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Open AccessArticle

Mitigation of Unmodeled Error to Improve the Accuracy of Multi-GNSS PPP for Crustal Deformation Monitoring

1
School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China
2
German Research Centre for Geosciences GFZ, Telegrafenberg, 14473 Potsdam, Germany
3
Institut für Geodäsie und Geoinformationstechnik, Technische Universität Berlin, 10623 Berlin, Germany
4
College of Liberal Arts and Sciences, National University of Defense Technology, Changsha 410073, China
*
Author to whom correspondence should be addressed.
Remote Sens. 2019, 11(19), 2232; https://doi.org/10.3390/rs11192232
Received: 26 August 2019 / Revised: 13 September 2019 / Accepted: 23 September 2019 / Published: 25 September 2019
High-rate multi-constellation global navigation satellite system (GNSS) precise point positioning (PPP) has been recognized as an efficient and reliable technique for large earthquake monitoring. However, the displacements derived from PPP are often overwhelmed by the centimeter-level noise, therefore they are usually unable to detect slight deformations which could provide new findings for geophysics. In this paper, Global Positioning System (GPS), GLObalnaya NAvigatsionnaya Sputnikovaya Sistema (GLONASS), and BeiDou navigation satellite system (BDS) data collected during the 2017 Mw 6.5 Jiuzhaigou earthquake were used to further exploit the capability of BDS-only and multi-GNSS PPP in deformation monitoring by applying sidereal filtering (SF) in the observation domain. The equation that unifies the residuals for the uncombined and undifferenced (UCUD) PPP solution on different frequencies was derived, which could greatly reduce the complexity of data processing. An unanticipated long-term periodic error term of up to ± 3 cm was found in the phase residuals associated with BDS satellites in geostationary Earth orbit (GEO), which is not due to multipath originated from the ground but is in fact satellite dependent. The period of this error is mainly longer than 2000 s and cannot be alleviated by using multi-GNSS. Compared with solutions without sidereal filtering, the application of the SF approach dramatically improves the positioning precision with respect to the weekly averaged positioning solution, by 75.2%, 42.8%, and 56.7% to 2.00, 2.23, and 5.58 cm in the case of BDS-only PPP in the east, north, and up components, respectively, and 71.2%, 27.7%, and 37.9% to 1.25, 0.81, and 3.79 cm in the case of GPS/GLONASS/BDS combined PPP, respectively. The GPS/GLONASS/BDS combined solutions augmented by the SF successfully suppress the GNSS noise, which contributes to the detection of the true seismic signal and is beneficial to the pre- and post-seismic signal analysis. View Full-Text
Keywords: BDS GEO; multi-GNSS; uncombined and undifferenced PPP; sidereal filtering; earthquake monitoring BDS GEO; multi-GNSS; uncombined and undifferenced PPP; sidereal filtering; earthquake monitoring
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MDPI and ACS Style

Zheng, K.; Zhang, X.; Li, X.; Li, P.; Chang, X.; Sang, J.; Ge, M.; Schuh, H. Mitigation of Unmodeled Error to Improve the Accuracy of Multi-GNSS PPP for Crustal Deformation Monitoring. Remote Sens. 2019, 11, 2232.

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