosphere-free combination. The numerical results of BDS-3 real data show that the triplefrequency ionosphere-free or ionosphere-reduced combinations can improve the single-point positioning accuracy by 16–20% and the phase differential positioning accuracy by 7–9%, respectively. The ambiguity resolution of the ionosphere-reduced combination (2, 2, − 3) is achieved with a fixing rate of 88.4% over long baseline up to 1600 km. The presented ionospherefree and ionosphere-reduced combinations are also very promising to be applied in current PPP applications to simplify the ambiguity fixing process as well as improve positioning accuracy and shorten convergence time. Keywords BDS-3 · Linear combination · Long baseline · Ambiguity resolution · Positioning accuracy
Introduction The BDS-3 basic system with 18 MEO satellites has started to provide initial global services on December 27, 2018 (Yang et al. 2020b), and it is expected to provide full operational capability services by June 2020. At present (March 24, 2020), there are a total of 29 BDS-3 satellites in orbit, including 24 medium earth orbit (MEO) satellites, 3 Inclined Geo-Synchronous Orbit (IGSO) satellites and 2 geostationary earth orbit (GEO) satellites. Except for the GEO satellite launched on March 9, which is undergoing in-orbit testing, the remaining 28 satellites have been providing operational services, of which 24 MEO satellites and 3 IGSO satellites
* Jinlong Li [email protected] 1
Beijing Satellite Navigation Center, Beijing 100094, China
National Key Laboratory of Geo-Information Engineering, Xi’an 710054, China
2
broadcast open service signals simultaneously on five frequencies including 1575.42 MHz (B1C), 1561.098 MHz (B1I), 1268.52 MHz (B3I), 1207.14 MHz (B2b) and 11
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